JP5183280B2 - Piston pump and fresh water generator using the piston pump - Google Patents

Description

  The present invention relates to a piston pump and a fresh water generator using the piston pump.

  As an apparatus for separating water (fresh water) from a liquid to be treated such as seawater, for example, a fresh water generator disclosed in Patent Document 1 is known. As shown in FIG. 4, the fresh water generator includes a reverse osmosis membrane device 101 and a piston pump 102 that supplies a liquid to be treated such as seawater to the reverse osmosis membrane device 101.

The piston pump 102 has two chambers 104 disposed on both sides of the double-acting hydraulic actuator 103, and has pistons 105 that can reciprocate in each chamber 104. The two pistons 105 and 105 are connected to each other by a sliding shaft 106 included in the double-acting hydraulic actuator 103. A piston 107 is provided at a substantially central portion of the sliding shaft 106. By supplying a driving hydraulic fluid to one side 107a of the piston 107, the sliding shaft moves forward and is driven to the other side 107b of the piston 107. By supplying the hydraulic fluid, the sliding shaft 106 is configured to return.
Special table 2003-502544 gazette

  However, when pumping the liquid to be treated such as seawater to the reverse osmosis membrane device using the above-mentioned piston pump, high pressure is repeatedly applied to the sliding shaft that connects the pistons, so damage such as wear occurs on the sliding shaft. There was a problem that it was easy to do.

  Moreover, in order to drive the above-mentioned piston pump, much energy was required, and there also existed a problem that it was difficult to drive a piston pump and a fresh water generator efficiently.

  The present invention has been made to solve such problems, and an object of the present invention is to provide a piston pump that is less likely to be damaged and that is excellent in energy saving efficiency, and a fresh water generator using the piston pump. .

  The object of the present invention is a piston pump comprising a cylinder having an internal space and a plurality of pistons slidably disposed in the internal space, wherein the cylinder has a first fluid in the internal space. A first inflow / outflow portion capable of inflow / outflow; and a second inflow / outflow portion arranged on both sides of the first inflow / outflow portion and capable of allowing the second fluid to flow into / out of the internal space. Is achieved by a piston pump disposed between the first inflow / outflow portion and each of the second inflow / outflow portions.

  Further, in this piston pump, a recess along the sliding direction of the piston is formed at an end portion of each piston on the first inflow / outflow portion side, and a first fluid is formed in the first inflow / outflow portion. It is preferable that a guide tube is provided to guide each of the recesses, and a part of the guide tube is configured to be slidable with the inner peripheral surface of each recess.

  Further, at least one of the pistons has a piston head that is in sliding contact with the inner peripheral surface of the cylinder, a diameter smaller than the diameter of the piston head, and is closer to the first inflow / outflow portion than the piston head. A piston shaft provided; and the cylinder communicates with the inner space, an end plate that forms a sealed space between the piston head and the piston shaft, and a third fluid. Is provided with a third inflow / outflow part capable of flowing into and out of the sealed space, and the end plate is preferably formed with an opening through which the outer peripheral surface of the piston shaft can slide.

  The above object of the present invention is to provide the above piston pump, first fluid supply means for supplying a first fluid to the first inflow / outflow portion, and second for supplying a second fluid to the second inflow / outflow portion. A fresh water generator comprising a fluid supply means and a water separation means for separating water from a second fluid, wherein the first fluid supply means is configured to change a supply pressure of the first fluid. The piston pump has a pressing force on the piston by the first fluid supplied from the first fluid supply means, rather than a pressing force on the piston by the second fluid supplied from the second fluid supply means. By lowering, each piston is slid toward the first inflow / outflow portion to guide the second fluid into the internal space through the second inflow / outflow portion, and supplied from the first fluid supply means. By the first fluid By making the pressing force on the piston higher than the pressing force on the piston by the second fluid supplied from the second fluid supply means, the pistons are slid in a direction away from each other, thereby causing the second outflow. The second fluid guided to the internal space via the inlet is configured to be able to be guided to the water separation unit, and is a second fluid that is a residual second fluid from which water has been separated by the water separation unit. 3 fluid is achieved by the fresh water generator configured to be able to supply the sealed space via the third inflow / outflow part.

  ADVANTAGE OF THE INVENTION According to this invention, it is hard to produce damage and can provide the piston pump excellent in energy saving efficiency, and the fresh water generator using this piston pump.

  Hereinafter, a piston pump according to the present invention and a fresh water generator using the piston pump will be described with reference to the accompanying drawings. FIG. 1 is a schematic configuration cross-sectional view of a piston pump 1 according to an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram of a fresh water generator 5 using the piston pump 1.

  As shown in FIG. 1, the piston pump 1 according to the present embodiment includes a cylinder 2 having an internal space 21 and two pistons 3 that are slidably disposed in the internal space 21. The cylinder 2 includes a first inflow / outflow portion 22 and two second inflow / outflow portions 23 that communicate with the internal space 21. The first inflow / outflow portion 22 is configured such that the first fluid can flow into and out of the recess 32 formed in the piston 2, and the second inflow / outflow portion 23 allows the second fluid to flow into and out of the internal space 21. It is configured.

  The first inflow / outflow portion 22 is provided at a substantially central portion of the cylinder 2. The first inflow / outflow portion 22 is provided with a guide tube 24 that guides a first fluid to a recess 32 provided in each piston 3. The guide tube 24 has a conduit 24a connected to the first inflow / outflow portion 22 and a conduit 24b extending along the sliding direction of the piston 3 (left and right direction in FIG. 1). One end of the pipe line 24 a connected to the pipe 22 has a substantially T-shape connected at a substantially central part of the pipe line 24 b extending along the sliding direction of the piston 3. A part of the outer peripheral surface 241 of the pipe line 24 b extending along the sliding direction of the piston 3 can be slidably contacted with the inner peripheral surface of the concave portion 32 formed in the piston 3, and the concave portion is interposed via the guide tube 24. The first fluid supplied to 32 is configured not to leak from the recess 32.

  The second inflow / outflow portions 23 and 23 are respectively arranged on both sides of the first inflow / outflow portion 22. In FIG. 1, the second inflow / outflow portions 23 and 23 are provided at both ends of the cylinder 2, respectively.

  As shown in FIG. 1, the piston 3 includes a piston head 31 and a piston shaft 33. The piston head is formed so that its outer peripheral surface is in sliding contact with the inner peripheral surface 21a of the cylinder. The piston shaft 33 is formed so that its diameter is smaller than the diameter of the piston head 31.

  In addition, the cylinder 2 includes end plates 25 that are respectively disposed between the first inflow / outflow portions 22 and the second inflow / outflow portions 23. An opening is provided in the center of each end plate 25, and the inner peripheral surface of the opening is formed so as to be in sliding contact with the outer peripheral surface of the piston shaft 33. Each end plate 25 has a function as a stopper that restricts movement of each piston 3 toward the first inflow / outflow portion 22 from a predetermined position. Each end plate 25 also has a function of forming a sealed space 4 between the piston head 31, the piston shaft 33, and the inner peripheral surface 21a of the cylinder.

  The cylinder 2 communicates with the sealed space 4 formed between the piston head 31, the outer peripheral surface of the piston shaft 33, the inner peripheral surface 21 a of the cylinder, and the end plate 25, and the third fluid is in the sealed space 4. A third inflow / outflow portion 26 capable of inflow / outflow is provided.

  Each piston 3 slidably disposed in the internal space 21 of the cylinder 2 is disposed between the first inflow / outflow portion 22 and the second inflow / outflow portion 23. Each piston 3 is arranged such that its piston head 31 is located closer to the second inflow / outflow portion 23 than each end plate 25 provided in the cylinder 2. A concave portion 32 extending along the sliding direction of the piston 3 is formed at the end of each piston shaft 33 on the first inflow / outflow portion 22 side. As described above, the inner peripheral surface of the recess 32 is formed so as to be slidable in contact with a part of the outer peripheral surface 241 of the guide tube 24.

  With such a configuration, the first fluid presses each piston 3 by appropriately setting the supply pressure of the first fluid guided to the concave portion 32 of the piston 3 through the first inflow / outflow portion 22 and the guide tube 24. The second fluid supplied to the internal space 21 of the cylinder 2 via the second inflow / outflow portion 23 is made lower than the pressing force that presses each piston 3 to cause each piston 3 to flow out to the first outflow. It is possible to guide the second fluid to the space formed between the head 31 of each piston 3 and the second inflow / outflow portion 23 through the second inflow / outflow portion 23 by sliding to the inflow portion 22 side.

  Further, by changing the supply pressure of the first fluid guided to the recess 32 of the piston 3 via the first inflow / outflow portion 22 and the guide tube 24, the pressing force by which the first fluid presses each piston 3 is changed. By setting the second fluid supplied to the internal space 21 of the cylinder 2 via the second inflow / outflow portion 23 to be higher than the pressing force for pressing the pistons 3, the pistons 3 are separated from each other. It is possible to discharge the second fluid guided to the space formed between the head 31 of each piston 3 and the second inflow / outflow portion 23 to the outside.

  Further, the sealed space 4 has its volume increased as each piston 3 slides away from each other, and conversely, when each piston 3 slides in a direction closer to each other, Since the volume is formed so as to decrease, the third fluid can be sucked into the sealed space 4 through the third inflow / outflow portion 26 by sliding the pistons 3 in the directions away from each other. As the pistons 3 slide in the direction approaching each other, the third fluid sucked into the sealed space 4 can be discharged to the outside through the third inflow / outflow portion 26.

  Next, the fresh water generator 5 comprised using the piston pump 1 mentioned above is demonstrated. As shown in the schematic configuration diagram of FIG. 2, the fresh water generator 5 includes the above-described piston pump 1, first fluid supply means 6, second fluid supply means 7, third fluid supply means 8, and reverse osmosis. And a membrane device 9.

  The fresh water generator 5 operates the reverse osmosis membrane device 9 with water to be treated such as seawater sucked into each space formed between each piston head 31 and each second inflow / outflow portion 23 by the operation of the piston pump 1. It is configured to be capable of being pumped. Since the piston pump 1 has the same configuration as described above, detailed description thereof is omitted.

  The first fluid supply means 6 is means for supplying the first fluid to the first inflow / outflow portion 22 of the cylinder 2 and is configured to be able to change the supply pressure of the first fluid. The first fluid supply means 6 includes a tank 61 that is open to the atmosphere for storing a working fluid such as a working fluid that is a first fluid, a first fluid pump 62 that pumps the working fluid in the tank 61, A first fluid supply pipe 63 that guides the working fluid pumped by the fluid pump 62 to the first inflow / outflow part 22; a first fluid return pipe 64 for returning the working fluid discharged from the first inflow / outflow part 22 to the tank 61; It has. Examples of the first fluid pump 62 include a positive displacement hydraulic oil pump. By changing the rotation speed of the first fluid pump 62, the supply pressure of the working fluid supplied to the cylinder 2 can be changed. In the middle of the first fluid supply pipe 63 and the first fluid return pipe 64, valve bodies 65 and 66 such as electromagnetic valves are provided, respectively.

  The second fluid supply means 7 guides a second fluid, such as seawater, to each second inflow / outflow portion 23 of the cylinder 2. The second fluid supply means 7 includes a second fluid pump 71 that pumps seawater (second fluid), and a second fluid supply pipe that guides the seawater pumped by the second fluid pump 71 to each second inflow / outflow portion 23. 72 and water separation means supply piping 73 for guiding seawater discharged from the cylinder 2 through the second inflow / outflow portions 23 to the reverse osmosis membrane device 9. As the second fluid pump 71, a general spiral pump can be exemplified. In the middle of the second fluid supply pipe 72 and the water separation means supply pipe 73, check valves 74 and 75 are arranged, respectively. One end of the water separation means supply pipe 73 is branched and connected to the second fluid supply pipe 72.

  The third fluid supply means 8 guides the third fluid (concentrated seawater), which is residual seawater from which water has been separated by the reverse osmosis membrane device 9, to the third inflow / outflow portion 26 of the cylinder 2. The third fluid supply pipe 81 is connected to the reverse osmosis membrane device 9 and the other end is branched and connected to each third inflow / outflow portion 26. A third fluid discharge pipe 82 is connected to the middle of the third fluid supply pipe 81. In addition, valve bodies 83 and 84 such as electromagnetic valves are provided in the middle of the third fluid supply pipe 81 and the third fluid discharge pipe 82, respectively.

  The reverse osmosis membrane device 9 is water separation means for separating and producing water (fresh water) for drinking or industrial use from seawater, for example. The reverse osmosis membrane device 9 is internally divided by a reverse osmosis membrane 91, and one side of the reverse osmosis membrane 91 is connected to the piston pump 1 via a water separation means supply pipe 73. Connected to the other side of the reverse osmosis membrane device 9 is a fresh water discharge pipe 92 for discharging water (fresh water) that has passed through the reverse osmosis membrane 91. Further, a third fluid supply pipe 81 is connected to one side of the reverse osmosis membrane 91 in the reverse osmosis membrane device 9, and the concentrated seawater in which the salinity is concentrated without passing through the reverse osmosis membrane 91 is supplied to the third fluid supply pipe 81. The fluid is configured to be guided to the third inflow / outflow portion 26 of the piston pump 1.

  Next, the operation of the piston pump 1 according to the present embodiment and the fresh water generator 5 using the piston pump 1 will be described.

  First, the 2nd fluid pump 71 of the 2nd fluid supply means 7 is driven, and to-be-processed water, such as seawater, is supplied toward the 2nd inflow / outflow part 23 of a cylinder 2 pump by substantially constant supply pressure. Further, the valve body 65 in the first fluid supply pipe 63 of the first fluid supply means 6 is closed, and the valve body 66 in the first fluid return pipe 64 is opened. Note that the driving of the first fluid pump 62 of the first fluid supply means 6 is stopped. In this case, the pressing force by which seawater (second fluid) supplied by the second fluid supply means 7 presses the piston 3 is the working fluid (first fluid) supplied to the recess 32 of each piston 3. 2 becomes higher than the pressing force that presses the piston 3, so that the pistons 3 arranged in the internal space 21 of the cylinder 2 slide in the direction approaching each other as shown in FIG. Seawater is sucked into the internal space 21 formed between the first and second inflow / outflow portions 23. Each piston 3 stops at a position where the head 31 comes into contact with each end plate 25.

  In addition, each sealed space 4 formed by the piston head 31, the outer peripheral surface of the piston shaft 33, the inner peripheral surface (sliding surface) 21a of the cylinder 2, and the end plate 25 slides in a direction in which the pistons 3 approach each other. By moving, the volume will decrease. At this time, residual seawater (concentrated seawater) from which water has been separated by the reverse osmosis membrane device 9 sucked into the sealed space 4 passes through a part of the third fluid supply pipe 81 and the third fluid discharge pipe 82. And discharged to the outside. The valve body 83 provided in the third fluid supply pipe 81 is set in a closed state, and the valve body 84 provided in the third fluid discharge pipe 82 is set in an open state.

  Next, the valve body 65 in the first fluid supply pipe 63 of the first fluid supply means 6 is set in the open state, and the valve body 66 in the first fluid return pipe 64 is set in the closed state. Then, by driving the first fluid pump 62 in the first fluid supply means 6, the working fluid (first fluid) is recessed in the pistons 3 formed in the pistons 3 via the first inflow / outflow portions 22 and the guide tubes 24. Supply in. At this time, the pressing force with which the working fluid (first fluid) presses the piston 3 is more than the pressing force with which the seawater (second fluid) supplied by the second fluid supply means 7 presses the piston 3. Pump the working fluid at a higher supply pressure. Since the pressing force on the piston 3 by the working fluid guided into the recess 32 of each piston 3 is higher than the pressing force on the piston 3 by seawater supplied by the second fluid pump 71, as shown in FIG. Is a reverse osmosis membrane device that slides in a direction away from each other and converts seawater in the internal space 21 between the head 31 of each piston 3 and each second inflow / outflow portion 23 through a water separation means supply pipe 73. Pump toward 9 In addition, since the check valve 74 is provided in the middle of the second fluid supply pipe 72, the seawater being pumped is prevented from flowing back through the second fluid supply means 7.

  Further, the volume of the sealed space 4 increases as the pistons 3 slide in a direction away from each other. At this time, seawater (concentrated seawater) from which water has been separated by the action of the reverse osmosis membrane device 9 is sucked into the sealed space 4 via the third fluid supply pipe 81. In addition, the valve body 83 provided in the 3rd fluid supply piping 81 is set to the open state, and the valve body 84 provided in the 3rd fluid discharge piping 82 is set to the closed state.

  As described above, the piston is driven by the pressing force acting on the piston 3 by the working fluid (first fluid) supplied by the first fluid supply means 6 and the seawater (second fluid) supplied by the second fluid supply means 7. By repeatedly changing the balance with the pressing force acting on 3, the pistons 3 are reciprocated to feed seawater to the reverse osmosis membrane device 9.

  In the reverse osmosis membrane device 9, which is the reverse osmosis membrane device 9, water (fresh water) that has passed through the reverse osmosis membrane 91 is discharged to the outside through the fresh water discharge pipe 92, while concentrated seawater that does not pass through the reverse osmosis membrane 91 is It is supplied to the third inflow / outflow part 26 of the cylinder 2 through the third fluid supply pipe 81. The water discharged through the fresh water discharge pipe 92 is used as drinking water or industrial water. Further, as described above, the concentrated seawater supplied toward the third inflow / outflow portion 26 of the cylinder 2 is sucked into the sealed space 4 by the reciprocating motion of the piston 3, and then externally passed through the third fluid discharge pipe 82. To be discharged.

  The piston pump 1 according to the present embodiment is disposed on the both sides of the first inflow / outflow portion 22 and the first inflow / outflow portion 22 through which the first fluid can flow into and out of the internal space 21 and in the internal space 21. The cylinder 2 is configured so as to include a second inflow / outflow portion 23 that communicates and allows the second fluid to flow into and out of the internal space 21, and each piston 3 that is slidable in the internal space 21 has the first Since it is configured to be disposed between the inflow / outflow portion 22 and the second inflow / outflow portion 23, a conventional shaft for connecting the pistons 3 can be omitted. As a result of omitting parts that may be frequently damaged due to wear and the like in this way, the life of the piston pump 1 and the fresh water generating device 5 using the piston pump 1 can be extended and the work load required for maintenance can be reduced. It becomes possible to reduce. Further, by omitting the shaft, the weight of the piston 3 reciprocated by the action of the first fluid (working fluid) and the second fluid (seawater) is reduced, so that the piston 3 is consumed to reciprocate. Energy to be greatly reduced, and energy saving of the piston pump 1 and the fresh water generator 5 using the piston pump 1 can be achieved.

  In addition, the piston pump 1 according to the present embodiment forms a recess 32 along the sliding direction of the piston 3 at the end of each piston 3 on the first inflow / outflow portion 22 side. A guide tube 24 that guides one fluid to each recess 32 is provided, and a part of the guide tube 24 is configured to be slidable in contact with the inner peripheral surface of each recess 32. With such a configuration, the piston 3 reciprocating in the internal space 21 can be stably supported.

  Further, the sealed space 4 is formed between the piston head 31, the outer peripheral surface of the piston shaft 33, the inner peripheral surface 21 a of the cylinder and the end plate 25, and a third inflow / outflow portion 26 communicating with the sealed space 4 is provided. Due to the configuration, the third fluid other than the first and second fluids can be sucked into the sealed space 4 by the reciprocating motion of the piston 3 and then pumped. In particular, when the pressing force of the third fluid that flows into the sealed space 4 via the third inflow / outflow portion 26 and presses the piston head 31 is greater than the pressing force that the second fluid presses the piston head 31, The third fluid exerts an action of moving the pistons 3 in directions away from each other, so that the driving energy of the first fluid pump 62 in the first fluid supply means 6 can be reduced.

  As mentioned above, although one embodiment of piston pump 1 concerning the present invention and fresh water generator 5 using this piston pump 1 was described, the concrete composition of the present invention is not limited to the above-mentioned embodiment. For example, the fresh water generator 5 may be configured by arranging a plurality of piston pumps in parallel. At this time, for example, the pistons in one piston pump are arranged at positions where they are farthest from each other, and the pistons in the other piston pump are arranged at an intermediate position. With such a configuration, while one piston pump is sucking in seawater, the other piston pump can discharge seawater to the reverse osmosis membrane device 9, so that the first fluid pump 62 is started and stopped. In addition, continuous seawater supply to the reverse osmosis membrane device 9 can be performed.

  Further, in the above embodiment, the recesses 32 extending in the direction along the sliding direction of each piston are provided at the end of each piston 3 on the first inflow / outflow portion 22 side, and the first fluid is guided to each recess 32. Although the pipe 24 is provided in the first inflow / outflow part 22 and a part of the guide pipe 24 is configured to be slidable in contact with the inner peripheral surface of each recess 32, the recess 32 and the guide pipe 24 are not provided. A configuration may be adopted.

  In the above embodiment, the sealed space 4 whose volume increases or decreases with the reciprocation of each piston is defined between the piston head 31, the outer peripheral surface of the piston shaft 33, the inner peripheral surface 21a of the cylinder 2, and the end plate 25. Although it is configured to form, a configuration in which the sealed space 4 is not provided may be employed.

  In the above embodiment, the first inflow / outflow portion 22 is provided with a guide tube 24 that guides the first fluid to the recess 32 provided in each piston 3, and a part of the outer peripheral surface 241 of the guide tube 24 is provided. Is configured to be slidable in contact with the inner peripheral surface of the recess 32 formed in the piston 3. When such a configuration is employed, the internal space of the cylinder 2 sandwiched between the end plates 25 and 25 does not need to be a sealed space, and for example, the first fluid flowing into and out of the recess 32 via the guide tube 24. However, an opening for confirming whether or not leakage has occurred from the end of the piston 3 on the first outflow portion 22 side is provided in a partial region of the cylinder 2 corresponding to a region sandwiched between the end plates 25 and 25. It may be formed.

It is a schematic structure sectional view of the piston pump concerning one embodiment of the present invention. FIG. 2 is a desalination apparatus using the piston pump shown in FIG. 1, and is a schematic configuration diagram showing a state in the middle of sucking seawater (second fluid). FIG. 2 is a desalination apparatus using the piston pump shown in FIG. 1, and is a schematic configuration diagram showing a state in the middle of discharging seawater (second fluid). It is a schematic block diagram which shows the conventional fresh water generator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piston pump 2 Cylinder 21 Internal space 21a Sliding contact surface (inner peripheral surface)
22 1st inflow / outflow part 23 2nd outflow / inflow part 24 Guide pipe 25 End plate 26 3rd inflow / outflow part 3 Piston 31 Piston head 32 Recessed part 33 Piston shaft 4 Sealed space 5 Fresh water generator 6 1st fluid supply means 7 2nd fluid supply means 8 Third fluid supply means 9 Reverse osmosis membrane device (water separation means)

Claims (4)

A piston pump comprising a cylinder having an internal space and a plurality of pistons slidably disposed in the internal space,
The cylinder includes a first inflow / outflow portion and two second inflow / outflow portions communicating with the internal space, and the second outflow / inflow portions are disposed on both sides of the first inflow / outflow portion, respectively.
The pistons are respectively disposed between the first inflow / outflow portions and the second inflow / outflow portions ,
At the end of each piston on the first inflow / outflow side, a recess is formed along the sliding direction of the piston,
The first fluid is supplied to the first inflow / outflow portion from the first fluid supply means so that the supply pressure can be changed, and the second fluid is supplied to the second inflow / outflow portion from the second fluid supply means. ,
The first fluid is a working fluid, the second fluid is a fluid pumped by the piston pump,
The second inflow / outflow portion is configured to allow the second fluid to flow into and out of the internal space,
The first inflow / outflow portion is provided with a guide pipe for guiding the first fluid to the recesses, and a part of the guide tube is configured to be slidable with an inner peripheral surface of the recesses,
The balance between the pressing force acting on each piston by the first fluid supplied by the first fluid supply means and the pressing force acting on each piston by the second fluid supplied by the second fluid supply means is balanced. A piston pump for sliding the pistons by changing . At least one of the pistons has a piston head that is in sliding contact with the inner peripheral surface of the cylinder, a diameter smaller than the diameter of the piston head, and is provided closer to the first inflow / outflow portion than the piston head. A piston shaft, and
The cylinder communicates with the sealed space between an inner peripheral surface thereof, the piston head and the piston shaft, and an end plate, and a third fluid can flow into and out of the sealed space. 3 inflow / outflow parts,
The piston pump according to claim 1 , wherein the end plate is formed with an opening through which an outer peripheral surface of the piston shaft can slide. A piston pump comprising a cylinder having an internal space and a plurality of pistons slidably disposed in the internal space ;
First fluid supply means for supplying a first fluid;
Second fluid supply means for supplying a second fluid;
A water separator comprising a water separation means for separating water from the second fluid,
The cylinders are respectively disposed on both sides of the first inflow / outflow portion and the first inflow / outflow portion through which the first fluid supplied from the first fluid supply means can flow into and out of the internal space. A second inflow / outflow part capable of inflow / outflow of the second fluid supplied from the fluid supply means into the internal space,
Each piston is disposed between the first inflow / outflow portion and the second inflow / outflow portion, respectively.
At least one of the pistons has a piston head that is in sliding contact with the inner peripheral surface of the cylinder, a diameter smaller than the diameter of the piston head, and is provided closer to the first inflow / outflow portion than the piston head. A piston shaft, and
The cylinder communicates with the sealed space between an inner peripheral surface thereof, the piston head and the piston shaft, and an end plate, and a third fluid can flow into and out of the sealed space. 3 inflow / outflow parts,
The end plate is formed with an opening capable of sliding contact with the outer peripheral surface of the piston shaft,
The first fluid supply means is configured to change the supply pressure of the first fluid,
The piston pump makes a pressing force on the piston by the first fluid supplied from the first fluid supply means lower than a pressing force on the piston by the second fluid supplied from the second fluid supply means. Accordingly, the piston is slid toward the first inflow / outflow portion to guide the second fluid into the internal space via the second inflow / outflow portion, and is supplied from the first fluid supply means. By making the pressing force on the piston by the first fluid higher than the pressing force on the piston by the second fluid supplied from the second fluid supply means, the pistons are slid in a direction away from each other. The second fluid guided to the internal space via the second inflow / outflow part is configured to be able to guide to the water separation means,
A fresh water generator configured to be able to supply a third fluid, which is a residual second fluid from which water has been separated by the water separation means, to the sealed space via the third inflow / outflow portion. A piston pump comprising a cylinder having an internal space and a plurality of pistons slidably disposed in the internal space ;
First fluid supply means for supplying a first fluid;
Second fluid supply means for supplying a second fluid;
A water separator comprising a water separation means for separating water from the second fluid,
The cylinders are respectively disposed on both sides of the first inflow / outflow portion and the first inflow / outflow portion through which the first fluid supplied from the first fluid supply means can flow into and out of the internal space. A second inflow / outflow part capable of inflow / outflow of the second fluid supplied from the fluid supply means into the internal space,
Each piston is disposed between the first inflow / outflow portion and the second inflow / outflow portion, respectively.
At the end portion on the first inflow / outflow portion side of each piston, a recess is formed along the sliding direction of the piston,
The first inflow / outflow part is provided with a guide pipe for guiding the first fluid to the respective recesses,
A part of the guide tube is configured to be slidable in contact with the inner peripheral surface of each recess.
At least one of the pistons has a piston head that is in sliding contact with the inner peripheral surface of the cylinder, a diameter smaller than the diameter of the piston head, and is provided closer to the first inflow / outflow portion than the piston head. A piston shaft, and
The cylinder communicates with the sealed space between an inner peripheral surface thereof, the piston head and the piston shaft, and an end plate, and a third fluid can flow into and out of the sealed space. 3 inflow / outflow parts,
The end plate is formed with an opening capable of sliding contact with the outer peripheral surface of the piston shaft,
The first fluid supply means is configured to change the supply pressure of the first fluid,
The piston pump makes a pressing force on the piston by the first fluid supplied from the first fluid supply means lower than a pressing force on the piston by the second fluid supplied from the second fluid supply means. Accordingly, the piston is slid toward the first inflow / outflow portion to guide the second fluid into the internal space via the second inflow / outflow portion, and is supplied from the first fluid supply means. By making the pressing force on the piston by the first fluid higher than the pressing force on the piston by the second fluid supplied from the second fluid supply means, the pistons are slid in a direction away from each other. The second fluid guided to the internal space via the second inflow / outflow part is configured to be able to guide to the water separation means,
A fresh water generator configured to be able to supply a third fluid, which is a residual second fluid from which water has been separated by the water separation means, to the sealed space via the third inflow / outflow portion.

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