JP2007100554A - Reciprocating pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an improved reciprocating pump having a switching means capable of exhibiting the function equal to a conventional switching means using two optical sensors while using only one optical sensor. <P>SOLUTION: This reciprocating pump is constituted to freely suck and discharge fluid via valves 24 and 26 by the pump action generated by driving and reciprocating a moving body 9 in a pump cylinder 14, and is equipped with the switching means A for switching the forward movement and the backward movement of the moving body 9 on the basis of detecting a position in the reciprocating direction of the moving body 9 by the optical sensor 34. The switching means A comprises the single optical sensor 34 arranged in a sensing action performing state in the direction for crossing the moving direction of the moving body 9, a reflector 19 integrally moving with the moving body 9 in a vicinal position of a light receiving surface 34a of this light sensor 34, and polarization parts h1 and h2 of two places formed in the reflector 19 by mutually separating an interval in the moving direction of the moving body 9 in a state of suddenly changing a reflected light quantity to the optical sensor 34. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a reciprocating pump suitable for quantitative transfer of chemicals and ultrapure water used for surface cleaning processing of ICs and liquid crystals, for example, in semiconductor manufacturing apparatuses.

  Conventionally, this type of reciprocating pump is configured so that fluid can be sucked and discharged freely through a valve by a pump action generated by driving and reciprocating a moving body in a pump cylinder. Switching means for switching between movement and return path movement based on detecting the position of the moving body with an optical sensor is provided. As such a prior art, what was disclosed in patent document 1, patent document 2, etc. is known.

  In any of the above reciprocating pumps, the switching means is configured by using two proximity sensors that detect the position of the moving body in any of the patent documents. First, in the reciprocating pump shown in Patent Document 1, a piston body (reference numeral 11) integrally connected to a closed end member (reference numeral 7b) connected to a bellows (reference numeral 7) via a connecting shaft. A first proximity sensor (reference numeral 35a) that detects a distance from the bottom wall part (reference numeral 6a) of the pump casing, and a second that detects a distance between the closed end member (reference numeral 7b) and the bottom wall part (reference numeral 6a). Proximity sensor (reference numeral 35b) is provided. In this structure, the closed end member (reference numeral 7b) corresponds to a “moving body”. Control for switching the moving direction of the closed end member (reference numeral 7b) using these two proximity sensors is performed as follows.

  That is, the first proximity sensor (reference numeral 35a) is paired with the bottom wall part (reference numeral 6a), and detection that the bottom wall part (reference numeral 6a) approaches the first proximity sensor (reference numeral 35a). From the information, the end position of the forward movement (movement in the direction of the arrow y) is detected immediately before the piston body (reference numeral 11) contacts the closed end member (reference numeral 7b), and the moving direction of the closed end member (reference numeral 7b) is determined. The air cylinder (reference numeral 14) is controlled so as to switch to the backward movement (movement in the arrow x direction). The second proximity sensor (reference numeral 35b) is paired with the closed end member (reference numeral 7b), and is based on detection information that the closed end member (reference numeral 7b) is approaching the second proximity sensor (reference numeral 35b). The end position of the backward movement immediately before the closed end member (symbol 7b) contacts the bottom wall part (symbol 6a) is detected, and the moving direction of the closed end member (symbol 7b) is switched to the forward movement. The cylinder part (reference numeral 14) is controlled. By repeating this, it is continuously driven as a reciprocating pump.

  Next, the reciprocating pump shown in Patent Document 2 basically has a structure using a bellows similar to that of Patent Document 1, and its switching means will explain the end of the piston (reference numeral 11). A sensor sensing plate (reference numeral 26) is attached to the part, and a pair of proximity sensors (reference numerals 25a and 25b) are arranged in a state straddling the sensor sensing plate (reference numeral 26). In other words, the switching means detects the closed end member (i.e., the movable body) of the piston (reference numeral 11) based on detection information indicating that any one of the proximity sensors (reference numerals 25a and 25b) and the sensor sensing plate (reference numeral 26) approach each other. The air cylinder (reference numeral 14) is controlled so that the movement direction of the reference numeral 7b) is switched between the forward movement and the backward movement, and this function is also the same as that of Patent Document 1.

  However, in the means that uses a proximity sensor as the switching means, there is a restriction that the counterpart member that forms a pair of sensor sensing plates and the like is limited to a metal member, and the detection distance is short. A dynamic pump always requires two proximity sensors. In addition, since it detects a potential change, it cannot be used in an explosion-proof atmosphere and is difficult to use, such as being restricted by the type of fluid used in the pump. Therefore, in order to obtain the advantage that the counterpart member to be paired with the sensor may be other than metal and the detection distance is longer than that of the proximity sensor, and it can be used even in an explosion-proof atmosphere and the above-mentioned restrictions can be avoided, Instead, it has been considered that the switching means is configured by using an optical sensor. For example, as a means using two optical sensors, as shown in FIG. 11, an outer peripheral surface 19A of a reflector 19 that reciprocates in the direction of arrow A and the direction of arrow B has a diameter whose outer periphery becomes a flat surface 100a. A large annular protrusion 100 is formed, and a pair of optical sensors 101 and 102 are arranged at two positions that are close to the annular protrusion 100 in the radial direction and that are separated from each other in the moving direction of the reflector 19. Switching means A is conceivable.

  In a general optical sensor, since there is a relationship that “the amount of received light is inversely proportional to the square of the distance” between the amount of received light and the detection distance, the optical sensors 101 and 102 shown in FIG. As the reflecting body 19 approaches the optical sensors 101 and 102, the amount of received light increases. The relationship between the amount of received light and the distance is represented in a graph as shown by line a in FIG. As can be seen from the line a in FIG. 12, the amount of received light increases abruptly when the reflector 19 comes close to the sensors 101 and 102, and the amount of received light shows a substantially constant value at a low level when separated by a certain distance. Understandable. Accordingly, for example, in the line a of FIG. 12, when the moving direction of the moving body is switched by the output signal when the light receiving amount of the photosensor is “2000”, the actual moving stroke StJ that becomes effective is tJ = 9. 0.5-0.5 = 9.0 mm can be secured, and the total moving stroke StZ is 10 mm, so the stroke rate StJ / StZ = 9.0 / 10 = 90%. The actual moving stroke StJ required for the pumping operation is reduced in a state where the useless moving stroke (10% in the line a in FIG. 12 is wasted and the surplus stroke is 1 mm) is reduced, that is, the switching means (reciprocating pump) ) Can be expected to be obtained.

In addition, because the reflector uses a sudden change in the amount of light received when the reflector moves in the vicinity of the light receiving surface of the optical sensor, for example, due to a decrease in light emission intensity due to aging of the light emitting portion of the optical sensor, dirt adhesion, etc. Even if the amount of received light changes from the initial value, such as when the amount of light is slightly reduced, it is considered that the amount of movement stroke caused by the change does not change. Therefore, it is expected that a preferable advantage that a stable pumping action due to the moving stroke of the moving body with a substantially constant value is exhibited over a long period of time can be obtained.
JP-A-10-196521 Japanese Patent Laid-Open No. 2001-293836

  However, in the structure using two optical sensors, two fibers and two amplifiers are required, resulting in high costs, and there is a disadvantage that the wiring becomes complicated, and the possibility of disconnection and miswiring increases. Therefore, the switching means by the comparative example 1 which can exhibit a required function with one optical sensor was considered. As in the switching means A of the first comparative example shown in FIG. 7, the single optical sensor 34 is in a sensing action in the direction along the moving direction of the moving body, that is, the coupling to which the piston 19 is externally fitted. In this configuration, the light reflected from the end surface 73 of the shaft 22 (in FIG. 2, the pump shaft that moves integrally with the movable plate portion 9 of the bellows 7) is received. With such a structure, the position of the coupling shaft 22 can be detected at any time with the change in the amount of light received by the optical sensor 34. Therefore, the forward movement is achieved by appropriately setting the threshold value of the amount of light received at two locations. It seems that it is possible to configure a switching means that can switch between the return path movement and the return path movement.

  FIG. 8 shows a relationship graph between the moving stroke of the movable plate portion 9 by the switching means of the comparative example 1 having the configuration shown in FIG. 7 and the amount of light received by the optical sensor 34. That is, as described above, since the amount of received light is inversely proportional to the square of the distance between the optical sensor 34 and the reflector 22, the switching means A using the two optical sensors 101 and 102 shown in FIG. Compared to the graph (see line a in FIG. 12), the relationship is a graph in which the change in the amount of received light is generally gentle. In this case, in a situation in which the end surface 73a of the connecting shaft 22 that is a reflector changes in distance near the position of the optical sensor 34, as shown on the left side of the graph in FIG. Although the amount of received light changes with a slightly clear inclination angle, when the distance between the connecting shaft 22 and the optical sensor 34 is large, the amount of received light is as shown on the right side of the graph in FIG. 8 (the movement distance is 10 mm side). The degree of change will be very slow.

  In other words, since the rate of change in the amount of received light is slow and the amount of change is small, the above-mentioned useless travel stroke cost becomes large, and the switching means is liable to be enlarged or disadvantageous as a switching means with poor efficiency. In addition, there is a situation in which the threshold value must be set within a range of change in which the amount of received light is less than 10%. Therefore, if the amount of change is less than 10%, the optical sensor is easily affected by hysteresis, and the emission intensity decreases due to the change over time of the light emitting diode (light emitting part of the optical sensor) in the amplifier, and the reflector (end surface of the connecting shaft). If the amount of light received decreases due to dust, abrasion powder or the like on the surface of the optical sensor, the pump switching timing (moving stroke of the moving body) changes greatly, and the pump performance tends to vary greatly. For this reason, there is a disadvantage that it is necessary to frequently adjust the switching timing of the switching means, and when the amount of received light is greatly reduced, the switching operation itself of the moving direction of the moving body becomes impossible, that is, the pump stops. The problem is also considered. Therefore, there is still room for further improvement in realizing the switching means that performs the same function as when two optical sensors are used with only a single optical sensor.

  An object of the present invention is improved by having a switching means capable of exhibiting the same function as the switching means in the case of using two photosensors, while using only one photosensor by devising the sensing structure. It is in providing a reciprocating pump.

The invention according to claim 1 is configured such that fluid can be freely sucked and discharged through the valves 24 and 26 by the pump action generated by driving and reciprocating the movable body 9 in the pump cylinder 14, and the movement In the reciprocating pump equipped with the switching means A for switching the forward movement and the backward movement of the body 9 based on detecting the position of the moving body 9 in the reciprocating direction by the optical sensor 34,
The switching means A includes a single optical sensor 34 provided in a sensing action in a direction crossing the moving direction of the moving body 9, and the moving body 9 at a position near the light receiving surface 34 a of the optical sensor 34. And two changing parts h1 formed on the reflector 19 with a gap in the moving direction of the moving body 9 in a state where the amount of light reflected on the optical sensor 34 is suddenly changed. , H2, and the like.

In the invention according to claim 2, the bellows 7 that can expand and contract in the pump cylinder 14 and the air cylinder portion C that expands and contracts the bellows 7 by reciprocating the movable side member 9 of the bellows 7 in the pump cylinder 14 are provided. A fluid suction passage 2a and a fluid escape passage 3a communicating with the pump chamber 11 formed by the pump cylinder 14 and the bellows 7, and only in a direction in which the fluid is directed from the suction passage 2a to the pump chamber 11. A suction-side check valve 24 that allows flow, and a discharge-side check valve 26 that allows fluid to flow only in the direction from the pump chamber 11 toward the exit passage 3a;
Reciprocating motion equipped with switching means A for switching the forward movement and the backward movement of the movable side member 9 based on detecting the position of the movable side member 9 in the reciprocating direction by the optical sensor 34. In the pump,
The switching means A includes a single optical sensor 34 arranged in a sensing action in a direction crossing the moving direction of the movable side member 9, and the movable side at a position near the light receiving surface 34a of the optical sensor 34. The reflector 19 that moves integrally with the member 9 and the change in two places formed on the reflector 19 in the moving direction of the movable side member 9 in a state of suddenly changing the amount of light reflected to the optical sensor 34. It is characterized by having pole portions h1 and h2.

  According to a third aspect of the present invention, in the reciprocating pump according to the first or second aspect, the pole changing portions h1 and h2 are provided with a step 19C in the reflector 19 so that the distance from the optical sensor 34 is mutually different. The different light reflecting surfaces 19A and 19B are formed adjacent to each other in the moving direction.

  According to a fourth aspect of the present invention, in the reciprocating pump according to the first or second aspect, the pole changing portions h1 and h2 are adjacent to the light reflecting surfaces 91 and 92 having different light reflectivities in the moving direction. In addition, the reflector 19 is formed and configured.

  The invention according to claim 5 is the reciprocating pump according to claim 4, wherein the light reflecting surfaces 91 and 92 having different light reflectivities are formed by adding shades of color to the reflector 19. It is characterized by that.

  According to the first aspect of the present invention, as will be described in detail in the section of the embodiment, the sensing action is performed in the direction crossing the moving direction of the moving body, and the two pole changing portions are provided on the reflecting body. Sensing performance equivalent to that of the conventional switching means using two optical sensors while using only one optical sensor (receiving of the optical sensor as the moving body moves at both ends of the moving stroke of the moving body) While obtaining high efficiency and stabilization of the movement stroke amount due to the sudden change of the amount, that is, stable pump performance can be obtained with a compact switching means), the risk of miswiring and disconnection is reduced. In addition, a single set of parts such as an optical sensor, a fiber, and an amplifier is required, and the cost of the switching means can be reduced to half that of the prior art. In addition, even if the light emission intensity of the light emitting element of the light sensor is reduced due to changes over time or the amount of light received is reduced due to dirt, dust, wear powder, etc. Pump performance can be maintained. As a result, there is a switching means that can perform the same function as the switching means in the case of using two photosensors and can be made more compact while using only one photosensor. An improved reciprocating pump can be provided.

  According to the invention of claim 2, the operation and effect of the invention of claim 1 can be achieved in a bellows type reciprocating pump.

  According to the third aspect of the present invention, the light receiving amount varies depending on the distance between the optical sensor and the reflector, and the polarity is changed by a simple and inexpensive structure in which a step is provided on the reflector. There is an advantage that a part can be formed.

  According to invention of Claim 4, it is a means made so that the light-receiving amount of an optical sensor may differ by changing the reflectance of a reflector, and a material, a color, surface finishing precision (roughness), surface treatment, etc. There is an advantage that the reflectance can be made different by a simple means for differentiating the general elements. In this case, it is possible to provide a means for varying the reflectance by adding light and shade as in claim 5.

  Embodiments of a reciprocating pump according to the present invention will be described below with reference to the drawings. 1 is a cross-sectional view showing the internal structure of a bellows type reciprocating pump, FIG. 2 is an enlarged view of the pump part of FIG. 1, and FIG. 3 is an enlarged cross-sectional view of the main part showing a state where the piston is moved to the return side end. FIG. 4 is a graph showing the relationship between the amount of light received by the optical sensor and the piston movement stroke by the switching means of the first embodiment. 5 and 6 are switching means and graphs according to Example 2, FIGS. 7 and 8 are switching means and graphs according to Comparative Example 1, FIGS. 9 and 10 are switching means according to Comparative Examples 2 and 3, and FIG. 11 is two optical sensors. Each of the conventional switching means using is shown. FIG. 12 is a graph showing the relationship between the amount of light received by the optical sensor and the piston movement stroke in each structure, and FIG. 13 is a cross-sectional view of the main part showing the switching means of another structure.

[Example 1]
The reciprocating pump 1 according to the first embodiment is a bellows type reciprocating pump used for transferring a chemical liquid, a solvent, pure water, or the like in a semiconductor manufacturing factory, for example, and includes a suction port 2 and a discharge port 3 for the transfer liquid. The pump body 4 which is a substantially square plate-shaped pump head formed with a pump portion 5 disposed on one side (right side in FIG. 1) of the pump body 4, and the other side of the pump body 4 (FIG. 1). And an accumulator portion 6 arranged on the left side in FIG. The pump part 5 has an air cylinder part C that expands and contracts a bellows 7 described later.

  A bellows 7 that can be expanded and contracted in the axial direction (left-right direction in FIG. 1) is disposed on one side of the pump body 4 (left side in FIG. 1). The bellows 7 has a bottomed cylindrical shape having a flange portion on the opening side edge, and the flange portion forms an annular joint portion 8 on the opening side end portion to join the pump body 4, and the bottom portion is a disc. A movable plate portion 9 (which is an example of a movable side member and corresponds to a moving body) 9 is formed, and the joint portion 8 and the movable plate portion 9 are integrated with each other via a cylindrical bellows-type telescopic body portion 10. The bellows 7 and the pump body 4 form a sealed variable-capacity cylindrical pump chamber (pump liquid chamber) 11.

  A circular concave portion 12 is formed concentrically with the bellows 7 in the joint surface 8 of the bellows 7 on the joint surface with the pump body 4, and the pump body 4 has a concave portion on the joint surface with the joint portion 8 of the bellows 7. A circular convex portion 13 that is fitted to 12 is formed concentrically with the pump body 4. The joints between the bellows 7 and the pump body 4 are hermetically sealed by the concave and convex portions 12 and 13 that are fitted to each other, and the bellows 7 is positioned in the radial direction and disposed on the same axis X as the pump body 4. Yes.

  A pump cylinder 14 that is a pump housing is disposed on one side of the pump body 4 (on the right side in FIG. 1) on the same axis X as the bellows 7. The pump cylinder 14 accommodates therein a cylinder head portion 15 having substantially the same shape as the pump body 4 disposed on the axially outer side (right outer side in FIG. 1) of the bellows 7 so as to face the pump body 4, and the bellows 7. A cylindrical first cylinder portion 16 that protrudes from the cylinder head portion 15 toward the pump body 4 side (left side in FIG. 1) on the same axis X as the bellows 7, The cylinder portion 16 includes a cylindrical second cylinder portion 17 that protrudes on the same axis X as the bellows 7 on the opposite side (right side in FIG. 1). The first cylinder portion 16 has an opening side end. The cylinder head portion 1 is placed outside the bellows 7 so that the opening side end portion (joint portion 8) of the bellows 7 is sandwiched between the pump body 4 and the movable plate portion 9 in the direction of arrow A. Forward air chamber 18 is formed which is sealed by the.

  A piston 19 is fitted in the second cylinder part 17 so as to be slidable in the axial direction (left and right direction in FIG. 1), and the opening side end of the second cylinder part 17 is detachably attached by bolting. The cover lid 20 is closed. Furthermore, a circular center hole 21 is formed in the cylinder head portion 15, and a pump shaft 22, which is a connecting shaft having a circular cross section disposed on the same axis X as the bellows 7, is provided in the center hole 21. The bellows 7 and the piston 19 are connected by this pump shaft 22 so as to be slidable in the direction (left and right direction in FIG. 1). In addition, a return air chamber 35 is formed in the second cylinder 17 for moving the piston 19 in the arrow B direction by supplying high pressure air.

  The pump body 4 includes a suction-side check valve 24 that opens and closes a suction port 23 that communicates with the transfer liquid suction port 2, and a discharge-side check valve 26 that opens and closes a discharge port 25 that communicates with the discharge port 3 of the transfer liquid. Is mounted in the pump chamber 11. In addition, an O-ring 27 that hermetically seals between the opening and the end of the bellows 7 of the pump cylinder 14 (joint 8), that is, the opening of the first cylinder 16 is attached. In addition, an O-ring 29 is attached to a sliding portion of the pump cylinder 14 with the pump shaft 22, that is, around the center hole 21 of the cylinder head portion 15 through a slipper ring 28 to seal these gaps. In addition, an O-ring 31 is mounted on a sliding portion of the pump cylinder 14 with the piston 19, that is, on the inner surface of the second cylinder portion 17 via a slipper ring 30 in order to seal these gaps.

  Further, in the cylinder head portion 15 of the pump cylinder 14, in order to reciprocate the bellows 7, an air supply port 32 for contracting bellows for supplying high-pressure air to the forward air chamber 18, and an O-ring 31 of the second cylinder 17. A bellows extension air supply port 33 for supplying high-pressure air to the return air chamber 35 on the cylinder head 15 side from the mounting position is formed. A single optical sensor 34 is attached to the second cylinder portion 17 of the pump cylinder 14 to detect the end position of the expansion / contraction stroke of the movable plate portion 9, that is, the bellows 7 by the reciprocating motion of the piston 19. As will be described in detail later, air supply from the air pump 82 to each of the air supply ports 32 and 33 is switched based on an output signal (detection information) of the optical sensor 34 to supply air to the forward air chamber 18 and the return air chamber 35. Are alternately performed, and switching control between the suction step and the discharge step of the transfer liquid in the reciprocating pump 1 is performed. The pump part 5 is comprised by one side part (left side part in FIG. 1) of the pump body 4 by the above each component.

  On the other hand, an accumulator bellows 36 that can be expanded and contracted in the axial direction (left-right direction in FIG. 1) is disposed on the other side (left side in FIG. 1) of the pump body 4. The accumulator bellows 36 has a bottomed cylindrical shape having a flange portion at the opening side end edge, and the flange portion forms an annular joint portion 37 at the opening side end portion to join the pump body 4, and the bottom portion is a circular shape. A plate-shaped movable plate portion 38 is configured, and the joint portion 37 and the movable plate portion 38 are integrally connected via a cylindrical bellows-type expansion / contraction body 39. The accumulator bellows 36 and the pump body 4, a sealed variable capacity cylindrical accumulator chamber (accumulator liquid chamber) 40 is formed.

  The accumulator chamber 40 is connected to the pump chamber 11 via a discharge passage check valve 26 and a communication passage 41 formed in the pump body 4, and is also connected to the discharge port 3 formed in the pump body 4. Then, the transfer liquid discharged from the pump chamber 11 through the discharge side check valve 26 is temporarily stored. A circular recess 42 is formed concentrically with the accumulator bellows 36 in the joint surface 37 of the accumulator bellows 36 at the joint portion 37 of the accumulator bellows 36, and the pump body 4 is joined with the joint portion 37 of the accumulator bellows 36. A circular convex portion 43 fitted to the concave portion 42 is formed concentrically with the pump body 4 on the surface. The joints between the accumulator bellows 36 and the pump body 4 are hermetically sealed by the concave and convex portions 42 and 33 fitted to each other, and the accumulator bellows 7 is positioned in the radial direction and arranged on the same axis X as the pump body 4. And is arranged on the same axis X as the bellows 7.

  An accumulator cylinder 44, which is an accumulator housing, is disposed on the same axis X as the accumulator bellows 36 on one side of the pump body 4 (left side in FIG. 1). The accumulator cylinder 44 has a cylindrical shape with a bottom, and the bottom portion has substantially the same shape as the pump body 4 that is disposed on the outer side in the axial direction of the accumulator bellows 36 (left outer side in FIG. 1) so as to face the pump body 4. The cylinder head portion 45 is configured, and the body portion projects on the same axis X as the accumulator bellows 36 from the cylinder head portion 45 toward the pump body 4 side (right side in FIG. 1) so as to accommodate the accumulator bellows 36 therein. A cylindrical cylinder part 46 is formed, and the cylinder part 46 sandwiches the opening side end part (joining part 37) of the accumulator bellows 36 between the opening side end part and the pump body 4, and the accumulator. Sealed accumulator air in which air for reducing pulsation is sealed by the cylinder head portion 45 outside the bellows 36. To form a 47.

  An O-ring 57 that hermetically seals between the accumulator cylinder 44 and the opening side end portion (joining portion 37) of the accumulator bellows 36, that is, the opening side end portion of the cylinder portion 46, is mounted. . In addition, a stopper 48 is formed on the inner surface of the accumulator cylinder 44 so as to project excessive stretch deformation of the accumulator bellows 36 and prevent its damage. The accumulator cylinder 44 includes an automatic pressure adjusting mechanism 49 including an automatic air supply valve mechanism and an automatic exhaust valve mechanism for balancing the air pressure in the accumulator air chamber 47 with the discharge pressure of the pump unit 5 according to the fluctuation. Is attached. The accumulator part 6 is comprised by the above each component on the same axis line X as the pump part 5 in the other side part (left side part in FIG. 1) of the pump body 4. FIG.

  Then, the cylinder head portions 15 and 45 on both sides of the pump body 4 are tightened with a plurality of metal tie rods 50 parallel to the axis X, so that the pump body 4, the pump portion 5 and the accumulator portion 6 are integrated. A pump 1 is configured. In this case, each tie rod 50 (including the metal nuts 51 and the like at both ends) is formed in the flange portions 52, 53, 54 formed on the outer surfaces of the pump body 4, the pump cylinder 14, and the accumulator cylinder 44 and joined in series. Both end openings of the housing portion are inserted and housed and closed by detachable caps 55 and 56 to prevent corrosion of the metal parts such as the tie rods 50 and the nuts 51 at both ends thereof by liquids. The pump body 4 is formed in a circular plate shape, male threads are formed on both sides of the outer peripheral surface, and a nut portion having a female screw threadedly engaged with the male screw is provided on each cylinder portion 16, 46. Reciprocating motion formed integrally with the opening side end portion, and the pump cylinder 14 and the accumulator cylinder 44 are connected to both sides of the pump body 4 by direct screw coupling, and the pump body 4, the pump portion 5 and the accumulator portion 6 are integrated. The pump 1 may be configured.

  A connection structure between the bellows 7 and the pump shaft 22 in the reciprocating pump 1 will be described. As shown in FIGS. 1 and 2, the pump shaft 22 is formed with a male screw 69 on an outer surface on one end side (an outer surface on the pump bellows 7 side), and the pump shaft 22 has a bolt structure. On the other hand, the bottomed cylindrical bellows 7 is formed with a bottom cylindrical shaft body screwed portion 70 protruding from the center of the bottom portion into the bellows 7 on the same axis X. On the inner surface, a female screw 71 is formed to be screwed with the male screw 69 of the pump shaft 22, and the bellows 7 is formed by integrating a shaft coupling at the center thereof. Thereby, the one end side of the pump shaft 22 is configured to be freely connectable to the central portion of the bellows 7 by direct screw connection.

  Further, the pump body 4 has a circular concave portion 72 having a diameter slightly larger than the outer diameter of the shaft body screwed portion 70 of the bellows 7 and a depth longer than the extension stroke of the bellows 7 at the center thereof. It is provided concentrically. The shaft body screwed portion 70 is formed such that the tip side is always fitted into the recess 72 of the pump body 4 (of course, when the bellows 7 is contracted, even when the bellows 7 is expanded), the shaft body screwed portion of the bellows 7. The front end side of 70 is always fitted in the recess 72 of the pump body 4.

  Next, a connection structure between the pump shaft 22 of the reciprocating pump 1 and the piston 19 will be described. As shown in FIGS. 1 and 2, the pump shaft 22 is integrally formed with a circular engagement head 73 having a diameter larger than the diameter at the other end (end on the piston 19 side). On the other hand, the piston 19 is formed with a stepped central hole 74 into which the other end of the pump shaft 22 can be fitted including the engaging head 73. The center hole 74 is a stepped hole having a circular cross section in which the hole diameter on one side (cylinder head portion 15 side) of the step surface 75 is larger than that on the other side (opposite side of the cylinder head portion 15 side). The hole diameter of the portion 76 is formed to be substantially the same as the outer diameter of the body portion of the pump shaft 22, and the hole diameter of the large diameter hole portion 77 is formed to be substantially the same as the outer diameter of the engaging head 73 of the pump shaft 22. . In addition, an annular seal member made of an elastic material, for example, an O-ring 78 made of fluororesin, is mounted on the pump shaft 22 to fill a gap with the center hole 74. The O-ring 78 is attached to a portion that fits into the small-diameter hole 76 of the pump shaft 22. Thereby, the other end side of the pump shaft 22 is configured to be connectable to the central portion of the piston 19 by fitting.

  Next, the basic operation of the reciprocating pump 1 configured as described above is as follows. The suction port 2 of the pump body 4 communicates with the pump chamber 11 through the suction passage 2 a and the suction side check valve 24, and the pump chamber 11 communicates with the accumulator chamber 40 through the discharge side check valve 26 and the communication passage 41. 40 communicates with the discharge port 3 of the pump body 4 through the discharge passage 3a. When the high-pressure air is supplied from the air pump 82 to the return air chamber 35 through the air supply port 33 (at this time, the air supply port 32 is opened to the atmosphere), the pump unit 5 has a pressure on the return air chamber 35 side. As a result, the piston 19 moves in the direction indicated by the arrow B (rightward in FIG. 1), and the pump shaft 22 and the movable plate portion 9 of the bellows 7 also move in the direction indicated by the arrow B. That is, the bellows 7 is extended.

  The extension operation of the bellows 7 opens the suction side check valve 24 and closes the discharge side check valve 26, so that the transfer liquid passes through the suction passage 2 a and the suction side check valve 24 from the suction port 2 of the pump body 4. Inhaled into the pump chamber 11 (inhalation process). Subsequently, when high pressure air is supplied from the air pump 82 to the forward air chamber 18 through the air supply port 32 (at this time, the air supply port 32 is opened to the atmosphere), the pressure of the forward air chamber 18 increases. The movable plate portion 9 is pushed in the direction of the arrow B, and the bellows 7 contracts.

  Since the suction side check valve 24 is closed and the discharge side check valve 26 is opened by the contraction operation of the bellows 7, the transfer liquid in the pump chamber 11 is discharged through the discharge side check valve 26. Further, when the bellows 7 is contracted, the pump shaft 22 and the piston 19 are integrally moved in the direction of the arrow (discharge process). The above operation is repeated by the switching control of the transfer liquid suction process and the discharge process by the switching means A (described later), and the pump action is performed.

  On the other hand, in the accumulator section 6, the transfer liquid discharged from the pump chamber 11 is received in the accumulator chamber 40 through the communication passage 41, temporarily stored in the accumulator chamber 40, and then discharged from the pump body 4 through the discharge passage 3 a. 3 is discharged. At this time, the accumulator bellows 36 extends so as to increase the volume of the accumulator chamber 40 when the accumulator bellows 36 is at the peak of the discharge pressure curve due to the pulsation of the discharge pressure of the pump unit 5. By this extension operation, the flow rate of the transfer liquid flowing out from the accumulator chamber 40 becomes smaller than the flow rate flowing in.

  Further, when approaching the valley of the discharge pressure curve, the discharge pressure becomes lower than the air sealing pressure of the accumulator air chamber 47 compressed as the accumulator bellows 36 is extended. Shrink to reduce. Due to this contraction operation, the flow rate of the transfer liquid flowing out of the accumulator chamber 40 becomes less than the flow rate of the flowing liquid. The above operation is repeated in accordance with the transfer liquid suction process and the discharge process of the pump unit 5 to perform a damper action.

  As described above, the reciprocating pump 1 draws the transfer liquid from the suction port 2 of the pump body 4 by the pumping action of the pump part 5 and the damper action of the accumulator part 6, and the pulsation is absorbed and attenuated and the discharge pressure is substantially smoothed. It is configured so that liquid can be transferred by continuously discharging from the discharge port 3 at a substantially constant flow rate.

  That is, as shown in FIGS. 1 to 3, the reciprocating pump 1 includes a pump body 4 in which a suction port 2 and a discharge port 3 for a transfer liquid are formed, and a pump unit disposed on one side of the pump body 4. 5 and an accumulator portion 6 disposed on the other side, and the pump portion 5 is disposed on one side portion of the pump body so that the opening-side end portion 8 is joined to the pump body 4 and is provided inside the pump chamber 11. A cylindrical bellows 7 with a bottom that can be expanded and contracted in the axial direction, a cylinder head portion 15 that is arranged on the outer side in the axial direction of the bellows 7 so as to face the pump body 4, and a cylinder head so as to accommodate the bellows 7 therein The cylinder head is formed on the outer side of the bellows 7 with the opening side end portion 8 of the bellows 7 projecting on the same axis X as the bellows 7 from the portion 15 toward the pump body 4 and sandwiching the opening side end portion 8 of the bellows 7 at the opening side end portion. Going to part 15 The piston 19 is slidably fitted in the axial direction so as to protrude from the first cylinder portion 16 and the cylinder head portion 15 forming the air chamber 18 on the same axis X as the bellows 7 on the opposite side of the first cylinder portion 16. A pump cylinder 14 comprising a second cylinder portion 17, a pump shaft 22 that slidably passes through the center of the cylinder head portion 15 in the axial direction, and connects the bellows 7 and the piston 19; A suction-side check valve 24 and a discharge-side check valve 26 mounted on the body 4 are provided, and the bellows 7, the pump shaft 22, and the piston 19 are supplied by high-pressure air that is alternately supplied into the forward air chamber 18 and the second cylinder part 17. And the bellows 7 repeatedly expand and contract, and when the bellows 7 is extended, the transfer liquid is pumped from the suction port 2 of the pump body 4 through the suction side check valve 24. The accumulator unit 6 is configured so as to be sucked into the chamber 11 and discharged from the discharge port 3 of the pump body 4 through the discharge side check valve 26 when contracted, while the accumulator unit 6 has an opening side end 37 on the other side of the pump body 4. An axially extendable bottom cylinder that forms an accumulator chamber 40 that is disposed so as to be joined to the pump body 4 and forms an accumulator chamber 40 that temporarily stores the transfer liquid discharged from the pump chamber 11 through the discharge-side check valve 26 therein. Accumulator bellows 36 and an accumulator which is arranged outside the accumulator bellows 36 and sandwiches air outside the accumulator bellows 36 with the opening side end 37 of the accumulator bellows 36 sandwiched between the pump body 4 at the opening side end. A cylinder accumulator cylinder 44 with a bottom that forms the air chamber 40, and the pulsation of the discharge pressure of the pump unit 5 is stored in the accumulator It is configured to absorb the expansion and contraction of the tabellows 36.

  Among the constituent elements of the reciprocating pump 1, the pump body 4, which is a wetted part of the pump unit 5 and the accumulator unit 6, the bellows 7, the suction check valve (including the valve case and the spring) 24, and the discharge side In addition to the check valve (including the valve case and the spring) 26 and the accumulator bellows 36, the pump cylinder 14, piston 19, pump shaft 22, and accumulator cylinder 44, which are non-wetted parts, are also made of resin and are made to reciprocate. The pump 1 is made of resin.

  Preferred materials for resinification are as follows. For the valve case of the pump body 4, bellows 7, slipper rings 28 and 30, accumulator bellows 36, suction side check valve 24 and discharge side check valve 26, a fluororesin such as PTFE (polytetrafluoroethylene) is preferable. . Fluorine resins such as PFA (polytetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) are also preferable for the valve main body and spring of the suction side check valve 24 and the discharge side check valve 26. For the pump cylinder 14, the cover lid 20, the accumulator cylinder 44, and the body 49a of the automatic pressure adjusting mechanism 49, a resin such as PP (polypropylene) is preferable. For the pump shaft 22 and the piston 19, a resin such as PPS (polyphenylene sulfide) is preferable. For the caps 55 and 56, a resin such as PE (polyethylene) is preferable. In addition to the O-rings 27, 29, 31, and 57, all of the O-rings used in the reciprocating pump 1 are made of fluoro rubber.

  The drive part K of the air cylinder part C will be described. As shown in FIG. 2, the drive unit K includes an air pump 82, a valve 83, an electromagnetic switching valve 81, an optical sensor 34, a control device 80, and the like. As described above, the forward air chamber 18 and the return air chamber By alternately supplying high-pressure air to 35, the movable plate portion 9 can be continuously reciprocated in the directions indicated by arrows A and B. Switching of the electromagnetic switching valve 81 in the driving unit K is performed by switching means A including a single optical sensor 34, a control device 80, and the like. The control device 80 is connected to the light emitting wiring r1 and the light receiving wiring r2 of the optical sensor 34 and to the electromagnetic driving portions 81a and 81a of the electromagnetic switching valve 81.

  The switching means A performs switching between the forward movement and the backward movement of the movable plate portion 9 that is a moving body, that is, switching of the electromagnetic switching valve 81 based on detecting the position of the movable plate portion 9 by the optical sensor 34. And a single optical sensor 34 arranged in a sensing action in a direction crossing the moving direction of the movable plate portion 9, and the movable plate portion 9 integrally at a position near the light receiving surface 34 a of the optical sensor 34. A moving piston (an example of a reflector) 19 and two variable pole portions h1 formed on the piston 19 at a distance from each other in the moving direction of the movable plate 9 in a state where the amount of light reflected to the optical sensor 34 is suddenly changed. h2.

  The first variable pole portion h1 is formed by providing a step 19C on the outer peripheral surface 19A of the piston 19 so that the light reflecting surfaces 19A and 19B having different distances from the optical sensor 34 are adjacent to each other in the moving direction of the movable plate portion 9. Is made up of. That is, the outer peripheral surface 19A having a large diameter is the first light reflecting surface 19A, and the outer peripheral surface 19B having a slightly smaller diameter (eg, 2 mm in radius) is the second light reflecting surface 19B. The second changing portion h2 is such that the second light reflecting surface 19B, which is the reflector of the optical sensor 34, disappears as the piston 19 moves in the outward direction (moving in the direction of arrow A), that is, as shown by a solid line in FIG. In the state, the end surface 19t of the piston 19 is configured by the end surface 19t of the piston 19 set so as to pass through the light receiving axis P slightly. Note that the distance L (see FIG. 2) between the light receiving surface 34a and the second light reflecting surface 19B is preferably set to approximately 5 mm or less (eg, 4 mm).

  As shown in FIGS. 2 and 3, the optical sensor 34 which is a reflection type photosensor is placed on the outer peripheral portion 20 a of the cover lid 20 attached to the end surface 14 t of the pump cylinder 14 in a state where the light emission and light reception directions are orthogonal to the axis X. The light-receiving surface 34a is set so as to be in the vicinity of the outer peripheral surface 19A of the piston 19 (eg, a position 2 mm away from the outer peripheral surface 19a in the outer diameter direction). The distance between the end surface 19t of the piston 19 and the inner surface 20b of the cover lid 20 in the direction of the axis X is set to 10 mm, which is the same amount as the total movement stroke StZ of the movable plate portion 9, and the movable plate portion 9 has the total movement stroke StZ. In the state approaching the limit in the forward direction (the state indicated by the solid line in FIG. 2), the end surface 19t is configured to pass through the light receiving axis P slightly. Further, as shown in FIG. 3, in a state where the movable plate portion 9 is close to the limit in the backward direction during the entire movement stroke, the light receiving axis P is slightly shifted to the pump cylinder side (left side in FIG. 2) of the step 19C. It is comprised so that it may become a position. The total movement stroke StZ (10 mm: see FIG. 4) is a design value, and the actual movement stroke StJ (9.5 mm: see FIG. 4) in which the piston 19 (movable plate portion 9) actually moves is the total movement. The value is slightly smaller than the stroke StZ.

  FIG. 4 shows a relationship graph in which the amount of light received by the reflected light from the piston 19 of the optical sensor 34 in the switching means A configured as described above varies depending on the stroke amount of the movable plate portion 9. The “movement stroke amount” in FIG. 4 means that the position of the piston 19 (of the movable plate 9) on the design of the most backward path movement (position of the inner surface 20b of the cover lid 20) is 0, and the design of the most forward path movement from there. The movement stroke to the side end, that is, the total movement stroke StZ (10 mm) is shown. Further, the “light receiving amount” in FIG. 4 is 4000 when the piston 19 (movable plate 9) is close to the most backward movement side (state in FIG. 3) where the light receiving amount of the optical sensor 34 is maximum. (Unit: digit). In other words, the amount of received light varies between the maximum value (4000) mainly reflected by the first reflecting surface 19A and the minimum value (100) due to the almost disappearance of the reflector by a moving stroke of 10 mm at the maximum. It is supposed to be.

  In the graph of FIG. 4, when the piston 19 moves from the designed most backward movement side position (position of the movement stroke 0) to the forward movement side, the first reflection surface 19A moves away and the second reflection surface 19B approaches. (The step 19C, that is, the first changing part h1 moves to the forward movement side), the amount of light received decreases sharply, and the amount of light received by the reflection of only the second reflecting surface 19B with a movement stroke of about 0.5 mm ( 500). Then, the amount of received light is kept approximately 500 until the moving stroke amount at which the second changing portion h2 approaches the light receiving axis P is about 9.3 mm, and the amount of received light suddenly decreases again to 10 mm thereafter. I understand that Note that a solid line d in the graph of FIG. 4 indicates a state where the optical sensor 34 is exhibiting the original irradiation amount, that is, a value when the received light amount is the initial value (100%), and a broken line d ′. Indicates a value when the amount of received light is reduced by 50% from the initial value due to changes over time, dirt, or the like.

  Here, if the control device 80 sets the first threshold value s1 of the detection information (received light amount) of the optical sensor 34 to 1600 and the second threshold value s2 to 200, the received light amount is 1600. The movement stroke in a range changing between 200 and 200 is the actual movement stroke (effective movement stroke) StJ of the movable plate portion 9, which is 9.5 mm between 0.3 mm and 9.8 mm when the graph is read. The first threshold value s1 is a gain for control for switching the movable plate portion 9 from the backward movement to the forward movement (switching the electromagnetic switching valve 81 from the H position to the O position). s2 is a control gain for switching the movable plate portion 9 from the forward movement to the backward movement (switching the electromagnetic switching valve 81 from the O position to the H position). These gains are stored in the control device 80 in advance.

  That is, it is possible to obtain an excellent performance that the stroke efficiency (shift efficiency) of 95% can be exhibited even though the switching means A uses only one optical sensor 34. In the line d ′ where the amount of received light is reduced by 50%, it can be read that the amount of movement stroke when the amount of received light is 1600 is 0.1 mm and the amount of movement stroke when the amount of received light is 200 is 09.6. Even in this case, the actual movement stroke is 9.5 mm, and even if the amount of received light changes, the actual movement stroke does not change. Therefore, the advantage that the pump performance is maintained at a constant level can be obtained. The stroke efficiency is the ratio of the actual movement stroke StJ by the switching means A to the total movement stroke StZ in the design of the movable plate 9 (moving body) (StJ / StZ = 9.5 mm / 10 mm in the first embodiment). = 95%), and the higher this, the fewer the extra strokes (StZ-StJ) that are required to secure the required movement stroke StJ, and there is the advantage that the compactness of the reciprocating pump is promoted.

  By the way, the detection sensitivity of the optical sensor 34 has a characteristic that it reacts more sensitively to the difference in the change rate of the received light amount than to the difference in the absolute value of the received light amount. Therefore, the rate of change (decrease rate) when the amount of received light changes from 4000 to 1600 by the first changing portion h1 is 60%, and the amount of received light changes from 500 to 200 by the second changing portion h2. Similarly, since the rate of change (decrease rate) is 60%, it is convenient that the detection operation can be performed with the same detection sensitivity in each case. Note that the rate of change (increase rate) when the amount of received light changes from 1600 to 4000 by the first changing portion h1, and the rate of change (increase) when the amount of received light changes from 200 to 500 by the second changing portion h2. The rate is naturally 250%, which is the same as each other.

  Next, the operation of the reciprocating pump according to the first embodiment will be described in detail including its drive control unit. As shown in FIG. 2, the volume of the pump chamber 11, which is a sealed space surrounded by the pump body 4 and the bellows 7, in which the movable plate portion 9 of the bellows 7 is at the front dead center DP 1 on the side close to the pump body 4. The electromagnetic switching valve 81 is manually operated by operating means (not shown) such as a push button attached to the control device 80 in a stopped state of the pump in which the electromagnetic switching valve 81 is held at the neutral position N. Is switched to the return path position H, the high pressure air supplied from the air pump 82 flows into the return path air chamber 35 through the path of the air supply pipe 84 → the electromagnetic switching valve 81 → the return path side path 33 a → the return path air supply port 33. At the same time, the high-pressure air sealed in the pump cylinder 14 and energizing the movable plate 9 in the direction of the front dead center DP1 is in the path of the forward path air supply port 32 → the forward path side path 32a → the electromagnetic switching valve 81. Released into the atmosphere. For this reason, the piston 19 moves in the direction indicated by the arrow B in the second cylinder portion 17 and retracts to the end position. With this retraction, the movable plate portion 9 of the bellows 7 moves away from the pump body 4 to the rear dead center DP2. Retreat to enlarge the volume of the pump chamber 11.

  As the volume of the pump chamber 11 increases, the negative pressure in the pump chamber 11 gradually increases, so that the transferred liquid passes through the suction port 2 of the pump body 4 → the suction passage 2 a → the suction side check valve 24 in the pump chamber 11. Inhaled (inhalation process). That is, the suction pressure of the transfer liquid sucked into the suction passage 2a overcomes the spring force of the winding spring 24A of the suction side check valve 24 and pushes the suction side check valve 24 (more specifically, the suction side check valve 24). The valve body 24B is retreated) and sucked into the pump chamber 11.

  The valve body 24B of the suction side check valve 24 is closed by the spring force of the winding spring 24A at the end of the suction stroke when the piston 19 is retracted to the end position and the movable plate portion 9 of the bellows 7 is retracted to the rear dead center DP2. start. At this time, the light receiving axis P of the optical sensor 34 is relatively in the state of passing through the step 19 </ b> C and facing the first reflecting surface 19 </ b> A of the piston 19, and the detected light reception amount (detection information) at that time is input to the control device 80. Is done. The control device 80 outputs a switching signal to the electromagnetic switching valve 81 by recognizing that the detected amount of received light input from the optical sensor 34 exceeds the first threshold value s1 (1600), and moves the electromagnetic switching valve 81 to the forward position. Switch to O. Thereby, the high pressure air supplied from the air pump 82 flows into the forward air chamber 18 through the air supply pipe 84 → the electromagnetic switching valve 81 → the forward path 32 a → the forward air supply port 32, and the return air chamber 35. The high-pressure air is discharged into the atmosphere through the path of the return path air supply port 33 → the return path side path 33 a → the electromagnetic switching valve 81. For this reason, the movable plate portion 9 of the bellows 7 is advanced to the front dead center DP 1 to reduce the volume of the pump chamber 11, and the piston 19 is advanced to the start end position in the second cylinder portion 17.

  By reducing the volume of the pump chamber 11, the transfer liquid in the pump chamber 11 overcomes the spring force of the winding spring 26 </ b> A of the discharge side check valve 26 and pushes the discharge side check valve 26 wide. The valve body 26B of the discharge-side check valve 26 is retracted), received in the accumulator chamber 40 from the communication passage 41, temporarily stored in the accumulator chamber 40, and then discharged from the pump body 4 through the discharge passage 3a. It is discharged from. At this time, the accumulator bellows 36 extends so as to increase the volume of the accumulator chamber 40 when the accumulator bellows 36 is at the peak of the discharge pressure curve due to the pulsation of the discharge pressure of the pump unit 5. By this extension operation, the flow rate of the transfer liquid flowing out from the accumulator chamber 40 becomes smaller than the flow rate flowing in. Further, when approaching the valley of the discharge pressure curve, the discharge pressure becomes lower than the air sealing pressure of the accumulator air chamber 47 compressed as the accumulator bellows 36 is extended. Shrink to reduce. Due to this contraction operation, the flow rate of the transfer liquid flowing out of the accumulator chamber 40 becomes less than the flow rate of the flowing liquid. The above operation is repeated in accordance with the suction process and the discharge process of the transfer liquid of the pump unit 5, and the damper action is performed.

  The discharge-side check valve 26 is closed at the end of the discharge stroke when the piston 19 moves forward to the start position and the movable plate portion 9 of the bellows 7 moves forward to the front dead center DP1. At this time, the light receiving axis P of the optical sensor 34 is relatively positioned to pass through the end surface 19t of the piston 19, and from a state in which weak reflected light from the second reflecting surface 19B of the piston 19 is received to a non-reflective state ( Therefore, the control device 80 performs electromagnetic switching by recognizing that the amount of received light received from the optical sensor 34 is below the second threshold value s2 (200). A switching signal is output to the valve 81 to switch the electromagnetic switching valve 81 to the return path position H. The following operation is repeated until the electromagnetic switching valve 81 is switched to the neutral position N by manual operation of the operating means attached to the control device 80, and the transfer liquid is sucked from the suction port 2 of the pump body 4 and pulsated. The liquid is continuously discharged at a substantially constant flow rate from the discharge port 3 at a discharge pressure that is absorbed and attenuated and is substantially smoothed.

[Example 2]
The reciprocating pump according to the second embodiment is different only in the switching means A in the drive unit K of the reciprocating pump according to the first embodiment, and the main part of the different switching means A will be described. As shown in FIG. 5, the switching means A according to the second embodiment is different from the switching means A according to the first embodiment in the specific structure of the changing parts h1 and h2, and the different first changing part h1 The light reflecting surfaces having different reflectances are formed on a piston (an example of a reflector) 19 adjacent to each other in the moving direction of the movable plate portion 9. The second changing portion h <b> 2 is the same as the second changing portion h <b> 2 of the first embodiment, and is configured by the end face 19 t of the piston 19. Even in this case, the distance L between the outer peripheral surface 19A of the piston 19 and the light receiving surface 34a is set to 5 mm or less, preferably 3 mm or less.

  Specifically, the first light reflecting surface 91 is constituted by the outer peripheral surface 19A of the color of the material of the piston 19 as it is, that is, a light color (light gray, silver or a light color close to them) having a high light reflectance. The second light reflecting surface 92 is formed by applying a dark color paint having a low light reflectance such as dark blue, dark green, black (or dark gray) to a portion having a predetermined interval from the end surface 19t on the outer peripheral surface of the piston 19. It consists of Therefore, the first changing portion h1 is configured by a boundary portion between the first light reflecting surface 91 and the second light reflecting surface 92, and the first changing portion h1 formed by this boundary portion is received by the light sensor 34. A detection signal in which the amount of received light rapidly changes by passing over the center P is input to the control device 80, whereby the switching operation of the electromagnetic switching valve 81 is performed.

  The second changing portion H2 is a configuration that is set so that the dark second light reflecting surface 92 disappears as the piston 19 moves in the forward direction (moving in the direction of arrow A). That is, in the state indicated by the solid line in FIG. 4 (the state where the movable plate 9 is at the front dead center DP1), the piston 19 is set so that the end surface 19t of the piston 19 slightly passes the light receiving axis P toward the pump body 4 side. The 19th end face 19t constitutes a second changing portion h2.

  FIG. 6 shows a relationship graph between the movement stroke of the piston 19 by the switching means A according to the second embodiment and the amount of light received by the optical sensor 34. The difference from the graph of FIG. 4 is that when the received light amount of the constant received light amount due to the reflection of only the second reflecting surface 92 is 600 (solid line) is 600, and when it is reduced by 50% (solid line) ( In the broken line), the point is 300, and it is considered that the other points are almost the same. In this case, it is convenient that the first threshold value s1 is set to 1600, which is the same as that in the first embodiment, and the second threshold value s2 is set to 240.

  Then, when the amount of received light is the initial value, the moving stroke of the first threshold value s1 is 0.3 mm, the moving stroke of the second threshold value s2 is 9.8 mm, and the actual moving stroke StJ is 9. 8−0.3 = 9.5 mm, which is the same as that of the switching means A according to the first embodiment. When the amount of received light is reduced by 50%, the moving stroke of the first threshold s1 is 0.1 mm, the moving stroke of the second threshold s2 is 9.6 mm, and the actual moving stroke is 9.6-0. .1 = 9.5 mm, and even if the amount of received light changes, the actual movement stroke does not change, so that the advantage that the pump performance is maintained at a certain preferable level can be obtained.

[Comparative Example 2]
For reference, FIG. 9 shows a configuration diagram in the case of Comparative Example 2 in which the position of the optical sensor 34 in the switching means A according to Example 1 shown in FIG. A relationship graph between the amount of received light and the movement stroke in this case is shown by a line e in FIG. In the configuration according to the comparative example 2, the distance L between the first light reflecting surface 19A and the second light reflecting surface 19B, which are the outer peripheral surfaces of the piston 19 that is a reflector, and the light receiving surface 34a is larger than that according to the first embodiment. Therefore, the amount of light received is clearly reduced as a whole by the diffusion of light, and the change gradient of the amount of light received by the first changing portion h1 due to the step 19C and the second changing portion h2 due to the end face 19t is also slow. It becomes. As a result, as shown by the line e in FIG. 12, it is difficult to establish a sudden change portion, and it is difficult to set the first and second threshold values s1 and s2, and even if they are set, there is little. There is a tendency that the movement stroke value at that time easily fluctuates greatly due to increase or decrease in the amount of received light, and the pump performance is difficult to stabilize.

[Comparative Example 3]
For reference, FIG. 10 shows a configuration diagram of Comparative Example 3 in which the diameter of the second reflecting surface 19B in the switching means A according to Example 1 shown in FIG. 2 is greatly reduced, and the received light amount and moving stroke in that case. Is shown in line c of FIG. In the configuration according to the comparative example 3, the absolute value of the distance between the first reflecting surface 19A and the light receiving surface 34a of the piston 19 that is a reflector is the same as that according to the first embodiment, but the radial dimension of the step 19C is large. Thus, the distance L between the second reflecting surface 19B and the light receiving surface 34a is clearly larger than that according to the first embodiment. Therefore, the sharply decreasing portion of the received light amount in the first half of the graph is in the same state as the relation graph (line d) of Example 1, but the light receiving amount is reduced because light diffusion is likely to occur in the latter half of the graph. The rate becomes slow. In addition, the gradient of change in the amount of received light (due to the end face 19t) by the second changing portion h2 is slow as in the case of the comparative example 2 described above.

  As a result, as shown by the line c in FIG. 12, the change behavior at the initial stage of the moving stroke is slightly preferable to that of the comparative example 1, but it is still difficult to establish a sudden change point. Thus, it is difficult to set the first and second threshold values s1, s2, and even if set, the movement stroke greatly fluctuates due to a slight increase / decrease in the amount of received light, and the pump performance tends to be difficult to stabilize. There is.

  For reference, FIG. 12 shows a graph of the relationship between the amount of received light and the movement stroke in this order in the conventional example, comparative example 1, comparative example 3, comparative example 1, and comparative example 2 using two optical sensors. Listed as e at once. Of these relationship graphs, there are four lines b to e by the structure using the single optical sensor 34, but only the line d according to the first embodiment of the present invention is in any of the positions near the both ends of the moving stroke. However, it is preferable that an ideal graph in which the amount of received light changes abruptly is obtained. In addition, the change in the amount of received light is more abrupt than when two sensors are used, and the sudden change location is located closer to the end of the stroke. Even if there is a change in quantity, there is no or less change in the moving stroke, and there is an advantage that excellent pump performance can be stably exhibited.

[Another Example]
As shown in FIG. 13, a pair of large-diameter annular projections 100 having a flat outer peripheral surface 100a are formed on the outer peripheral surface of the piston 19 at intervals in the moving direction (axis X direction). The switching means A having a configuration in which the single photosensor 34 is disposed in a state where the light receiving surface 34a is located in proximity to each other may be used. In this case, the annular end surfaces 100b and 100b on the opposite sides of the annular protrusions 100 and 100 correspond to the changing parts h1 and h2, and the light receiving center P moves so as to pass the changing parts h1 and h2 slightly. Stroke is set. The relationship graph between the amount of received light and the movement stroke in this case is substantially as shown by line a in FIG. 11, and it is possible to obtain the same sensing performance as in the case of using two optical sensors. .

  By making the step 19C of the piston 19 in FIG. 2 a little smaller, the graph of the relationship between the amount of received light and the moving stroke shows the characteristic that the amount of received light suddenly changes at both ends of the moving stroke as shown by the line f in FIG. Switching means A having a sensing characteristic to be exhibited may be used.

  In the above-described bellows type reciprocating pump, the movable plate portion 9 corresponds to the “moving body” of claim 1. For example, in the case of a general piston pump that pumps by the reciprocating motion of the piston in the cylinder. The piston that forms the pump chamber corresponds to the “moving body”. Therefore, the movable plate portion 9 and the piston are collectively referred to as “moving body”. The “reflector” may be the above-described piston 19 or a “sensor sensing plate” shown in the prior art. In short, the “reflector” reciprocates integrally with the “moving body” and reflects light to reflect the optical sensor. It is sufficient if it is for receiving light.

Sectional view showing structure of bellows type reciprocating pump Sectional drawing which shows the sensing part by a pump part and an optical sensor (Example 1) Sectional view of the optical sensor with the piston positioned at the end of the return path The figure which shows the relationship graph of a bellows movement stroke and the optical sensor light reception amount of FIG. Sectional drawing which shows the 1st another structure of a sensing part (Example 2) The figure which shows the relationship graph of a bellows movement stroke and the optical sensor light reception amount of FIG. Sectional drawing of the principal part which shows the structure of the sensing part by the comparative example 1 The figure which shows the relationship graph of a bellows movement stroke and the optical sensor light reception amount of FIG. Sectional drawing of the principal part which shows the structure of the sensing part by the comparative example 2 Sectional drawing of the principal part which shows the structure of the sensing part by the comparative example 3 Sectional drawing of the principal part which shows the structural example of the sensing part in the case of using two optical sensors The figure which shows the various relational graphs of the bellows movement stroke and the amount of light received by the optical sensor Sectional view of the main part showing another structure of the sensing part

Explanation of symbols

2a Suction passage 3a Discharge passage 7 Bellows 9 Moving body, movable side member 11 Pump chamber 14 Pump cylinder 19 Reflector 19A, 19B Light reflection surface 19C Step 24 Valve, suction side check valve 26 Valve, discharge side check valve 34 Light Sensor 34a Light-receiving surface 91, 92 Light reflecting surface A Switching means C Air cylinder part h1, h2 Second changing part

Claims (5)

The pump action generated by driving and reciprocating the moving body in the pump cylinder allows the fluid to be sucked and discharged freely through the valve, and switching between the forward movement and the backward movement of the moving body is performed as described above. A reciprocating pump equipped with a switching means that is based on detecting the position of the moving body in the reciprocating direction with an optical sensor,
The switching means includes a single optical sensor arranged in a state of sensing in a direction crossing the moving direction of the moving body, and a reflector that moves integrally with the moving body at a position near the light receiving surface of the optical sensor. And two reversing portions formed on the reflector at intervals in the moving direction of the moving body in a state in which the amount of reflected light to the optical sensor is suddenly changed. Dynamic pump. A bellows that can be expanded and contracted in the pump cylinder, an air cylinder part that expands and contracts the bellows by reciprocating a movable side member of the bellows in the pump cylinder, and a pump chamber formed by the pump cylinder and the bellows A fluid suction passage and a fluid discharge passage, a suction-side check valve that allows fluid to flow only in a direction from the suction passage toward the pump chamber, and a fluid from the pump chamber toward the discharge passage. A discharge side check valve that allows flow only in the direction,
A reciprocating pump equipped with switching means for performing switching between the forward movement and the backward movement of the movable side member based on detecting the position of the movable side member in the reciprocating direction with an optical sensor,
The switching means moves integrally with the movable member at a position in the vicinity of the light receiving surface of the single optical sensor arranged in a state of sensing action in a direction crossing the moving direction of the movable member. A reflector, and two pole changing portions formed on the reflector spaced apart from each other in the moving direction of the movable member in a state in which the amount of light reflected to the optical sensor is suddenly changed. Reciprocating pump.   3. The pole changing part according to claim 1 or 2, wherein a step is provided on the reflector, and light reflecting surfaces having different distances from the optical sensor are formed adjacent to each other in the moving direction. The described reciprocating pump.   3. The reciprocating pump according to claim 1, wherein the pole changing portion is configured by forming light reflecting surfaces having different light reflectivities adjacent to each other in the moving direction on the reflector. The reciprocating pump according to claim 4, wherein the light reflecting surfaces having different light reflectances are formed by adding shades of color to the reflector.

Images