Filter element and bag type filter with same

Abstract

The filter element comprises an upper end piece, a lower end piece, an inner center rod and an outer center rod, the inner center rod is located on the radial inner side of the outer center rod, the space between the inner center rod and the outer center rod is filled with a filter membrane, and the upper end and the lower end of the filter membrane are welded to the upper end piece and the lower end piece respectively; the lower end of the inner center rod and the lower end of the outer center rod are each provided with a first annular connecting part, and a first annular space is defined by the two first annular connecting parts. At least one of the first annular connecting part of the outer center rod and the first annular connecting part of the inner center rod is provided with a first penetrating groove in a penetrating mode in the radial direction, and the groove wall of the first penetrating groove and the upper surface of the lower end piece define a first liquid through hole allowing liquid to pass through so that the liquid can be guided into the first annular space. According to the filter element and the bag type filter, the utilization rate of the filter membrane can be improved, dead zones are eliminated, the cleanliness requirement of the filter element is met, and the utilization rate of the filter membrane is improved.

Description

Technical Field

[0001] This utility model relates to the field of filter technology, and in particular to a filter element and a capsule filter having the same. Background Technology

[0002] Existing capsule filters include cylindrical filter elements. The filter element structure includes an upper end piece and a lower end piece that are axially spaced apart, a cylindrical porous inner central rod and a cylindrical porous outer central rod that are axially connected between the upper end piece and the lower end piece, the porous inner central rods being spaced apart on the radially inner side of the porous outer central rods, and a pleated filter membrane being disposed and supported in the space between the porous inner central rods and the porous outer central rods.

[0003] As disclosed in application number CN210993221U, in a filter element, the liquid to be filtered enters the housing, and the liquid fills the housing from the bottom to the top. When the liquid passes through the through hole on the central rod, the axially upward portion of the filter membrane is utilized first. When the liquid flow is blocked by a solid ring at the lower end of the central rod, it is then blocked by the first annular connecting part. Refer to the appendix to this patent specification. Figure 1 and 2 As the liquid flow direction changes to an upward angle, the upward-flowing liquid does not directly penetrate the filter membrane within the first annular space. This can easily create dead zones (hereinafter referred to as dead zones) within the first annular space. For example, when cleaning the filter membrane with cleaning solution before using the filter element, it is difficult to flush out impurities in the dead zones. Also, when using the filter element, it is difficult to fully utilize the liquid to be filtered to displace the cleaning solution that has moistened the filter membrane in the first annular space. Furthermore, the utilization rate of the filter membrane within the first annular space decreases when the filter element is filtering liquid. Therefore, when filtering liquid or cleaning the filter element, the obstruction of the liquid flow by the first annular connection creates dead zones within the first annular space, thus affecting the cleanliness requirements of the filter element and reducing the utilization rate of the filter membrane. Utility Model Content

[0004] To address the issues of low utilization rate of the filter membrane and the presence of dead zones within the first annular space, this invention provides a filter element and a capsule filter incorporating it. By providing a first through groove at the lower end of the outer central rod, the first annular space is connected to an external liquid inlet channel, allowing liquid to directly enter the first annular space and act on the internal filter membrane, thus ensuring the cleanliness requirements of the filter element and improving the utilization rate of the filter membrane.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A filter element for a capsule filter, the filter element comprising an upper end member and a lower end member axially spaced apart, a cylindrical inner center rod and an outer center rod having multiple through holes disposed axially between the upper end member and the lower end member, the inner center rod being located radially inside the outer center rod, the space between the inner center rod and the outer center rod being filled with a filter membrane, the upper and lower ends of the filter membrane being welded to the upper end member and the lower end member respectively;

[0007] The upper ends of the inner center rod and the upper ends of the outer center rod each have a second annular connecting portion that is sealed and fixed to the upper end member. The second annular connecting portion is located above the uppermost through hole on each center rod, and the two second annular connecting portions form a second annular space. The lower ends of the inner center rod and the lower ends of the outer center rod each have a first annular connecting portion that is sealed and fixed to the lower end member. The first annular connecting portion is located below the lowermost through hole on each center rod, and the two first annular connecting portions form a first annular space.

[0008] At least one of the first annular connecting portion of the outer center rod and the first annular connecting portion of the inner center rod has a first through groove on its lower surface. The first through groove radially penetrates the first annular connecting portion. The groove wall of the first through groove and the upper surface of the lower end member form a first liquid passage hole for liquid to pass through, so as to introduce liquid into the first annular space.

[0009] The filter element provided by this utility model has a first through groove that connects the first annular space at the lower end of the filter element with the liquid inlet channel on its outer or inner side. The first through groove and the upper surface of the lower end piece form a first liquid passage hole. The first liquid passage hole connects the first annular space and the liquid inlet channel. So when filtering liquid, the liquid can enter the first annular space through the first liquid passage hole and pass through the filter membrane in the first annular space, so that it can be fully utilized. Or when cleaning the filter element, the cleaning liquid can also enter the first annular space through the first liquid passage hole to clean the first annular space and the filter membrane located therein, so as to avoid the formation of dead zones that affect the cleanliness requirements of the filter element.

[0010] Preferably, the first through grooves located on the same central rod are provided in multiple ways, and the multiple first through grooves are distributed at intervals along their circumference, so that the first annular connecting part on the corresponding central rod has multiple downwardly protruding lower teeth, and the lower teeth are welded to the lower end piece.

[0011] This configuration allows for multiple first through grooves along the circumference of the same central rod, each forming multiple first liquid passage holes on the upper surface of the lower end piece. The first annular space can be connected to the liquid inlet channel through these multiple first liquid passage holes, which are distributed at multiple different positions around the circumference. Liquid can enter the first annular space from these first liquid passage holes at various circumferential positions, fully utilizing the filter membrane within, resulting in better filter element cleanliness and higher filter membrane utilization. Furthermore, lower protrusions are formed between adjacent first through grooves, allowing multiple lower protrusions to be welded to the upper surface of the lower end piece, thus achieving a stable connection between the central rod and the lower end piece.

[0012] Preferably, the circumference of the first through groove is equal to the circumference of the through hole located on the same central rod, and the first through groove is connected to the adjacent through hole located on the same central rod.

[0013] This design, with the circumference of the first through groove equal to that of the through hole, facilitates processing and ensures that the filter membranes located within the first annular space and those above the first annular space that receive liquid through the through hole have the same circumferential circumference at the same time. This maintains consistency in the utilization efficiency of the filter element within the first annular space with that of the filter membranes in other parts of the space, resulting in a consistent service life. Furthermore, the first through groove connects to adjacent through holes on the same central rod, allowing for a larger diameter for the first liquid inlet hole and a larger inlet diameter between the first annular space and the external liquid inlet channel. During filtration or cleaning, this not only ensures more thorough utilization or rinsing of the filter membrane within the first annular space but also allows for the full utilization or complete rinsing of filter membranes that were previously blocked by the rod wall between adjacent through holes and the first through groove.

[0014] Preferably, the total circumference of the plurality of lower teeth located on the same central rod is 1 / 5 to 1 / 2 of the circumference of the corresponding first annular connecting part.

[0015] With this configuration, due to the interaction between the circumference of the first through groove and the circumference of the lower protrusion, the larger the circumference of the first through groove, the smaller the circumference of the lower protrusion. This results in the total circumference of the lower protrusion being 1 / 5 to 1 / 2 of the circumference of the first annular connecting part. This ensures both the flow rate of the first liquid passage formed between the first through groove and the upper surface of the lower end piece, as well as the welding stability between the lower protrusion and the lower end piece. Furthermore, when welding the upper and lower ends of the filter membrane, the filter membrane will not be compressed and will not protrude from the first liquid passage.

[0016] Preferably, the first through groove is arranged in a ring, and the upper ends of the outer center rod and the inner center rod are both welded to the upper end piece.

[0017] With this configuration, the first through groove is arranged in a ring, meaning the lower end of the central rod is suspended. The lower surface of the central rod and the upper surface of the lower end piece are spaced apart axially, so that the first annular space and the liquid inlet channel are connected in all circumferential directions. This allows for full utilization or rinsing of the filter membrane within the first annular space, resulting in better filter element cleanliness and higher filter membrane utilization.

[0018] Preferably, the first through groove on the outer center rod and the first through groove on the inner center rod are arranged radially correspondingly.

[0019] With this configuration, when both the outer and inner center rods are equipped with first through grooves, regardless of whether the liquid flow direction is outward inward or inward outward, the first through groove on the outer center rod corresponds to the first liquid passage hole formed on the upper surface of the lower end piece, and the first through groove on the inner center rod corresponds to the first liquid passage hole formed on the upper surface of the lower end piece. Thus, the first liquid passage hole on one rod is used for liquid inlet, and the first liquid passage hole on the other rod is used for liquid outlet. This ensures that the liquid inlet and outlet directions in the first annular space are consistent, allowing the liquid to pass directly through the filter membrane, resulting in shorter filtration time and better filter membrane utilization efficiency.

[0020] Preferably, at least one of the second annular connecting portion of the outer center rod and the second annular connecting portion of the inner center rod has a second through groove on its upper surface. The second through groove radially penetrates the second annular connecting portion. The groove wall of the second through groove and the lower surface of the upper end member form a second liquid passage hole for liquid to pass through, so as to introduce liquid into the second annular space.

[0021] With this configuration, the second through groove opens up the second annular space at the upper end of the filter element and the liquid inlet channel on its outer or inner side. The second through groove and the lower surface of the upper part form a second liquid passage hole, which connects the second annular space and the liquid inlet channel. Thus, when filtering liquid, the liquid can enter the second annular space through the second liquid passage hole and pass through the filter membrane in the second annular space, allowing more liquid to enter the second annular space and be utilized more fully. Alternatively, when cleaning the filter element, more cleaning liquid can also enter the second annular space through the second liquid passage hole to clean the second annular space and the filter membrane located inside.

[0022] Preferably, multiple second through slots are provided on the same central rod, and the multiple second through slots are distributed at intervals along their circumference, so that the second connecting part on the corresponding central rod has multiple upwardly protruding upper teeth, and the upper teeth are welded to the upper end piece.

[0023] With this configuration, multiple second through slots located on the same central rod will form multiple second liquid passage holes with the lower surface of the upper end piece. The second annular space can be connected to the liquid inlet channel through multiple second liquid passage holes. Moreover, the second liquid passage holes are distributed at different positions around the central rod. The liquid inlet channel can be connected to the second annular space from multiple positions of the second liquid passage holes. The liquid enters the second annular space through multiple second liquid passage holes and fully acts on the filter membrane inside, which can make the filter element cleaner and the filter membrane utilization rate higher. Furthermore, upper protrusions will be formed between adjacent second through slots, so that the upper protrusions are welded to the lower surface of the upper end piece to achieve a stable connection between the central rod and the upper end piece.

[0024] This utility model also provides a capsule filter, including a housing, a first interface and a second interface disposed in the housing, and a filter element of either of the above. The filter element is disposed inside the housing. The outer central rod and the inner sidewall of the housing form an outer liquid flow channel, and the inner central rod surrounds an inner liquid flow channel. The first interface is connected to the outer liquid flow channel, and the second interface is connected to the inner liquid flow channel.

[0025] Preferably, the inner center rod includes a first inner tube and a second inner tube arranged radially at intervals, and the first inner tube and the second inner tube form the inner liquid flow channel;

[0026] The upper part is provided with a first through hole and a second through hole, and the lower part is provided with a third through hole;

[0027] The first interface is a liquid inlet, the second interface is a liquid outlet, the upper end of the first inner tube is connected to the first interface through the first through hole, the lower end of the first inner tube is connected to the external liquid flow channel through the third through hole, and the internal liquid flow channel is connected to the second interface through the second through hole.

[0028] The outlet of the first inner tube is configured as a first flared opening, and the end of the third through hole near the first inner tube is configured with a second flared opening. The first flared opening and the second flared opening have the same maximum inner diameter and are connected, and the inner diameter of the first inner tube is less than or equal to the inner diameter of the third through hole.

[0029] This configuration, by setting a second flared opening at the inlet of the third through hole to cooperate with the first flared opening at the outlet of the first inner tube, avoids the formation of an edge dead zone between the first flared opening and the upper surface of the lower end piece. On the one hand, it can prevent impurities from being retained, and on the other hand, it can prevent the flow of liquid from being obstructed, thus promoting the liquid velocity. Furthermore, the inner diameter of the first inner tube is less than or equal to the inner diameter of the third through hole, which further ensures the amount of liquid entering through the third through hole, and ensures the amount of liquid entering the external liquid channel and the liquid filtration flow rate of the filter element.

[0030] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0031] The first through groove opens up the first annular space at the lower end of the filter element and the liquid inlet channel on its outer or inner side. The first through groove and the upper surface of the lower end piece form a first liquid passage hole. The first liquid passage hole connects the first annular space and the liquid inlet channel. So when filtering liquid, the liquid can enter the first annular space through the first liquid passage hole and pass through the filter membrane in the first annular space, so that it can be fully utilized. Or when cleaning the filter element, the cleaning liquid can also enter the first annular space through the first liquid passage hole to clean the first annular space and the filter membrane located therein, so as to avoid the formation of dead zones that would affect the cleanliness requirements of the filter element. Attached Figure Description

[0032] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 This is an overall cross-sectional view of the existing filter element described in Example 1;

[0034] Figure 2 This is a cross-sectional view of the existing filter cartridge with the filter membrane removed, as described in Example 1.

[0035] Figure 3 A cross-sectional view of the first annular connecting part at the lower end of the outer center rod of the filter element in Embodiment 1, which is provided with a first through groove and forms a first liquid passage hole (wherein the first through groove is connected to the upper through hole);

[0036] Figure 4 A cross-sectional view of the first annular connecting part at the lower end of the outer center rod of the filter element in Embodiment 1, which is provided with a first through groove and forms a first liquid passage hole (wherein the first through groove is not connected to the upper through hole);

[0037] Figure 5 A cross-sectional view of the first annular connecting part at the lower end of the inner center rod of the filter element in Embodiment 1, which is provided with a first through groove and forms a first liquid passage hole (wherein the first through groove is connected to the upper through hole);

[0038] Figure 6 In Embodiment 1, the first annular connecting part at the lower end of the inner center rod and the outer center rod of the filter element is provided with a first through groove and forms a first liquid passage hole. This is an overall cross-sectional view (wherein the first through groove is connected to the upper through hole).

[0039] Figure 7The first annular connecting part at the lower end of the inner center rod and the outer center rod of the filter element in Embodiment 1 is provided with a first through groove and forms a first liquid passage hole, and the first through groove is arranged in an annular shape.

[0040] Figure 8 The first annular connecting part at the lower end of the inner center rod and the outer center rod of the filter element in Embodiment 1 is provided with a first through groove and the second annular connecting part at the upper end is provided with a second through groove (wherein the first through groove and the second through groove are connected to the corresponding through hole, and 16 in the figure is the groove wall of the first through groove and 18 is the groove wall of the second through groove).

[0041] Figure 9 This is a three-dimensional schematic diagram of the first through groove at the bottom of the outer center rod in Embodiment 1, wherein the circumference is set to L (wherein the first through groove is connected to the upper through hole);

[0042] Figure 10 This is a schematic diagram of the first liquid passage hole formed by the outer center rod and the lower end piece in Embodiment 1 (wherein the first through groove is connected to the upper through hole);

[0043] Figure 11 This is another structure of the filter element in Example 1 (its structure is described in detail in Example 2);

[0044] Figure 12 This is an overall cross-sectional view of the capsule filter in Example 2;

[0045] Figure 13 This is a schematic diagram of the overall capsule filter in Example 2.

[0046] Explanation of reference numerals in the attached figures:

[0047] 1. Filter element; 11. Upper end piece; 12. Lower end piece; 13. Inner center rod; 131. First inner tube; 132. Second inner tube; 14. Outer center rod; 141. First annular connecting part; 142. Second annular connecting part; 15. Filter membrane; 16. First through groove; 17. First annular space; 18. Second through groove; 19. Second annular space; 20. Lower convex tooth; 21. Upper convex tooth; 22. Through hole; 23. First liquid passage hole;

[0048] 2. Housing; 3. First interface; 4. Second interface; 5. External liquid flow channel; 6. Internal liquid flow channel; 7. First through hole; 8. Second through hole; 9. Third through hole; 10. First flared opening; 101. Second flared opening. Detailed Implementation

[0049] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0050] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of this utility model, it should be noted that unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0051] Embodiment 1 of this utility model provides a filter element for a capsule filter, such as... Figures 1-9 As shown, the filter element 1 includes an upper end piece 11 and a lower end piece 12 arranged axially spaced apart. An inner center rod 13, an outer center rod 14, and a filter membrane 15 are arranged axially between the upper end piece 11 and the lower end piece 12. Both the inner center rod 13 and the outer center rod 14 are cylindrical, and each rod has multiple through holes 22. The multiple through holes 22 are evenly distributed along their axial and circumferential directions. The inner center rod 13 is located radially inside the outer center rod 14, that is, the outer center rod 14 is sleeved on the outside of the inner center rod 13. The two are coaxially arranged. The filter membrane 15 fills the installation space enclosed by the outer center rod 14 and the inner center rod 13. Specifically, the filter membrane 15 is folded into an existing pleated cylindrical shape and supported in the installation space. The upper and lower ends of the filter membrane 15 are respectively welded to the lower surface of the upper end piece 11 and the upper surface of the lower end piece 12, thereby fixing the filter membrane 15.

[0052] During use, the liquid inlet direction of filter element 1 can be divided into two types: external inlet and internal outlet, or internal inlet and external outlet. The external inlet and internal outlet method specifically involves liquid entering through the through hole 22 at the outer central rod 14 into the space where the filter membrane 15 is installed, then passing through the filter membrane 15, and exiting through the through hole 22 at the inner central rod 13. The internal inlet and external outlet method specifically involves liquid entering through the through hole 22 at the inner central rod 13 into the space where the filter membrane 15 is installed, then passing through the filter membrane 15, and exiting through the through hole 22 at the outer central rod 14. The aforementioned upper end piece 11 and lower end piece 12 are specifically upper and lower sealing end plates that are vertically aligned during filter element 1 filtration. The axial direction refers to the vertical direction shown in the figure, which is the axis direction of the cylindrical rod, and the radial direction is the diameter direction of the cylindrical shape.

[0053] Specifically, the lower ends of the inner center rod 13 and the outer center rod 14 each have a first annular connecting portion 141 that is sealed and fixed to the lower end member 12. The first annular connecting portion 141 is located below the lowest through hole 22 on each center rod and is an annular solid part fixedly connected to the lower end member 12 below the lowest through hole 22. The two first annular connecting portions 141 form a first annular space 17. The through holes 22 are arranged in several layers at intervals in the axial direction, and each layer of through holes 22 has multiple through holes distributed at intervals in the circumferential direction. For example, the uppermost layer and the lowermost layer refer to the uppermost and lowermost layers in the axial direction. Therefore, when defining the first annular connecting portion 141, it must be extended axially upwards by a predetermined distance from the connection and fixing end with the lower end member 12.

[0054] In this embodiment, as Figure 1 and Figure 2 As shown, in the existing filter element 1, the liquid to be filtered enters the housing 2, and the liquid is filled from the bottom to the top of the housing 2. The liquid enters through the through hole 22 at the outer central rod 14 (outer inlet, inner outlet). When the liquid flow is blocked by the ring-shaped solid at the bottom of the central rod, the liquid flow direction becomes obliquely upward. The obliquely upward liquid does not directly penetrate the filter membrane 15 in the first annular space 17, which easily makes the first annular space 17 a dead zone. When cleaning the filter membrane 15 before use, it is not easy to wash out the impurity particles in the dead zone, which affects the cleanliness requirements of the filter element 1 and reduces the utilization rate of the filter membrane 15.

[0055] To solve the above problems, such as Figure 3 , Figure 4 , Figure 9 , Figure 10As shown, a first through groove 16 is provided on the lower surface of the first annular connection portion 141 of the outer center rod 14. The first through groove 16 is a groove axially extending upward on the lower surface of the first annular connection portion 141 and then radially penetrating the inner and outer surfaces of the outer center rod 14. That is, the first through groove 16 is axially opened on the lower end surface of the outer center rod 14, and the two groove walls distributed radially extend inward and outward to the inner and outer surfaces of the outer center rod 14 respectively, so that the first through groove 16 radially penetrates the first annular connection portion 141. Thus, the notch of the first through groove 16 faces the upper surface of the lower end member 12, and the groove wall of the first through groove 16 and the upper surface of the lower end member 12 enclose a first liquid through hole 23 in a square shape. And in Figure 9 and 10 the figures shown illustrate the process of forming the first through groove 16 with an unclosed notch into a closed first liquid through hole 23. Therefore, the liquid inlet flow path outside the outer center rod 14 is directly connected to the first annular space 17, so that external liquid directly enters the first annular space 17 through the first liquid through hole 23. That is, it can enter the first annular space 17 along the upper surface of the lower end member 12, and then enter the filter membrane 15 from the outer side of the filter membrane 15, making use of the filter membrane 15 in the first annular space 17. Specifically, when filtering liquid, the liquid can directly act on the filter membrane 15 in the first annular space 17, making full use of the filter membrane 15. Or when cleaning the filter element 1, the cleaning liquid can also enter the first annular space 17 through the first liquid through hole 23 to clean the first annular space 17 and the filter membrane 15 located therein, which can avoid the occurrence of dead zones affecting the cleanliness requirements of the filter element 1.

[0056] Preferably, in order to further make full use of the filter membrane 15 in the first annular space 17 or be cleaner when cleaning the filter element 1, as Figure 6 shown, a first through groove 16 is also provided on the first annular connection portion 141 of the inner center rod 13. The groove wall of the first through groove 16 and the upper surface of the lower end member 12 form a first liquid through hole 23. The liquid in the external liquid inlet flow path enters the first annular space 17 through the first liquid through hole 23 on the outer center rod 14, then passes through the outer side of the filter membrane 15 to the inside of the filter membrane 15, flows out from the inner side of the filter membrane 15, and finally flows out to the internal liquid outlet flow path through the first liquid through hole 23 on the inner center rod 13. Liquid is incident and flows out at the same height of the filter membrane 15, so that the liquid can act completely on the entire filter membrane 15 in the first annular space 17. When filtering liquid, both sides inside and outside the filter membrane 15 are fully utilized. Or when cleaning the first annular space 17, the impurity particles in the inner corner of the first annular space 17 can also be completely cleaned.

[0057] Of course, in another embodiment, the filter element 1 can be set in an internal liquid inlet manner, such as Figure 2As shown, due to the solid obstruction of the first annular connecting part 141 at the inner central rod 13, the liquid cannot directly act on the inner side of the filter membrane 15 in the first annular space 17. It enters and passes through the filter membrane 15 obliquely upward from above the first annular connecting part 141, which also creates dead zones in the first annular space 17, especially in the corners of the space near the inner central rod 13. When filtering liquid, the filter membrane 15 in the first annular space 17 is not fully utilized, or when cleaning the filter element 1, the filter membrane 15 in the first annular space 17 is not completely cleaned, and the impurity particles in the dead zones cannot be completely washed out. To solve the above problems, such as Figure 5 As shown, a first through groove 16 is radially provided at the first annular connecting part 141. The groove extends axially downward on the upper surface of the first annular connecting part 141 and then radially penetrates the inner and outer surfaces of the inner and outer center rods 13. That is, the first through groove 16 is opened on the lower surface of the inner center rod 13, and the two groove walls distributed radially extend inward and outward to the inner and outer outer walls of the inner center rod 13, so that the first through groove 16 radially penetrates the first annular connecting part 141. Thus, the groove opening of the first through groove 16 faces the upper surface of the lower end member 12. The groove wall of the first through groove 16 and the upper surface of the lower end member 12 form a first liquid passage hole 23. The liquid in the internal liquid inlet channel directly enters the first annular space 17 from the first liquid passage hole 23 and enters the filter membrane 15 from the inner side of the filter membrane 15. Then it leaves the filter membrane 15 from the outer side of the filter membrane 15, so that the filter membrane 15 in the first annular space 17 can be fully utilized, further ensuring the cleanliness requirements of the filter element 1 and the utilization rate of the filter membrane 15. Of course, furthermore, the setup of the filter element 1 with external liquid inlet is the same as described above, such as... Figure 6 As shown, the first annular connecting part 141 at the outer center rod 14 is also provided with a first through groove 16 in the radial direction, and a first liquid passage hole 23 is also formed with the upper surface of the lower end part 12. Thus, the first liquid passage hole 23 on the inner and outer center rods allows the first annular space 17 to communicate with the internal liquid inlet channel and the external liquid outlet channel, so that the filter membrane 15 in the first annular space 17 can be fully utilized, and dead zones are avoided, ensuring the cleaning of the filter membrane 15 in the first annular space 17.

[0058] Preferably, in both this embodiment and other embodiments, that is, regardless of whether the liquid enters from the outside and exits from the inside or from the inside and exits from the outside, the arrangement of the first through groove 16 on the inner center rod 13 and the outer center rod 14 is divided into two types.

[0059] The first type: Multiple first through slots 16 are provided on the same central rod, i.e., the inner central rod 13 and / or the outer central rod 14 are provided with first through slots 16, such as... Figures 3-5 As shown. It should be noted that, understandably, Figure 3 , Figure 7 , Figure 8as well as Figure 11 The dashed / dotted lines in the text are used to represent the wall of the virtual first through groove 16, which can be understood as the first liquid passage hole 23.

[0060] like Figure 3 and Figure 5 As shown, multiple first through grooves 16 are provided around the inner center rod 13 or the outer center rod 14, forming multiple first liquid passage holes 23 in the circumferential direction. The first annular space 17 can be connected to the outer liquid inlet channel through the multiple first liquid passage holes 23, and the first liquid passage holes 23 are distributed in multiple different positions in the circumferential direction, so that liquid can enter the first annular space 17 from the first liquid passage holes 23 in multiple different positions in the circumferential direction, and fully exert the filter membrane 15 inside.

[0061] Furthermore, the circumference of the first through groove 16 on the outer center rod 14 is equal to the circumference of its upper through hole 22, or the circumference of the first through groove 16 on the inner center rod 13 is equal to the circumference of its upper through hole 22. This facilitates processing and ensures that the liquid inlet side of the filter membrane 15 located in the first annular space 17 and the liquid inlet side of the filter membrane 15 located above the first annular space 17 and entering liquid through the through hole 22 have the same liquid inlet width in the same circumferential time. This allows the utilization efficiency of the filter element 1 located in the first annular space 17 to be consistent with the utilization efficiency of the filter membrane 15 in other parts, resulting in a consistent service life and facilitating the unified cleaning of the filter membrane 15. Furthermore, the first through groove 16 is connected to the adjacent through hole 22 on the same central rod, thereby making the overall diameter of the first liquid passage 23 larger and the liquid inlet diameter between the first annular space 17 and the external liquid inlet channel larger. During filtration or cleaning, not only can the filter membrane 15 in the first annular space 17 be fully utilized or rinsed clean, but the filter membrane 15 that was originally blocked by the rod wall and not fully utilized between the adjacent through holes 22 and the first through groove 16 can also be fully utilized or rinsed completely.

[0062] like Figure 6As shown, multiple first through grooves 16 are provided on both the inner center rod 13 and the outer center rod 14. The inner and outer sides of the first annular space 17 can be connected to the outer liquid inlet channel and liquid outlet channel through multiple first liquid passage holes 23. The first liquid passage holes 23 are distributed in multiple different positions around the circumference, so that liquid can enter and exit the first annular space 17 from the first liquid passage holes 23 in multiple different positions around the circumference, and fully utilize the filter membrane 15 inside. Furthermore, the circumference of the first through groove 16 on the outer center rod 14 is equal to the circumference of its upper through hole 22, and the circumference of the first through groove 16 on the inner center rod 13 is equal to the circumference of its upper through hole 22. This facilitates processing and ensures that the liquid inlet width of the filter membrane 15 located in the first annular space 17 and the liquid inlet width of the filter membrane 15 located above the first annular space 17 and entering liquid through the through hole 22 are equal in the same circumferential liquid inlet time. It also ensures that the liquid outlet width of the filter membrane 15 located in the first annular space 17 and the liquid outlet width of the filter membrane 15 located above the first annular space 17 and exiting liquid through the through hole 22 are equal in the same circumferential liquid outlet time. This further ensures that the utilization efficiency of the filter element 1 located in the first annular space 17 is consistent with the utilization efficiency of the filter membrane 15 in other parts, so that the service life is also consistent and it is convenient to clean the filter membrane 15 uniformly. Simultaneously, the first through groove 16 on the outer center rod 14 is connected to the adjacent through hole 22, and the first through groove 16 on the inner center rod 13 is also connected to the adjacent through hole 22. This makes the overall diameter of the first liquid passage 23 larger, and the inlet and outlet diameters between the first annular space 17 and the external liquid inlet and liquid passages larger. During filtration or cleaning, the filter membrane 15 in the first annular space 17 can be more fully utilized or rinsed clean. Moreover, the filter membrane 15 that was originally blocked by the rod wall and not fully utilized between adjacent through holes 22 and the first through groove 16 can be fully utilized or completely rinsed. The aforementioned circumference L is as follows: Figure 9 As shown.

[0063] Of course, in other embodiments, the circumference of the first through groove 16 on the outer center rod 14 may not be equal to the circumference of its upper through hole 22, and the circumference of the first through groove 16 on the inner center rod 13 may not be equal to the circumference of its upper through hole 22. The first through groove 16 and its upper through hole 22 may also not be connected. The specific settings are determined by human intervention.

[0064] Preferably, the plurality of first through grooves 16 provided on the outer center rod 14 and the plurality of first through grooves 16 provided on the inner center rod 13 are respectively arranged radially in a one-to-one correspondence, and the number of first through grooves 16 on the outer center rod 14 and the inner center rod 13 is equal, so that the liquid inlet direction and the liquid outlet direction are consistent, and the liquid directly passes through the filter membrane 15 of the first annular space 17, resulting in a shorter filtration time and better utilization efficiency of the filter membrane 15.

[0065] Specifically, regardless of whether the inner center rod 13 and / or the outer center rod 14 are provided with multiple first through grooves 16, the multiple first through grooves 16 located on the same center rod are distributed circumferentially at intervals, so that each of the adjacent first through grooves 16 on the same center rod has an axially downward protruding lower tooth 20. By welding the multiple lower teeth 20 to the upper surface of the lower end member 12, the sealing connection between the inner and outer center rods 14 and the lower end member 12 is completed. Of course, if the first annular connecting part 141 of a certain center rod is not provided with a first through groove 16, the entire first annular connecting part 141 can be welded to the upper surface of the lower end member 12.

[0066] Preferably, regardless of whether the inner center rod 13 and / or the outer center rod 14 are provided with multiple first through grooves 16, due to the interaction between the circumference of the first through groove 16 and the circumference of the lower protrusion 20, if the circumference of the first through groove 16 is larger, the circumference of the lower protrusion 20 will be smaller, resulting in a smaller welding area between the lower protrusion 20 and the lower end piece 12, leading to insufficient welding strength. This is because the ends of the filter membrane 15 and the ends of the inner and outer center rods are heated and welded to the end piece simultaneously. When the filter membrane 15 solidifies, it needs to be axially pressed against the end piece at both ends. The inner and outer center rods restrict the deformation of the filter membrane 15 inward or outward. Therefore, insufficient welding strength between the lower protrusion 20 and the lower end piece 12 will cause the filter membrane 15 to bend and protrude through the first through groove 16. The advantage of a larger circumference of the first through groove 16 is that more liquid to be filtered can directly enter the first annular space 17, facilitating the flow of liquid into the first annular space 17. For better cleaning and utilization of the filter membrane 15, if the circumference of the first through groove 16 is smaller, the circumference of the lower protrusion 20 will be larger, resulting in a larger welding area between the lower protrusion 20 and the lower end piece 12 and sufficient welding strength. However, the disadvantage of a smaller circumference of the first through groove 16 is that less liquid to be filtered enters the first annular space 17, which reduces the utilization of the filter membrane 15 in the first annular space 17 and the cleaning efficiency of the filter membrane 15 and the dead zone in the first annular space 17. Therefore, the total circumference of the multiple lower protrusions 20 located on the same central rod is set to be 1 / 5 to 1 / 2 of the circumference of the corresponding first annular connecting part 141. This ensures the liquid flow of the first liquid passage hole 23 formed on the upper surface of the first through groove 16 and the lower end piece 12, the liquid flow of the first annular space 17, and the welding stability of the lower protrusion 20 and the lower end piece 12. It is known that the circumference of the aforementioned lower convex tooth 20 is consistent along the axial direction for easy processing. Of course, it can also be inconsistent. If it is inconsistent, then the same lower convex tooth 20 has a maximum circumference and a minimum circumference. The average of the maximum circumference and the minimum circumference of each lower convex tooth 20 is taken as the circumference of the lower convex tooth 20.

[0067] The second type: such as Figure 7As shown, a first through groove 16 is provided on the inner center rod 13 and / or the outer center rod 14, but the first through groove 16 is arranged in a ring, that is, the lower part of the center rod is suspended, and the lower surface of the center rod and the upper surface of the lower end piece 12 are spaced apart in the axial direction.

[0068] A first through groove 16 is provided on either the inner center rod 13 or the outer center rod 14. The first annular space 17 and the outer inlet channel are connected in all directions, allowing liquid to enter the filter membrane 15 from the inlet side within the first annular space 17, thus fully utilizing or rinsing the filter membrane 15 within the first annular space 17. Similarly, a first through groove 16 is provided on both the inner center rod 13 and the outer center rod 14. The first annular space 17 is connected in all directions to the outer inlet and outlet channels, allowing liquid to enter the filter membrane 15 from the inlet side within the first annular space 17 and then flow out from the outlet side, ensuring that the liquid fully acts on the entire filter membrane 15 within the first annular space 17, fully utilizing or rinsing the filter membrane 15 within the first annular space 17. It is known that the two first through grooves 16 are always correspondingly provided. The upper ends of both the outer center rod 14 and the inner center rod 13 are welded to the lower surface of the upper end piece 11.

[0069] Specifically, the upper ends of the inner center rod 13 and the outer center rod 14 each have a second annular connecting portion 142 that is sealed and fixed to the upper end member 11. The second annular connecting portion 142 is located above the uppermost through hole 22 on each center rod and is the annular solid portion from the lowermost through hole 22 downwards. The two second annular connecting portions 142 form a second annular space 19. The through holes 22 are arranged in several layers at intervals in the axial direction, and each layer of through holes 22 has multiple through holes distributed at intervals in the circumferential direction. For example, the uppermost and lowermost layers refer to the uppermost and lowermost layers in the axial direction. Therefore, when defining the second annular connecting portion 142, it must be extended axially downwards by a predetermined distance from the connection and fixing end with the upper end member 11. In this embodiment and in another embodiment, that is, whether it is a liquid inlet-outlet or liquid inlet-outlet method, such as Figure 1 and Figure 2As shown, due to the upward flow of the liquid and the obstruction of the second annular connection 142 at the inner central rod 13 and outer central rod 14, the second annular space 19 does not form a large dead zone and the filter element within it can be basically utilized. However, in order to further ensure the utilization rate of the filter membrane 15 within the second annular space 19 and the cleanliness requirements of the entire filter element 1, in this embodiment and other embodiments, at least one of the second annular connection 142 of the outer central rod 14 and the second annular connection 142 of the inner central rod 13 can be provided with a second through groove 18 radially. That is, the second through groove 18 is axially opened on the upper surface of the central rod, and the two groove walls distributed radially extend inward and outward to the inner and outer walls of the central rod, so that the second through groove 18 radially penetrates the second annular connection 142, and the groove opening of the second through groove 18 faces the lower surface of the upper end member 11, so that... The wall of the second through groove 18 and the lower surface of the upper end piece 11 are arranged to form a second liquid passage hole for liquid to pass through. The opening and formation principle of the second through groove 18 and the second liquid passage hole are similar to those of the first liquid passage hole 23, and will not be described in detail. The second liquid passage hole is not marked in the attached drawings. It connects the liquid inlet channel on the outer or inner side and the second annular space 19. So whether the second annular connecting part 142 on the outer center rod 14 is provided with the second through groove 18, or the second annular connecting part 142 on the inner center rod 13 is provided with the second through groove 18, or both the second annular connecting parts 142 on the outer center rod 14 and the inner center rod 13 are provided with the second through groove 18, the liquid inlet channel will always be connected to the second annular space 19 through the second liquid passage hole, so that the liquid can enter the second annular space 19 and act on the filter membrane 15. It will also make some dead zones in the second annular space 19 disappear, flush away the particles in the dead zones, and ensure the cleanliness of the filter element 1.

[0070] The most preferred solution, in this embodiment, for the liquid inlet-outlet method, is that the second annular connecting portion 142 on the outer center rod 14 is provided with a second through groove 18, allowing the liquid to directly enter the filter membrane 15 from the inlet side through the second liquid passage, or as... Figure 8 As shown, the second annular connecting portions 142 on the outer center rod 14 and the inner center rod 13 are both provided with second through grooves 18, thereby forming an inner second liquid passage hole and an outer second liquid passage hole. This allows liquid to enter the second annular space 19 through the outer second liquid passage hole, and then directly pass through the filter membrane 15 in the second annular space 19 and be discharged from the inner second liquid passage hole. This ensures that the filter membrane 15 can be fully utilized. Moreover, when rinsing the filter element 1, since the inner and outer corners of the second annular space 19 are connected to the external liquid flow channel through the inner and outer second liquid passage holes, the impurities present in the corners of the space will also be washed away, thus eliminating the dead zone in the second annular space 19 and further ensuring the cleanliness of the filter element 1.

[0071] In another embodiment, specifically for a liquid inlet-outlet configuration, the second annular connecting portion 142 on the inner central rod 13 is provided with a second through groove 18. Liquid directly enters the filter membrane 15 from the inlet side through the second liquid passage, or as... Figure 8 As shown, the second annular connecting portions 142 on the outer center rod 14 and the inner center rod 13 are both provided with second through grooves 18, thereby forming an inner second liquid passage hole and an outer second liquid passage hole. This allows the liquid to pass through the inner second liquid passage hole and then directly through the filter membrane 15 in the second annular space 19, and flow out from the outer second liquid passage hole, so that the filter membrane 15 can be fully utilized. Moreover, when rinsing the filter element 1, since the inner and outer corners of the second annular space 19 are connected to the external liquid flow channel through the inner and outer second liquid passage holes, the impurities in the corners of the space will also be rinsed away, so that the dead zone in the second annular space 19 disappears, further ensuring the cleanliness of the filter element 1.

[0072] Specifically, for the second through groove 18 on the second annular connecting part 142, multiple second through grooves 18 located on the same central rod are provided. That is, multiple second through grooves 18 are provided on the second annular connecting part 142 on the inner central rod 13, or multiple second through grooves 18 are provided on the second annular connecting part 142 on the outer central rod 14, or multiple second through grooves 18 are provided on the second annular connecting part 142 on either the inner central rod 13 or the outer central rod 14. In any case, the multiple second through grooves 18 located on the same central rod are distributed circumferentially at intervals, thereby forming with the lower surface of the upper end member 11. Multiple second liquid passages are provided, and the second annular space 19 can be connected to the liquid inlet channel through multiple second liquid passages. Moreover, the multiple second liquid passages are distributed at different positions around the center rod. The liquid inlet channel can be connected to the second annular space 19 through the second liquid passages at multiple positions. The liquid enters the second annular space 19 through the multiple second liquid passages, which fully acts on the filter membrane 15 inside, so that the cleanliness of the filter element 1 is better and the utilization rate of the filter membrane 15 is higher. Furthermore, an upper protrusion 21 is formed between adjacent second through grooves 18, so that the upper protrusion 21 is welded to the lower surface of the upper end piece 11 to achieve a stable connection between the center rod and the upper end piece 11.

[0073] like Figures 11-12As shown, Embodiment 2 of this utility model also provides a capsule filter, specifically including a housing 2, a first interface 3 and a second interface 4 located at the upper end of the housing 2, and a filter element 1 as described in any of the above. The filter element 1 is disposed inside the housing 2. The outer central rod 14 and the inner sidewall of the housing 2 form an external liquid flow channel 5, and the inner central rod 13 forms an internal liquid flow channel 6. The first interface 3 is connected to the external liquid flow channel 5, and the second interface 4 is connected to the internal liquid flow channel 6. Specifically, if the first interface 3 is connected to an external liquid inlet pipe and the second interface 4 is connected to an external liquid outlet pipe, then the filter element 1 located in the housing 2 is in an external liquid inlet mode, and the liquid to be filtered flows from the first interface 3. The liquid enters the external liquid flow channel 5, then passes through the through hole 22 on the outer center rod 14 into the filter membrane 15. The liquid passes through the filter membrane 15 and enters the internal liquid flow channel 6 through the through hole 22 on the inner center rod 13, and finally exits from the second interface 4. If the first interface 3 is connected to the external liquid outlet pipe and the second interface 4 is connected to the external liquid inlet pipe, then the filter element 1 located in the housing 2 is in the internal liquid inlet mode. The liquid enters the internal liquid flow channel 6 from the second interface 4, then passes through the through hole 22 on the inner center rod 13 into the filter membrane 15. The liquid passes through the filter membrane 15 and enters the external liquid flow channel 5 through the through hole 22 on the outer center rod 14, and finally exits from the first interface 3.

[0074] Specifically, regarding the liquid inlet / outlet method of filter element 1, such as... Figure 10 and Figure 11 As shown, the inner center rod 13 of the filter element 1 specifically includes a first inner tube 131 and a second inner tube 132 arranged radially at intervals. The second inner tube 132 is sleeved on the outside of the first inner tube 131. The upper and lower ends of the first inner tube 131 and the second inner tube 132 are welded to the lower surface of the upper end member 11 and the upper surface of the lower end member 12, respectively. The first inner tube 131 and the second inner tube 132 form an inner liquid passage 6. Correspondingly, the upper end member 11 has a first through hole 7 and a second through hole 8, and the lower end member 12 has a third through hole 9. The first interface 3 is the liquid inlet, and the second interface 4 is the liquid outlet. The upper end of the first inner tube 131 is connected to the first interface 3 through the first through hole 7, and the lower end... The component 12 is spaced apart from the lower end of the outer shell, and the space formed between them is connected to the external liquid channel 5. The lower end of the first inner tube 131 is connected to the space between the lower component 12 and the lower end of the outer shell through the third through hole 9, and thus connected to the external liquid channel 5. The internal liquid channel 6 is connected to the second interface 4 through the second through hole 8. Thus, when filtering liquid or rinsing the filter element 1, the liquid enters the first inner tube 131 from the first interface 3, and then passes through the first inner tube 131, the third through hole 9, the external liquid channel 5, the through hole 22 of the outer center rod 14, the filter membrane 15, and the through hole 22 on the second sleeve to the internal liquid channel 6, and finally exits from the second interface 4 through the second through hole.

[0075] However, in the prior art, the outlet of the first inner tube 131 is set as the first flared mouth 10, and the diameter of its third through hole 9 is smaller than the diameter of the first inner tube 131. This causes a dead zone to be formed between the first flared mouth 10 and the upper surface of the lower end member 12, which will affect the liquid inlet volume. Therefore, a second flared mouth 101 is also provided at the end of the third through hole 9 near the first inner tube 131, and the maximum inner diameter of the first flared mouth 10 and the second flared mouth 101 are the same, and the flared mouth edges of the two are seamlessly welded together. This prevents a dead zone from being formed between the first flared mouth 10 and the upper surface of the lower end member 12, and also makes the inner diameter of the first inner tube 131 smaller than or equal to the inner diameter of the third through hole 9, so as to ensure the liquid inlet volume passing through the third through hole 9 and the liquid inlet volume of the external liquid channel 5.

[0076] The above embodiments are merely preferred embodiments of this utility model and should not be construed as limiting the scope of protection of this utility model. Any non-substantial changes and substitutions made by those skilled in the art based on this utility model shall fall within the scope of protection claimed by this utility model.

Claims

1. A filter element for a capsule filter, the filter element comprising an upper end member and a lower end member axially spaced apart, a cylindrical inner center rod and an outer center rod having multiple through holes disposed between the upper end member and the lower end member axially, the inner center rod being located radially inside the outer center rod, the space between the inner center rod and the outer center rod being filled with a filter membrane, the upper and lower ends of the filter membrane being welded to the upper end member and the lower end member respectively; The lower ends of the inner and outer center rods each have a first annular connecting portion that is sealed and fixed to the lower end member. The first annular connecting portion is located below the lowest through hole on each center rod, and the two first annular connecting portions form a first annular space. The upper ends of the inner and outer center rods each have a second annular connecting portion that is sealed and fixed to the upper end member. The second annular connecting portion is located above the highest through hole on each center rod, and the two second annular connecting portions form a second annular space. The feature is that... At least one of the first annular connecting portion of the outer center rod and the first annular connecting portion of the inner center rod has a first through groove on its lower surface. The first through groove radially penetrates the first annular connecting portion. The groove wall of the first through groove and the upper surface of the lower end member form a first liquid passage hole for liquid to pass through, so as to introduce liquid into the first annular space.

2. The filter cartridge of claim 1, wherein, Multiple first through slots are provided on the same central rod, and the multiple first through slots are distributed circumferentially so that the first annular connecting part on the corresponding central rod has multiple downward protruding teeth, and the downward protruding teeth are welded to the lower end piece.

3. The filter cartridge of claim 2, wherein, The circumference of the first through groove is equal to the circumference of the through hole located on the same central rod, and the first through groove is connected to the adjacent through hole located on the same central rod.

4. The filter cartridge of claim 2 wherein, The total circumference of the plurality of lower teeth located on the same central rod is 1 / 5 to 1 / 2 of the circumference of the corresponding first annular connecting part.

5. The filter cartridge of claim 1 wherein, The first through groove is arranged in a ring, and the upper ends of the outer center rod and the inner center rod are both welded to the upper end piece.

6. The filter cartridge of claim 1, wherein, The first through groove on the outer center rod and the first through groove on the inner center rod are arranged radially correspondingly.

7. The filter cartridge of claim 1 wherein, At least one of the second annular connecting portion of the outer center rod and the second annular connecting portion of the inner center rod has a second through groove on its upper surface. The second through groove radially penetrates the second annular connecting portion. The groove wall of the second through groove and the lower surface of the upper end member form a second liquid passage hole for liquid to pass through, so as to introduce liquid into the second annular space.

8. The filter cartridge of claim 7, wherein, The second through slots located on the same central rod are provided in multiple ways, and the multiple second through slots are distributed at intervals along their circumference, so that the second connecting part on the corresponding central rod has multiple upwardly protruding upper teeth, and the upper teeth are welded to the upper end piece.

9. A capsule filter characterized in that, The device includes a housing, a first interface and a second interface disposed in the housing, and a filter element as described in any one of claims 1-8. The filter element is disposed inside the housing. The outer central rod and the inner sidewall of the housing form an outer liquid flow channel, and the inner central rod forms an inner liquid flow channel. The first interface is connected to the outer liquid flow channel, and the second interface is connected to the inner liquid flow channel.

10. The bladder filter of claim 9, wherein, The inner central rod includes a first inner tube and a second inner tube arranged radially at intervals, and the first inner tube and the second inner tube form the inner liquid flow channel. The upper part is provided with a first through hole and a second through hole, and the lower part is provided with a third through hole; The first interface is a liquid inlet, the second interface is a liquid outlet, the upper end of the first inner tube is connected to the first interface through the first through hole, the lower end of the first inner tube is connected to the external liquid flow channel through the third through hole, and the internal liquid flow channel is connected to the second interface through the second through hole. The outlet of the first inner tube is configured as a first flared opening, and the end of the third through hole near the first inner tube is configured with a second flared opening. The first flared opening and the second flared opening have the same maximum inner diameter and are connected, and the inner diameter of the first inner tube is less than or equal to the inner diameter of the third through hole.

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