JP4925921B2 - Piston pump - Google Patents

Description

  The present invention relates to a piston pump, and more particularly to a piston pump that transports fluid by reciprocating movement of a piston.

  A piston pump is known that includes a cylinder and a piston that is provided so as to freely advance and retract within the cylinder. In a piston pump, fluid is normally sucked into the cylinder by retracting the piston, and fluid is transported by discharging the fluid in the cylinder when the piston advances.

  Also, in the piston pump, when the piston advances, the fluid in the downstream direction of the advancement from the piston in the cylinder is discharged, and by retracting the piston, the fluid in the upstream direction of the piston in the cylinder is discharged. That is, what can always transport a fluid by the advance and retreat of a piston is known.

For example, the cross-sectional area of the piston rod is about ½ of the cross-sectional area of the cylinder, the amount of oil discharged in the piston rod expansion process, and the amount of oil discharged in the piston rod reduction process It has been proposed to equalize the oil discharge amount in the piston rod extension step and the reduction step (see, for example, Patent Document 1).
JP-A-8-135565

  However, in the above-described piston pump, in order to ensure slidability and sealing performance between the cylinder and the piston, the cylinder is required to have a mirror surface polishing, an inner diameter tolerance accuracy, and a central axis accuracy tolerance, etc. Pistons are required to prevent wear and tear. Therefore, when manufacturing cylinders and pistons, strict processing accuracy is required, and it is necessary to use a dedicated processing machine to increase the number of processing steps, which inevitably increases the manufacturing cost.

  In order to prevent damage to the inner surface of the cylinder and the piston, some pistons can be replaced from non-metallic materials (resins, etc.), but frequent replacement of the pistons is very expensive and reduces running costs. The rise is inevitable.

  Furthermore, with a small-capacity or small-capacity pump, the outer diameter of the piston becomes small, making it difficult to manufacture the piston, and it may not be possible to provide a packing or anti-abrasion prevention member on the piston because of its capacity. is there.

  An object of the present invention is to reduce the manufacturing cost and running cost with a simple configuration while ensuring fluidity and sealing performance while allowing fluid to be transported by pressure at a constant flow rate by the advance and retreat of the piston. It is to provide a piston pump.

  In order to achieve the above object, an invention according to claim 1 is a piston pump comprising a cylinder and a piston provided so as to be able to advance and retreat in the cylinder. The first space formed on the downstream side in the advance direction of the piston when arranged on the upstream side, and the upstream side in the advance direction of the piston when the piston is arranged on the most downstream side in the advance direction. And a direction in which the first cross-sectional area in the direction perpendicular to the advancing / retreating direction of the piston in the first space is perpendicular to the advancing / retreating direction of the piston in the second space. The second cross-sectional area is substantially doubled, and when the piston advances, the fluid flows out from the first space, and the fluid flows into the first space. An advancing flow path is formed to flow into the space and discharge the remaining fluid, and when the piston is retracted, the fluid flows into the first space and the fluid is discharged from the second space. A time channel is formed, and the cylinder is orthogonal to the piston and the advancing and retreating direction of the piston both when the piston is disposed on the most upstream side in the advancing direction and when disposed on the most downstream side in the advancing direction. It is characterized by having a facing portion that faces in the direction, and a sealing member interposed between the inner peripheral surface of the cylinder and the outer peripheral surface of the piston is provided in the facing portion.

  According to such a configuration, in the cylinder, there is a facing portion that faces the piston both when the piston is disposed on the most upstream side in the advancing direction and when disposed on the most downstream side in the advancing direction. The portion is provided with a seal member interposed between the inner peripheral surface of the cylinder and the outer peripheral surface of the piston.

  That is, in this configuration, the piston does not slide with the inner surface of the cylinder but slides with the seal member. Therefore, if the processing accuracy of the sliding portion of the piston with the sealing member is ensured, the sliding property and sealing property between the sealing member and the piston can be ensured, and the fluid can be transported with high accuracy. . Therefore, the clearance between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder can be increased to reduce the machining accuracy required for the inner peripheral surface of the cylinder. As a result, it is possible to reduce manufacturing costs by reducing the labor of processing.

  Moreover, in this structure, since a piston slides with a sealing member, durability of a piston can be improved. Therefore, the replacement of the piston can be made unnecessary for a long time, and the running cost can be reduced.

  Furthermore, in this configuration, the piston can be formed simply because it can be formed so as to be slidable with the seal member. Therefore, even a piston having a small outer diameter can be easily manufactured. Therefore, a small capacity or minute capacity pump can be realized at low cost.

  Furthermore, in this configuration, since the first cross-sectional area is substantially twice the second cross-sectional area, the maximum capacity of the first space is substantially twice the maximum capacity of the second space. Therefore, when the advancing flow path is formed by the advancement of the piston, the fluid having half the maximum capacity of the first space flows into the second space and the remaining amount of fluid is discharged. On the other hand, when the retraction flow path is formed by the retraction of the piston, fluid flows into the first space, and from the second space, the second space, that is, half of the maximum capacity of the first space flows. Discharged. As a result, since the same volume of fluid is discharged every time the piston advances or retracts, the fluid can be pressure transported at a constant flow rate by the advance and retreat of the piston.

  According to a second aspect of the present invention, in the first aspect of the present invention, a resin sleeve is provided on the inner peripheral surface of the cylinder.

  As described above, according to the first aspect of the present invention, the clearance between the outer peripheral surface of the piston and the inner peripheral surface of the cylinder can be increased. Therefore, as in this configuration, a resin sleeve can be provided on the inner circumferential surface of the cylinder.

  According to such a configuration, since the resin sleeve is provided on the inner peripheral surface of the cylinder, damage to the piston can be further reduced. Moreover, the unnecessary volume in a cylinder can be reduced and transportation efficiency can be improved. Furthermore, even if the sleeve needs to be replaced, it can be replaced at a low cost. Therefore, the durability and reliability of the apparatus can be further improved with a simple and inexpensive configuration.

  According to the first aspect of the present invention, while the fluid can be pressure-transported at a constant flow rate by the advancement and retraction of the piston, the manufacturing cost and the running cost can be reduced with a simple configuration while ensuring the sliding property and the sealing property. Can be reduced.

  According to the second aspect of the present invention, the durability and reliability of the device can be further improved.

  FIG. 1 is a schematic configuration diagram showing an advanced state of one embodiment of the piston pump of the present invention, and FIG. 2 is a schematic configuration diagram showing a retracted state of the piston pump shown in FIG. In the following description, for the sake of convenience, the advancing / retreating direction of the piston 3 described later is defined as the up / down direction, and the direction orthogonal to the advancing / retreating direction of the piston 3 is defined as the left / right direction.

  In FIG. 1, the piston pump 1 includes a block 2, a piston 3 disposed so as to be able to advance and retreat in a cylinder 5 of the block 2, and a rod 4 connected to the piston 3.

  The block 2 is made of metal, and includes a cylinder 5, an upper passage (advancing direction downstream passage) 6, a lower passage (advancing direction upstream passage) 7, and a communication passage 8.

  The cylinder 5 is formed in a cylindrical shape extending in the vertical direction along the axis of the block 2. The upper end of the cylinder 5 is disposed below the upper end of the block 2, and the lower end of the cylinder 5 is opened downward from the lower end portion of the block 2. A cylinder member 25 with a collar for fixing a sleeve 21 (described later) is provided at the lower end of the cylinder 5, and a ring-shaped lower end seal member 9 is provided at the lower end of the cylinder member 25 with the collar. The inner diameters of the flanged cylinder member 25 and the lower end seal member 9 are smaller than the outer diameter of the piston 3 and are sized so that the rod 4 can slide in close contact. The lower end seal member 9 prevents fluid from leaking from the lower space 17 (described later), and the flanged cylinder member 25 restricts further withdrawal of the piston 3.

  The upper passage 6 is formed so as to penetrate between the upper outer side of the block 2 and the upper part (upper space 16) in the cylinder 5 in the left-right direction. In the upper passage 6, a large-diameter supply port 10 is formed at the outer end of the block 2.

  A supply-side check valve 11 is provided between the supply port 10 and the upper passage 6. The supply side check valve 11 restricts the fluid in the upper space 16 from flowing back from the upper passage 6 to the supply port 10 by the advancement of the piston 3 described later.

  The lower passage 7 is formed so as to penetrate between the lower outer side of the block 2 and the lower portion (lower space 17) in the cylinder 5 in the left-right direction. In the lower passage 7, a large-diameter discharge port 12 is formed at the outer end of the block 2.

  The communication path 8 is disposed along the vertical direction, and its upper end is connected to the middle of the upper path 6, and its lower end is connected to the middle of the lower path 7. The upper passage 6 and the lower passage 7 are communicated with each other by the communication passage 8.

  A communication-side check valve 13 is provided in the middle of the communication path 8. This communication-side check valve 13 allows passage of fluid from the upper passage 6 to the lower passage 7 by advancement of the piston 3 described later, and from the lower passage 7 by retraction of the piston 3 described later. The passage of fluid toward the upper passage 6 is restricted.

  In addition, the block 2 is formed by dividing it into two vertically. Specifically, the block 2 includes an upper block 14 and a lower block 15.

  The upper block 14 forms an upper half portion of the block 2, and includes an upper half portion of the cylinder 5, an upper passage 6 and a supply port 10, and an upper middle portion of the communication passage 8. Is provided. The lower block 15 forms a lower half portion of the block 2, and includes a lower half portion of the cylinder 5, a lower passage 7 and a discharge port 12, and a lower middle portion of the communication passage 8. A stop valve 13 is provided.

  In the block 2, the upper block 14 and the lower block 15 are aligned so that the upper half portion and the lower half portion of the cylinder 5 communicate with each other, and the upper middle portion and the lower half portion of the communication path 8 communicate with each other. Are formed by overlapping each other.

  The piston 3 is made of metal and has a cylindrical shape with an outer diameter slightly smaller than the inner diameter of the cylinder 5. Within the cylinder 5, the upper end portion and the lower end portion of the cylinder 5 are arranged along the axial direction (vertical direction). It is arranged so that it can move forward and backward. The clearance between the outer peripheral surface of the piston 3 and the inner peripheral surface of the cylinder 5 is set to 0.5 to 3.0 mm, for example.

  The piston 3 is advanced and retracted along the axial direction of the cylinder 5 while the outer peripheral surface slides with the inner peripheral surfaces of the upper and lower two partition seal members 19 as seal members described later. As a result, when the piston 3 is disposed at the bottom dead center (the most upstream side in the advancing direction), as shown in FIG. In FIG. 1, the upper space 16 as the first space formed above the upper partition seal member 19) (downstream in the advance direction) and the piston 3 as shown in FIG. And the lower space 17 as a second space formed below (upstream in the advance direction) than the piston 3 (specifically, the lower partition seal member 19). The

  The piston 3 is the same as the inner peripheral surface of the cylinder 5 (hereinafter, referred to as a facing portion 18) both when the piston 3 is disposed at the bottom dead center and when disposed at the top dead center. It is formed with a vertical length that can be opposed in the left-right direction (radial direction). That is, the piston 3 is formed with a length exceeding half of the stroke length that advances and retreats in the cylinder 5.

  The rod 4 is made of metal and has a shaft shape. The rod 4 is disposed along the vertical direction on the axis of the cylinder 5, and an upper end portion of the rod 4 is connected (fixed) to the lower surface of the piston 3 in the cylinder 5. The lower end portion extends downward from the lower surface of the block 2. In the middle of this, the lower end seal member 9 is slidably in contact.

  Thus, in the piston pump 1, the radial cross-sectional area (circular: cross section of the cylinder 5) in the upper space 16 as the first cross-sectional area is the radial cross-sectional area (annular shape) in the lower space 17 as the second cross-sectional area. : A cross-section in which the rod 4 is inserted into the cylinder 5).

  In the piston pump 1, two partition seal members 19 are provided on the opposed portion 18 of the cylinder 5 in the vertical direction. The upper partition seal member 19 is provided in the upper block 14 in the vicinity of the boundary between the upper block 14 and the lower block 15. The lower partition seal member 19 is provided in the lower block 15 in the vicinity of the boundary between the upper block 14 and the lower block 15. In addition, a fixing ring 26 for fixing the partition seal members 19 is provided between the upper partition seal member 19 and the lower partition seal member 19 in the facing portion 18 of the cylinder 5. The fixing ring 26 is disposed at the boundary between the upper block 14 and the lower block 15 so as to straddle them.

  Each partition seal member 19 and the fixing ring 26 are formed in a ring shape from a seal material made of resin or the like that does not damage the piston 3 even if it slides on the piston 3. Each partition seal member 19 is provided in the facing portion 18 so as to slightly bulge inward in the radial direction from the inner peripheral surface of the cylinder 5 (swells more than a sleeve 21 described later). As a result, the partition seal member 19 is interposed between the inner peripheral surface of the cylinder 5 and the outer peripheral surface of the piston 3 so as to be in close contact with each other and so that the piston 3 can slide. The space 17 is sealed so as to be isolated from the space 17.

  An O-ring 20 is further embedded between the upper block 14 and the lower block 15 on the radially outer side of the fixing ring 26.

  A resin sleeve 21 is provided on the inner peripheral surface of the cylinder 5. The sleeve 21 is provided above and below the respective partition seal members 19, and the end portions in contact with the respective partition seal members 19 are fixed by the respective partition seal members 19. The sleeve 21 is provided so as to cover the inner peripheral surface of the cylinder 5 over the entire length of the cylinder 5 in the vertical direction. The thickness of the sleeve 21 is, for example, 0.2 to 3.0 mm, and the gap between the outer peripheral surface of the piston 3 and the inner peripheral surface of the sleeve 21 is set to 0.05 to 0.5 mm, for example.

  The rod 4 is connected to a drive cylinder such as a hydraulic cylinder or an air cylinder (not shown) as advancing / retreating drive means for moving the rod 4 back and forth. The supply port 10 is connected to a supply line (not shown) for supplying fluid. Further, a discharge line (not shown) for discharging the fluid is connected to the discharge port 12.

  Next, the operation of the piston pump 1 will be described.

  First, as shown by the solid line arrow in FIG. 2, when the rod 4 moves upward in conjunction with the advance operation (or retraction operation) of a drive cylinder (not shown), the piston 3 advances and the fluid in the upper space 16 is moved. Flows out into the upper passage 6. The fluid that has flowed out to the upper passage 6 flows into the lower passage 7 via the communication passage 8 because the backflow to the supply port 10 is regulated by the supply-side check valve 11. The fluid that flows into the lower passage 7 is divided into left and right from the communication passage 8, and the fluid that flows into the right side flows into the lower space 17. Further, the fluid flowing into the left side is discharged from the discharge port 12 to a discharge line (not shown).

  That is, when the piston 3 advances, the fluid flows out from the upper space 16 and flows into the lower space 17, and the remaining fluid that has not flowed into the lower space 17 is discharged from the discharge port 12. The advancing channel (indicated by the solid arrow in FIG. 2) is formed.

  As shown in FIG. 1, when the piston 3 reaches the top dead center, the volume of the fluid flowing into the lower space 17 and the volume of the fluid discharged from the discharge port 12 become the same amount.

  Next, as shown by a solid arrow in FIG. 1, when the rod 4 moves downward in conjunction with a retracting operation (or advancement operation) of a drive cylinder (not shown), the piston 3 is retracted and supplied from a supply line (not shown). A fluid is supplied to the upper passage 6 through the port 10, and the fluid flows from the upper passage 6 into the upper space 16. At the same time, the fluid in the lower space 17 flows out to the lower passage 7. The fluid flowing out to the lower passage 7 is discharged from the discharge port 12 to a discharge line (not shown) because the backflow to the communication passage 8 is restricted by the communication check valve 13.

  That is, when the piston 3 is retracted, the fluid flows into the upper space 16 and the fluid flows out from the lower space 17 and is discharged from the discharge port 12 (shown by a solid arrow in FIG. 2). Is formed.

  The capacity of the fluid discharged from the lower space 17 through the discharge port 12 when the piston 3 reaches the bottom dead center is the same as the discharge port 12 from the upper space 16 when the piston 3 reaches the top dead center. It becomes the same amount as the volume of the fluid discharged through the.

  When the rod 4 is moved upward again, an advancing passage shown in FIG. 1 is formed. When the rod 4 is moved downward, a retracting passage shown in FIG. 2 is formed. . In the piston pump 1, a fixed amount of fluid is transported by the fluid by moving the piston 3 back and forth as described above.

  In the piston pump 1, the cylinder 5 has a facing portion 18 that faces the piston 3 both when the piston 3 is disposed at the top dead center and when the piston 3 is disposed at the bottom dead center. A partition seal member 19 is provided on the facing portion 18. Therefore, the piston 3 does not slide with the inner peripheral surface of the cylinder 5 but slides with the partition seal member 19. Therefore, if the processing accuracy of the sliding portion of the piston 3 with the compartment seal member 19 is ensured, the slidability and sealability between the compartment seal member 19 and the piston 3 are ensured, and the fluid can be transported with high accuracy. Can be realized. For this reason, the clearance between the outer peripheral surface of the piston 3 and the inner peripheral surface of the cylinder 5 is set large so that the processing accuracy required for the inner peripheral surface of the cylinder 5, such as polishing of the mirror surface, the tolerance accuracy of the inner diameter, and the central axis The shaft tolerance accuracy can be reduced. As a result, it is possible to reduce manufacturing costs by reducing the labor of processing. Furthermore, if the clearance between the outer peripheral surface of the piston 3 and the inner peripheral surface of the cylinder 5 is increased, the bearing mechanism of the rod 4 can be simplified.

  Moreover, in this piston pump 1, since the piston 3 slides with the partition seal member 19, the durability of the piston 3 can be improved. In particular, in this piston pump 1, since the inner peripheral surface of the cylinder 5 is covered with the resin sleeve 21, damage to the piston 3 can be further reduced. Therefore, the replacement of the piston 3 can be made unnecessary for a long time. Further, if the inner peripheral surface of the cylinder 5 is covered with the resin sleeve 21, the unnecessary volume in the cylinder 5 can be reduced, the transportation efficiency can be improved, and further, Even if the need for replacement occurs, it can be replaced at low cost. Therefore, the running cost can be reduced. As a result, the durability and reliability of the apparatus can be further improved with a simple and inexpensive configuration.

  Further, in this piston pump 1, the piston 3 may be formed so as to be slidable with the partition seal member 19, and the inner peripheral surface of the cylinder 5 is covered with the resin sleeve 21. It is not necessary to provide a packing, an anti-abrasion preventing member, or the like, and the piston 3 can be formed simply. Therefore, even the piston 3 having a small outer diameter can be easily manufactured. Therefore, a small capacity or minute capacity pump can be realized at low cost.

  Furthermore, in this piston pump 1, the radial cross-sectional area in the upper space 16 is set to be substantially twice the radial cross-sectional area in the lower space 17. The capacity is substantially twice the maximum capacity of the lower space 17. For this reason, when the advancing flow path is formed by the advancement of the piston 3, half of the maximum capacity of the upper space 16 flows into the lower space 17, and the same amount of remaining fluid is discharged. On the other hand, when the retracting flow path is formed by retracting the piston 3, the fluid flows into the upper space 16, and from the lower space 17, the lower space 17, that is, half of the maximum capacity of the upper space 16. Fluid is discharged. As a result, the same volume of fluid is discharged every time the piston 3 advances or retreats, so that the fluid can be pressure-transported at a constant flow rate by the advance and retreat of the piston 3.

  In the above description, the fluid includes compressible or incompressible gas, liquefied gas, liquid, or the like. Specifically, carbon dioxide, nitrogen, argon, combustible gas (hydrocarbon), water and the like are included.

  The piston pump 1 can be used without any particular limitation as long as it is an application for transporting fluid continuously or intermittently at a constant volume. For example, it can be effectively used as a fine capacity pump that can be continuously supplied. Specifically, it can be effectively used as an application for supplying a liquefied gas by pressurization, for example, as a supply device for a foaming agent (liquefied gas) in foam molding.

  In addition, the piston pump 1 does not need to be formed in the block 2 as long as the cylinder 5, the upper passage 6, the lower passage 7, and the communication passage 8 can be provided. It can also be configured.

It is a schematic block diagram which shows the advance state of one Embodiment of the piston pump of this invention. It is a schematic block diagram which shows the retracted state of the piston pump shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piston pump 3 Piston 5 Cylinder 6 Upper channel | path 7 Lower channel | path 8 Communication channel | path 16 Upper space 17 Lower space 18 Opposed part 19 Compartment seal member 21 Sleeve

Claims (2)

A cylinder, and a piston provided so as to freely advance and retract in the cylinder,
In the cylinder, when the piston is arranged on the most upstream side in the advance direction, a first space formed on the downstream side in the advance direction of the piston, and when the piston is arranged on the most downstream side in the advance direction And a second space formed upstream of the piston in the advancing direction, and the cylinder has a first cross-sectional area in a direction perpendicular to the advancing / retreating direction of the piston in the first space. Formed so as to be substantially twice the second cross-sectional area in the direction orthogonal to the advancing and retreating direction of the piston in the space;
When the piston has advanced, a fluid flow is made to flow out from the first space, and the fluid is made to flow into the second space, and a flow channel for advancement is formed to discharge the remaining fluid,
When the piston is retracted, a fluid passage is formed into the first space, and a retraction channel for discharging the fluid from the second space is formed.
The cylinder is opposed to the piston in a direction orthogonal to the forward / backward direction of the piston both when the piston is disposed on the most upstream side in the advance direction and when disposed on the most downstream side in the advance direction. With
The piston pump according to claim 1, wherein a seal member interposed between an inner peripheral surface of the cylinder and an outer peripheral surface of the piston is provided in the facing portion.   The piston pump according to claim 1, wherein a resin sleeve is provided on an inner peripheral surface of the cylinder.

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