JPWO2010143469A1 - Double reciprocating pump - Google Patents

Abstract

Stable pump operation is possible at all times, suppressing pulsation. The case member 2 forms a pair of spaces along the axial direction inside. The movable partition member 3 is disposed in the pair of spaces so as to be deformable in the axial direction, and partitions the pair of spaces into the pump chamber 5 and the working chamber 6 in the axial direction. The connecting shaft 11 connects the movable partition member 3 so as to be extendable and contractable in the axial direction via the extendable member 14. The valve mechanism 27 introduces the working fluid into the working chamber 6 and discharges the working fluid from the working chamber 6. The controller 25 partially overlaps the compression process of one pump chamber 5 and the compression process of the other pump chamber 5 based on the output of the displacement sensor 23 that continuously detects the displacement of the pair of movable partition members 3. The pair of movable partition members 3 is driven by switching the valve mechanism 27 so as to have an overlapping distance. [Selection] Figure 1

Description

  The present invention is a two-way reciprocation in which a pair of pump chambers formed by a pair of bellows, diaphragms, plungers and other movable partition members connected by a connecting shaft perform a pump operation by alternately repeating a compression step and an expansion step. More particularly, the present invention relates to a double reciprocating pump in which elastic means is provided on a connecting shaft to reduce pulsation of a transfer fluid.

  A pair of closed spaces are partitioned into a pump chamber and a working chamber by a movable partition member such as a bellows connected by a connecting shaft, and the connecting shaft is reciprocated by alternately introducing working fluid into the pair of working chambers. 2. Description of the Related Art A double reciprocating pump in which a pump chamber is alternately compressed and extended is known. In this type of pump, at the end of the reciprocating stroke of the connecting shaft, the pair of suction valves and the pair of discharge valves are switched from one pump chamber side to the other pump chamber side, and as a result, the number of strokes in the discharge flow rate A pulsation corresponding to is generated. Such pulsation causes various obstacles. For semiconductor applications, for example, particles clogged in the filter are pushed out by pulsation and mixed downstream, leak from the joint due to vibration of piping, the liquid level of the washing tank undulates, and the nozzle that injects liquid onto the wafer There is a problem that the tip vibrates and the cleaning efficiency is lowered, or the inertial resistance of the liquid is increased and the flow rate is not stable. In particular, it is a major issue to be improved in the manufacturing process fields of semiconductors, liquid crystals, solar cells, medicines, foods and the like.

  In order to solve this problem, conventionally, a technique for reducing the above-described pulsation by providing a coil spring on a part of the connecting shaft and elastically connecting the movable partition member in the reciprocating direction is also known. (Patent Documents 1 and 2).

Japanese Patent Publication No. 11-504098 (page 7, lines 20-25, FIG. 1) WO 00/15962 (page 4, line 37 to page 5, line 5, FIG. 1)

  However, in the double reciprocating pump disclosed in Patent Document 1 described above, the expansion process of the other pump chamber is started at the stroke end where one pump chamber changes from the expansion process to the compression process. Since the delay is intended to be absorbed by the contraction of the coil spring, there is a problem that the pulsation removing effect is less than in a method in which the end and start periods of the compression process are positively overlapped in a pair of pump chambers.

  Further, in the double reciprocating pump disclosed in Patent Document 2, since the switching timing of the expansion process and the compression process of the pump chamber is controlled by time, the heat generation of the elastic member after the start of operation and the change of the surrounding environment When the change over time such as the above or the number of strokes is changed, there is a problem that the phase of the reciprocating motion gradually changes and the pump operation becomes unstable.

  The present invention has been made in view of such a point, and an object thereof is to provide a double reciprocating pump capable of always performing a stable pump operation and suppressing pulsation.

  The double reciprocating pump according to the present invention includes a case member that forms a pair of spaces along the axial direction therein, and a pair of spaces that are disposed in the pair of spaces so as to be deformable or movable in the axial direction. A pair of movable partition members for partitioning the pump chamber and the working chamber in the axial direction, a connecting shaft for connecting the pair of movable partition members so as to be expandable and contractable in the axial direction via an extendable member, and a suction side of the pump chamber A suction valve provided to guide the transfer fluid to the pump chamber; a discharge valve provided on the discharge side of the pump chamber for discharging the transfer fluid from the pump chamber; and a working fluid introduced into the working chamber; A valve mechanism for discharging the working fluid from the working chamber, a displacement sensor for continuously detecting displacement of the pair of movable partition members, and a pressure in one pump chamber based on the output of the displacement sensor. Process and the other pump chamber of the compression process is characterized by comprising a controller that drives the pair of movable partition member by switching the valve mechanism so as to have overlapping distance partially overlapping.

  In a preferred embodiment, the controller has setting means for setting an overlapping rate indicated by a ratio of the overlapping distance to the total stroke length of the movable partition member, and the overlap set by the setting means The overlap rate is controlled based on a set value of the rate and an output of the displacement sensor.

  In another embodiment, the controller increases the overlapping rate indicated by the ratio of the overlapping distance to the total stroke length of the movable partition member as the number of strokes of the pair of movable partition members increases.

  In another embodiment, the controller has a value that is 1 to 3% less than the limit value of the overlap rate at which the pump operation stops, the overlap rate indicated by the ratio of the overlap distance to the total stroke length of the movable partition member. The movable partition member is driven so as to be maintained.

  In another embodiment, the controller changes the optimal overlap rate periodically or dynamically.

  In another embodiment, the expansion / contraction member of the connecting shaft has a damper that relaxes a biasing force when the connection shaft extends from a compressed state.

  In another embodiment, the elastic member is a coil spring or an air cushion.

  In another embodiment, the apparatus further includes a proximity sensor that detects that the pair of movable partition members has reached the end of the moving stroke.

  In another embodiment, the valve mechanism adjusts the pressure of the working fluid from a pair of valves provided in the pair of working chambers and a working fluid supply source, and supplies the working fluid to the pair of valves, respectively. And a pair of regulators to be supplied.

  Another two-way reciprocating pump of the present invention has a pump head and a pump chamber which is attached to both sides of the pump head so that the opening sides face each other, and each has a pump chamber therein and can be expanded and contracted in the axial direction. A pair of bottomed cylindrical bellows and an opening that is coaxially disposed with respect to the bellows so as to accommodate the pair of bellows therein, and forms an operating chamber between the pair of bellows. A pair of bottomed cylindrical cylinders mounted on the pump head so as to face each other, and bottom portions of the pair of cylinders are airtight and slidable along the central axis of the cylinder, respectively, and one end of each pair of the pair of cylinders. A pair of pump shafts connected to the bottoms of the bellows, and the other ends of the pair of pump shafts are connected to each other so as to be extendable in the axial direction via an extension member. And a valve mounted on the pump head in the pump chamber to guide the transfer fluid from the suction port of the transfer fluid to the pump chamber and to guide the transfer fluid from the pump chamber to the discharge port of the transfer fluid A unit, a valve mechanism for introducing a working fluid into the working chamber and discharging the working fluid from the working chamber, a displacement sensor for continuously detecting displacement of the pair of bellows, and a displacement sensor A controller that drives the pair of bellows by switching the valve mechanism so that the compression process of the one pump chamber and the compression process of the other pump chamber partially overlap based on the output. It is characterized by having.

  According to the present invention, since it is possible to control the overlap distance of the optimum compression process based on continuous displacement detection by the displacement sensor, it is possible to always perform stable pump operation and effectively suppress pulsation. it can.

It is a figure which shows the structure of the double reciprocating pump which concerns on the 1st-3rd embodiment of this invention. It is a wave form diagram which shows operation | movement of the pump. It is a graph which shows the ratio of the overlap distance with respect to the stroke number of the pump, and the discharge side pulsation pressure. It is a graph which shows the range of the ratio of the overlap distance with respect to the stroke number of the pump. It is a fragmentary sectional view of the connection shaft in the double reciprocating pump which concerns on the 4th Embodiment of this invention. It is a fragmentary sectional view of the connection shaft in the double reciprocating pump which concerns on the 5th Embodiment of this invention. It is a fragmentary sectional view of the connection shaft in the double reciprocating pump which concerns on the 6th Embodiment of this invention. It is a figure which shows the structure of the double reciprocating pump which concerns on the 7th Embodiment of this invention. It is a figure which shows the structure of the double reciprocating pump which concerns on the 8th Embodiment of this invention. It is a figure which shows the structure of the double reciprocating pump based on the 9th Embodiment of this invention. It is a figure which shows the structure of the double reciprocating pump based on the 10th Embodiment of this invention. It is a figure which shows the structure of the double reciprocating pump based on the 11th Embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 is a cross-sectional view of a double reciprocating bellows pump according to a first embodiment of the present invention and a view showing a peripheral mechanism thereof. On both sides of the pump head 1 arranged at the center, bottomed cylindrical cylinders 2a and 2b, which are case members, are coaxially arranged, and a pair of spaces are formed inside them. In these spaces, bottomed cylindrical bellows 3a and 3b are coaxially arranged. The open ends of the bellows 3a, 3b are fixed to the pump head 1, and the shaft fixing plates 4a, 4b are fixed to the bottom. The bellows 3a, 3b constitute a movable partition member that partitions the internal space of the cylinders 2a, 2b with the pump chambers 5a, 5b on the inside and the working chambers 6a, 6b on the outside.

  One ends of shafts 7a and 7b extending coaxially are fixed to the shaft fixing plates 4a and 4b. The other ends of the shafts 7a and 7b extend through the center of the bottoms of the cylinders 2a and 2b through the seal member 8 to the outside of the cylinders 2a and 2b. Connecting plates 9a and 9b are fixed to the other ends of the shafts 7a and 7b by nuts 10, respectively. The connecting plates 9a and 9b are connected by connecting shafts 11a and 11b at positions above and below the cylinders 2a and 2b. Each of the connecting shafts 11a and 11b includes a shaft portion 12 and 13 and a coil spring 14 that is an elastic member mounted between the shaft portions 12 and 13, and is fixed to the connecting plates 9a and 9b by bolts 15. .

  The pump head 1 is provided with a suction port 16 and a discharge port 17 for the transfer fluid at a position facing the side surface of the pump, and suction valves 18a and 18b are provided at positions from the suction port 16 to the pump chambers 5a and 5b. Discharge valves 19a and 19b are provided in a path from the pump chambers 5a and 5b to the discharge port 17.

  Proximity switches 21a and 21b are mounted on the bottom outer wall surfaces of the cylinders 2a and 2b. The proximity switches 21a and 21b are for detecting that the bottoms of the bellows 3a and 3b are most retracted. For example, the proximity switches 21a and 21b detect that the inner side surfaces of the connecting plates 9a and 9b are close to each other. Displacement sensors 23a and 23b are mounted on the fixing plates 22a and 22b extending from the cylinders 2a and 2b. The displacement sensors 23a and 23b detect displacement with respect to the outer surfaces of the connecting plates 9a and 9b. For example, a laser displacement meter, an MR (magnetoresistive element) sensor, a capacitance sensor, a linear encoder, a high-frequency oscillation type proximity displacement A sensor, an optical fiber type displacement sensor, or the like can be suitably used. Detection signals from the proximity switches 21 a and 21 b and the displacement sensors 23 a and 23 b are input to the controller 25.

  On the other hand, a working fluid such as air from a working fluid source such as an air compressor (not shown) is restricted to a predetermined pressure by regulators 26a and 26b and supplied to electromagnetic valves 27a and 27b. The controller 25 inputs detection outputs of the proximity switches 21a and 21b and the displacement sensors 23a and 23b, and controls opening and closing of the electromagnetic valves 27a and 27b based on these detection outputs.

  Next, the operation of the double reciprocating pump according to this embodiment configured as described above will be described.

  FIG. 2 is a waveform diagram of each part for explaining the operation of the pump according to the present embodiment.

  Air from the air source is supplied to the electromagnetic valves 27a and 27b after being restricted to a predetermined pressure by the regulators 26a and 26b, respectively. For this reason, since the pressure fluctuation of one working chamber 6a, 6b does not affect the pressure of the other working chamber 6b, 6a, there is also a pulsation reducing effect. Note that the number of regulators is not limited to two, and may be one. In this case, it is more desirable to use a precision regulator. Assume that the solenoid valve 27a is in an off state (exhaust state), the solenoid valve 27b is in an on state (air introduction state), the pump chamber 5a is in an expansion process, and the pump chamber 5b is in a contraction process. At this time, since the suction valve 18a and the discharge valve 19b are opened and the suction valve 18b and the discharge valve 19a are closed, the liquid to be transferred is introduced into the pump chamber 5a from the suction port 16 and discharged from the pump chamber 5b. It is discharged through.

  At this time, the output of the displacement sensor 23b drops as the connecting plate 9a is separated. The controller 25 monitors the output of the displacement sensor 23b, and when the output of the displacement sensor 23b falls below a predetermined threshold value THR, the electromagnetic valve 27a is turned on to introduce air into the working chamber 6a. Thereby, the pump chamber 5a is switched from the expansion process to the compression process. However, at this time, since air is continuously supplied to the other working chamber 6b, the pump chamber 5b also maintains the compression process. Accordingly, the suction valves 18a and 18b are closed, the discharge valves 19a and 19b are opened, and the liquid is discharged from both the pump chambers 5a and 5b. The coil springs 14 of the connecting shafts 11a and 11b are compressed in order to absorb the dimensional change between both ends of the bellows 3a and 3b.

  When the proximity switch 21b detects the stroke end, the electromagnetic valve 27b is switched to air exhaust, and the bellows 3b is pulled by the connecting shafts 11a and 11b to start extending, so that the pump chamber 5b is switched to the expansion process. The above operation is repeated in the left and right pump chambers 5a and 5b.

  FIG. 2 shows the overlap distance PO in which both pump chambers 5a and 5b are in the compression process. As described above, the pulsation on the discharge side is suppressed by discharging the liquid from the other pump chamber immediately before the final stage of the discharge process in which the discharge pressure of the one pump chamber decreases. This overlap distance PO can be adjusted by setting values of threshold values THL and THR of displacement sensors 23a and 23b that define switching timing. More specifically, the output values of the displacement sensors 23a and 23b are sampled at both stroke ends of the reciprocating operation when the pump is started, and the ratio of the overlapping distance PO to the total stroke length (hereinafter, “ This is called “overlap rate”.) The controller 25 is provided with a ratio setting means (not shown), and an arbitrary ratio can be set using the setting means.

  According to the experiments by the present inventors, the optimum overlap rate is various, such as the number of strokes of the pump, the physical characteristics of the bellows 3a and 3b, the spring constant of the coil spring 14, the supply air pressure, and the supply / exhaust conditions of the supply air. Varies depending on the elements.

  For example, FIG. 3A is a graph showing the optimum overlap rate (%) and discharge-side pulsation pressure width (MPa) at each stroke number of the reciprocating operation of the pump. FIG. 3A also shows the discharge-side pulsation pressure width due to operation when there is no overlap as a comparative example. As is apparent from this figure, it is desirable to increase the optimum overlap rate as the number of strokes increases. When the number of strokes is 20 to 120 (spm), according to the graph, the overlap rate (%) is 11 to 29 (%). This is the result when the specific supply / exhaust conditions are specific conditions. And when considering various conditions, it is desirable that it is 11-50 (%).

  According to this embodiment, since the displacement sensors 23a and 23b can continuously detect the displacement at the stroke end portions of the connecting plates 9a and 9b, the overlap rate (%) is set by setting the threshold values THL and THR. ) Can be set freely. For this reason, the optimal setting which can suppress the pulsation of discharge fluid most can be performed. Further, according to the present embodiment, the optimum overlap rate can be selected without feedback from the discharge liquid and suction liquid pressure sensors.

[Second Embodiment]
In the previous embodiment, no particular mention was made of the point at which the overlap rate has a limit value. However, if the overlap rate is too large, the force that advances one movable partition member and the force that moves the other movable partition member forward. Antagonizes and causes pump operation to stop. The overlap rate at which the pump operation stops in this way is hereinafter referred to as “limit overlap rate”.

  FIG. 3B shows the limit overlap rate at each stroke number under certain conditions. In order not to stop the pump operation, it is desirable to control the operation of the pump so that the overlap rate is maintained within the range indicated by the hatching in the figure where the limit overlap rate is not exceeded and the pulsation can be taken. More desirably, it is desirable to maintain an overlap rate that is several percent (eg, 1 to 3%) less than the limit overlap rate. This optimal overlap rate varies depending on the number of strokes.

Therefore, in the second embodiment, based on the detection signals from the proximity switches 21a and 21b and the displacement sensors 23a and 23b shown in FIG. 1, the controller 25 monitors the overlapping rate of the pumps, and the number of strokes during the pump operation. The overlap rate is dynamically changed according to the situation.
Specifically, a control table is created in advance by obtaining the optimum overlap ratio in the hatching of FIG. 3B for various supply / exhaust conditions. The control table may be created by obtaining an optimum duplication rate by two-point calibration and obtaining other duplication rates by interpolation. Then, during the pump operation, the control table is referred to from the number of strokes and the outputs of the displacement sensors 23a and 23b, and when it is detected that the number of strokes has changed, control is performed to reduce or increase the overlap rate.

Thereby, it becomes an optimal duplication rate according to the number of strokes, and the pump can be operated with low pulsation.
It should be noted that the optimum overlap rate may vary depending on changes in the pump and surrounding environment over time, operating conditions including supply / exhaust conditions, and the like. Therefore, periodic calibration of the control table and dynamic calibration based on the output of the displacement sensors 23a, 23b, etc. may be performed.
Further, it is possible to operate while always searching for -1% to -3% of the "limit overlap rate" without creating a control table from the outputs of the displacement sensors 23a and 23b. At that time, feedback from the liquid pressure sensor is unnecessary.

[Third Embodiment]
FIG. 4 is a partial cross-sectional view of a connecting shaft 31a (31b) used in a double reciprocating pump according to the third embodiment of the present invention.

  In the first embodiment, the coil spring 14 is used as the expansion and contraction member of the coupling shafts 11a and 11b. However, in this embodiment, an air cushion is used as the expansion and contraction member. That is, the connecting shaft 31a (31b) includes shaft portions 32 and 33 and an air cushion portion 34 that couples both. The air cushion portion 34 includes an air cylinder 35 attached to the tip of the shaft portion 33 and a piston 36 attached to the tip of the shaft portion 32, and air having a predetermined pressure is supplied to the air cylinder 35 through the air introduction port 37. Is supplied.

  According to this embodiment, not only the optimal overlap rate but also the optimal spring pressure can be easily set. Further, the spring pressure can be changed with time.

[Fourth Embodiment]
FIG. 5 is a partial cross-sectional view of a connecting shaft 41a (41b) used in a double reciprocating pump according to the fourth embodiment of the present invention.

  In the previous embodiment, when one of the pump chambers is switched from the compression process to the expansion process, the energy accumulated in the coil spring 14 is released, so that an excessive suction pressure is generated on the suction side. Pulsations can be amplified. Therefore, in this embodiment, a damper is provided for reducing the urging force when the expansion / contraction member of the connecting shaft extends from the compressed state.

  The connecting shaft 41a (41b) of this embodiment includes shaft portions 42 and 43, a coil spring 44 that contracts when compressed, and a coil spring 45 for damper that contracts when expanded.

  According to this embodiment, when the pump chamber shifts from the compression process to the expansion process, the damper coil spring 45 suppresses rapid expansion of the pump chamber, so that pulsation on the suction side can be suppressed.

[Fifth Embodiment]
FIG. 6 is a further modification of the embodiment of FIG. 5 and shows an example in which an air cushion is used as a damper.

  In this embodiment, the connecting shaft 51a (51b) is constituted by shaft portions 52 and 53 and a cushion portion 54 provided between them, and the cushion portion 54 is formed by a balance between the coil spring 55 and the air cushion portion 56. It expands and contracts. By appropriately adjusting the air pressure introduced into the air cushion portion 56 from the air introduction port 57, pulsation on both the discharge side and the suction side can be reduced.

[Sixth Embodiment]
FIG. 7 shows an embodiment in which the embodiment of FIG.

  In the following embodiments, the same parts as those in the previous embodiment are denoted by the same reference numerals, and redundant descriptions are omitted.

  The connecting shafts 61a and 61b are constituted by shaft portions 62 and 63 and an air cushion portion 64 provided therebetween, and the air cushion portion 64 is constituted by an air cylinder 65 and a piston 66. The pulsation on both the discharge side and the suction side can be reduced by the balance between the pressure in the air cylinder 65 introduced from the air introduction ports 67 and 68 and the pressure on the back surface of the piston 66.

  In this embodiment, in addition to the regulators 26a and 26b and the electromagnetic valves 27a and 27b in the pump of FIG. 1, the regulators 28a and 28b and the electromagnetic valves 29a and 29b are provided in order to control the air cushion 64.

[Seventh Embodiment]
FIG. 8 is a diagram illustrating a modification of the sixth embodiment.

  This embodiment is an example in which the pressure control on the back surface of the piston 66 of the air cushion part 64 is realized by a check valve 69 and a low speed speed controller (speed controller).

  In this embodiment (when the connecting shaft 61a contracts), air is always supplied from the air introduction port 67 and air is introduced into the back surface of the piston 66, and when the connecting shaft 61a extends, a low-speed speed controller is used. 70 restricts the exhaust of air behind the piston 66. Thereby, it functions as a damper.

  According to this embodiment, it can be set as a simpler structure than 6th Embodiment.

[Eighth Embodiment]
FIG. 9 is a sectional view showing a double reciprocating pump according to the eighth embodiment of the present invention.

  In the previous embodiment, a bellows is used as the movable partition member. However, in this embodiment, a piston is used as the movable partition member.

  On both sides of the pump head 71 arranged in the center, cylindrical cylinders 72a and 72b, which are case members, are coaxially arranged, and a pair of spaces are formed inside them. In these spaces, pistons 73a and 73b are reciprocally arranged, respectively. The front ends of the pistons 73a and 73b face the pump head 71, and pump chambers 75a and 75b are formed between the pistons 73a and 73b. The proximal ends of the pistons 73a and 73b form working chambers 76a and 76b, and the shafts 77a and 77b are coaxially fixed. The other ends of the shafts 77a and 77b extend through the center of the bottom of the cylinders 72a and 72b through the seal member 78 to the outside of the cylinders 72a and 72b.

  The pump head 71 is provided with a suction port 86 and a discharge port 87 for the transfer fluid at positions facing the side surfaces of the pump, and ball-shaped suction valves 88a and 88b at positions from the suction port 86 to the pump chambers 75a and 75b. And discharge valves 89a and 89b are provided at positions from the pump chambers 75a and 75b to the discharge port 87.

  Other configurations are the same as those in FIG.

  Also in this pump, the optimum overlap rate can be set based on continuous displacement detection by the displacement sensors 23a and 23b, and pulsation can be effectively suppressed.

[Ninth Embodiment]
FIG. 10 is a sectional view showing a double reciprocating pump according to the ninth embodiment of the present invention.

  In the previous embodiment, a bellows or a piston is used as the movable partition member, but in this embodiment, a diaphragm is used as the movable partition member.

  Covers 92a and 92b, which are case members that form a space together with the main body 91, are mounted on both sides of the main body 91 in which the pump head disposed at the center is formed. Diaphragms 93a and 93b are mounted in spaces formed by the main body 91 and the covers 92a and 92b so as to divide the spaces into pump chambers 95a and 95b and working chambers 96a and 96b, respectively. The diaphragms 93 a and 93 b are connected by a connecting shaft 94 whose central portion penetrates the main body portion 91. The connection shaft 94 includes a coil spring 97 as an expansion / contraction member, and is configured to be expandable / contractible as a whole.

  The main body portion 91 is provided with a suction port 106 and a discharge port 107 for the transfer fluid, and ball-like suction valves 108a and 108b are provided in a path from the suction port 106 to the pump chambers 95a and 95b. , 95b to the discharge port 107 are provided with discharge valves 109a, 109b.

  Further, the covers 92a and 92b are provided with proximity switches 111a and 111b that face the rear surfaces of the diaphragms 93a and 93b and detect that the diaphragms 93a and 93b are most retracted. Displacement sensors 113a and 113b including linear encoders for detecting the displacement of the connection shaft 94 in the reciprocating direction are provided on the side surfaces of the connection shaft 94.

  Other configurations are the same as those in FIG.

  Also in this pump, the optimum overlap rate can be set based on continuous displacement detection by the displacement sensors 113a and 113b, and pulsation can be effectively suppressed.

[Tenth embodiment]
FIG. 11 is a sectional view showing a double reciprocating pump according to the tenth embodiment of the present invention.

  In the first embodiment, each of the connecting shafts 11a and 11b includes the coil spring 14 that is mounted at a substantially intermediate position between the shaft portions 12 and 13, but in this embodiment, the coil spring 14 is biased toward the shaft portion 12 side. It is mounted in the position. In addition, a pipe (not shown) of the suction port 16 and a pipe (not shown) of the discharge port 17 are provided with liquid pressure sensors 116, 117, and air pressure sensors 127a, 127b and a leak sensor 150a so as to face the working chambers 6a, 6b. , 150b. Furthermore, the displacement sensors 123a and 123b are formed of a laser displacement meter, and detect the displacement amounts of the connecting shafts 11a and 11b. The detection outputs of the pressure sensors 116, 117, 127 a and 127 b are input to the controller 25.

  According to this embodiment, since the coil springs 14 of the respective connecting shafts 11a and 11b are mounted at positions that are biased, it is possible to have a structure that does not contact the pipes of the suction port 16 and the discharge port 17 of the pump. Miniaturization can be achieved and the degree of freedom of piping can be improved.

  Further, the controller 25 can acquire and control not only the detection outputs from the proximity sensors 21a and 21b and the displacement sensors 123a and 123b but also the detection outputs from the pressure sensors 116, 117, 127a and 127b. For example, the following control is possible.

That is, the controller 25 can detect the pulsation of the transfer fluid on the suction side and the discharge side based on the outputs of the liquid pressure sensors 116 and 117, and can control the overlap rate so that the pulsation is minimized.
Further, when the pressure of the supply air changes, the optimum overlap rate (%) also changes. In this embodiment, the controller 25 monitors the supply air pressure with the air pressure sensors 127a and 127b and detects the detected air pressure. It is possible to control the overlap rate (%) based on
Furthermore, even when the controller 25 uses an electro-pneumatic regulator for the regulators 26a and 26b and the controller 25 controls the supply air pressure, the flow rate constant control is performed to keep the number of strokes constant regardless of the change in the discharge pressure. It is possible to change the overlap rate (%) according to the supply air pressure.

  In addition, the pump may be operated by correcting the zero point of the displacement sensors 123a and 123b in consideration of the influence of temperature change and aging of each part of the pump. For the zero point correction, for example, the controller 25 obtains a value at the time of maximum movement of the coupling shafts 11a and 11b at the start of the pump, and incorporates this in the control, or periodically checks based on this. You can drive like that.

[Other Embodiments]
In the eighth and ninth embodiments described above, it goes without saying that a damper as shown in FIGS. 5 to 7 may be provided on the connecting shaft in order to prevent pulsation on the discharge side.

  DESCRIPTION OF SYMBOLS 1,71 ... Pump head, 2a, 2b, 72a, 72b ... Cylinder, 3a, 3b ... Bellows, 5a, 5b ... Pump chamber, 6a, 6b ... Working chamber, 11a, 11b, 31a, 31b, 41a, 41b, 51a 51b, 94 ... connecting shaft, 14, 44, 45, 55, 97 ... coil spring, 16, 86, 106 ... suction port, 17, 87, 107 ... discharge port, 18a, 18b, 88a, 88b, 108a, 108b ... Suction valve, 19a, 19b, 89a, 89b, 109a, 109b ... discharge valve, 21a, 21b, 111a, 111b ... proximity switch, 23a, 23b, 113a, 113b ... displacement sensor, 25 ... controller, 26a, 26b, 28a, 28b ... Regulator, 27a, 27b, 29a, 29b ... Solenoid valve.

Claims (11)

A case member that forms a pair of spaces along the axial direction inside;
A pair of movable partition members arranged in the pair of spaces so as to be deformable or movable in the axial direction and partitioning the pair of spaces into the pump chamber and the working chamber in the axial direction;
A connecting shaft for connecting the pair of movable partition members in an axial direction via an elastic member;
A suction valve that is provided on the suction side of the pump chamber and guides a transfer fluid to the pump chamber;
A discharge valve provided on the discharge side of the pump chamber for discharging the transfer fluid from the pump chamber;
A valve mechanism for introducing a working fluid into the working chamber and discharging the working fluid from the working chamber;
A displacement sensor for continuously detecting the displacement of each of the pair of movable partition members;
Based on the output of the displacement sensor, the pair of movable partition members is formed by switching the valve mechanism so that the compression process of one pump chamber and the compression process of the other pump chamber partially overlap each other. A double reciprocating pump characterized by comprising a controller for driving. The controller has setting means for setting an overlapping rate indicated by a ratio of the overlapping distance to the total stroke length of the movable partition member, and the setting value of the overlapping rate set by the setting unit and the displacement The double reciprocating pump according to claim 1, wherein the overlap rate is controlled based on an output of a sensor. 2. The duplex according to claim 1, wherein the controller increases the overlapping rate indicated by the ratio of the overlapping distance to the total stroke length of the movable partition member as the number of strokes of the pair of movable partition members increases. Reciprocating pump. The controller is configured to maintain the overlap rate indicated by the ratio of the overlap distance with respect to the total stroke length of the movable partition member at a value 1 to 3% less than a limit value of the overlap rate at which the pump operation stops. The double reciprocating pump according to claim 1, wherein the movable partition member is driven. The double reciprocating pump according to claim 4, wherein the controller changes the optimum overlap rate periodically or dynamically.   2. The double reciprocating pump according to claim 1, wherein the expansion / contraction member of the connection shaft has a damper that relaxes an urging force when the connection shaft extends from a compressed state.   2. The double reciprocating pump according to claim 1, wherein the elastic member is a coil spring.   2. The double reciprocating pump according to claim 1, wherein the elastic member is an air cushion.   The double reciprocating pump according to claim 1, further comprising proximity sensors that respectively detect that the pair of movable partition members have reached the end of the moving stroke. The valve mechanism is
A pair of valves respectively provided in the pair of working chambers;
A pair of regulators for adjusting the pressure of the working fluid from a working fluid supply source and supplying the working fluid to the pair of valves, respectively. Double reciprocating pump. A pump head,
A pair of bottomed cylindrical bellows which are attached to both sides of the pump head so that the opening sides face each other to form a pump chamber inside and expand and contract in the axial direction.
The pair of bellows are coaxially arranged with respect to the bellows so as to accommodate the pair of bellows, respectively, and an operating chamber is formed between the pair of bellows. A pair of bottomed cylindrical cylinders;
A pair of pump shafts that are airtight and slidable through the bottoms of the pair of cylinders, respectively, and whose one ends are respectively connected to the bottoms of the pair of bellows;
A connecting shaft that connects the other ends of the pair of pump shafts in an axial direction via an elastic member;
A valve unit that is mounted on the pump head in the pump chamber, guides the transfer fluid from the suction port of the transfer fluid to the pump chamber, and guides the transfer fluid from the pump chamber to the discharge port of the transfer fluid;
A valve mechanism for introducing a working fluid into the working chamber and discharging the working fluid from the working chamber;
A displacement sensor for continuously detecting the displacement of the pair of bellows,
Based on the output of the displacement sensor, the pair of bellows is driven by switching the valve mechanism so that the compression process of the one pump chamber and the compression process of the other pump chamber partially overlap each other. A double reciprocating pump characterized by comprising:

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