GB2234019A

GB2234019A - Liquid pumping and metering apparatus

Info

Publication number: GB2234019A
Application number: GB9011936A
Authority: GB
Inventors: Tsuneo Kimura; Teruo Shibata
Original assignee: NAKA LIQUID CONTROL Ltd
Current assignee: NAKA LIQUID CONTROL Ltd
Priority date: 1989-06-28
Filing date: 1990-05-29
Publication date: 1991-01-23
Also published as: JPH0317184U; GB9011936D0; DE4017797A1; FR2649198A1

Abstract

The apparatus includes a vertically disposed cylinder (18) attached to the base of a sealed tank (2) so that its upper end opens within the base of the tank. A piston (28) moves vertically in the cylinder from a position uncovering liquid entry ports (25) from the tank. The piston has a piston rod (33) which passes through a seal (34) in the top of the tank to a reciprocating drive mechanism (29), whereby operation of the latter expels liquid from the cylinder through a one-way valve (35). A number of stirring vanes (8) are located in the tank base area, such vanes being carried by a tubular shaft (6) which surrounds the piston rod and extends up through a seal (11) in the tank to a rotational drive device (9, 10) situated above the tank. The liquid level in the tank is maintained at a level which ensures that liquid adhering to the piston rod does not come into contact with piston rod seal (24). The tank may be evacuated. <IMAGE>

Description

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SPECIFICATION LIQUID PUMPING AND METERING APPARATUS BACKGROUND OF THE INVENTION

This invention relates to an apparatus f or the intermittent pumping or metering of a low to high viscosity liquid, such as a liquid resin, which is connected through a supply pipe to a storage vessel. Such a vessel may suitable f or the degassing of the liquid through the application of a vacuum within the vessel and to facilitate this process, a form of agitator may be operated within the vessel. Furthermore, when a liquid resin system contains a f iller, many of which are abrasive, the agitator may perform another function in maintaining the suspension of that filler within the resin. In addition, such a storage vessel may be heated and pressurized with gas or air.

Such a system is illustrated in Fig. 3 whereby the storage vessel 41 assembly is connected to the metering pump assembly 47. The storage vessel assembly 41 comprises a vacuum vessel 43 and an agitation vane 44 which moves within the liquid 42. Furthermore, a vacuum pump 45 is connected to, and produces a vacuum within the tank 43.

The metering pump assembly 47 comprises a vertically disposed cylinder 48. Fitted within the upper end of said cylinder 48 is a vertically movable piston 49 having a piston rod 50 extending upwards therefrom, said piston rod 50 being connected to a reciprocating drive mechanism 51. A sealing member 52 is interposed between the upper end of said cylinder 48 and said 1 1 1 piston rod 50.

A stop valve 53 is installed at the base of the said tank 43, the discharge port from which being connected to the upper end of said cylinder 48 by an inclined communication pipe 54. Further, a check valve 55 is provided which allows the liquid 42 to f low only in one direction from said cylinder 48.

When it in desired to meter the liquid 42, the driving mechanism 51 is actuated to reciprocate the piston 49. When the piston 49 moves from the lowermost position to the uppermost position, as shown in solid lines, a negative pressure is produced in the lower region of the cylinder 48. This negative pressure draws the liquid 42 from the tank 43 via the stop valve 53 and pipe 54 into the lower region of the cylinder 48. Thus, when the piston 49 is moved to the lowermost position again as shown in phantom lines, the liquid 42, now within the region of the cylinder 48, is discharged through the check valve 55. The degree of discharge may be varied by the relative movement of the piston 49, so as to meter the liquid being discharged.

The conventional arrangement described above has the following problem:

In the case where liquids contain a solid filler, and in particular ones of high specific weight, said fillers tend to separate out and to settle out at the base of storage vessel 41, causing partial or total potential blockage of, the pipe 54, the valve 53, the metering cylinder 48, and the check valve 55. Thus the flow of the liquid may be impeded, and furthermore, the liquid 2 1 may vary in the content of the filler with a resultant variation in density from one sample to another.

SUMMARY OF THE INVENTION in this invention, a vertically inclined pumping or metering cylinder is attached within the base of a sealable tank. The upper end of the cylinder has open ports above the base area of the tank. The lower end of the metering cylinder has a check valve system which only allows the liquid to flow out of the lower end of the cylinder. A piston is provided which in vertically reciprocated between a position within the cylinder and outside and above the cylinder. The extent of the movement of the piston within the cylinder may be varied for the metering of various liquid volumes. A piston driving rod is attached to the piston and this is reciprocated by a drive mechanism outside of the tank.

When the piston is withdrawn to the top of the cylinder, the resultant negative pressure within the cylinder causes the liquid to be drawn into the cylinder ports from the tank. When the piston is lowered below the ports and into the cylinder, the piston displaces the liquid out of the lower end of the cylinder and out through the one way valve. Thus, when this operation is repeated, the liquid is intermittently recharged within and discharged out of the cylinder.

One or more blades rotate around the metering cylinder within the base of the tank with a minimal distance between the blade and 3 1 the tank yet allowing the piston to withdraw in part f rom the cylinder. The blade rotation is achieved through a rotary drive mechanism fitted to the exterior of the tank which connects to the blade through a tubular shaf t surrounding metering pump piston drive shaft. The reciprocating piston drive shaft and the rotating tubular shafts may be sealed to prevent air, gas or vacuum leakage between the tank and the atmosphere outside of the tank.

One purpose of the invention is to maintain the suspension of fillers in an even manner within a liquid and therefore to avoid f iller sedimentation towards and at the base of the tank, thus preventing clogging of the base area of the tank and the metering cylinder and one way valve.

Another purpose of the invention is to incline the pump and pump drive mechanism in a vertical position with the piston rod shaft above the liquid surface and with sufficient clearance between the liquid surface and the seal so as to not have contact liquid and the seal and between liquid adhering to the piston rod and the seal, thus eliminating problems of wear and leakage from a seal that would otherwise be in contact with the liquid.

4 1 BRIEF DESCRIPTION OF THE DRAWINGS

Pigs. 1 and 2 show a preferred embodiment of the invention; Fig. 1 is a.complete ride view in section; Pig. 2 is a fragmentary enlarged sectional view of the embodiment shown in Fig. 1; and Fig. 3 is a complete side view, in section, corresponding to Fig. 1, showing a conventional example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figs. I and 2 show an apparatus for effecting the heating, stirring, degassing and metering of a f illed liquid. In the figures, the numeral I denotes the body of said apparatus having a tank 2 of sheet metal which comprises a hopper 3 and a tank ceiling plate 4 adapted to close the opening in the hopper.

A vertically disposed tubular stirrer shaft 6, extending through said ceiling plate 4, is supported in a bearing 7 and has a plurality of stirring vanes 8 affixed thereto. Disposed above the ceiling plate 4 is a stirring electric motor 9, to which said stirring shaft 6 is connected via a belt drive device 10. Further, a first seal 11 is interposed between the stirring shaft and the bearing 7.

A liquid 12 is contained in said tank 2. This liquid 12 is a compound consisting of substances different in specific weight, such as a thermosetting liquid silicone resin and a highly abrasive aluminum oxide filler with a resultant high viscosity.

When the electric motor 9 is actuated, the stirring vanes are rotated as shown by the arrow A through the driving belt device 10 and stirring shaft 6; thereby, stirring and mixing the liquid 12. The numeral 13 denotes a liquid f eed pipe f or f eeding said liquid into the tank 2. A vacuum pipe and shut of f valve 14 is connected to a vacuum pump 15 and to the tank 2 for the purpose of the degassing of the liquid 12. The outer surface 3 of said tank 2 is covered with a heater 16 which heats the liquid 12. The numeral 17 denotes a pressure gage for detecting a vacuum in the tank 2.

The lower region of the tank 2 is conical, with a vertically disposed cylinder 18 attached to the lower and of said tank. The cylinder 18 comprises a cylinder body 19 attached to the lower end of said tank 2 and a cylinder sleeve 20 coaxial with and removable from said cylinder body 19. A cover plate 21 for preventing the cylinder sleeve 20 from slipping off the cylinder body 19 is removable and attached to the lower end of the cylinder body 19 by bolts 22. Extending from and coaxial with the cylinder body 19 is a body extension 23, while the upper end of the cylinder sleeve 20 is provided with a cylinder sleeve extension 24 coaxial with the cylinder sleeve 20.

The body extension 23 and sleeve extension 24 are respectively positioned with the openings 25 in line with each other. The openings 25 are circular and the base of said openings are flush with the inner surface of the base of the tank 3. The upper end of the cylinder sleeve 20 opens to the base of the tank 3 through said openings 25.

In addition, when the liquid 12 contains an abrasive filler, 6 c 4 said cylinder sleeve 20 is made of an abrasion resistant ceramic material rather than steel or plastic alternatives.

A piston..,28 is f itted to both seal and to be capable of reciprocation vertically within the cylinder sleeve 20 and cylinder sleeve extension 24. The said piston 28 is connected to a piston rod 33 which is coaxial to and within the said stirring shaft 6. The said piston rod 33 is connected at the upper end to a reciprocating drive mechanism 29 comprising an electric motor 30 and a speed reducer 31. Thus, when the electric motor is actuated, the piston 28 is vertically reciprocated via the piston rod 33 through an adjustable amount of travel and speed within the cylinder 20 and into the cylinder sleeve extension 24.

A second seal 34 is positioned between the stirring shaft 6 and the piston rod 33. The second sealing member 34 and the first sealing member 11 adjoin the ceiling plate 4 and serve to keep the tank 2 airtight. The level of the liquid 12 in the tank 2 is maintained well below the level of the sealing members 11 and 34 and at a point whereby any liquid 12 which may adhere to the piston rod 33 does not come into contact and damage the said seals 11 and 33 when the piston rod 33 is in the uppermost position.

A one way valve 35 only allows the liquid 12 to f low downwards and away from the cylinder sleeve 20. In this case, said one way valve maybe a mechanical valve, electrically controlled, so that it opens when the piston 28 moves downward and closes when the piston 28 moves upwards.

When it is desired to deliver the liquid 12 which is being 1 stirred by the vanes 8 within the tank 2, the piston 28 is moved from its A position within the cylinder sleeve 20 to its uppermost position withir. ,the cylinder sleeve extension 24 causing a negative pressure through the open ports 25 which are no longer blocked by the piston 28. This said negative pressure causes the liquid 12 to be drawn through the openings 25 and into the cylinder sleeve 20. When the piston is moved downwards and past the openings 25 into the cylinder sleeve 20, the piston displaces the liquid 12 out of the cylinder sleeve 20 and through the one way valve 35. As the piston 28 is further reciprocated, the cycle of recharging and displacement is repeated.

In the above case, the cylinder 18 is attached to the base of the tank 2 and the displacement takes place at this point of even filler content rather than later on in a feed system where sedimentation could occur through a lack of stirring.

Further, since the cylinder sleeve 20 and the cylinder sleeve extension 24 are on the same axis and the inner peripheral surfaces are in line with each other, the movement of the piston from the displacement bore to the recharging bore is smoothly accomplished. This arrangement provides the following merit.

In prior art, as shown in Pig. 3, when the pi ston 49 is moved to its uppermost position, it goes out of the upper end of the cylinder 48. When the piston 49 is lowered to enter the cylinder 48, any piston rod 50 misalignment can cause damage or wear between the piston 49 and the cylinder 48 or lumps and uneven concentrations of fillers at the cylinder 48 entrance may do so

8 I 1 1 also.

in this embodiment, however, even when the piston 28 assumes its uppermost position, it is still within the cylinder sleeve extension 24 and cannot misalign with the cylinder sleeve 20. Further, since the base of the openings 25 is flush with the base of the tank 2, effectively all of the liquid can be drawn out of the tank 2 or such openings 25 may be positioned slightly above or partially below the base of the tank 2.

In addition, unlike the piston rod seal 52 in Fig. 3, the piston rod seal 34 in Fig. 1 is not below or within the liquid surface, thus its working condition are more ideal for seal performance and seal life. Any malfunction of that seal will not allow the induction of air into the liquid in the form of bubbles with potential pumping out within that liquid as in Fig. 3, but rather into the area above the liquid for evacuation out of the tank as in Fig. 1.

In Fig. 2, when the piston 28 is lif ted past the openings 25, the liquid 12 flows into the cylinder sleeve under its own weight irrespective of any negative pressure caused by a recharge effect by the upward movement of said piston. Thus, even when the liquid in the tank 12 is being degassed, the liquid 12 recharges into the cylinder 28 as desired.

While the above is based upon the illustrated example. a process for a liquid 12 in the tank 2 may not require evacuation and degassing of the liquid, in which case the f irst and second sealing members 11 and 34 may not be required to be fitted.

9 1

Claims

WHAT IS CLAIMED:

1. A liquid pumping and metering apparatus within a tank in which said liquid is stored, said apparatus comprising a vertically disposed cylinder attached to the base of said tank and opening to the base of said tank, a one way valve attached to the base of said cylinder for the one way discharge of liquid out of said cylinder, a piston within said cylinder capable of reciprocation within said cylinder and a piston rod connecting said piston to a driving mechanism positioned above the tank ceiling.

2. A liquid pumping and metering apparatus as set forth in Claim 1, including a sealing member for sealing pressure or vacuum within the tank with their position within the ceiling of the tank and surrounding the piston rod, said seals to be above the liquid level in the tank with a distance between any liquid level within the tank and the ceiling of the tank to prevent any liquid adhering to the piston rod from contact with the sealing member.

3. A liquid pumping and metering apparatus as set forth in Claim 1 and Claim 2, whereby the piston cylinder sleeve has a coaxial and an in-line upper extension cylinder sleeve suitable for the retreat of a piston within that upper extension cylinder sleeve, the upper and lower cylinder sleeves having side open ports between them which communicate with the base area of the tank.

4. A liquid pumping and metering apparatus as set forth in Claim 3, wherein the base of side open ports between the upper and lower portions of the piston cylinder are substantially flush with the inner surface of the base of the tank.

5.. A liquid pumping and metering apparatus substantially as hereinbefore described with reference to the accompanying drawings.

11 Published 1991 at 77he Patent Office. State House, 66/71 High Holborn. London WC I R47P. Further copies may be obtained from Sales Branch, Unit

6. Nine Mile point, Cwmfe"ch. Cross Keys. Newport, NPI 7HZ. Printed by Multiplex techniques ltd. St Mary Cray, Kent-