Double strainer

Abstract

To provide a novel duplex strainer which can effectively prevent strain from being caused in a case body by fastening of bolts even when the bolts are used for joining or fixing a left body main unit or a right body main unit to a case body forming a cock case.SOLUTION: A duplex strainer includes: a left body fixed to a left side of a case body 2 of a cock case by left fixing bolts; and a right body fixed to a right side of the case body 2 by right fixing bolts. Left blocking spaces 2m and right blocking spaces 2n which block fastening force of the individual left fixing bolts and right fixing bolts are formed from terminals of all bolt holes, each of which is formed at the case body 2 and allows the left fixing bolt or the right fixing bolt to be inserted thereinto or threadedly engaged therewith, in a fastening direction of the left fixing bolt or the right fixing bolt.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention is used to remove foreign substances such as sludge and dust mixed in a liquid, which is arranged in the middle of a liquid flow path flowing from the upstream side to the downstream side in a pipe body. The present invention relates to a duplex strainer in which left and right bodies having screens for capturing the foreign substances accommodated therein are fixed to the left and right of a cock case having a cock for flow path switching accommodated therein.

Background Art

[0002] So far, in many chemical plants, industrial facilities or structures, a pipe body (pipeline) as a liquid flow path is arranged, and in the middle of such a pipe body, a strainer for removing foreign substances such as sludge contained in the liquid flowing from the upstream side is arranged. Such a strainer has a screen for filtering foreign substances contained in the liquid as a component.

[0003] Incidentally, when the above-mentioned strainer is used for a long period of time, a large amount of captured foreign matter will adhere to the inner or outer surface of the screen. This adhesion of foreign matter leads to a decrease or reduction in the flow rate or velocity of the liquid per unit time flowing through the pipe (increased pressure loss), so it becomes necessary to remove the foreign matter attached to the screen periodically or as needed. One way to remove the foreign matter attached to the screen is to remove the screen and wash it, but this method requires temporarily stopping the flow of liquid through the pipe and is therefore not feasible. Therefore, a double-type strainer has been used to provide a structure that can remove the foreign matter without stopping the flow of liquid. This double-type strainer is connected in the middle of the pipe through which the liquid flows and consists of a cock case that houses a cock for switching the flow path, and left and right bodies fixed to the left and right of the cock case, each housing a screen for capturing the foreign matter. For example, the double strainer described in Japanese Patent Publication No. 54-39633 (Patent Document 1), proposed by the applicant of this application, has a structure that, by rotating a flow path switching cock located inside the cock case, causes liquid flowing into the cock case from the upstream side to flow in either the left body direction or the right body direction, passes through a screen housed in the left or right body, and then flows the liquid that has passed through either of these screens into the cock case before flowing downstream. For example, when liquid flows into the left body via the cock, no liquid flows into the right body, so in this state, foreign matter adhering to the screen can be removed by taking out the screen housed in the right body.

[0004] Furthermore, the double strainer 100 shown in Figure 11 is an improvement on the double strainer described in Patent Document 1, and comprises a cock case 101 formed in a substantially block shape, a left body 102 whose right side is fixed to the left side of the cock case 101, and a right body 103 whose left side is fixed to the right side of the cock case 101. The cock case 101 comprises a case body 104 in which the lower side of the shaft portion 106a of the cock 106 (described later) is housed and a liquid storage space (reference numerals omitted) into which liquid flows from the upstream side is formed, and a case lid 105 which closes the liquid storage space formed in the case body 104 at the top, and a shaft insertion space (reference numerals omitted) is formed in the center of the case lid 105 through which the shaft portion 106a is inserted from below to above. A pivot shaft 107 is fixed to the upper end of the shaft portion 106a, and the base end of an operating handle 108 for rotating the entire cock is detachably attached to the pivot shaft 107. The case body 104 also has an inlet port 104a for allowing liquid from an upstream pipeline (not shown) to flow into the liquid storage space, and an outlet port (not shown) for discharging liquid that has passed through either a left screen (not shown) or a right screen 115 (described later) to a downstream pipeline (not shown). Furthermore, the case body 104 has the following features: an upper left outflow passage 104b that directs the liquid flowing in from the inflow port 104a towards the left body 102; a lower left inflow passage 104c through which liquid filtered by a left screen (not shown) housed in the left body 102 flows into (recirculates) the case body 104; an upper right outflow passage 104d that directs the liquid flowing in from the inflow port 104a towards the right body 103; and a lower right inflow passage 104e through which liquid filtered by a right screen 115 housed in the right body 103 flows into (recirculates) the case body 104. The upper left outflow passage 104b and the upper right outflow passage 104d, and the lower left inflow passage 104c and the lower right inflow passage 104e are each formed at 180-degree angles to the central axis of the case body 104. Furthermore, a cock (flow path switching valve) 106 is positioned inside the case body 104, which has a shaft portion 106a at its upper part and is rotatable by the rotational operation of the operating handle 108.The cock 106 comprises a shaft portion 106a inserted into a shaft insertion space formed in the center of the case lid 105, a liquid inlet chamber 106b formed below the shaft portion 106a and located within the liquid storage space formed inside the case body 104, with its interior always communicating with the inlet port 104a, a liquid outlet chamber 106c into which liquid filtered by either a left screen or a right screen 115 (not shown) flows, and which is connected to a liquid outlet passage that is always communicating with an outlet port (not shown), and a partition plate portion 106d separating the liquid inlet chamber 106b and the liquid outlet chamber 106c. Furthermore, the cock 106 has an upper opening 106e formed above the partition plate portion 106d that connects the liquid inlet chamber 106b with either the upper left outlet passage 104b or the upper right outlet passage 104d, and the cock 106 also has a lower opening 106f that connects the liquid discharge chamber 106c with either the lower left inlet passage 104c or the lower right inlet passage 104e. The bottom surface of the cock 106 has a bottom opening 106g that connects the filtered liquid that has flowed into the liquid discharge chamber 106c to the liquid discharge passage (not shown). Figure 11 shows the state in which the liquid inlet chamber 106b and the upper right outlet passage 104d formed in the case body 104 are in communication through the upper opening 106e, and the liquid discharge chamber 106c and the lower right inlet passage 104e formed in the case body 104 are in communication through the lower opening 106f. Therefore, when the cock 106 is in the state shown in Figure 11, the liquid that flows into the liquid inlet chamber 106b from the upstream side via the inlet port 104a passes through the upper opening 106e and the upper right outlet passage 104e, flows into the right body 103 (right body main body 116, which will be described later), passes through the right screen 115, then passes through the lower right inlet passage 104e and the lower opening 106f, passes through the liquid discharge chamber 106c, and further passes through the bottom opening 106g, flows into a liquid discharge passage (not shown), and then flows into the downstream pipeline from the discharge port (not shown).

[0005] Furthermore, the left body 102 comprises a left body body 112 having a left screen (not shown) housed inside and an opening formed at the top, a left cover 113 that closes the opening formed in the left body body 112, and a left handle 114 that secures the left body body 112 and the left cover 113. The right body 103 comprises a right body body 116 having a right screen 115 housed inside and an opening formed at the top, a right cover 117 that closes the opening formed in the right body body 116, and a right handle 118 that secures the right body body 116 and the right cover 117. Furthermore, a disc-shaped left fixing plate portion 120 is formed on the right side of the left body 112, which is joined and fixed to the left side of the block-shaped case body 104. On the central side of this left fixing plate portion 120, there is an upper left inflow passage (not shown) that connects the upper left outflow passage 104b formed in the case body 104 to the inside of the left body 112, and a lower left outflow passage (not shown) that connects the lower left inflow passage 104c formed in the case body 104 to the inside of the left body 112. Furthermore, a disc-shaped right fixing plate portion 121 is formed on the left side of the right body 116, which is joined and fixed to the right side of the block-shaped case body 104. On the central side of this right fixing plate portion 121, there is an upper right inflow passage (not shown) that connects the upper right outflow passage 104d formed in the case body 104 to the inside of the right body 116, and a lower right outflow passage (not shown) that connects the lower right inflow passage 104c formed in the case body 104 to the inside of the right body 116. On the outer peripheral end of the left fixing plate portion 120, there are bolt insertion holes (not shown) through which a plurality of stud bolts 130 are inserted, while on the left side of the case body 104, there are a plurality of bolt holes (not shown) into which each of the stud bolts 130 is screwed, and nuts 131 are screwed onto the stud bolts 130. Furthermore, a bolt insertion hole is formed on the outer peripheral end of the right fixing plate portion 121, through which a stud bolt (not shown) similar to the stud bolt 130 is inserted. Multiple bolt holes (not shown) are formed on the right side of the case body 104, through which the multiple stud bolts are screwed, and nuts are screwed onto the stud bolts. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Special Publication No. 54-39633 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, in the double strainer 100 with the structure shown in Figure 11 above, the case body 104 is slightly distorted when the nuts 131 screwed onto the multiple stud bolts 130 are rotated to firmly fasten the stud bolts 130, and as a result when the cock 106 is assembled inside the case body 104, the sealing performance of the cock 106 cannot be ensured. Therefore, in order to eliminate this distortion of the case body 104, a lapping method can be adopted in which the cock 106 is assembled inside the case body 104 and rubbed against each other with an abrasive. However, this method requires a long period of work and is extremely unproductive.

[0008] Therefore, the present invention was proposed to solve the problems of the conventional double strainer described above, and aims to provide a novel double strainer that can effectively prevent distortion of the case body from occurring due to fastening by bolts, even when bolts are used to join and fix the left body body and the right body body to the case body that constitutes the cock case. [Means for solving the problem]

[0009] The present invention was proposed to solve the above problems, and the first invention (the invention described in claim 1) comprises a cock case having a case body in which a cock for switching flow paths is rotatably housed inside, a left body fixed to the left side of the case body and having a left body body in which a left screen is housed inside, and a right body fixed to the right side of the case body and having a right body body in which a right screen is housed inside, wherein the case body has a left port that allows liquid flowing into the case body from the upstream side through the inflow port to flow towards the left body body side An upper outflow passage, a lower left inflow passage that allows liquid filtered by the left screen to flow into the case body from the left body side, an upper right outflow passage that allows liquid that has flowed into the case body from the upstream side via the inflow port to flow into the right body side, a lower right inflow passage that allows liquid filtered by the right screen to flow into the case body from the right body side, and a discharge port that allows liquid that has flowed into the case body from either the lower left inflow passage or the lower right inflow passage to flow downstream, and the left body body is provided with an upper left outflow passage that communicates with the upper left outflow passage and allows liquid from the upper left outflow passage to flow into the left body The main body has an upper left inlet passage for flowing liquid and a lower left outlet passage that communicates with the lower left inlet passage and allows the liquid filtered by the left screen to flow into the lower left inlet passage. The right body has an upper right inlet passage that communicates with the upper right outlet passage and allows the liquid from the upper right outlet passage to flow into the right body, and a lower right outlet passage that communicates with the lower right inlet passage and allows the liquid filtered by the right screen to flow into the lower right inlet passage. The right side of the left body has the upper left outlet passage and the lower left inlet passage formed inside, and the outer circumference is connected to the left side of the case body and the left body. A left fixing plate section is formed, through which multiple left insertion holes are formed for inserting left fixing bolts to secure the case. On the left side of the right body, an upper right inflow passage and a lower right outflow passage are formed internally. On the outer circumference, a right fixing plate section is formed, through which multiple right insertion holes are formed for inserting right fixing bolts to secure the right side of the case body to the right body. On the left side of the case body, a left fixing section is formed, through which an upper left outflow passage and a lower left inflow passage are formed internally, and which has a left joining surface that joins with the right side surface of the left fixing plate section. On the right side of the case body,The above-mentioned upper right outflow passage and lower right inflow passage are formed internally, and a right fixing portion is formed having a right joining surface that is joined to the left side surface of the right fixing plate portion. Multiple left bolt holes are formed in the middle of the outer circumference of the left fixing portion, through which the left fixing bolts are inserted or screwed. Multiple right bolt holes are formed in the middle of the outer circumference of the right fixing portion, through which the right fixing bolts are inserted or screwed. Left-side blocking spaces are formed from all ends of the multiple left bolt holes in the tightening direction of the left fixing bolts to block the tightening force of each left fixing bolt, and right-side blocking spaces are formed from all ends of the multiple right bolt holes in the tightening direction of the right fixing bolts to block the tightening force of each right fixing bolt.

[0010] In the double strainer according to this first invention, when liquid from the upstream side flows into the case body constituting the cock case via the inflow port, it flows into the left body body or the right body body through either the upper left outflow passage or the upper right outflow passage formed in the case body, and then through either the upper left inflow passage formed in the left body body or the upper right inflow passage formed in the right body body. The selection of whether the liquid flowing into the case body from the upstream side flows out through the upper left outflow passage or the upper right outflow passage is made by a flow path switching cock housed in the case body. The liquid that flows into the left body body is filtered by the left screen housed in the left body body, then passes through the lower left outflow passage, and further passes through the lower left inflow passage formed in the case body before flowing into the case body. Similarly, the liquid that flows into the right body body is filtered by the right screen housed in the right body body, then passes through the lower right outflow passage, and further passes through the lower right inflow passage formed in the case body before flowing into the case body. The liquid that has been filtered by either the left or right screen and entered the case body then flows downstream through the discharge port.

[0011] In this first invention, a left fixing plate is formed on the right side of the left body, and a right fixing plate is formed on the left side of the right body. The left fixing plate has an upper left outflow passage and a lower left inflow passage formed inside, and a plurality of left insertion holes are formed in the middle of the outer circumference through which left fixing bolts that fix the left side of the case body to the left body are inserted. The right fixing plate has an upper right inflow passage and a lower right outflow passage formed inside, and a plurality of right insertion holes are formed in the middle of the outer circumference through which right fixing bolts that fix the right side of the case body to the right body are inserted. On the other hand, a left fixing part is formed on the left side of the case body, and a right fixing part is formed on the right side of the case body. The left fixing portion has an upper left outflow passage and a lower left inflow passage formed inside, and has a left joining surface that is joined to the right side surface of the left fixing plate portion. Furthermore, a plurality of left bolt holes are formed in the middle of the outer circumference through which the left fixing bolts are inserted or screwed. The right fixing portion has an upper right outflow passage and a lower right inflow passage formed inside, and has a right joining surface that is joined to the left side surface of the right fixing plate portion. Furthermore, a plurality of right bolt holes are formed in the middle of the outer circumference through which the right fixing bolts are inserted or screwed.

[0012] Furthermore, a left-side blocking space is formed from all ends of the multiple left bolt holes in the direction of tightening the left fixing bolts, blocking the tightening force of each individual left fixing bolt. Similarly, a right-side blocking space is formed from all ends of the multiple right bolt holes in the direction of tightening the right fixing bolts, blocking the tightening force of each individual right fixing bolt. Therefore, even when the individual left and right fixing bolts are firmly fastened, the fastening force is interrupted by the left and right blocking spaces, eliminating any risk of the space formed within the case body becoming distorted, and allowing the flow path switching cock to be housed in a stable state and rotated stably.

[0013] In this first invention, the external shape of the left side of the left fixing part formed on the left side of the case body and the external shape of the right side of the right fixing part formed on the right side of the case body may be formed in a circular shape, in addition to being a rectangular shape with both the upper and lower ends and both the left and right ends formed in straight lines. Furthermore, the left-side blocking space and the right-side blocking space only need to be a space that can block the tightening force of the left fixing bolt or the right fixing bolt, and may be, for example, a slit, recess or through hole formed in the tightening direction of the left fixing bolt or the right fixing bolt, or it may be formed in an annular shape that surrounds from the outside the part in which the upper left outflow passage and the lower left inflow passage are formed inside, or the part in which the upper right outflow passage and the lower right inflow passage are formed inside (see the second invention).

[0014] Furthermore, the second invention (the invention described in claim 2) is characterized in that, in the first invention, the left-side blocking space is formed in an annular shape so as to surround the left-side conduit section, in which the left upper outflow passage and the left lower inflow passage are formed from the outside, and the right-side blocking space is formed in an annular shape so as to surround the right-side conduit section, in which the right upper outflow passage and the right lower inflow passage are formed from the outside.

[0015] In the double strainer according to this second invention, the left-side blocking space and the right-side blocking space are formed in an annular shape so as to surround the left-side conduit section or the right-side conduit section from the outside, and are not slits, recesses, or through holes. Therefore, even if sand, dust, or other foreign matter enters or accumulates in the left-side blocking space and the right-side blocking space, it can be easily cleaned and removed. Furthermore, the overall load of the case body constituting this double strainer can be reduced, thereby improving workability when carrying it or when performing maintenance by removing the entire unit from the liquid flow path.

[0016] Furthermore, the third invention (the invention described in claim 3) is characterized in that, in the second invention, a left partition plate portion having a length in the direction of liquid passage is formed in the left conduit portion, the upper left outflow passage is formed above the left partition plate portion, and the lower left inflow passage is formed below the left partition plate portion, a right partition plate portion having a length in the direction of liquid passage is formed in the right conduit portion, the upper right outflow passage is formed above the right partition plate portion, and the lower right inflow passage is formed below the right partition plate portion, and the cross-sectional shapes of the upper left outflow passage and the lower left inflow passage and the upper right outflow passage and the lower right inflow passage are formed into a substantially semicircular shape with the upper or lower surface of the left partition plate portion or the right partition plate portion being flat, and the positions of the left bolt holes formed in the left fixing portion are equidistant from the center of the left conduit portion, and the positions of the right bolt holes formed in the right fixing portion are equidistant from the center of the right conduit portion.

[0017] In the double strainer according to this third invention, the positions of the left bolt holes formed in the left fixing part are equidistant from the center of the left conduit section, and the positions of the right bolt holes formed in the right fixing part are equidistant from the center of the right conduit section. As a result, the bonding force or pressure force between the right side surface of the left fixing plate part constituting the left body and the left joint surface formed on the left side of the case body, and the bonding force or pressure force between the left side surface of the right fixing plate part constituting the right body and the right joint surface formed on the right side of the case body, are uniform without variation depending on the position of each fixing bolt. Therefore, with the double strainer according to this third invention, the risk of the liquid before filtration or the liquid after filtration leaking to the outside from between the right side surface of the left fixing plate part and the left joint surface, and from between the left side surface of the right fixing plate part and the right joint surface, can be effectively prevented. [Effects of the Invention]

[0018] According to the present invention, even when bolts are used to join and fix the left body main body and the right body main body to the case main body constituting the cock case, it is possible to effectively prevent the case main body from being distorted by the fastening with the bolts. In particular, according to the second invention (the invention described in claim 2), even when sand, dust, or other foreign substances enter or accumulate in the left blocking space and the right blocking space, they can be easily cleaned and removed, and the load of the entire case main body constituting this double strainer can be reduced. Further, according to the third invention (the invention described in claim 3), it is possible to effectively prevent the risk that the liquid before filtration or the liquid after filtration leaks to the outside from between the right side surface of the left fixing plate portion and the left joining surface or between the left side surface of the right fixing plate portion and the right joining surface.

Brief Description of the Drawings

[0019] [Figure 1] It is a plan view showing a double strainer according to an embodiment of the present invention. [Figure 2] It is a perspective view showing a double strainer according to an embodiment of the present invention. [Figure 3] It is a front view of the double strainer shown in FIG. 1. [Figure 4] It is a left side view of the double strainer shown in FIG. 1. [Figure 5] It is a plan view of the cock case constituting the double strainer shown in FIG. 1. [Figure 6] It is a cross-sectional view taken along line A-A of the double strainer shown in FIG. 5. [Figure 7] It is a side view showing the left joining surface or the right joining surface of the case main body. [Figure 8] It is an end view showing the configuration of the left fixing portion and the right fixing portion constituting the case main body. [Figure 9] It is a perspective view schematically showing the main part of the second example of the blocking space constituting the present invention. [Figure 10] It is a perspective view schematically showing the main part of the third example of the blocking space constituting the present invention. [Figure 11]This is a cross-sectional view showing a conventional double-type strainer. [Modes for carrying out the invention]

[0020] The following describes a double strainer according to the best mode for carrying out the present invention.

[0021] As shown in Figures 1 to 5, this double strainer comprises a case body 2 that constitutes the cock case, a left body 3 fixed to the left side of the case body 2 on its right side, a right body 4 fixed to the right side of the case body 2 on its left side, and a cock for switching the flow path (not shown). The case body 2 has an inflow space 2a (see Figure 1) into which liquid flowing from the upstream side flows. The case body 2 is also composed of a case lid (not shown) that closes the inflow space 2a from above, and the case body 2 and this case lid constitute the cock case. The case lid, the pivot shaft attached to the case lid, and the operating handle attached to the pivot shaft are the same as in the conventional configuration shown in Figure 11, so a detailed explanation of them is omitted. The left body 3 has an opening 3a at the top and a housing space (reference numerals omitted) inside into which a left screen (not shown) is housed. The left body 3 is fitted with a left cover (not shown) that closes the opening 3a, and the left cover and the left body 3 together constitute the left side of the body. The left body 3, the left cover, and the left handle that secures the left cover are basically the same in configuration as the left body 112, left cover 113, and left handle 114 shown in Figure 11, so their explanation will be omitted. Similarly, the right body 4 has an opening 4a formed at the top, and a storage space (reference numerals omitted) is formed inside which a right screen (not shown) is housed. A right cover (not shown) that closes the opening 4a is attached to the right body 4, and the right cover and the right body 4 together constitute the right side of the body. The right body 4, the right cover, and the right handle that secures the right cover are basically the same in configuration as the right body 116, the right cover 117, and the right handle 118 that secures the right body 116 and the right cover 117 shown in Figure 11, so their explanation will be omitted. Also, the right screen (not shown) housed inside the right body 4 has the same configuration as the right screen 115 shown in Figure 11.

[0022] Furthermore, the case body 2 has an upstream fixing plate portion 21 which is joined and fixed to an upstream fixing plate portion (not shown) formed at the tip of an upstream conduit (not shown) by four bolts and nuts 6 (see Figure 1 or Figure 2) (not shown). The case body 2 also has a downstream fixing plate portion 22 which is joined and fixed to a downstream fixing plate portion (not shown) formed at the base end of a downstream conduit (not shown) by four bolts and nuts 7 (see Figure 1) (not shown). In the center of the upstream fixing plate portion 21, as shown in Figure 6, an inflow port 21a is formed which communicates with the upstream conduit, and the liquid flowing in from this inflow port 21a (liquid before filtration) is configured to flow into the inflow space 2a formed in the case body 2 via the inflow conduit 2b shown in Figure 1 or Figure 5. In addition, bolt insertion holes (not shown) through which the four bolts (not shown) are inserted are formed at equal intervals in the circumferential direction of the upstream fixing plate portion 21 in the middle of the outer circumference of the upstream fixing plate portion 21. Furthermore, as shown in Figure 2 or Figure 3, an outlet port 2c is formed in the center of the downstream fixing plate portion 22, which communicates with a downstream pipeline (not shown). The outlet port 2c and the case body 2 are connected to an outlet pipeline 2d through which liquid (filtered liquid) that has flowed into the case body 2 from the left body 3 or right body 4 flows. In addition, bolt insertion holes 2e through which the four bolts are inserted are formed at equal intervals in the circumferential direction of the downstream fixing plate portion 22 in the middle of the outer circumference of the downstream fixing plate portion 22.

[0023] Furthermore, as shown in Figure 7, the case body 2 has the following features: an upper left outlet passage 2f that directs the liquid that has entered the inlet space 2a before filtration towards the left body 3; a lower left inlet passage 2g through which the liquid filtered by a left screen (not shown) housed in the left body 3 flows into the case body 2 (recirculates); an upper right outlet passage 2h that directs the liquid that has entered the inlet space 2a before filtration towards the right body 4; and a lower left inlet passage 2i through which the liquid filtered by a right screen (not shown) housed in the right body 4 flows into the case body 2 (recirculates). The upper left outlet passage 2f and the upper right outlet passage 2h, and the lower left inlet passage 2g and the lower right inlet passage 2i are each formed at positions 180 degrees symmetrical with respect to the central axis of the case body 2. In this embodiment, as shown in Figure 7 or Figure 8, the upper left outflow passage 2f and the lower left inflow passage 2g, and the upper right outflow passage 2h and the lower right inflow passage 2i, are formed above and below the left partition plate portion 2j or right partition plate portion 2k, which are formed between the upper left outflow passage 2f and the lower left inflow passage 2g, and between the upper right outflow passage 2h and the lower right inflow passage 2i, respectively. That is, as shown in Figure 8, the upper left outflow passage 2f has a cross-sectional shape that is approximately semicircular with the upper surface of the left partition plate portion 2j as its lower surface, and the lower left inflow passage 2g is formed in a line-symmetric shape with the left partition plate portion 2j in between. The upper right outflow passage 2h has a cross-sectional shape that is approximately semicircular with the upper surface of the right partition plate portion 2k as its lower surface, and the lower right inflow passage 2i is formed in a line-symmetric shape with the right partition plate portion 2k in between.

[0024] Furthermore, a cock (flow path switching valve), not shown, having the same configuration as the cock 106 shown in Figure 11, is rotatably arranged inside the case body 2. The partition plate portion 106d, which separates the liquid inlet chamber 106b and the liquid outlet chamber 106c described earlier and is formed inside the cock 106, is located between the left partition plate portion 2j and the right partition plate portion 2k shown in Figure 7. Therefore, in the double strainer according to this embodiment, the liquid before filtration that flows into the case body 2 from the upstream pipeline (not shown) via the inlet pipeline 2b flows into the liquid inlet chamber 106b partitioned by the partition plate portion 106d, and does not flow into the liquid outlet chamber 106c formed below the partition plate portion 106d. Instead, it flows from the liquid inlet chamber 106b in either the direction of the upper left outlet passage 2f or the upper right outlet passage 2h. Furthermore, the liquid filtered by either the left screen housed in the left body 3 or the right screen housed in the right body 4 flows into the liquid discharge chamber 106c from either the lower left inlet passage 2g or the lower right inlet passage 2i without mixing with the liquid in the liquid inlet chamber 106b before filtration. Also, as shown in Figure 6, a discharge channel 2l is formed on the lower side of the case body 2, into which liquid flows out from the bottom opening 106g shown in Figure 11, which is formed at the bottom of the cock 106, and which is connected to the discharge pipeline 2d. Therefore, the liquid that flows into the liquid discharge chamber 106c passes through the discharge channel 2l to the discharge pipeline 2d, and then flows from the discharge port 2c into a downstream pipeline (not shown).

[0025] On the left side of the case body 2, a left fixing portion 23 (see Figure 7) is formed, which has an upper left outflow passage 2f and a lower left inflow passage 2g formed internally, and a left joining surface 23a that is joined to the right side of the left fixing plate portion 31 formed on the right side of the left body body 3 shown in Figure 1. On the right side of the case body 2, a right fixing portion 24 (see Figure 7) is formed, which has an upper right outflow passage 2h and a lower right inflow passage 2j formed internally, and a right joining surface 24a that is joined to the left side of the right fixing plate portion 32 formed on the left side of the right body body 4 shown in Figure 1. In the middle of the outer circumference of the left fixing portion 23, six left insertion holes 23b are formed (see Figure 8) through which six left fixing bolts 8 that fix the left fixing plate portion 31 formed on the left body 3 and the left fixing portion 23 are inserted. Furthermore, six right insertion holes 24b are formed in the middle of the outer circumference of the right fixing portion 24, through which six right fixing bolts 9 that fix the right fixing plate portion 32 formed in the right body 4 and the right fixing portion 24 are inserted (see Figure 8). As shown in Figure 7, a left-side blocking space 2m is formed from all ends of the six left insertion holes 23b in the tightening direction of the left fixing bolts 8, blocking the tightening force of each left fixing bolt 8, and a right-side blocking space 2n is formed from all ends of the six right insertion holes 23b in the tightening direction of the right fixing bolts 9, blocking the tightening force of each right fixing bolt 9. The left-side blocking space 2m is formed in an annular shape so as to surround the outer circumference of the left-side conduit portion 2p, which has the upper left outflow passage 2f and the lower left inflow passage 2g formed inside. Furthermore, the right-side blocking space 2n is formed in an annular shape so as to surround the outer circumference of the right-side conduit section 2q, which has the upper right outflow passage 2h and the lower right inflow passage 2i formed inside it. Moreover, the six left insertion holes 23b through which the six left fixing bolts 8 are inserted and the six right insertion holes 24b through which the six right fixing bolts 9 are inserted are formed at equidistant distances from the center of the left-side conduit section 2p or the right-side conduit section 2q, respectively.

[0026] Then, as shown in Figure 1, left fixing nuts 10 are screwed onto the shafts of the six left fixing bolts 8, each with a tip portion of a shaft (not shown) inserted through the six left insertion holes 23b, and exposed in the left-side blocking space 2m, respectively. Similarly, right fixing nuts 11 are screwed onto the shafts of the six right fixing bolts 9, each with a tip portion of a shaft (not shown) inserted through the six right insertion holes 23b, and exposed in the right-side blocking space 2n, respectively. In addition, left bolt insertion holes (not shown) are formed in the middle of the outer circumference of the left fixing plate portion 31, through which the shaft portions of the six left fixing bolts 8 are inserted, and the heads (reference numerals omitted) of each of the left fixing bolts 8 are pressed against the left side surface of the left fixing plate portion 31 by fastening the left fixing nuts 10 to the shafts. Furthermore, right bolt insertion holes (not shown) are formed in the middle of the outer circumference of the right fixing plate portion 32, through which the shafts of the six right fixing bolts 9 are inserted. The heads (reference numerals omitted) of each of the right fixing bolts 9 are pressed against the right side surface of the right fixing plate portion 32 by fastening the right fixing nuts 11 to the shafts.

[0027] Therefore, according to the double strainer of this embodiment, when each of the six left fixing bolts 8 is screwed into the left fixing nut 10 and the right side surface of the left fixing plate portion 31 constituting the left body 3 is joined to the left joining surface 23a of the left fixing portion 23 formed on the case body 2, the fastening force between the left fixing bolt 8 and the left fixing nut 10 does not act on the case body 2. Similarly, when each of the six right fixing bolts 9 is screwed into the right fixing nut 11 and the left side surface of the right fixing plate portion 32 constituting the right body 4 is joined to the right joining surface 24a of the right fixing portion 24 formed on the case body 2, the fastening force between the right fixing bolt 9 and the right fixing nut 11 does not act on the case body 2. As a result, the case body 2 is slightly distorted, allowing the cock 105 (flow path switching valve) described earlier to be housed stably within the case body 2 and to rotate stably. In particular, in the double strainer according to this embodiment, the left-side blocking space 2m and the right-side blocking space 2n are formed in an annular shape so as to surround the outer circumference of the left-side conduit section 2p or the right-side conduit section 2q. Therefore, even if sand, dust, or other foreign matter enters or accumulates in the left-side blocking space 2m and the right-side blocking space 2n, it can be easily cleaned and removed, and the overall load of the case body 2 constituting this double strainer can be reduced. Furthermore, in the double strainer according to this embodiment, the six left insertion holes 23b through which the six left fixing bolts 8 are inserted and the six right insertion holes 24b through which the six right fixing bolts 9 are inserted are formed at equidistant distances from the center of the left-side conduit section 2p or the right-side conduit section 2q2p. Therefore, the risk of the liquid before filtration or the liquid after filtration leaking to the outside from between the right side surface of the left fixing plate section 31 and the left joint surface 23a, or between the left side surface of the right fixing plate section 22 and the right joint surface 24a can be effectively prevented.

[0028] In the double strainer according to the above embodiment, the left fixing portion 23 formed on the left side of the case body 2 and the right fixing portion 24 formed on the right side of the case body 2 are formed in a disc shape in a side view (see Figure 1 or Figure 2). However, the outer shape of these left fixing portion 23 and right fixing portion 24 in a side view may be rectangular, and the left blocking space 2m and right blocking space 2n may be spaces that can block the tightening force of at least the left fixing bolt 8 or the right fixing bolt 9. For example, Figure 9 schematically shows the main part of the left side configuration of the case body 42 described below. In Figure 9(a), the case body 42 has left blocking portions 42b, 42c, 42d, and 42e formed in a slit shape on the upper surface, front, lower surface, and back surface to the right of the left joining surface 42a formed on the left side of the case body 42, respectively. The left joint surface 42a described above is the part that is joined to the right side surface of the left fixing plate portion 31 formed on the right side of the left body 3 described earlier. The part from these left blocking portions 42b, 42c, 42d, 42e to the left joint surface 42a constitutes the left fixing portion 42f of the present invention. In this left fixing portion 42f, eight bolt holes 42g are formed, each having a screw (reference numeral omitted) threaded on its inner circumference into which eight fixing bolts (stud bolts) (not shown) that fasten the case body 42 to the left fixing plate portion 31 constituting the left body 3 are screwed. In the fastening direction of each of the above bolt holes 42g, one of the above left blocking portions 42b, 42c, 42d, or 42e is located, as shown in Figure 9(b). The right side of the case body 42 also has the same configuration as the left side (it is a symmetrical configuration).

[0029] Furthermore, the left-side and right-side blocking spaces constituting the present invention may be as shown in Figure 10. Figure 10 schematically shows the main part of the left side configuration of the case body 52, and to the right of the left joint surface 52a formed on the left side of the case body 52, a first left-side blocking space 52b and a second left-side blocking space 52c are formed, penetrating from the top surface to the bottom surface of the case body 52, and a third left-side blocking space 52d and a fourth left-side blocking space 52e are formed, penetrating from the front to the back surface. The first left-side blocking space 52b is formed on the back side of the case body 52, and the second left-side blocking space 52c is formed on the front side of the case body 52, and the second left-side blocking space 52b and the second left-side blocking space 52c are parallel to each other. Furthermore, the third left-side blocking space 52d is formed on the upper side of the case body 52, and the fourth left-side blocking space 52e is formed on the lower side of the case body 52, with the third left-side blocking space 52d and the fourth left-side blocking space 52e being parallel to each other. In this example, the left fixing portion 52f that constitutes the present invention is to the left of the area where the first to fourth left-side blocking spaces 52b, 52c, 52d, and 52e are formed. In this left fixing portion 52f, eight bolt holes 52g are formed, each having a screw (reference numeral omitted) threaded on its inner circumference into which eight fixing bolts (stud bolts) (not shown) that fasten the case body 52 to the left fixing plate portion 31 that constitutes the left body body 3 are screwed. In the fastening direction of each of the bolt holes 52g, one of the left blocking portions 52b, 52c, 52d, and 52e is located, as shown in Figure 10(b). Furthermore, the right side of the case body 52 also has the same configuration as the left side (it is a symmetrical configuration).

[0030] Even when using the case body 42 shown in Figure 9 or the case body 52 shown in Figure 10, and even when fixing bolts are used to join and secure the left body body or right body body to the case body 42 or 52, it is possible to effectively prevent distortion from occurring in the case body 42 or 52 due to fastening with the fixing bolts. [Explanation of symbols]

[0031] 2 Case body 2a Inflow space 2b Inflow pipe 2c Leakage Port 2d outflow pipe 2f Upper left outflow channel 2g Lower left inflow channel 2h Upper right outflow channel 2i Lower right inflow channel 2j Left partition plate section 2k Right partition panel section 2m left-side barrier space 2n Right side isolation space 2p Left pipe section 2q Right pipe section 3. Left body 4 Right body 8 Left fixing bolt 9 Right fixing bolt 21a Inflow port 23 Left fixed part 23a Left joint surface 23b Left insertion hole 24 Right fixed part 24a Right joint surface 24b Right insertion hole 31 Left fixing plate part 32 Right fixing plate part 42 Case body 42a Left joint surface 42b, 42c, 42d, 42e Left blocking section 42f left joint 52 Case body 52a Left joint surface 52b First left-side barrier space 52c Second left-side barrier space 52d Third left-side barrier space 52e Fourth left-side barrier space 102 Left side body 103 Right side body 106 Cook 106b Liquid inlet chamber 106d Partition plate section 106e Upper opening 106f downward opening 115 Right Screen

Claims

1. The device comprises a cock case having a case body that rotatably houses a cock for switching flow paths, a left body fixed to the left side of the case body and having a left body body that houses a left screen inside, and a right body fixed to the right side of the case body and having a right body body that houses a right screen inside, The case body is formed with the following: an upper left outflow passage that allows liquid flowing into the case body from the upstream side via the inflow port to flow towards the left body body; a lower left inflow passage that allows liquid filtered by the left screen to flow into the case body from the left body body; an upper right outflow passage that allows liquid flowing into the case body from the upstream side via the inflow port to flow towards the right body body; a lower right inflow passage that allows liquid filtered by the right screen to flow into the case body from the right body body; and a discharge port that allows liquid flowing into the case body from either the lower left inflow passage or the lower right inflow passage to flow downstream. The left body has an upper left inlet passage that communicates with the upper left outlet passage and allows liquid from the upper left outlet passage to flow into the left body, and a lower left outlet passage that communicates with the lower left inlet passage and allows liquid filtered by the left screen to flow into the lower left inlet passage. The right body is formed with an upper right inlet passage that communicates with the upper right outlet passage and allows liquid from the upper right outlet passage to flow into the right body, and a lower right outlet passage that communicates with the lower right inlet passage and allows liquid filtered by the right screen to flow into the lower right inlet passage. On the right side of the left body, the left upper outflow passage and the left lower inflow passage are formed internally, and a left fixing plate portion is formed in the middle of the outer circumference, through which a left fixing bolt that fixes the left side of the case body to the left body is inserted. On the left side of the right body, the upper right inlet passage and the lower right outlet passage are formed internally, and a right fixing plate portion is formed in the middle of the outer circumference, through which a right fixing bolt that secures the right side of the case body to the right body is inserted. On the left side of the case body, a left fixing portion is formed, which has an upper left outflow passage and a lower left inflow passage formed internally, and a left joining surface that is joined to the right side of the left fixing plate portion. On the right side of the case body, a right fixing portion is formed, which has an upper right outflow passage and a lower right inflow passage formed internally, and a right joining surface that is joined to the left side of the right fixing plate portion. Multiple left bolt holes are formed in the middle of the outer circumference of the left fixing portion, through which the left fixing bolt is inserted or screwed, and multiple right bolt holes are formed in the middle of the outer circumference of the right fixing portion, through which the right fixing bolt is inserted or screwed. A double strainer characterized in that a left-side blocking space is formed from all ends of the multiple left bolt holes in the direction of tightening the left fixing bolts, blocking the tightening force of each individual left fixing bolt, and a right-side blocking space is formed from all ends of the multiple right bolt holes in the direction of tightening the right fixing bolts, blocking the tightening force of each individual right fixing bolt.

2. The double strainer according to claim 1, characterized in that the left-side blocking space is formed in an annular shape so as to surround the left-side conduit section, in which the upper left outflow passage and lower left inflow passage are formed from the outside, and the right-side blocking space is formed in an annular shape so as to surround the right-side conduit section, in which the upper right outflow passage and lower right inflow passage are formed from the outside.

3. Within the left-side conduit section, a left-side partition plate section having a length in the direction of liquid passage is formed, the upper left outflow passage is formed above this left-side partition plate section, and the lower left inflow passage is formed below this left-side partition plate section. Within the right-side conduit section, a right-side partition plate section having a length in the direction of liquid passage is formed, above this right-side partition plate section the right-right outflow passage is formed, and below this right-side partition plate section the right-down inflow passage is formed. The cross-sectional shapes of the upper left outflow passage and the lower left inflow passage, and the upper right outflow passage and the lower right inflow passage, respectively, are formed into a substantially semicircular shape with the upper or lower surface of the left partition plate or the right partition plate being flat, The double strainer according to claim 2, characterized in that the positions of the left bolt holes formed in the left fixing part are equidistant from the center of the left pipe section, and the positions of the right bolt holes formed in the right fixing part are equidistant from the center of the right pipe section.

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