JP2818410B2 - Leakless reciprocating pump - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reciprocating pump that performs a pumping operation by reciprocating a plunger or a piston, and more particularly, to prevent a transfer liquid from leaking outside. The present invention relates to a non-leakage reciprocating pump configured. [Related Art] In general, a reciprocating pump is excellent in high-pressure property and quantitative property as its characteristics, but has a drawback that the structure cannot be inevitably leaked to the outside of a transfer liquid in a normal configuration. Therefore, a reciprocating pump configured to solve the above-described difficulties and prevent leakage to the outside, such as a diaphragm pump or a bellows pump having a diaphragm or a bellows as a sealing member (hereinafter referred to as a seal pump), Conventionally, a reciprocating pump having a special configuration such as a hydraulic diaphragm pump or a hydraulic bellows pump in which one side of a seal member of the seal pump is further configured as a hydraulic chamber (hereinafter referred to as a hydraulic seal pump) has been developed and used. Has been offered to. Next, a bellows pump as an example of a seal pump and a hydraulic diaphragm pump as an example of a hydraulic seal pump will be briefly described. As shown in FIG. 5, for example, a bellows pump has a cylindrical bellows 18 protrudingly arranged inside a pump chamber 16 set between a suction valve 10 and a discharge valve 12 so as to be surrounded by a casing 14. It is configured. The bellows 18 is liquid-tightly attached at one end 18a to a partition wall 14a of the casing and at the other end 18b to an annular plate 22 fixed to the plunger 20 via screws, respectively, and is driven by a driving device (not shown). It is expanded and contracted by the reciprocating plunger 20. As a result, a volume fluctuation occurs in the pump chamber 16, that is, a pump action occurs, and the transfer liquid is supplied to the suction valve 10 and the discharge valve 12.
In this case, since the inside of the pump chamber 16 is kept liquid-tight by the bellows 18, the transfer liquid does not leak from the pump chamber 16. In the hydraulic diaphragm pump, for example, as shown in FIG. 6, a pump chamber 16 is divided between a suction valve 10 and a discharge valve 12 into a pump-side casing 24 and a diaphragm 26, A hydraulic chamber 28 is formed on the surface side. Diaphragm 26 is pump side casing
Liquid-tightly mounted between the drive casing 24 and the drive-side casing 30 through perforated backup plates 32
Is connected to an oil reservoir 36 through a hydraulic path 34. In such a configuration, the plunger 20 is driven by a driving device (not shown).
When reciprocating, the pressure fluctuation occurs in the hydraulic chamber 28, which causes the diaphragm to pulsate, causing a volume fluctuation in the pump chamber 16, that is, a pump action occurs, and the transfer liquid is sucked into the suction valve 10 and discharged. It is pumped through the valve 12. In this case, since the inside of the pump chamber 16 is maintained in a liquid-tight manner by the diaphragm 26, the transfer liquid does not leak from the pump chamber 16. [Problems to be Solved by the Invention] However, such a conventional pump as described above is
Due to its structure, positive and negative pressure loads are repeatedly and reversibly applied to the seal member constituting the pump, so that the seal member is damaged in a short period of time and suddenly. It had inherent disadvantages such as inferiority. Further, the structure is also complicated and heavy. That is, in a bellows pump (seal pump), the pressure Pa in the pump chamber 16 under the action of the pump usually fluctuates from negative pressure to a high pressure equal to or higher than the pump discharge pressure, whereas the pressure Pb in the drive chamber is usually large. The bellows 18 is repeatedly and pulsatively loaded with internal and external pressures, particularly strong external pressures, corresponding to its expansion and contraction.
For this reason, pumps of this type have a short service life and are inferior in quantitative performance, especially in applications of relatively high pressures. On the other hand, a hydraulic diaphragm pump (hydraulic seal pump)
, The pressure Pa in the pump chamber 16 and the pressure in the hydraulic chamber 28
Although the pressure difference from Pc is relatively small, the pressure Pa is equal to the pressure Pc
, The front and rear pressure loads are repeatedly and pulsatively applied to the diaphragm 26 in the same manner as in the case of the seal pump described above. Occurs. In addition, the pump of this type has a hydraulic chamber 28 on one side of the diaphragm 26.
Is formed, the hydraulic oil in the hydraulic chamber 28 penetrates and mixes into the transfer liquid in the pump chamber 16 on the way of the fatigue failure of the diaphragm 26, thereby causing serious danger and damage in, for example, a chemical process. Occur. Further, this type of pump has a high-pressure hydraulic chamber 28, a hydraulic path 34, and an oil reservoir 36 on the drive unit side, and has a major drawback in that the structure is complicated and the weight is increased. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a reciprocating pump having a simple structure, achieving leak-free performance, and having excellent reliability. [Means for Solving the Problems] To achieve the above object, a non-leak reciprocating pump according to the present invention includes a suction chamber set between a suction port and a suction valve, a suction valve and a discharge valve. A reciprocating unit including a pump chamber set between the valve, a piston disposed reciprocally in the cylinder chamber to perform a pumping operation, and a communicating part that communicates the pump chamber with the cylinder chamber and is filled with the transfer liquid. In the dynamic pump, a piston rod for driving the piston is inserted and disposed in the suction chamber, and a flexible seal member for sealing against a transfer liquid in the suction chamber is mounted on the piston rod, The effective cross-sectional area of the flexible seal member is set to about 1/2 of the cross-sectional area of the piston. In the discharge step, the space between the suction chamber and the flexible seal member is one direction of the piston. By moving In the suction step, the space between the suction chamber and the flexible seal member is reduced by the movement of the piston in the other direction, but the transfer liquid is transferred through the communication portion. The suction is performed by being transferred to the cylinder chamber. In this case, bellows or bellows flam can be suitably used for the flexible seal member. [Operation] Since the seal member for the transfer liquid of the piston rod is mounted in the suction chamber, a slight and substantially constant differential pressure corresponding to the suction pressure is applied to the seal member regardless of the discharge pressure. The load is always applied from a certain direction without reversing during the entire operation. Therefore, the life of the seal member is extended, and no leakage of the pump is reliably guaranteed for a long period of time. Also, since the pump does not require high-pressure hydraulic oil, the structure of the pump is simple, lightweight and inexpensive, and the hydraulic oil is erroneously mixed into the transfer liquid, which may cause a serious accident or loss. Absent. Embodiment Next, an embodiment of a non-leakage reciprocating pump according to the present invention will be described in detail with reference to the accompanying drawings. In addition,
For convenience of description, the same components as those of the conventional structure shown in FIGS. 5 and 6 are denoted by the same reference numerals, and detailed description thereof will be omitted. In FIG. 1, a leak-free reciprocating pump 10 according to the present invention is shown.
0 is a suction chamber 42 set between the suction port 40 and the suction valve 10.
And a pump chamber 16 set between the suction valve 10 and the discharge valve 12.
And the pump chamber 16 through the communication portion 44 and the suction chamber 42
A piston 48 is disposed in a cylinder chamber 46 continuous with the piston 48 and performs a pump action. A piston rod 50 for driving the piston 48 is reciprocally disposed in the suction chamber 42, and the piston rod 50 has a suction chamber. A bellows 52 for sealing the transfer liquid in 42 is mounted. An O-ring for liquid sealing and packing are mounted on the sliding contact surface between the cylinder chamber 46 and the piston 48, and an O-ring for liquid sealing is mounted on the fitting portion between the piston 48 and the piston rod 50. ing. The bellows 52 has a bottom surface 52b attached to the piston 48 in a liquid-tight manner via a screw, and a peripheral portion of the opening flange 52a is provided in a liquid-tight manner with respect to the pump-side casing 54 via a drive-side casing 56. The bellows 52
Keeps the inside of the pump liquid tight. The piston rod 50 is connected to a driving device (not shown), so that the piston 48 reciprocates and the bellows 52 expands and contracts at the same time. In such a configuration, the operation will be described with reference to FIG. 7. When the piston 48 moves rightward in the figure via the piston rod 50 (hereinafter, referred to as a discharge step), the cylinder chamber 46, the communication chamber 44, The transfer liquid in a portion including the pump chamber 16 (hereinafter, collectively referred to as a pump action chamber 58) is pressurized, the discharge valve 12 is opened, and a volume change (decrease) q1 is discharged from the discharge port 60. In this case, the suction chamber 42 has its volume increased and the inside thereof becomes slightly negative pressure, and the volume changes (increases).
The transfer liquid of q2 is sucked into the suction chamber 42 from the suction port 40. On the other hand, when the piston 48 moves to the left in the drawing (hereinafter, referred to as a suction step), the volume of the pump action chamber 58 is increased and the inside thereof becomes a slight negative pressure, and a predetermined amount of the transfer liquid is supplied to the suction valve.
10 is opened to be sucked into the pump action chamber 58. In this case, the volume of the suction chamber 42 is reduced by q2. Since the reduced amount q2 is smaller than the volume increase q1 in the pump action chamber 58 as described below, the predetermined amount (q1−q2) The transfer liquid is sucked into the suction chamber 42 from the suction port 40. That is,
In the reciprocating pump 100 according to the present invention, a predetermined amount of the transfer liquid is continuously sucked into the suction chamber 42 in all steps of discharge and suction. Here, assuming that the reciprocating pump is a crank drive or an eccentric cam drive, the crank radius or cam eccentric amount is R, the crank rotation angle is θ, and the piston displacement amount is χ, generally ΔR sin θ is established. Therefore, assuming that θ = R sin θ, (1) in the discharge step (0 ≦ θ ≦ π), the cylinder chamber 46
Change in the volume of the (reduced) amount q1 is by the piston 48 of a diameter _{D P, q1 = (π /} 4) RD P 2 sinθ , and the discharge valve 12 is opened,
Since the suction valve 10 is closed, q1 = (π / 4) to the discharge port 60 side
Discharge of the amount of RD _P ² sinθ is performed. At this time, the suction chamber 42, the piston 48, the volume change (increase) q2 is, q2 = (π / 4) R (D P 2 -D B 2) occurs by an amount of sin [theta. Therefore, the suction chamber 42 is suctioned by the amount of q2. (2) In the suction step (π ≦ θ ≦ 2π), the discharge valve 12 is closed and the suction valve 10 is open. By this reason, the piston 48 of a diameter D _P, suction by q1 = (π / 4) the amount of volume change of the RD _P ² sinθ (increase) is is carried out in the cylinder chamber 46, the discharge valve 12 is closed, the suction valve Since 10 is open, it is not discharged to the discharge port 60, and the suction chamber 42 is set at a negative pressure. At this time, in the suction chamber 42, opposite to occur volumetric change by the piston 48 (decrease), the decrease amount q2 becomes q2 = (π / 4) R (D P 2 -D B 2) The amount of sin [theta. As a result, the suction chamber 42 and the cylinder chamber 46 are moved by the piston 48.
Suction to is performed, q1-q2 = (π / 4) RD P 2 sinθ-
_{{(Π / 4) RD P} 2 sinθ- (π / 4) R (D P 2 -D B 2) sinθ}
= (Π / 4) ingestion of amounts of RD _B ² sin [theta is performed. (3) Therefore, in the discharge step, q1 = (π / 4) RD _P ² sin θ
Is discharged, and q2 = (π / 4) R (D _P ² −D _B ² )
The suction of the amount of sin θ is performed, and in the suction process, q1−q
2 = (π / 4) RD _P ² Suction of the amount of sinθ is performed. Here, the effective cross-sectional area (πD _B ² ) of the bellows 52 is smaller than the cross-sectional area (πD _P ² ) of the piston 48 (πD _P ² > π).
D _B ^2), for example, setting the _{D B / D P = 0.6~0.8,} D B 2 /
The D _P ² = 0.36~0.64. Therefore, Then, D _B ² / D _P ² = 1/2. Under such conditions, in both the discharge step and the suction step, | (π / 4) RD _P ²
Sin θ | = | (π / 4) RD _P ² Suction is performed in the amount of sin θ | / 2. This is shown in the table below. (4) At this time, the total discharge amount of the discharge process and the suction process, if the discharge flow rate of the discharge process and Q _D, If the stroke length is L, from L = 2R, Becomes At the same time, if the suction flow rate of the discharge process and Q _U, Furthermore, the suction flow rate Q _V in the suction process is Becomes Therefore, as described above, the cross-sectional area of the piston 48 (πD _P
² ), the effective cross-sectional area (πD _B ² ) of the bellows 52 is reduced (πD _P ² > πD _B ² ), and the ratio of the effective diameter D _B / D _P = 0.6 to 0.8;
For example By setting ^{_{a, D B 2 = D P 2}} /2 , and the discharge flow rate The suction flow rate is Q _V It becomes 1/2, and it flows in by the same amount at the time of suction and discharge, so
The load on the bellows is minimized. FIG. 2 shows the waveforms of the discharge and suction flow rates in such a case. (5) In addition, in the reciprocating pump, the load applied to the suction is not only the pipe frictional resistance but also the inertial resistance. If there is no bellows, the suction flow rate of the pump is q = (π
/ 4) RD _P ² sin θ, and if the inside diameter of the suction pipe is d, the flow velocity v is Becomes Therefore, the acceleration α of the transfer liquid in the pipe is Assuming that (dθ / dt) = ω with the rotation speed constant, Assuming that the mass of the liquid filled in the suction pipe is m, the pump Receive the power of However, the bellows, the suction flow rate of the pump, since the ^{_{(π / 8) RD P 2}} sinθ, suction acceleration also And the suction load And halved. Therefore, the load on the bellows is reduced, and the bellows also has a long life. Further, only negative pressure is always applied to the bellows, and positive pressure is not applied. For this reason, since the bellows do not reverse, the bellows has a longer life. As described above, in the reciprocating pump 100 according to the present invention, the transfer liquid is sucked into the suction chamber 42 over all the steps of the discharge and the suction, that is, the entire period during the pumping operation.
The bellows 52 is normally loaded with a slight one-way load corresponding to the suction pressure in the suction chamber 42, that is, an internal pressure. Therefore,
The service life of the bellows 52 can be greatly extended in comparison with a conventional pump in which a reversal stress is applied to the bellows, and at the same time, the pulsation rate of the pump flow rate can be reduced. Further, since the suction of the pump is performed in the form of a two-stage pump, the maximum flow velocity value in the suction pipe is reduced, and the acceleration resistance is reduced, so that the suction performance can be further improved. For this reason, the diameter of the suction pipe is smaller than that of another single reciprocating pump, and the cost of piping equipment is also reduced. Furthermore, since the pump does not require high-pressure hydraulic oil, the structure is simple and inexpensive, and the hydraulic oil is not erroneously mixed into the transfer liquid. FIG. 3 shows another embodiment of the leak-free reciprocating pump according to the present invention. The pump 102 in this embodiment is different from the pump working chamber 58 in the embodiment shown in FIG.
Configuration of communication part 44 and cylinder chamber 46, and suction valve
10 and the arrangement of the discharge valve 12 are changed. That is, the discharge valve 12 is disposed above the cylinder chamber 46 in the drawing, and the pump chamber is provided with the suction valve chamber 62, the communication portion 64, and the discharge chamber 66.
And the cylinder chamber 46 communicates with the discharge chamber via a communication portion 68.
It communicates with 66. In this embodiment, the same operation or effect as in the embodiment shown in FIG. 1 is surely achieved. FIG. 4 shows still another embodiment of the non-leak reciprocating pump according to the present invention. The pump 104 in this embodiment is obtained by replacing the bellows 52 in the embodiment shown in FIG. The bellows flam 70 has its folded annular portion 70a attached to the piston 48 in a fluid-tight manner via screws, and the peripheral edge of the expanded flange 70b is fluid-tightly attached to the pump-side casing 54 via the drive-side casing 56. The bellows flam 70 holds the inside of the pump in a liquid-tight manner. In such a configuration, the bellows flam
Since 70 is always loaded with a slight internal pressure, it is smoothly and smoothly displaced and deformed in response to the reciprocation of the piston rod 50, and the effective volume in the suction chamber 42 fluctuates proportionally. Therefore, with this configuration, the same operation or effect as that of the embodiment shown in FIG. 1 or FIG. 2 can be achieved, and the bellow flam 70 having a simpler structure than the bellows 52 is used. The advantage of this is added. Although the preferred embodiment of the present invention has been described above, it is needless to say that many design changes can be made to the present invention without departing from the spirit thereof. [Effects of the Invention] As described above, the non-leak reciprocating pump according to the present invention arranges the piston rod of the piston that performs the pumping action on the pump chamber in the suction chamber, and the piston rod moves the piston rod in the suction chamber. By mounting a flexible seal member for sealing the transfer liquid, for example, a bellows or a bellows flam, the stress acting on the seal member is reduced, and at the same time, it is configured to be always loaded from a certain direction. As compared with conventional seal members, the life and reliability of the seal member can be greatly improved. That is, the leak-free property of the pump is reliably ensured for a long period of time. Further, in the reciprocating pump of the present invention, since high-pressure hydraulic oil is not required, the structure is simple and lightweight, and can be manufactured at low cost. In addition, the hydraulic oil is erroneously mixed into the transfer liquid, and a serious accident or There is no risk of causing losses. Furthermore, in the reciprocating pump of the present invention, the suction of the pump is performed in a double pump shape and the pulsation rate is reduced, so that the suction performance and quantitativeness of the pump can be improved. That is, in the present invention, by setting the effective cross-sectional area of the flexible seal member to about 1/2 of the cross-sectional area of the piston, the amount of suction into the suction chamber in the discharge step and the amount of suction into the suction chamber in the suction step are set. Since the amount of the liquid to be transferred is equal to the amount of the liquid transferred into the suction chamber throughout the entire discharge and suction process, the function of the liquid on the suction side always performs a suction operation like a dual pump. Thus, improved suction conditions are achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing one embodiment of a non-leakage reciprocating pump according to the present invention, and FIG. 2 is a waveform diagram of discharge and suction flow rates of the non-leakage reciprocating pump shown in FIG. FIG. 3 is a cross-sectional view showing another embodiment of the leak-free reciprocating pump according to the present invention.
FIG. 4 is a sectional view showing still another embodiment of the non-leak reciprocating pump according to the present invention, FIG. 5 is a sectional view showing a conventional bellows pump, and FIG. 6 is a sectional view showing a conventional hydraulic diaphragm pump. FIG. 7 is a schematic configuration diagram showing an operation state. 10 ... Suction valve, 12 ... Discharge valve 16 ... Pump chamber, 40 ... Suction port 42 ... Suction chamber, 44 ... Communication part 46 ... Cylinder chamber, 48 ... Piston 50 ... Piston rod, 52 ... Bellows 54 ... Pump side casing 56 ... Drive side casing, 58 Pump working chamber 60 Discharge port, 62 Suction valve chamber 64 Communication part, 66 Discharge chamber 68 Communication part, 70 Bellow flam 100, 102, 104 Reciprocating pump with no leakage

Claims (1)

(57) [Claims] A suction chamber set between the suction port and the suction valve, a pump chamber set between the suction valve and the discharge valve, a piston reciprocatingly arranged in the cylinder chamber to perform a pump action, and a pump. A reciprocating pump having a communication section that communicates the chamber with the cylinder chamber and is filled with the transfer liquid, wherein a piston rod for driving the piston is inserted through the suction chamber, and the piston rod is provided in the suction chamber. A flexible seal member for sealing against a transfer liquid is attached and mounted, and an effective sectional area of the flexible seal member is set to about 1/2 of a sectional area of a piston. The space between the chamber and the flexible seal member is increased by one-way movement of the piston, and suction is performed. In the suction step, the space between the suction chamber and the flexible seal member is: Said Although reduced by another movement of the piston, leak-free reciprocating pump, characterized in that the suction is performed by the transported liquid is transferred to the cylinder chamber via the communicating portion. 2. 2. The leak-free reciprocating pump according to claim 1, wherein the flexible sealing member comprises a bellows or a bellows flam.