Anti-blocking miniature direct-current brushless water pump

Abstract

The invention provides an anti-blocking miniature direct-current brushless water pump, and particularly relates to the technical field of water pumps, the anti-blocking miniature direct-current brushless water pump comprises a main shell, a brushless motor is installed in the main shell, an impeller is connected to the output shaft end of the brushless motor, a water inlet ring body coaxial with the impeller is arranged on the side, close to an output shaft of the brushless motor, of the main shell, and the impeller is located in the water inlet ring body; according to the anti-blocking miniature direct-current brushless water pump, the active impurity filtering mechanism and the recycling assembly which are coaxial with the impeller are arranged on the inner side of the water inlet hole and the inner side of the machine body end cover, the impeller drives the impurity filtering mechanism to rotate to form a centrifugal force field to achieve impurity separation, and impurity collection is completed in cooperation with the recycling assembly; the problems that an existing miniature direct-current brushless water pump depends on filtering of a filter screen to be blocked easily, impurities enter a pump body easily, and an impeller is clamped are solved, front active impurity filtering and blocking prevention of the water inlet end of the water pump are achieved, water and impurities can be separated efficiently without an additional driving device, the pump body is prevented from being blocked by the impurities from the source, and stable and continuous operation of the water pump is guaranteed.

Description

Technical Field

[0001] This application provides a clog-resistant miniature DC brushless water pump, specifically relating to the field of water pump technology. Background Technology

[0002] Miniature DC brushless water pumps are widely used in various fluid transfer scenarios due to their low energy consumption, low noise, and long lifespan. Anti-clogging performance is a key indicator for measuring their operational stability. The core requirement is to effectively block impurities in the water while achieving efficient water delivery, preventing impurities from entering the pump body and causing impeller jamming and component wear, thus ensuring continuous operation of the water pump.

[0003] In the existing technology, the miniature sewage pump with authorization announcement number CN215633811U uses a filter screen structure to achieve anti-clogging. A fixed filter screen is set at the inlet to intercept impurities. Although it can achieve basic filtration, the filter screen is easily clogged by impurities, requiring frequent disassembly and cleaning, which affects the continuous operation of the pump. Moreover, this structure can only passively intercept impurities and cannot achieve active separation and collection of impurities. Small impurities can easily penetrate the filter screen and enter the pump body. Long-term accumulation will cause impeller wear and reduce the service life of the pump. At the same time, this filter structure lacks an anti-backflow design. Some intercepted impurities can easily flow back into the pump body with the water flow, resulting in poor anti-clogging effect. It also does not utilize the pump's own power to filter impurities, requiring an additional cleaning structure, which increases the overall complexity of the pump. Summary of the Invention

[0004] In view of the deficiencies of the existing technology, this application provides a clog-resistant miniature DC brushless water pump, which can effectively solve the related technical problems mentioned in the background art.

[0005] To achieve the above objectives, this application provides the following technical solution: This application discloses a clog-resistant miniature DC brushless water pump, including a main housing, a brushless motor installed inside the main housing, an impeller connected to the output shaft end of the brushless motor, an inlet ring coaxial with the impeller on the side of the main housing near the output shaft of the brushless motor, the impeller located in the inlet ring, an outlet pipe connected to the inlet ring, a machine end cover on the side of the main housing near the impeller, an ring end cover connected to one side of the inlet ring by bolts, an inlet hole opened in the center of the ring end cover, and the inlet hole communicating with the interior of the inlet ring; An active impurity filtration mechanism and a recovery assembly, coaxial with the impeller, are provided between the water inlet and the inner side of the end cover of the machine body. The active impurity filtering mechanism is fixed coaxially with the impeller and driven to rotate by the impeller, and the active impurity filtering mechanism is rotatably and sealed to the outer side of the ring end cover. The recovery component surrounds the outer peripheral surface of the active impurity filtration mechanism, and there is a gap between the recovery component and the active impurity filtration mechanism. The recovery component is provided with an impurity collection structure and a water-permeable structure.

[0006] Preferably, the active impurity filtration mechanism includes an extended linkage shaft, a cross linkage rod, an annular filter element, and spiral ribs; The extended linkage shaft is fixed coaxially with the impeller. A cross linkage rod is fixed at the end of the extended linkage shaft away from the impeller. The outer end of the cross linkage rod is fixedly connected to the annular filter element. The spiral rib is integrally set on the inner circumferential surface of the annular filter element. The annular filter element and the outer side of the annular end cover are connected by a sealing bearing to achieve a rotational seal.

[0007] Preferably, the annular filter element has an annular flared shape on the side away from the impeller, and a plurality of filter holes are evenly distributed on the outer circumferential surface of the annular filter element. The filter holes are the impurity discharge structure of the active impurity filtration mechanism.

[0008] Preferably, each of the filter holes is provided with an integrally formed elastic guide flap, which opens only towards the outer peripheral surface of the annular filter element.

[0009] Preferably, the spiral ribs are distributed in a ring at equal intervals on the inner circumferential surface of the annular filter element.

[0010] Preferably, the recycling component includes two semi-rings, which are closed to each other to form a complete ring structure; The impurity collection structure is located at the bottom of the two semi-rings.

[0011] Preferably, the bottom of each of the two semi-rings is integrally formed with an extended rectangular body, and the two extended rectangular bodies are tightly connected by a tenon and a slot block. After the two extended rectangular bodies are closed, a complete rectangular cavity structure is formed, and the impurity collection structure is inserted and disposed in the rectangular cavity structure.

[0012] Preferably, the impurity collection structure is a rectangular container with an open top that is connected to the bottom of the two semi-rings. The permeable structure includes a first strip-shaped hole formed on the semi-ring and a second strip-shaped hole formed on the side wall of the rectangular receiving box.

[0013] Preferably, an anti-stick coating is provided on the inner ring surface of both semi-rings.

[0014] Preferably, the rectangular container is made of a rigid transparent material and can be horizontally pulled out from the rectangular cavity structure formed by the closure of two extended rectangular bodies.

[0015] In summary, the technical solution provided in this application has at least one of the following advantages compared with the prior art: This anti-clogging miniature DC brushless water pump uses an active impurity filtration mechanism and a recovery component coaxial with the impeller, set on the inside of the water inlet and the end cover of the pump body. The impeller drives the filtration mechanism to rotate, forming a centrifugal force field to separate impurities. The recovery component completes the collection of impurities. This solves the problems of existing miniature DC brushless water pumps that rely on filter screens and are prone to clogging, and impurities can easily enter the pump body and cause impeller jamming. It achieves front-end active impurity filtration and anti-clogging at the water inlet of the pump. It can complete the efficient separation of water and impurities without the need for an additional drive device, avoid impurities clogging the pump body from the source, and ensure the stable and continuous operation of the water pump. The active impurity filtration mechanism and the ring end cap are connected by a rotating seal, which can prevent water from leaking through the fitting gap when the pump is working, maintain stable water pressure in the pump body, and ensure that the impurity filtration mechanism rotates normally with the impeller without generating additional frictional resistance due to the sealing structure. At the same time, the ring filter element of the impeller mechanism is designed with an flared shape on the side away from the impeller, which effectively increases the water inlet flow area, reduces the resistance to water flow, and can also guide the water flow to form a vortex, providing initial guidance for centrifugal impurity filtration and improving the overall smoothness of impurity filtration. The elastic guide vane set at the filter hole opens only to the outside of the ring filter element, which can realize the one-way blocking and discharge of impurities. It prevents impurities that have entered the recovery component from re-entering the filter mechanism under the action of water flow back, effectively preventing pump blockage caused by secondary backflow of impurities. Moreover, the guide vane and the filter hole are integrally formed, with a solid structure that can adapt to the water environment working requirements of the water pump. It is not easily damaged under the impact of water flow and impurities, ensuring a long-term stable one-way flow effect. The recycling component adopts a structure in which two semi-rings are inserted and connected. The rectangular container can be horizontally pulled out from the rectangular cavity structure. When cleaning impurities, only the end cover of the machine body needs to be removed. After separating the semi-rings, the container can be pulled out for pouring and rinsing. There is no need to disassemble the core components of the water pump. The operation is simple and quick. The transparent and rigid container allows for a direct observation of the amount of impurities inside, which is convenient for timely cleaning. This greatly reduces the maintenance difficulty and cost of the water pump and improves the ease of use. The active impurity filtration mechanism and the impeller are linked by a coaxial fixed mechanism. The impeller's rotational power is used to drive the impurity filtration mechanism directly, eliminating the need for additional drive devices such as motors and cylinders. This simplifies the overall structure of the water pump, saves energy from additional drives, and improves the pump's energy efficiency. Attached Figure Description

[0016] Figure 1 This is a front-view stereoscopic structural diagram of this application; Figure 2 This is a partial three-dimensional structural diagram of the relevant components in the cut-and-separated state of the end cap of the fuselage in this application; Figure 3 This is a partial three-dimensional structural diagram of the relevant components in the state where the annular end cap and the water inlet annular body are separated in this application; Figure 4This is a partial three-dimensional structural diagram of the relevant components at the annular filter element in this application; Figure 5 This is a partial exploded three-dimensional structural view of the relevant components at the annular filter element in this application; Figure 6 This is a partial three-dimensional structural view of the relevant components at the annular filter element in this application from another perspective. Figure 7 This is a side view of the relevant components at the annular filter element in this application; Figure 8 This is a partial three-dimensional structural diagram of the relevant components at the semi-ring body in this application; Figure 9 This is a partial three-dimensional structural diagram of the relevant components in the separated state at the semi-ring body in this application; Figure 10 This is a partial exploded three-dimensional structural diagram of the relevant components at the semi-annular body in this application.

[0017] The labels in the diagram represent: 1. Main housing; 11. Brushless motor; 12. Impeller; 13. Inlet ring; 131. Ring end cap; 132. Inlet hole; 14. Outlet pipe; 15. Machine body end cap; 2. Active impurity filtration mechanism; 21. Extending linkage shaft; 22. Cross linkage rod; 23. Ring filter element; 231. Filter hole; 24. Spiral ribs; 25. Sealed bearing; 3. Recycling component; 31. Semi-ring body; 32. Extended rectangular body; 33. First strip hole; 34. Rectangular receiving box; 35. Second strip hole. Detailed Implementation

[0018] The present application will be further described below with reference to embodiments.

[0019] Reference Appendix Figures 1 to 10 As shown, a clog-resistant miniature DC brushless water pump includes a main housing 1, inside which a brushless motor 11 is installed. An impeller 12 is connected to the output shaft of the brushless motor 11. A water inlet ring 13, coaxial with the impeller 12, is provided on the side of the main housing 1 near the output shaft of the brushless motor 11. The impeller 12 is located inside the water inlet ring 13. A water outlet pipe 14 is connected to the water inlet ring 13. A machine end cover 15 is provided on the side of the main housing 1 near the impeller 12. An end cover 131 is bolted to one side of the water inlet ring 13. A water inlet hole 132 is opened in the center of the end cover 131 and is connected to the interior of the water inlet ring 13. An active impurity filtration mechanism 2 and a recovery assembly 3, coaxial with the impeller 12, are provided between the water inlet 132 and the inner side of the end cover 15 of the machine body. Specifically, in order to ensure the coaxiality of the active impurity filtration mechanism 2, the recovery assembly 3 and the impeller 12, a coaxial positioning boss adapted to the active impurity filtration mechanism 2 is provided on the outer side of the annular end cover 131, and an annular positioning groove adapted to the recovery assembly 3 is provided on the inner side of the end cover 15 of the machine body. The positioning structure avoids the eccentric rotation of each component from affecting the impurity filtration effect. Furthermore, the active impurity filtering mechanism 2 is coaxially fixed with the impeller 12 and driven to rotate by the impeller 12, and the active impurity filtering mechanism 2 is rotatably sealed to the outer side of the ring end cover 131; its function is that the rotatable sealing structure can prevent water from leaking from the fit gap between the active impurity filtering mechanism 2 and the ring end cover 131 when the water pump is working, while ensuring the normal rotation of the active impurity filtering mechanism 2 and maintaining the stability of the water pressure inside the water pump. The recovery component 3 surrounds the outer periphery of the active impurity filtration mechanism 2, and there is a gap between the recovery component 3 and the active impurity filtration mechanism 2. This gap provides a space for impurities to be contained after they are thrown away from the active impurity filtration mechanism 2, while preventing the recovery component 3 from contacting and rubbing against the rotating active impurity filtration mechanism 2, thus preventing wear of the components and affecting their service life. The recovery component 3 is provided with an impurity collection structure and a water-permeable structure.

[0020] Furthermore, the active impurity filtration mechanism 2 includes an extended linkage shaft 21, a cross linkage rod 22, an annular filter element 23, and a spiral rib 24. The extended linkage shaft 21 is coaxially fixed with the impeller 12, and the end of the extended linkage shaft 21 away from the impeller 12 is fixed with the cross linkage rod 22. The outer end of the cross linkage rod 22 is fixedly connected to the annular filter element 23. The spiral rib 24 is integrally set on the inner circumferential surface of the annular filter element 23. The annular filter element 23 and the outer side of the annular end cap 131 are rotated and sealed through a sealing bearing 25. Specifically, the sealing bearing 25 simultaneously undertakes the dual functions of radial support and rotational sealing. It not only supports and guides the rotation of the annular filter element 23, but also effectively blocks water flow, simplifying assembly while improving the sealing effect.

[0021] Furthermore, the side of the annular filter element 23 away from the impeller 12 is annularly flared. This flared structure can increase the flow area of ​​the water inlet, reduce the resistance when the water flows into the annular filter element 23, and guide the water flow to make swirling motion along the inner wall of the annular filter element 23, providing initial guidance for centrifugal impurity filtration. A plurality of filter holes 231 are evenly distributed on the outer peripheral surface of the annular filter element 23. The filter holes 231 are the impurity discharge structure of the active impurity filtration mechanism 2. Each filter hole 231 is provided with an integrally formed elastic guide flap, which opens only towards the outer peripheral surface of the annular filter element 23.

[0022] Furthermore, the spiral ribs 24 are distributed in an annular and equidistant pattern on the inner circumferential surface of the annular filter element 23. The recovery component 3 includes two semi-annular bodies 31, which are closed to each other to form a complete annular structure. The impurity collection structure is located at the bottom of the two semi-annular bodies 31. The bottom of each of the two semi-annular bodies 31 is integrally formed with an extended rectangular body 32. The two extended rectangular bodies 32 are tightly connected by a tenon and a slot block. After the two extended rectangular bodies 32 are closed, they form a complete rectangular cavity structure. The impurity collection structure is inserted into the rectangular cavity structure.

[0023] Furthermore, the impurity collection structure is a rectangular container 34, with an open top that is connected to the bottom of the two semi-rings 31. The permeable structure includes a first strip hole 33 on the semi-ring 31 and a second strip hole 35 on the side wall of the rectangular container 34. The permeable structure allows the water that enters the recycling component 3 with the impurities to be discharged smoothly, leaving only the impurities inside the recycling component 3. This avoids water accumulation inside the recycling component 3, which would cause the impurities to suspend and not settle, thus ensuring the impurity collection effect. The inner ring surfaces of the two semi-ring bodies 31 are provided with an anti-stick coating. The rectangular container 34 is made of a hard transparent material and can be horizontally pulled out from the rectangular cavity structure formed by the closure of the two extended rectangular bodies 32.

[0024] As a second embodiment of this application The elastic guide vane in the aforementioned anti-clogging miniature DC brushless water pump is integrally molded from a rigid elastic plastic material at the filter hole 231. This material has good elasticity and water resistance, can adapt to the working environment of the water pump, and is not easily deformed or aged under the impact of water flow and impurities, ensuring the unidirectional conduction characteristic of the elastic guide vane opening only to the outside. The filter holes 231 are arranged in multiple layers circumferentially on the outer circumferential surface of the annular filter element 23. The multi-layer arrangement of filter holes 231 can increase the discharge area of ​​impurities, avoid the impact of impurity discharge effect after a single row of filter holes 231 is blocked, and at the same time allow impurities to be thrown away from different positions of the annular filter element 23, improving the uniformity of impurity filtration.

[0025] As a third embodiment of this application In the aforementioned anti-clogging miniature DC brushless water pump, the recovery component 3 has a low surface energy fluoride coating on the inner ring surface of the semi-ring 31. This coating effectively reduces the adhesion between impurities and the inner ring surface of the semi-ring, allowing impurities thrown to the inner wall of the semi-ring 31 to settle smoothly downwards under gravity, preventing impurities from adhering to the wall and forming scale, thus ensuring the long-term performance of the recovery component 3. The tenon and slot between the two extended rectangular bodies 32 adopt a dovetail fit structure. This fit structure can improve the tightness and stability of the two extended rectangular bodies 32 after insertion, preventing the two semi-ring bodies 31 from separating due to vibration during pump operation. At the same time, it can guide the insertion of the extended rectangular bodies 32, facilitating assembly.

[0026] Furthermore, the rectangular cavity structure formed by the extended rectangular body 32 is provided with an axial pull-out guide groove inside, and the outer side of the rectangular receiving box 34 is provided with a guide protrusion that matches the groove. The cooperation between the guide groove and the guide protrusion can make the pull-out of the rectangular receiving box 34 smoother, and at the same time, it can position the rectangular receiving box 34 to prevent the rectangular receiving box 34 from shaking when the water pump is working, and ensure that impurities can fall into the rectangular receiving box 34 smoothly. The first strip hole 33 and the second strip hole 35 are both arranged vertically. The vertically arranged strip holes can cause some suspended impurities to move downward when the water flows out, promote the deposition of impurities, and at the same time prevent impurities from flowing out of the strip holes again, thereby improving the water-impurity separation effect.

[0027] The complete working and usage principle of the above embodiments is as follows: During operation, the brushless motor 11 is powered on to drive the output shaft to rotate, which in turn drives the impeller 12 to rotate synchronously. The active impurity filtering mechanism 2, which is fixed coaxially with the impeller 12, rotates together with the impeller 12, realizing power linkage without additional drive, saving water pump energy consumption and simplifying the overall structure. External water flows into the annular filter element 23 of the active impurity filtering mechanism 2 through the water inlet 132 of the annular end cover 131. Under the guidance of the spiral ribs 24 on the inner circumference of the annular filter element 23 and driven by the rotation of the annular filter element 23, the water flow forms a high-speed swirling motion. Using the action of centrifugal force, solid impurities in the water flow are thrown to the outer circumference of the annular filter element 23.

[0028] When impurities are thrown to the filter hole 231, under the impact of centrifugal force and water flow, the elastic guide valve on the filter hole 231 opens to the outside of the annular filter element 23. The impurities, along with some of the water flow, enter the gap between the recovery component 3 and the active impurity filtration mechanism 2 through the filter hole 231. The elastic guide valve quickly resets under its own elasticity, preventing the impurities that have entered the recovery component 3 from re-entering the annular filter element 23 under the backflow of water flow, thus achieving one-way blocking and discharge of impurities. The water flow entering the gap is discharged through the first strip hole 33 on the semi-annular body 31, while the impurities are deposited downwards under the action of gravity and finally fall into the rectangular receiving box 34 connected to the bottom of the semi-annular body 31. If a small amount of water flows into the rectangular receiving box 34 with the impurities, it can be discharged through the second strip hole 35 on the side wall of the rectangular receiving box 34, leaving only the impurities in the rectangular receiving box 34, thus completing the collection of impurities.

[0029] The clean water, filtered by the active impurity filtration mechanism 2 and the recovery component 3, enters the inlet ring 13 and is thrown into the outlet pipe 14 under the centrifugal force of the impeller 12, thus realizing the water pump's water delivery function. When it is necessary to clean the impurities, the end cover 15 of the machine body can be removed from the main housing 1 first, and then the two interlocking semi-rings 31 can be separated. The rectangular receiving box 34 can be directly pulled out horizontally from the rectangular cavity structure formed by the extended rectangular body 32. After emptying the impurities inside, the rectangular receiving box 34 and the semi-rings 31 can be rinsed to complete the maintenance. The entire cleaning process does not require disassembling the core components of the water pump, making the operation simple and ensuring the subsequent impurity filtration and working effect of the water pump.

[0030] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application. It should be understood that in this application, the rotating, sliding, meshing, belt-driven and other moving parts are well lubricated and not prone to slipping or wear, and each of them is provided with a corresponding protective shell. However, in the accompanying drawings of this application, the connection state of each moving part is not shown. It should also be understood that each part in this application is made of metal or plastic material with adaptable strength in the relevant field to ensure that its structural rigidity meets the actual requirements.

Claims

1. A clog-resistant miniature DC brushless water pump, comprising a main housing (1), a brushless motor (11) installed inside the main housing (1), an impeller (12) connected to the output shaft end of the brushless motor (11), an inlet ring (13) coaxial with the impeller (12) provided on the side of the main housing (1) near the output shaft of the brushless motor (11), the impeller (12) located inside the inlet ring (13), the inlet ring (13) connected to an outlet pipe (14), a machine end cover (15) provided on the side of the main housing (1) near the impeller (12), an ring end cover (131) connected to the side of the inlet ring (13) by bolts, an inlet hole (132) provided in the center of the ring end cover (131), the inlet hole (132) communicating with the interior of the inlet ring (13), characterized in that, An active impurity filtration mechanism (2) and a recovery assembly (3) coaxial with the impeller (12) are provided between the water inlet (132) and the inner side of the end cover (15) of the machine body. The active impurity filtering mechanism (2) is fixed coaxially with the impeller (12) and driven to rotate by the impeller (12), and the active impurity filtering mechanism (2) is rotatably sealed to the outer side of the ring end cover (131); The recycling component (3) surrounds the outer periphery of the active impurity filtration mechanism (2), and there is a gap between the recycling component (3) and the active impurity filtration mechanism (2). The recycling component (3) is provided with an impurity collection structure and a water-permeable structure.

2. The anti-clogging miniature DC brushless water pump according to claim 1, characterized in that, The active impurity filtration mechanism (2) includes an extended linkage shaft (21), a cross linkage rod (22), an annular filter element (23), and a spiral rib (24). The extended linkage shaft (21) is fixed coaxially with the impeller (12). A cross linkage rod (22) is fixed at the end of the extended linkage shaft (21) away from the impeller (12). The outer end of the cross linkage rod (22) is fixedly connected to the annular filter element (23). The spiral rib (24) is integrally set on the inner circumferential surface of the annular filter element (23). The annular filter element (23) and the outer side of the annular end cap (131) are connected by a sealed bearing (25) to achieve a rotational sealing connection.

3. The anti-clogging miniature DC brushless water pump according to claim 2, characterized in that, The annular filter element (23) has an annular flared shape on the side away from the impeller (12), and a number of filter holes (231) are evenly distributed on the outer circumferential surface of the annular filter element (23). The filter holes (231) are the impurity discharge structure of the active impurity filtration mechanism (2).

4. The anti-clogging miniature DC brushless water pump according to claim 3, characterized in that, Each of the filter holes (231) is provided with an integrally formed elastic guide flap, which opens only towards the outer peripheral surface of the annular filter element (23).

5. The anti-clogging miniature DC brushless water pump according to claim 2, characterized in that, The spiral ribs (24) are distributed in an annular equidistant pattern on the inner circumferential surface of the annular filter element (23).

6. The anti-clogging miniature DC brushless water pump according to claim 1, characterized in that, The recycling component (3) includes two semi-rings (31), which are closed to each other to form a complete ring structure; The impurity collection structure is located at the bottom of the two semi-annular bodies (31).

7. The anti-clogging miniature DC brushless water pump according to claim 6, characterized in that, The bottom of each of the two semi-ring bodies (31) is integrally formed with an extended rectangular body (32). The two extended rectangular bodies (32) are tightly connected by a tenon and a slot block. After the two extended rectangular bodies (32) are closed, they form a complete rectangular cavity structure. The impurity collection structure is inserted into the rectangular cavity structure.

8. The anti-clogging miniature DC brushless water pump according to claim 7, characterized in that, The impurity collection structure is a rectangular container (34), the top of which is an open structure, and the open structure is connected to the bottom of the two semi-rings (31). The permeable structure includes a first strip hole (33) opened on the semi-annular body (31) and a second strip hole (35) opened on the side wall of the rectangular receiving box (34).

9. The anti-clogging miniature DC brushless water pump according to claim 6, characterized in that, An anti-stick coating is provided on the inner ring surface of both semi-rings (31).

10. The anti-clogging miniature DC brushless water pump according to claim 8, characterized in that, The rectangular container (34) is made of a hard transparent material and can be horizontally pulled out from the rectangular cavity structure formed by the closure of two extended rectangular bodies (32).

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