Reciprocating Pump

Abstract

A reciprocating pump comprising: a cylinder having a discharge check valve in the neighborhood of an end thereof; a diaphragm or a bellows forming a diaphragm chamber with a recess at the other end of said cylinder; a plunger driving means casing holding said diaphragm or bellows between itself and said cylinder; a hollow tubular plunger connected at an end with said diaphragm and having at the other end a plunger check valve; a conduit for connecting a liquid inlet means communicating with said cylinder and said diaphragm chamber; and a partition dividing the inside of said cylinder between a suction side chamber and a discharge side chamber.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a reciprocating pump incorporating a plunger and a diaphragm or bellows and having superior characteristics in safety, uniformity in pumping volume, durability, and high pressure applicability.

2. Description of the Prior Art

Prior art liquid suction and discharge means of this type may be classified into two main types, namely a plunger type reciprocating pump and a diaphragm type reciprocating pump. However, the plunger type reciprocating pump has a disadvantage in that it is difficult to completely prevent leakage of liquid from a gland packing. In such a plunger reciprocating pump which is completely sealed at first, the gland packing and the plunger itself are worn through daily usage for years resulting in leakage of the liquid. This disadvantage of the plunger reciprocating pump becomes a serious difficulty when it is used with a poisonous liquid, an air-hardening liquid, or a liquid corrosive to the materials constructing the pump. The diaphragm type reciprocating pump, though free from the disadvantage inherent in the plunger reciprocating pump, has disadvantages in that its pumping is inferior in uniformity in volume to the plunger reciprocating pump and that the life of the diaphragm is exceedingly short since it is subjected to high pressure on the discharge side.

SUMMARY OF THE INVENTION

The reciprocating pump according to the present invention, has the advantages of both the plunger type and the diaphragm type reciprocating pumps while obviating the disadvantages thereof.

The primary object of the present invention is to provide a reciprocating pump having the characteristic of the diaphragm type reciprocating pump, namely resistance to leakage while keeping the characteristics of the plunger type reciprocating pump, namely uniformity in pumping volume and high discharge pressure (high lift).

Another object of this invention is to provide a reciprocating pump obviating the disadvantage of the plunger type reciprocating pump in which the gland packing is exposed to the atmosphere and which has the advantage that the leaked liquid is sent back to the suction side.

Still another object of this invention is to provide a reciprocating pump obviating another disadvantage of the plunger type reciprocating pump, namely the danger that the liquid leaks through the gland packing into the plunger drive means by adopting the advantage of the sealed construction of the diaphragm type reciprocating pump.

Yet another object of this invention is to provide a reciprocating pump having the advantage that the diaphragm is exposed only to the low pressure on the suction side in order to overcome the disadvantage of the diaphragm that it is too weak to stand the high discharge pressure.

A further object of this invention is to provide a reciprocating pump having the advantage that the pressure on the gland packing is freely controlled from the outside of the pump.

To achieve these objects, the reciprocating pump according to the present invention comprises:

a cylinder provided with a discharge valve case means having a discharge check valve in the neighborhood of an end thereof, a recess at the other end, and a liquid inlet means in the neighborhood of the other end;

a diaphragm or bellows closing the recess at the other end of said cylinder to form a diaphragm chamber with said recess;

a plunger driving means casing having an opening provided with a peripheral wall for holding said diaphragm or bellows between itself and the peripheral walls of the other end of said cylinder;

a hollow tubular plunger connected at an end to a crosshead reciprocably received within said casing and to said diaphragm or bellows, having at the other end a plunger check valve, and having in the neighborhood of the other end an inlet port;

a conduit communicating between said diaphragm chamber and said liquid inlet means; and,

a partition dividing the inside of said cylinder into a suction side chamber and a discharge side chamber; and, when required, further comprises:

a lantern ring provided in the neighborhood of said liquid inlet means within said cylinder, and having a bore for communicating with said liquid inlet means and a hole for receiving said plunger therethrough;

a gland packing on the diaphragm chamber side for sealing between said lantern ring and said diaphragm chamber; and,

a gland packing on the discharge chamber side for sealing between said lantern ring and the discharge side chamber within said cylinder;

and, when required, further comprises:

a gland packing extra tightening means, comprising: a gland packing gland having a ring-shaped end urged against the discharge chamber side surface of the gland packing at said discharge chamber side, said ring-shaped end being connected with the other end by means of a plurality of legs; and an adjust screw having the tip thereof urged against said other end of said gland packing gland and the head end thereof being operable from the outside of said one end of said cylinder.

These and other objects, concrete examples of the construction and operational effects thereof will be better understood from the following description and accompanying drawings illustrating the embodiment of the present invention in detail, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of an embodiment of the reciprocating pump according to the present invention;

FIGS. 2 and 3 are sectional views showing the manner in which the apparatus of the invention operates.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIG. 1, an embodiment of the present invention has a pump body A comprising cylindrical casing B and a plunger driving means housing C. The cylinder B has a check valve 1 in the neighborhood of an end thereof, a discharge conduit 2 having a flange 2', a liquid inlet conduit 3 having a flange 3' in the neighborhood of the other end thereof, and an adjusting screw 4 threaded into one end thereof.

Within said cylinder B there is axially slidably and closely fitted a tubular plunger 7 having an outlet port 5 provided with a check valve 5' at an end thereof and an inlet port 6 in the neighborhood of the other end thereof. Said inlet port 6 of the plunger 7 opens within a lantern ring 8 having a through hole 8' communicating with the liquid inlet means 3 of said cylinder B. Said lantern ring 8 is held between two groups of gland packings 9 and 10. The gland packing group 9 has its surface on the side opposed to the lantern ring urged against the inside base surface of the cylinder B. A gland packing gland 11 is urged against the surface of the gland packing group 10 on the side opposed to the lantern ring. The gland packing gland 11 has a ring-shaped portion 11a at an end and a disk portion 11b at the other end. The ring-shaped portion 11a and the disk portion 11b are connected integrally by means of a plurality of legs 11c. The ring-shaped portion 11a is urged against said gland packing group 10, and the disk portion 11b abuts adjusting screw 4 provided for adjusting the tightness of the gland packing by adjusting screw 4.

The plunger driving means casing C comprises a crankshaft 12, a crank 13, a slide bar 14, a crosshead 15, and a diaphragm 16.

A cylindrical crank 13 is eccentrically fixed to the crank shaft 12 an end of which is extends outside the driving means casing C. The slide bar 14 is at an end pivotally fitted to said crank 13 and at the other end pivotally supported at the base of the crosshead 15 through a pin 17. At the tip of the crosshead 15 is mounted a diaphragm 16 the pheripheral of which is held and fixed between the cylinder B and housing C.

From the tip of the crosshead 15 extends a bolt 15' the tip of which is threadably fixed to the base of said plunger 7 while a conduit 19 extends from a diaphragm chamber 18 formed by the diaphragm 16 and the top inner surface of the driving means, the tip of said conduit being connected to the inlet means 3 of the cylinder B.

Numeral 20 designates an O-ring surrounding screw 4. Numerals 21 and 22 designate valve locking means respectively provided by projections at the upper dead points of the check valve 1 and the plunger valve 5'.

The crank-shaft 12 is connected at an end with a motor (not shown) for driving the crank-shaft 12 through suitable means such as, for example, a reduction mechanism.

The operation of the reciprocating pump according to the present invention having the above described construction will now be described in connection with the attached figures.

When a rotational motion is transmitted to the crankshaft 12, the rotational motion is translated into a reciprocating motion and transmitted to the crosshead 15 with the stroke equal to twice the eccentric radius S of the crank 13. Since tubular plunger 7 is integrally connected with the crosshead 15 by the bolt 15', it reciprocates with the crosshead 15. During the forward movement of the plunger 7 (discharge stroke), as shown in FIG. 2, the check valve 1 opens and the plunger valve 5' closes to discharge the liquid from discharge conduit 2 in the amount equal to the product of the sectional area of the plunger 7 and the distance of the forward movement.

During the rearward movement of the plunger 7 (suction stroke), as shown in FIG. 3, the check valve 1 closes and the plunber valve 5' opens. Accordingly, the liquid in the liquid inlet 3 flows through the inlet port 6 of the plunger 7 and pushes the plunger valve 5' up to enter the pump chamber. The volume of the liquid sucked into the pump chamber during said stroke is, likewise, roughly equal to the product of the distance over which the plunger 7 moved back from the gland packing group 10 and the sectional area of the plunger 7. In other words, the volume of liquid discharged from the discharge valve body 2 is equal to the product of the sectional area of the plunger 7 and the stroke dimension thereof.

As described above, the reciprocating pump according to the present invention conveys the liquid repeating suction and discharge strokes by the reciprocating movement of the hollow plunger. The diaphragm 16 pulsates synchronously with the reciprocating movement of the plunger 7. Therefore, even when a portion of the liquid sucked into the lantern ring infiltrates into suction chamber 18 through a space between the gland packing group 9 and the inner wall of the cylinder B or the hollow plunger 7, the liquid is returned to liquid inlet means 3 by the conduit 19. And, even when the liquid at the discharge side leaks by the discharge pressure through the space between the gland packing group 10 and the inner wall of the cylinder B or the hollow plunger 7, the leaked liquid is automatically returned to the liquid inlet means 3. Therefore, the pump according to the present invention is completely free from the possibility that the liquid leaks out of the pump.

While the specific embodiment has a diaphragm to prevent the leakage of the liquid, it is, of course, possible within the scope of the present invention to replace such diaphragm with another flexible sealing member such, for example, as a metallic bellows operating similar to the diaphragm.

With the construction and operation described above, the reciprocating pump according to the present invention has the following effects which cannot be achieved by any of the known reciprocating pumps of this type:

a. Leakage-free

In the known plunger type reciprocating pump, since the gland packing is exposed to the atmosphere, it is inevitable that the liquid leaks outside through the packing after use for a long time. In the reciprocating pump according to the present invention, however, since the gland packings 10 separate the pump chamber from the liquid inlet means 3 but is not exposed to the atmosphere, even if a portion of the liquid leaks through the gland packings 10 into the pump chamber, the liquid within the pump chamber is only returned to the suction side. Further, even if the liquid at the suction side leaks through the gland packings 9 into suction chamber 18, diaphragm 16 will prevent leakage of the liquid outside of the cylinder B.

b. Uniformity in Pumping Volume

The known plunger type and diaphragm type reciprocating pumps have the possibility that, when the amount of suction is less than 100 percent, it cannot secure sufficient uniformity in pumping volume. Particularly, the known diaphragm type reciprocating pump has a serious disadvantage in that the diaphragm is deformed by the discharge pressure to considerably interrupt the uniformity in pumping volume. In the reciprocating pump according to the present invention, however, as is obvious from the operating principle described above, a volume of liquid equal to the sectional area of the plunger 7 and the suction and discharge strokes is constantly discharged regardless of the distance of said strokes, thus securing a uniform pumping rate.

c. Durability

The known diaphragm type reciprocating pump is not suitable for discharging at high pressure, for example 300 - 500 atmospheres, since there is naturally a limit to the thickness of the diaphragm and the discharge pressure is exerted directly onto the diaphragm. In contrast to this, in the pump according to the present invention, even when the discharge side of the pump chamber is under high pressure, the inside of the suction chamber 18 and the suction side is always maintained at a pressure below 1 Kg/cm.sup.2 since the high pressure on the discharge side is checked by the plunger valve 5', thereby achieving a smooth reciprocating motion without the possibility of damage to diaphragm 16 by the high pressure. The known plunger type reciprocating pump has a disadvantage in that the leakage through the gland packing increases as the pressure increases. However, in the pump according to the present invention, as described above, even when leakage occurs, the leaked liquid is returned to the suction side under normal pressure. Accordingly, the pump according to the present invention can be safely used for liquid requiring a high discharge pressure.

The operational effects obtained by the pump according to the present invention may be tabulated as follows in comparison to the advantages and disadvantages of the known pumps.

__________________________________________________________________________ Pump of this Known pumps Invention Plunger type Diaphragm type __________________________________________________________________________ Leak-prevention good poor good Uniform pumping good good poor rate Discharge pressure high high low (light) Viscous liquid applicable not applicable not applicable Safety good poor poor __________________________________________________________________________

Claims

What I claim is:

1. In a reciprocating pump, the combination of

1. a cylindrical casing having two closed ends,

2. a liquid discharge conduit near one end of the cylindrical casing,

a. a check valve being mounted in the discharge conduit,

3. a liquid inlet conduit near the outer end of the cylindrical casing,

4. a partition means dividing the cylindrical casing into a suction chamber adjacent the other end and a discharge chamber adjacent the one end,

a. the partition means including a lantern ring having a bore communicating with the inlet conduit and gland packings adjacent the lantern ring and providing a seal between the lantern ring and the suction and discharge chambers, respectively,

5. a flexible sealing member closing the other end of the cylindrical casing, the sealing member and the partition means defining the suction chamber therebetween,

6. a housing having an open end in alignment with the other end of the cylindrical casing,

a. the flexible sealing member being held between the open end of the housing and the other end of the cylindrical casing,

7. a tubular plunger defining an axial bore reciprocably received in the cylindrical casing in an axial passage of the lantern ring, the tubular plunger having two ends and one of the plunger ends being connected to the flexible sealing member,

a. an inlet port being arranged in the plunger adjacent the one end thereof and communicating with the axial bore,

b. an outlet port being arranged in the plunger adjacent the outer end thereof and communicating with the axial bore, and

c. a check valve being mounted in the outlet port,

8. a drive means mounted in the housing and connected to the one end of the tubular plunger for reciprocating the plunger in the cylindrical casing between positions wherein the inlet port is in and out of register with the inlet conduit, and

9. a conduit interconnecting the suction chamber and the liquid inlet conduit.

2. In the reciprocating pump of claim 1, further comprising a tightening means for the gland packing providing a seal between the lantern ring and the discharge chamber, the tightening means comprising a gland packing gland having two ends and a plurality of legs interconnecting the two gland packing gland ends, and an adjusting screw threadedly mounted in the one cylindrical casing end being operable from the outside of the casing, the adjusting screw bearing against one of the ends of the gland packing gland and urging the other end thereof against the gland packing.