JP2001263223A - Twin plunger pumps - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide twin plunger pumps for enhancing operational reliability by almost completely eliminating pulsation of a delivery flow rate and delivery pressure, and eliminating an opening-closing operation type valve. SOLUTION: In these twin plunger pumps connecting two plunger pumps in parallel to each other and being provided with an interlocking means of both plungers, the interlocking means is constituted so as to be actuated to close both a delivery port and a suction port at stopping time by stopping reciprocating motion of the plungers once in a transfer period of both delivery and suction strokes. A disk-like rotary can is used as the interlocking means. The respective base end sides of both plungers are brought into pressure contact with a ring-shaped can surface projected in the board surface peripheral edge part. A flat surface having the prescribed length is arranged on the cam surface. The suction port and the delivery port are oppositely arranged on the cylinder wall in the plunger pumps, and a cutout part for selectively communicating a cavity part of a cylinder with the suction port and the delivery port is arranged in a tip part of the reciprocating and rotating plungers.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a construction in which two plunger pumps are connected in parallel, in which pulsation of the flow rate and discharge pressure of a combined discharge flow from both pumps can be almost completely eliminated, and the operation reliability is improved. The present invention relates to a dual plunger pump with an increased pressure.

[0002]

2. Description of the Related Art FIG. 12 shows an example of the structure of a conventional plunger pump. In the single plunger pump 50 having high discharge accuracy, the main body of the pump is immersed in the storage tank 70 for the liquid to be transferred. A suction port 53 is provided at the bottom end side of the cylinder block 52 in which the plunger 51 is loosely fitted.
A discharge port 54 is provided on the upper end side. Each of the suction valve 55 and the discharge valves 56 and 57 uses a ball valve.

A connecting rod 61 extends from the upper end of the plunger 51, and the upper end of the connecting rod 61 projects upward through the top wall 70a of the storage tank 70. On the top wall 70a, a cylindrical cam 63 driven to rotate by a motor 62 is installed vertically. A cam follower 64 attached to the upper end of the connecting rod 61 is loosely fitted into a cam groove 65 provided on the peripheral wall of the cylindrical cam 63 in a wavy shape.

The operation of the plunger pump 50 is as follows. When the cylindrical cam 63 is rotated, the plunger 51 moves up and down with a predetermined stroke and cycle, and pressurizes and discharges the liquid to be transferred sucked intermittently through the suction port 53. Discharge is performed intermittently from the outlet 54.

The conventional dual plunger pump described at the beginning has, for example, two plunger pumps 50 having a structure as shown in FIG. The suction port and the discharge port of the pump communicate with each other.

[0006]

FIGS. 13 (a) and 13 (b) are graphs showing the respective operating cycles of the above-mentioned dual plunger pump in which two plunger pumps A and B are connected in parallel. Shown. The vertical axis indicates the amount of suction and discharge, and the horizontal axis indicates the elapsed time. FIG. 13C is a composite graph of these two graphs, that is, a graph showing a change over time of the flow rate of the combined discharge flow from the dual plunger pump.

As shown in FIGS. 13A and 13B, this dual plunger pump has one pump A
The start timing of the discharge stroke is synchronized with the start timing of the suction stroke of the other pump B. Therefore, the degree of intermittent discharge, which is a major drawback of the single plunger pump, is shown in FIG.
As shown in FIG. 3 (c), the number can be considerably reduced.

However, the waveform of the graph showing the change over time of the discharge flow rate is not a rectangular wave but a waveform wave.
As shown in FIG. 13C, the pulsation of the discharge flow rate cannot be completely eliminated.

As shown in FIG. 12, a conventional plunger pump in which a valve of a type that opens and closes, such as a Volu valve, is attached to each of a suction port and a discharge port, requires a slight time lag due to the movement of the valve body. Pulsation was caused even by a large pressure change, and it was easy to win. In addition, between the valve body and the valve seat, precipitated crystals of liquid components,
Foreign matter, air bubbles, and the like adhere to the seal, resulting in poor sealing, impairing the reliability of operation, and requiring maintenance.

Accordingly, an object of the present invention is to make it possible to almost certainly eliminate the pulsation of the flow rate and discharge pressure of the discharge fluid, to provide sufficient operation reliability, and to greatly reduce the maintenance work. To provide a double plunger pump.

[0011]

In order to achieve the above object, a dual plunger pump according to the present invention comprises two plunger pumps connected in parallel and an interlocking means for both plungers. , The interlocking means,
In the transition period between both the suction strokes, the reciprocating movement of the plunger is temporarily stopped, and the operation is performed so as to close both the discharge port and the suction port during the stop, thereby pulsating the discharge pressure from the plunger pump. It is characterized by being eliminated. As the interlocking means, a disk-shaped rotary cam is used, and the base ends of the two plungers opposed to each other in parallel are pressed against the ring-shaped cam surface protruding from the peripheral surface of the disk by pressing urging means. It is preferable that the ring-shaped cam surface in which the protrusion height changes in the circumferential direction of the ring is provided with a flat surface having a predetermined length. The plunger pump has a suction port and a discharge port opposing each other on a cylinder wall of the plunger pump. It is preferable to provide a notch for selectively communicating.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a vertical sectional side view of a dual plunger pump of this embodiment, and FIG.
Is a longitudinal sectional view of a pump body D, and FIG. 3 is a view showing each plunger 1 of two plunger pumps arranged in parallel.
FIG. 4 is a vertical sectional front view of a pump driving unit (interlocking means) E that reciprocates in an interlocking manner. FIG. 4 shows a cam surface of a disk-shaped rotary cam F for moving both plungers 1 up and down with a timing shift. FIG. 2 is a front view of a state in which upper ends (base ends) of both plungers 1 are in contact with each other.

In FIG. 2, reference numeral 2 denotes a cylinder in which the plunger 1 is loosely fitted, the bottom end of which is closed by a plug 2a, and the cylinder wall has a suction port 3 and a discharge port 4 for the fluid to be transferred. Are provided to face each other. 3a and 4a are pipe joints, respectively.
The detailed configuration and operation of the pump body D will be described later.

Next, the detailed structure of the pump driving section E will be described with reference to FIG. Reference numeral 11 denotes a box-shaped casing in which a main rotating shaft 12 is vertically arranged at the center of the inside. On the left and right sides of the main rotating shaft 12, a pair of up-and-down / rotational movement mechanisms G for vertically moving and rotating the two plungers 1 individually are assembled vertically. I have.

A disk-shaped rotary cam F is fitted on the upper end of the main rotary shaft 12. The rotating cam F has a main rotating shaft 12
And a variable speed motor H installed on the casing 11.
Is driven to rotate.

As shown in FIG. 4, a ring-shaped cam surface 13 protrudes from the downwardly facing surface of the rotary cam F, as shown in FIG. The protruding height h (see FIGS. 1 and 10) of the ring-shaped cam surface 13 is, of course, not uniform in the circumferential direction of the ring, but is inclined, for example, as schematically shown in FIG. Plural types of cam surfaces 13a to 13 having different angles and lengths
c is connected.

Each of the up / down / rotational movement mechanisms G includes a casing 1
A lower shaft member 15 supported by a bearing 14 attached to the first shaft member 1 and capable of vertical movement and rotational movement, and an upper shaft member 16 capable of only vertical movement are connected via a cap nut 17. Have. An upper end of the plunger 1 is connected to a lower end of the lower shaft member 15 via a flexible joint 18.

The upper shaft member 16 is loosely fitted in a sleeve 19 attached to the casing 11. Upper shaft member 16
Is connected to a sliding contact roller 20 which is brought into contact with the ring-shaped cam surface 13. And, this sliding contact roller 20
Is pressed onto the ring-shaped cam surface 13, and a compression spring 21 as a urging means is externally fitted to a small-diameter portion provided below the upper shaft member 16.

Further, a drive gear 22 is axially fitted to a position near the lower end of the main rotary shaft 12, and a driven gear 23 meshing with this gear is axially fitted to the lower shaft member 15. Thus, when the motor H is started, the rotating cam F rotates and the plungers 1, 1 also rotate at a predetermined speed.

Next, the structure of the pump body D will be described with reference to FIG.
This will be described with reference to FIGS. As shown in FIG. 5, a suction port 3 and a discharge port 4 for the fluid to be transferred are provided on the cylinder wall of the cylinder 2 with the lower end closed.

On the other hand, as shown in FIGS. 6 and 7, the plunger 1 has a notch 1a having a flat surface parallel to the axial direction by partially cutting off the peripheral wall surface at the lower end. Let me. This notch 1a allows the inner space of the cylinder 2 to be connected to the suction port 3 or the discharge port 4 as shown in FIG. 8 during the suction stroke or the discharge stroke of the plunger 1 rotating while moving up and down. It plays the role of selectively communicating.

FIG. 9 is a bottom view of the dual plunger pump. In a pair of plunger pumps arranged in parallel, the pipe joints 3a attached to each suction port 3 and the pipe joints 4a attached to each discharge port 4 are connected via a suction pipe 24 and a discharge pipe 25. , Each of which is in communication with one another.

Next, the function of the double plunger pump will be described with reference to FIGS. When a power switch (not shown) of the dual plunger pump is turned on, the rotating cam F fitted to the main rotating shaft 12 and the two plungers 1, 1 rotate at a preset speed with the rotation of the variable speed motor H. Start spinning.

On the ring-shaped cam surface 13 of the rotary cam F, both plungers 1 urged by a compression spring 21 are pressed.
The upper ends of the ring-shaped cam surfaces 13 are pressed against the respective ends on the diameter line of the ring-shaped cam surface 13 via a vertical movement / rotational movement mechanism G and a sliding contact roller 20.

The ring-shaped cam surface 13 of this embodiment
As shown schematically in FIG. 11, the upwardly inclined cam surface 13a for controlling the discharge stroke of the plunger 1 and the flat cam surface 1 for temporarily stopping the movement of the plunger 1 in the circumferential direction.
3c, a downwardly inclined cam surface 13b which controls the suction stroke of the plunger 1, and a flat cam surface 13c different from the above are connected in this order.

In this embodiment, when the ratio of the length of each of the cam surfaces 13a to 13c in the circumferential direction is replaced by the rotation angle of the rotary cam F, in this embodiment, 13a is 200 degrees and 13b is 1 degree.
00 degrees and 13c are set to 30 degrees respectively.

When the rotary cam F having the ring-shaped cam surface 13 having the above-mentioned shape rotates, as shown in FIG. 11, the fluid from one of the two plunger pumps A and B is discharged from the pump A. The discharge amount changes with time in a trapezoidal locus as shown in FIG.

After the end of the discharge stroke, the plunger 1 does not move to the suction stroke, but temporarily stops in order to prevent a sudden change in the hydraulic pressure in the cylinder 2. Thereafter, when the process proceeds to the suction stroke, the fluid suction amount of the pump A changes with time, drawing a steep trapezoidal locus as shown in FIG. Then, when this step is completed, the plunger 1 once again stops moving.

On the other hand, for the other pump B, which performs the same operation as the pump A, the end of its discharge stroke is the start of the discharge stroke of the pump A, as shown in FIG. Operates with somewhat overlapping timing. As a result, the combined discharge flows from the two plunger pumps A and B constituting the double plunger pump almost completely reduce the pulsation of the flow rate as shown by the reference symbol f in FIG. Can be eliminated.

Furthermore, the transition between the discharge stroke and the suction stroke is not performed continuously, but a temporary stop period of the plunger 1 is provided during this transition. This prevents sudden changes in hydraulic pressure.

Further, as shown in FIG. 8 as an explanatory diagram of the operation of each plunger pump, as shown in FIG.
Switching to the discharge process of (c) and (d) is not performed instantaneously, but involves a transition period in which both the suction and discharge ports 3 and 4 are closed as shown in (b). Therefore, this dual plunger pump can also almost completely eliminate the pulsation of the hydraulic pressure of the discharge fluid.

Furthermore, each plunger pump is different from the conventional type shown in FIG. 12 in that it does not include an opening / closing type valve such as a Volu valve, and the opening / closing structure of the suction / discharge ports 3 and 4. Has been greatly simplified. Therefore, as in the conventional type, pulsation occurs due to a slight pressure change due to the time lag of the movement of the valve body, and precipitated crystals of liquid components, foreign matter, bubbles, etc. adhere between the valve body and the valve seat. As a result, the sealing is not good, the reliability of the operation is impaired, and the troubles such as troublesome maintenance are eliminated at the same time.

In the above embodiment, a disk-shaped rotary cam F having a ring-shaped cam surface 13 is used as an interlocking means of a pair of plungers 1 arranged in parallel. However, the object of the present invention can be achieved by selecting an appropriate cam mechanism from various known cam mechanisms instead of the rotating cam F.

In the dual plunger pump according to the present invention, three or more plunger pumps may be replaced by one if necessary.
It is also possible to configure such that they are linked by one or more cam mechanisms or the like. In this case, the suction port and the discharge port of each plunger pump do not always need to communicate with each other depending on the use of the pump.

[0035]

As is apparent from the above description, according to the present invention, there is provided a special cam for interlocking the two plungers, and omitting an opening / closing type valve such as a Volu valve which has difficulty in operating reliability. The double plunger pump is, for example, compared to the conventional one described with reference to FIGS.
It exhibits significantly better functions as listed below. (A) By providing a pause for the plunger,
The pulsation of the flow rate and the discharge pressure of the discharge fluid can be almost completely eliminated. (B) Since two plunger pumps share one cam, the structure of the pumps can be simplified accordingly. (C) If a dedicated cam is provided for each pump, the problem that a phase shift due to individual differences easily occurs is also solved. (D) By simply changing the shape of the cam surface, it is possible to easily produce pumps having fluids having various properties such as viscosity and specific gravity, each having optimum operating characteristics. (E) Since it is not necessary to attach an opening / closing valve such as a ball valve to the suction / discharge port, the structure can be simplified accordingly. (F) Of course, since there is no possibility that foreign matter adheres between the valve body and the valve seat, sufficient operation reliability can be ensured.
Maintenance work can be saved. (G) Since there is no pulsation of the discharge flow rate and the discharge pressure, precision painting and the like on small parts can be performed easily and accurately. (H) For example, even when a plurality of types of fluids are joined and mixed in a fluid flow path, the above-mentioned pulsation does not occur, so that it is easy to mix quickly and uniformly. (I) Even when the hardener discharged from the pump is continuously and quantitatively mixed with the casting sand for casting, the discharge flow has no pulsation, so that it is easy to mix uniformly.

[Brief description of the drawings]

FIG. 1, showing an embodiment of the present invention, is a longitudinal sectional side view of a double plunger pump.

FIG. 2 is a longitudinal sectional view of the pump body according to the first embodiment;

FIG. 3 is a vertical sectional front view of the pump drive unit.

FIG. 4 is a front view showing a state in which upper ends of two plungers are respectively brought into contact with a cam surface of a rotary cam.

FIG. 5 is a longitudinal sectional view and a transverse sectional view of the cylinder.

FIG. 6 is a side view and an end view of the plunger.

FIG. 7 is a top view of the plunger.

FIG. 8 is an operation explanatory view of the plunger pump.

FIG. 9 is a bottom view of the double plunger pump.

FIG. 10 is a graph showing, in comparison with the above, changes in the circumferential unevenness of the cam surface of the rotary cam and changes in the discharge / suction cycle of the plunger pump.

FIG. 11 is a graph showing an individual discharge / suction cycle of two plunger pumps constituting a dual plunger pump and a combined cycle of both pumps.

FIG. 12 shows a conventional example, and is a longitudinal sectional view of a single plunger pump assembled in a storage tank for a liquid to be transferred.

FIG. 13 is a diagram corresponding to FIG. 11;

[Explanation of symbols]

 D Pump body E Pump drive unit (interlocking means) F Rotating cam G Vertical movement / rotational movement mechanism H Motor 1 Plunger 1a Notch 2 Cylinder 2a Plug 3 Suction port 4 Discharge port 3a, 4a Pipe joint 11 Casing 12 Main rotating shaft Reference Signs List 13 ring-shaped cam surface 14 bearing 15 lower shaft member 16 upper shaft member 17 cap nut 18 flexible joint 19 sleeve 20 sliding contact roller 21 compression spring (press urging means) 22 drive gear 23 driven gear 24 suction pipe 25 discharge pipe h Projection height of cam surface 13c Flat cam surface

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F04B 13/00 F04B 13/00 B 53/10 21/02 Z 53/14 21/04 Z F term (reference ) 3H070 AA07 BB04 BB07 BB17 CC01 CC11 CC31 CC32.

Claims (3)

[Claims] 1. A system in which two plunger pumps are connected in parallel and an interlocking means for both plungers is provided, wherein the interlocking means temporarily reciprocates the plunger during a transition period between both the discharge and suction strokes. A dual plunger pump, wherein the dual plunger pump is configured to stop and operate to close both the discharge port and the suction port during the stop, thereby eliminating the pulsation of the discharge pressure from the plunger pump. 2. A disk-shaped rotary cam is used as the interlocking means, and a ring-shaped cam surface protruding from a peripheral edge of the disk surface is
Each base end side of both plungers opposed in parallel is pressed against each other by pressing urging means, and a flat surface of a predetermined length is provided on the ring-shaped cam surface where the protrusion height changes in the circumferential direction of the ring. The dual plunger pump according to claim 1, wherein: 3. The plunger pump has a suction port and a discharge port opposing each other on a cylinder wall thereof, and an inner space of the cylinder is provided at the tip of the plunger which is rotated while reciprocating. The dual plunger pump according to claim 1, further comprising a cutout portion selectively communicating with the discharge port.