JP2013119800A - Plunger pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pump in which gas mixed inside the pump is easily discharged, in a reciprocating plunger pump.SOLUTION: The reciprocating plunger pump is a serial twin plunger pump in which two combinations of pump chambers and plungers are connected in series. A control means provided in the pump transmits signals which reciprocate two plungers to a drive means such that volume change of a pump chamber provided at an upstream side and volume change of a pump chamber provided at a downstream side are in opposite directions. The signals include, at least, a signal which controls such that the ratio of volume change speed of the pump chamber provided at the downstream side with respect to volume change speed of the pump chamber provided at the upstream side is approximately one half and a signal which increases the ratio of the volume change speed.

Description

  The present invention relates to a plunger pump for feeding a liquid provided in a liquid chromatograph apparatus or the like.

In the liquid chromatograph, for the purpose of sending the eluent at high pressure,
A pump chamber that operates by reciprocating movement of the plunger;
A check valve for controlling the flow of liquid by reciprocating movement of the plunger in a certain direction;
Drive means for reciprocating the plunger;
A reciprocating plunger pump provided with

  In the reciprocating plunger pump, the liquid is sucked into the pump chamber by pulling out the plunger, and the liquid in the pump chamber is discharged by pushing out the plunger. Thereby, the liquid is intermittently fed. By providing a pressure damper such as a Bourdon tube downstream of the reciprocating plunger pump (discharge side), pressure fluctuation due to intermittent discharge operation can be reduced. However, when the reciprocating motion cycle of the plunger is long, it is difficult to reduce the pressure fluctuation by the pressure damper.

  One way to reduce pressure fluctuation is to shorten the time for sucking liquid into the pump chamber and lengthen the time to discharge liquid in the pump chamber, while the reciprocating motion by the plunger is almost constant speed. A pump is given. Although the pump can reduce the pressure fluctuation at the time of discharge, since the liquid is sucked in a short time, there is a drawback that the pressure in the suction side pipe is lowered and bubbles are easily generated.

  As another method for reducing the pressure fluctuation, there is a method of using two parallel plunger pumps in which two reciprocating plunger pumps are connected in parallel and the reciprocating motions of the plungers by the respective plunger pumps are in opposite phases. Further, as another method for reducing the pressure fluctuation, the first plunger pump and the second plunger pump are connected in series so that the first plunger pump is on the upstream side, and the plunger provided in the first plunger pump is provided. There is a method of using a series double plunger pump in which the stroke is made larger than the stroke of the plunger provided in the second plunger pump and the reciprocating motions by the plunger pumps are in opposite phases to each other (Patent Document 1). Note that the series double plunger pump does not require the discharge valve side check valve of the second plunger pump. In the series double plunger pump, the flow rate fluctuation and the pressure fluctuation can be reduced because the flow rate fluctuation on the first plunger pump side is canceled by the volume change caused by the reciprocating motion of the plunger provided in the second plunger pump.

JP 2000-104659 A

  When the eluent is sent using a reciprocating plunger pump, if the eluent is aspirated in a state where air is mixed, not only the flow rate and pressure will change temporarily, but the mixed air If it catches on, the operation of the check valve will be hindered, which may lead to poor liquid feeding. Therefore, when starting the pump with the pump chamber or check valve empty, connect a syringe or the like to the discharge side of the pump, and suck air from the liquid container into the pump chamber or check valve. Perform the unplug operation. However, the operation has a problem that air is difficult to escape. In particular, when a parallel dual plunger pump is used as an eluent pump, the flow path is divided in parallel, so that air may remain in the other pump even if air escapes from one pump. . Further, in a reciprocating plunger pump for feeding a minute flow rate by reducing the amount of discharged liquid per cycle by reducing the plunger diameter and stroke length, it is very difficult to remove the mixed air.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a reciprocating plunger pump that facilitates escape of gas mixed in the pump.

  The present invention made in view of the above problems includes the following inventions.

The first aspect of the present invention is:
A first pump chamber actuated by reciprocation of the first plunger;
A second pump chamber actuated by reciprocating movement of the second plunger;
A first check valve provided on the liquid suction port side of the first pump chamber;
A second check valve provided on the liquid discharge port side of the first pump chamber;
A flow path communicating the liquid discharge port side of the first pump chamber and the liquid suction port side of the second pump chamber;
Drive means for reciprocating the first and second plungers;
Control means for sending a control signal for reciprocating the first plunger and the second plunger to the drive means so that the volume change of the first pump chamber and the volume change of the second pump chamber are in opposite directions;
A reciprocating motion of each plunger, a series double plunger pump that performs continuous liquid feeding from the liquid suction port side of the first pump chamber to the liquid discharge port side of the second pump chamber,
The control signal sent from the control means to the driving means is at least a signal for controlling the ratio of the volume change rate of the second pump chamber to the volume change rate of the first pump chamber to be approximately 0.5 times, and the volume change Including a signal having a speed ratio larger than the ratio,
The plunger pump.

The second aspect of the present invention is as follows.
The control means is
During steady operation, a signal for controlling the ratio of the volume change rate of the second pump chamber to the volume change rate of the first pump chamber to be approximately 0.5 times is sent to the driving means,
Means for sending a signal to the drive means until the discharge pressure reaches a predetermined pressure or when the gas is mixed into the pump chamber or the check valve so that the ratio of the volume change rate is larger than the ratio. Is,
The plunger pump according to the first aspect.

The third aspect of the present invention is as follows.
The drive means is a means provided with a first eccentric cam and a first drive part, a second eccentric cam and a second drive part, and the first drive part makes the first When the first plunger moves to the side of discharging the liquid in the first pump chamber due to the movement of the eccentric cam, the second eccentric cam moves by the second drive unit to move the second plunger The plunger moves to the side that draws liquid into the second pump chamber,
When the first eccentric cam is moved by the first drive unit and the first plunger moves to the side that sucks the liquid into the first pump chamber, the second drive unit causes the second eccentric cam to move. The second plunger is a means that moves to the side that discharges the liquid in the second pump chamber as the cam moves.
The plunger pump according to the first or second aspect.

The fourth aspect of the present invention is:
The drive means is a means provided with a first feed screw and a first drive part, a second feed screw and a second drive part, and the first drive part uses the first feed screw and the first drive part. When the first plunger moves to the side that discharges the liquid in the first pump chamber, the second drive screw moves by the second drive unit, so that the second plunger Move to the liquid suction side of the pump chamber,
When the first drive screw moves by the first drive unit and the first plunger moves to the liquid suction side in the first pump chamber, the second drive screw causes the second feed screw to move. It is a means for the second plunger to move to the side for discharging the liquid in the second pump chamber by moving,
The plunger pump according to the first or second aspect.

The fifth aspect of the present invention provides
The drive means is a means provided with an eccentric cam, a two-stage eccentric cam, and a drive unit for simultaneously driving the two cams,
When the first plunger moves to the side that discharges the liquid in the first pump chamber by the movement of the eccentric cam, the second plunger sucks the liquid into the second pump chamber by the movement of the two-stage eccentric cam. Exercise on the side
When the first plunger moves to the side that sucks liquid into the first pump chamber by the movement of the eccentric cam, the second plunger discharges the liquid in the second pump chamber by the movement of the two-stage eccentric cam. Exercise on the side
And it is a plunger pump as described in the said 1st or 2nd aspect which changes the reciprocation amount of a 2nd plunger by changing the use angle area | region of the said 2 step | paragraph eccentric cam.

  The sixth aspect of the present invention is the plunger pump according to any one of the first to fifth aspects, further comprising a third check valve on the liquid discharge port side of the second pump chamber. .

  Hereinafter, the present invention will be described in detail.

In the plunger pump of the present invention, the first and second plungers are controlled by the control means so that at least the ratio of the volume change rate of the second pump chamber to the volume change rate of the first pump chamber is approximately 0.5 times. A mode to exercise (hereinafter referred to as the first mode),
A mode in which the first and second plungers are moved so that the ratio of the volume change speed is larger than the ratio of the first mode (hereinafter, second mode);
This is a switchable pump. In this specification, “approximately 0.5 times” means that it is not necessary to accurately set 0.5 times, specifically, it may be in a range from 0.4 times to 0.6 times, Preferably it is the range from 0.45 times to 0.55 times. In the second mode, the ratio of the volume change rate of the second pump chamber to the volume change rate of the first pump chamber depends on the ratio in the first mode. When it is 5 times, it becomes larger than 0.5 times, when the first mode is 0.45 times, it becomes larger than 0.45 times, and when the first mode is 0.55 times, it becomes 0.00. It becomes larger than 55 times.

  In the plunger pump of the present invention, the amount of liquid discharged from each pump chamber by the reciprocating motion of the first and second plungers per cycle is the stroke length when the cross-sectional areas of the first and second plungers are equal. When the cross-sectional areas of the first and second plungers are different from each other, they are proportional to the product of the cross-sectional area and the stroke length. Specifically, in the plunger pump of the present invention, during the steady operation, the first mode is set to reduce pressure fluctuation. In this case, for example, the diameter of the first plunger and the diameter of the second plunger The ratio is 1.414: 1, and the first mode can be obtained by making the stroke length and the reciprocating speed of the plunger equal to each other. On the other hand, until the discharge pressure reaches a predetermined pressure, the second mode is set by making the stroke length of the second plunger larger than the stroke length of the first plunger. By doing so, when the liquid is discharged from the first pump chamber, the liquid suction into the second pump chamber increases, so that the pressure on the liquid discharge port side of the first pump chamber decreases (depressurized state) Therefore, the escape of gas mixed in the pump is improved. In addition, it is good also as a 2nd mode by making the stroke length of a 1st plunger larger than the stroke length at the time of steady operation, and making the stroke length of a 2nd plunger pump larger than the stroke length of said 1st plunger. . In the above aspect, the pressure on the liquid discharge port side of the first pump chamber is lowered by the liquid suction into the second pump chamber (depressurized state), and the liquid discharge amount itself is increased. The escape of gas mixed in is further improved.

  During steady operation, if the liquid is sucked into the pump chamber while gas is mixed, the second plunger stroke length is changed to the first plunger until the discharge pressure reaches the specified pressure even if the liquid feed is poor. By setting the second mode to be larger than the stroke length of the first pump chamber, when the liquid is discharged from the first pump chamber, the pressure on the liquid discharge side of the first pump is reduced by the liquid suction into the second pump chamber. Since it is in a lowered state (depressurized state), the escape of gas mixed in the pump is improved.

  The first mode is used during steady operation, and the second plunger stroke length is set to be greater than the first plunger stroke length when a suction failure occurs due to gas suction. Until the discharge pressure reaches a predetermined pressure, the stroke length of the first plunger is made larger than the stroke length during steady operation, and the stroke length of the second plunger pump is made larger than the stroke length of the first plunger. You may employ | adopt the aspect made into a 2nd mode.

  In the plunger pump of the present invention, it is preferable that a third check valve is further provided on the liquid discharge port side of the second pump chamber. The reason for this is that even if gas is mixed into the first pump chamber or the first check valve and liquid feeding is poor, liquid is sucked from the first pump chamber into the second pump chamber by the second plunger. This is because sometimes the liquid can be prevented from flowing back from the downstream side, so that the mixed gas can be easily removed.

  In the present invention, the reciprocating plunger pump is a series double plunger pump in which two combinations of a pump chamber and a plunger are connected in series, and the control means provided in the pump includes a volume change and a downstream of a pump chamber provided on the upstream side. A means for sending a signal for reciprocating the two plungers to the driving means so that the volume change of the pump chamber provided on the side is opposite, and the signal is at least a volume change of the pump chamber provided on the upstream side A signal for controlling the ratio of the volume change rate of the pump chamber provided downstream with respect to the speed to be approximately 0.5 times, and a signal for setting the ratio of the volume change speed to be greater than the ratio. It is said.

  For example, when starting or when gas is mixed in the pump chamber or the check valve, a control signal for increasing the ratio of the volume change rate to more than 0.5 is used. .5 times the control signal is sent to the driving means, so that the gas mixed in the plunger pump can be removed well even when the plunger pump is started or when the liquid mixed with gas is sucked. Can do.

The figure which shows an example of the plunger pump of this invention. The figure which shows another example of the plunger pump of this invention. The figure which shows another example of the plunger pump of this invention. The figure which shows an example of the liquid feeding pattern by the plunger pump of this invention. The figure which shows an example of an eccentric cam. The figure which shows an example of a linear cam. The figure which shows an example of a two-stage eccentric cam. The figure which shows an example of a two-stage linear cam.

  Hereinafter, the present invention will be described in more detail with reference to the drawings.

An example of the plunger pump of the present invention is shown in FIG. The pump 100 shown in FIG.
A pump chamber 11 that operates by reciprocating movement of the plunger 21;
A pump chamber 12 that is actuated by reciprocating movement of the plunger 22;
A check valve 31 provided on the liquid suction port side of the pump chamber 11,
A flow path 40 for communicating the liquid discharge port side of the pump chamber 11 with the pump chamber 12,
A check valve 32 provided in the flow path;
A driving device 50 for reciprocating the plungers 21 and 22;
Control means 60 for sending a control signal to the driving device 50;
It has. The drive device 50 includes a motor 51a and an eccentric cam 52a for reciprocating the plunger 21, and a motor 51b and an eccentric cam 52b for reciprocating the plunger 22. Examples of the motor 51 include a pulse motor and a servo motor. The control means 60 sends a signal that causes the reciprocating motion of the plunger 21 and the reciprocating motion of the plunger 22 to be in opposite phases to the driving device 50, thereby changing the volume change of the pump chamber 11 and the volume change of the pump chamber 12. Is in the opposite direction. The eccentric cam 52 (FIG. 5) consists of a disk provided with a rotation shaft at a position off the center. When the rotation speed of the motor 51 is constant, the eccentric cam 52 has a pattern similar to a sine wave depending on the rotation amount of the eccentric cam 52. The speed changes. By changing the rotational speeds of the motors 51a and 51b according to the angles of the eccentric cams 52a and 52b, the plungers 21 and 22 can be reciprocated at a substantially constant speed. As the eccentric cam 52, cams having different relations between the rotation angle and the stroke length may be used.

  During steady operation, the ratio of the volume change rate of the pump chamber 12 to the volume change rate of the pump chamber 11 is approximately 0.5 times (for example, 0) by adjusting the diameters, stroke lengths, and reciprocating speeds of the plungers 21 and 22. (5 times), a signal for reciprocating the plungers 21 and 22 is sent from the control means 60 to the driving device 50. On the other hand, the rotation speed and the rotation amount of the motors 51a and 51b are increased so that the ratio of the volume change speed is larger than the ratio (for example, larger than 0.5 times) until reaching a predetermined pressure such as at the time of starting. A signal to be transmitted is sent to the driving device 50. As a result, the stroke length of the plunger 22 is changed to increase the volume change rate of the pump chamber 12, whereby a liquid that may be mixed with gas is sucked from the pump chamber 11 into the pump chamber 12, and then from the pump chamber 12. Discharge. Also, when gas is mixed in the pumps such as the pump chambers 11 and 12 and the check valves 31 and 32, a signal similar to that until the predetermined pressure is reached is sent to the driving device 50, so that the mixed gas Remove quickly. In the pump 100 shown in FIG. 1, the eccentric cam 52 is used as means for transmitting the rotational force of the motor 51 to the plungers 21 and 22. However, a linear cam (FIG. 6) may be used, and in this case, the stroke position Is proportional to the rotation amount, the plunger reciprocates at a constant speed by keeping the rotation speed of the motor constant.

  The liquid feeding pattern of the plunger pump of the present invention during the above-described steady operation, start-up, or gas mixing (that is, until a predetermined pressure is reached) is collectively shown in FIG. 4A shows the change over time in the discharge amount from the pump chamber 12 during steady operation or startup or gas mixing, and FIG. 4B shows the plungers 21 and 22 during steady operation or startup or gas mixing. The change with time of the position is shown.

  Another example of the plunger pump of the present invention is shown in FIG. The difference between the pump 100 shown in FIG. 2 and the pump shown in FIG. 1 is that a feed screw 53 is used as means for transmitting the rotational force of the motor 51 to the plungers 21 and 22. When the plungers 21 and 22 are reciprocated by the feed screws 53a and 53b, the movement direction, movement speed and movement distance of the plungers 21 and 22 are controlled by controlling the rotation direction, rotation speed and rotation amount of the motors 51a and 51b. It can be driven arbitrarily. When the rotational speed of the motor is constant, the plunger 12 moves back and forth at a constant speed. As in the pump shown in FIG. 1, until a predetermined pressure is reached, or when gas is mixed into the pumps such as the pump chambers 11 and 12 or the check valves 31 and 32, a signal from the control means 60 The volume change speed of the pump chamber 12 is increased by increasing the rotation speed and rotation amount of the motor 51 b and increasing the stroke length of the plunger 22.

  Another example of the plunger pump of the present invention is shown in FIG. The difference between the pump 100 shown in FIG. 3 and the pump shown in FIG. 1 is that the driving device 50 has a motor 51, an eccentric cam 52 that transmits the rotational force of the motor 51 to the plunger 21, and a rotational force of the motor 51 to the plunger 22. Is a means provided with a two-stage eccentric cam. Similar to the pump shown in FIG. 1, a linear cam (FIG. 6) may be provided instead of the eccentric cam 52. The two-stage eccentric cam 54 (FIG. 7) is a cam in which the circumference of the eccentric cam (FIG. 5) is divided into two regions, and the amount of plunger reciprocation per angle is changed in each region. For example, the two-stage eccentric cam 54 is provided with a first region where the forward speed is equal to the forward speed of the plunger 21 and a second region where the forward speed of the plunger 21 is 0.5 times higher. The ratio of strokes can be changed by selecting a rotation at and a rotation within the second region. In the pump 100 shown in FIG. 3, a cam obtained by dividing the circumference of the eccentric cam 52 (FIG. 5) into two regions is used as the two-stage eccentric cam 54, but the number of divisions is not particularly limited, and the pump 100 It may be set as appropriate according to the number of suction / discharge modes required for the operation. In the pump 100 shown in FIG. 3, the two-stage eccentric cam 54 is used as means for transmitting the rotational force of the motor 51 to the plunger 22, but a two-stage linear cam (FIG. 8) may be used.

  The plunger pump of the present invention can satisfactorily remove the gas mixed in the pump even when the pump is started or when the liquid mixed with gas is sucked. Therefore, the possibility of stopping liquid feeding due to air suction is reduced, and stable liquid feeding becomes possible.

11.12: Pump chamber 21.22: Plunger 31.32: Check valve 40: Flow path 50: Drive device 51: Motor 52: Eccentric cam 53: Feed screw 54: Two-stage eccentric cam 60: Control means 100 : Plunger pump

Claims (6)

A first pump chamber actuated by reciprocation of the first plunger;
A second pump chamber actuated by reciprocating movement of the second plunger;
A first check valve provided on the liquid suction port side of the first pump chamber;
A second check valve provided on the liquid discharge port side of the first pump chamber;
A flow path communicating the liquid discharge port side of the first pump chamber and the liquid suction port side of the second pump chamber;
Drive means for reciprocating the first and second plungers;
Control means for sending a control signal for reciprocating the first plunger and the second plunger to the drive means so that the volume change of the first pump chamber and the volume change of the second pump chamber are in opposite directions;
A reciprocating motion of each plunger, a series double plunger pump that performs continuous liquid feeding from the liquid suction port side of the first pump chamber to the liquid discharge port side of the second pump chamber,
The control signal sent from the control means to the driving means is at least a signal for controlling the ratio of the volume change rate of the second pump chamber to the volume change rate of the first pump chamber to be approximately 0.5 times, and the volume change Including a signal having a speed ratio larger than the ratio,
The plunger pump. The control means is
During steady operation, a signal for controlling the ratio of the volume change rate of the second pump chamber to the volume change rate of the first pump chamber to be approximately 0.5 times is sent to the driving means,
Means for sending a signal to the drive means until the discharge pressure reaches a predetermined pressure or when the gas is mixed into the pump chamber or the check valve so that the ratio of the volume change rate is larger than the ratio. Is,
The plunger pump according to claim 1. The drive means is a means provided with a first eccentric cam and a first drive part, a second eccentric cam and a second drive part, and the first drive part makes the first When the first plunger moves to the side of discharging the liquid in the first pump chamber due to the movement of the eccentric cam, the second eccentric cam moves by the second drive unit to move the second plunger The plunger moves to the side that draws liquid into the second pump chamber,
When the first eccentric cam is moved by the first drive unit and the first plunger moves to the side that sucks the liquid into the first pump chamber, the second drive unit causes the second eccentric cam to move. The second plunger is a means that moves to the side that discharges the liquid in the second pump chamber as the cam moves.
The plunger pump according to claim 1 or 2. The drive means is a means provided with a first feed screw and a first drive part, a second feed screw and a second drive part, and the first drive part uses the first feed screw and the first drive part. When the first plunger moves to the side that discharges the liquid in the first pump chamber, the second drive screw moves by the second drive unit, so that the second plunger Move to the liquid suction side of the pump chamber,
When the first drive screw moves by the first drive unit and the first plunger moves to the liquid suction side in the first pump chamber, the second drive screw causes the second feed screw to move. The plunger pump according to claim 1 or 2, wherein the plunger pump is a means for moving the second plunger toward a side for discharging the liquid in the second pump chamber. The drive means is a means provided with an eccentric cam, a two-stage eccentric cam, and a drive unit for simultaneously driving the two cams,
When the first plunger moves to the side that discharges the liquid in the first pump chamber by the movement of the eccentric cam, the second plunger sucks the liquid into the second pump chamber by the movement of the two-stage eccentric cam. Exercise on the side
When the first plunger moves to the side that sucks liquid into the first pump chamber by the movement of the eccentric cam, the second plunger discharges the liquid in the second pump chamber by the movement of the two-stage eccentric cam. Exercise on the side
And the plunger pump of Claim 1 or 2 which changes the reciprocation amount of a 2nd plunger by changing the use angle area | region of the said 2 step | paragraph eccentric cam. The plunger pump according to any one of claims 1 to 5, further comprising a third check valve on the liquid discharge port side of the second pump chamber.

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