A gearbox for wind power

Abstract

The utility model belongs to mechanical drive technical field especially relates to a gear box for wind power generation. The utility model provides a gear box for wind power generation, include: cooling box, the one side of cooling box is provided with and is connected with the discharge pipe of gear box's discharge port, cooling device, cooling device sets up in cooling device inside, cooling device is used for cooling the lubricating oil of temperature rise, circulating device, circulating device is connected with gear box, circulating device is used for the lubricating oil after cooling to feed gear box again. High temperature lubricating oil enters into cooling box through discharge pipe, under the cooling effect of cooling device, lubricating oil is cooled, and the lubricating oil after cooling reenters gear box under the action of circulating device, replaces the lubricating oil of high temperature and lubricates gear, makes gear box more safe in the working process, improves the service life of gear box, saves the cost simultaneously.

Description

Technical Field

[0001] This utility model belongs to the field of mechanical transmission technology, and in particular relates to a gearbox for wind power generation. Background Technology

[0002] The gearbox in a wind turbine generator set is a crucial mechanical component. Its primary function is to transmit the power generated by the wind turbine under wind force to the generator, enabling it to achieve the required rotational speed. Typically, the wind turbine's rotational speed is very low, far below the speed required for generator operation. Therefore, the gearbox's gear pairs must increase the speed, hence the name "speed increaser." Depending on the overall layout requirements of the unit, sometimes the drive shaft (commonly known as the main shaft), directly connected to the wind turbine hub, is integrated with the gearbox. Alternatively, the main shaft and gearbox may be arranged separately, connected by a shrink-fit sleeve or coupling. To increase the unit's braking capacity, braking devices are often installed at the input or output end of the gearbox, working in conjunction with tip braking (for fixed-pitch wind turbines) or variable-pitch braking devices to jointly brake the unit's transmission system.

[0003] Existing patent CN107763180 discloses a gearbox for wind power generation, comprising: a gearbox, a main shaft, tapered roller bearings, a first planetary gear transmission stage, a second planetary gear transmission stage, a flexible pin, and an integrated flexible pin bearing. The tapered roller bearings are mounted on the input end of the gearbox, and the main shaft is supported on the input end of the gearbox via the tapered roller bearings, distributing the power of the main shaft to the first and second planetary gear transmission stages. The flexible pins are mounted within the integrated flexible pin bearings. Through this method, the gearbox of this invention can reduce the contact load on the gears and improve the transmission stability and reliability of the gearbox. However, the long-term mutual friction between the gears within the gearbox can lead to an increase in the internal temperature of the gearbox, causing an increase in the temperature of the lubricating oil flowing through the gearbox, which can create safety hazards and reduce the service life of the gearbox. Utility Model Content

[0004] The purpose of this invention is to address the aforementioned technical problems by providing a gearbox for wind power generation that can cool and dissipate heat from the lubricating oil in the gearbox, preventing spontaneous combustion, making the gearbox safer during operation, and extending its service life.

[0005] In view of this, the present invention provides a gearbox for wind power generation, characterized in that it comprises:

[0006] A cooling box, wherein a discharge pipe is provided on one side of the cooling box and connected to the discharge port of the gearbox;

[0007] A cooling device, wherein the cooling device is disposed inside a cooling device, and the cooling device is used to cool the heated lubricating oil;

[0008] A circulation device is disposed above the cooling tank and connected to the gearbox. The circulation device is used to resupply the cooled lubricating oil to the gearbox.

[0009] In this technical solution, the lubricating oil in the gearbox experiences a temperature rise due to gear friction. The high-temperature lubricating oil is then discharged from the gearbox outlet through the discharge pipe into the cooling tank. Under the cooling effect of the cooling device, the lubricating oil is cooled. The cooled lubricating oil then re-enters the gearbox under the action of the circulation device, replacing the already high-temperature lubricating oil to lubricate the gears, forming a cycle. This makes the gearbox safer during operation, extends its service life, and saves costs.

[0010] Furthermore, the circulation device includes:

[0011] An oil supply pipe is provided at the oil supply port of the gearbox;

[0012] An oil pump is installed on top of the cooling tank, and one end of the oil pump is fixedly connected to the oil supply pipe.

[0013] A conduit is provided through the upper surface of the cooling tank. One end of the conduit is connected to an oil pump, and the other end is connected to a cooling device.

[0014] In this technical solution, the cooled lubricating oil enters the oil supply port of the gearbox through the oil supply pipe under the action of the oil pump. By continuously discharging the high-temperature lubricating oil from the gearbox through the discharge pipe and adding the cooled lubricating oil, the temperature inside the gearbox will not be too high, thus preventing damage to the parts inside the gearbox. At the same time, the lubricating oil can be reused multiple times, which can also save costs.

[0015] Furthermore, the cooling device includes:

[0016] A refrigeration pipe is installed inside the cooling box along the height direction of the cooling box, and the refrigeration pipe is fixedly connected to the side wall of the cooling box.

[0017] A circulation pipe is installed inside the cooling tank, one end of which is connected to a conduit, and coolant is provided in the space between the circulation pipe and the cooling tank.

[0018] A flow assembly is disposed at the bottom of the cooling tank and is used to circulate the coolant within the cooling tank.

[0019] In this technical solution, high-temperature lubricating oil flows in a circulation pipe, the outside of which is filled with coolant. The refrigeration pipe cools the coolant in the cooling tank, and the coolant can cool down the high-temperature lubricating oil. The flow components allow the coolant to flow in the cooling tank, which can better and more evenly dissipate heat from the lubricating oil.

[0020] Furthermore, the circulation pipe is made of a thermally conductive metal material and is spiral-shaped.

[0021] In this technical solution, the circulation pipe can be made of copper or aluminum, which has good thermal conductivity to facilitate heat dissipation. The spiral shape of the circulation pipe can prolong the time that the lubricating oil spends flowing through the cooling box, thereby extending the cooling time of the lubricating oil and improving the heat dissipation and cooling effect of the circulation pipe.

[0022] Furthermore, the flow component includes:

[0023] A rotating shaft is disposed inside the cooling box along the length of the cooling box, and one end of the rotating shaft passes through the side wall of the cooling box and is rotatably connected to the opposite side wall of the cooling box.

[0024] A stirring block is spirally arranged on a rotating shaft in a circumferential direction, and there is a gap between the top end of the stirring block and the bottom end of the circulation pipe.

[0025] The motor is fixedly mounted outside the cooling box, and its output end is connected to one end of the rotating shaft.

[0026] In this technical solution, the motor starts working, driving the rotating shaft to rotate, causing the stirring block on the rotating shaft to rotate as well. Under the rotation of the stirring block, the coolant in the cooling tank begins to flow. The flowing coolant facilitates the cooling pipes to cool the coolant, and at the same time facilitates better heat dissipation for the lubricating oil.

[0027] Furthermore, a filter device is installed inside the cooling box, and the filter device is connected to the discharge pipe. The filter device is used to filter impurities in the high-temperature lubricating oil.

[0028] In this technical solution, when the lubricating oil flows through the gearbox, some impurities such as iron filings will be generated due to the friction of the gears during long-term rotation. The impurities in the lubricating oil can be filtered out by the filtration device so that the lubricating oil can be recycled in the future.

[0029] Furthermore, a filter box is fixedly installed inside the cooling box, the filter box is fixedly connected to the discharge pipe, and the side wall of the filter box is fixedly connected to the circulation pipe.

[0030] Furthermore, the filtration device includes:

[0031] A filter screen is fixedly installed inside the filter box. The position of the filter screen is higher than the position of the circulation pipe on the filter box, and lower than the position of the discharge pipe on the filter box.

[0032] A cleaning component is disposed above the filter screen and is used to clean impurities from the filter screen.

[0033] In this technical solution, the lubricating oil in the discharge pipe enters the filter box, and the impurities in the lubricating oil are retained by the filter screen, while the lubricating oil enters the circulation pipe. The retained impurities will clog the mesh of the filter screen, and the cleaning component can clean the impurities on the filter screen.

[0034] Furthermore, the cleaning component includes:

[0035] The guide rail is fixedly installed on the side wall of the filter box along the width direction of the filter box;

[0036] A cleaning brush is slidably disposed above a filter screen. Both ends of the cleaning brush are slidably connected to a guide rail, and one end of the cleaning brush is provided with a toothed groove.

[0037] A rotating block is rotatably mounted outside the filter box. The rotating block is provided with a rack corresponding to the cleaning brush, and the rack and the tooth groove mesh with each other.

[0038] A power source is fixedly installed outside the cooling box, and the output shaft of the power source is connected to one end of the rotating block.

[0039] In this technical solution, the power source starts to move, driving the rotating block to rotate. Due to the meshing of the rack and tooth groove, the cleaning brush slides on the guide rail, thereby cleaning the impurities on the filter screen.

[0040] Furthermore, a collection box with an upward opening is detachably provided on the lower side of the filter screen, and a magnet is fixedly provided in the collection box.

[0041] In this technical solution, the cleaning brush sweeps the impurities into the collection box, and the collection box is fixedly equipped with a magnetic block to attract the metal in the impurities, making it easy to collect.

[0042] The beneficial effects of this utility model are:

[0043] 1. This utility model enables high-temperature lubricating oil to circulate in a circulation pipe, the outside of which is filled with coolant. The cooling pipe cools the coolant in the cooling tank, and the coolant can cool down the high-temperature lubricating oil. The flow component allows the coolant to flow in the cooling tank, which can better and more evenly dissipate heat from the lubricating oil.

[0044] 2. This utility model realizes that when lubricating oil flows through the gearbox, some impurities such as iron filings will be generated during the long-term rotation and friction of the gears. The impurities in the lubricating oil can be filtered out by the filtration device, so as to facilitate the subsequent recycling of the lubricating oil. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the overall design of this utility model;

[0046] Figure 2 This is a structural diagram of the internal structure of the cooling box of this utility model;

[0047] Figure 3 This is a partial schematic diagram of the cooling device of this utility model;

[0048] Figure 4 This is a schematic diagram of the interior of the filter box of this utility model;

[0049] Figure 5 This is a schematic diagram of the structure of the cleaning component of this utility model;

[0050] The markings in the diagram are as follows:

[0051] 1. Gearbox; 2. Cooling tank; 3. Cooling device; 4. Circulation device; 5. Discharge pipe; 6. Oil supply pipe; 7. Oil pump; 8. Conduit; 9. Refrigeration pipe; 10. Circulation pipe; 11. Flow component; 12. Coolant; 13. Rotating shaft; 14. Stirring block; 15. Motor; 16. Filter device; 17. Filter screen; 18. Cleaning component; 19. Guide rail; 20. Cleaning brush; 21. Rotating block; 22. Power source; 23. Rack; 24. Gear groove; 25. Collection box; 26. Magnetic block; 27. Filter box. Detailed Implementation

[0052] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0053] In the description of this application, it should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. For ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0054] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such use of data can be interchanged where appropriate so that embodiments of this application can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and are not limited in number; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0055] It should be noted that in the description of this application, the directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description. Unless otherwise stated, these directional terms 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 the scope of protection of this application. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0056] It should be noted that, in this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. Furthermore, it should be noted that the scope of the methods and apparatuses in the embodiments of this application is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. Additionally, features described with reference to certain examples may be combined in other examples.

[0057] Example 1:

[0058] like Figure 1-3 As shown, this utility model provides a gearbox 1 for wind power generation, comprising:

[0059] Cooling box 2, with a discharge pipe 5 connected to the discharge port of gearbox 1 on one side;

[0060] Cooling device 3, the cooling device 3 is disposed inside the cooling device 3, the cooling device 3 is used to cool the heated lubricating oil;

[0061] The circulation device 4 is located above the cooling tank 2 and is connected to the gearbox 1. The circulation device 4 is used to resupply the cooled lubricating oil to the gearbox 1.

[0062] The lubricating oil in gearbox 1 heats up due to friction between the gears. The hot lubricating oil then enters the cooling tank 2 through the discharge pipe 5 at the outlet of gearbox 1. Under the cooling effect of the cooling device 3, the lubricating oil is cooled. The cooled lubricating oil then re-enters gearbox 1 under the action of the circulation device 4, replacing the hot lubricating oil to lubricate the gears, forming a cycle. This makes gearbox 1 safer during operation, extends its service life, and saves costs.

[0063] The circulation device 4 includes:

[0064] Oil supply pipe 6, wherein the oil supply pipe 6 is provided at the oil supply port of gearbox 1;

[0065] An oil pump 7 is installed on top of the cooling tank 2, and one end of the oil pump 7 is fixedly connected to the oil supply pipe 6.

[0066] The conduit 8 is installed through the upper surface of the cooling tank 2. One end of the conduit 8 is connected to the oil pump 7, and the other end of the conduit 8 is connected to the cooling device 3.

[0067] After cooling, the lubricating oil enters the oil supply port of the gearbox 1 from the oil supply pipe 6 through the conduit 8 under the action of the oil pump 7. By continuously discharging the high-temperature lubricating oil from the discharge pipe 5 into the gearbox 1 and adding the cooled lubricating oil, the temperature inside the gearbox 1 will not be too high, thus preventing damage to the parts inside the gearbox 1. At the same time, the lubricating oil can be used multiple times, which can also save costs.

[0068] The cooling device 3 includes:

[0069] A refrigeration pipe 9 is installed inside the cooling box 2 along the height direction of the cooling box 2, and the refrigeration pipe 9 is fixedly connected to the side wall of the cooling box 2.

[0070] A circulation pipe 10 is installed inside the cooling tank 2. One end of the circulation pipe 10 is connected to the conduit 8. Coolant 12 is installed in the space between the circulation pipe 10 and the cooling tank 2.

[0071] A flow assembly 11 is disposed at the bottom of the cooling tank 2, and the flow assembly 11 is used to make the coolant 12 in the cooling tank 2 flow.

[0072] High-temperature lubricating oil flows in the circulation pipe 10, and the outside of the circulation pipe 10 is filled with coolant 12. The cooling pipe 9 cools the coolant 12 in the cooling tank 2. The coolant 12 can cool down the high-temperature lubricating oil. The flow component 11 makes the coolant 12 flow in the cooling tank 2, which can better dissipate heat evenly on the lubricating oil.

[0073] The circulation pipe 10 is made of a thermally conductive metal material and is spiral in shape.

[0074] In this technical solution, the circulation pipe 10 can be made of copper or aluminum, which has good thermal conductivity to facilitate heat dissipation. The spiral shape of the circulation pipe 10 can prolong the time that the lubricating oil flows through the interior of the cooling box 2, thereby extending the cooling time of the lubricating oil and improving the heat dissipation and cooling effect of the circulation pipe 10.

[0075] The flow component 11 includes:

[0076] A rotating shaft 13 is disposed inside the cooling box 2 along the length of the cooling box 2, and one end of the rotating shaft 13 passes through the side wall of the cooling box 2 and is rotatably connected to the opposite side wall of the cooling box 2.

[0077] A stirring block 14 is spirally arranged on a rotating shaft 13 in a circumferential direction, and there is a gap between the top end of the stirring block and the bottom end of the circulation pipe 10.

[0078] Motor 15 is fixedly installed outside the cooling box 2, and the output end of motor 15 is connected to one end of rotating shaft 13.

[0079] The motor 15 starts working, driving the rotating shaft 13 to rotate, causing the stirring block 14 on the rotating shaft 13 to rotate as well. Under the rotation of the stirring block 14, the coolant 12 in the cooling tank 2 begins to flow. The flowing coolant 12 facilitates the cooling pipe 9 to cool the coolant 12, and at the same time facilitates better heat dissipation for the lubricating oil.

[0080] Example 2:

[0081] like Figure 4 and 5 As shown, a filter device 16 is provided inside the cooling box 2. The filter device 16 is connected to the discharge pipe 5 and is used to filter impurities in the high-temperature lubricating oil.

[0082] When the lubricating oil flows through the gearbox 1, some impurities such as iron filings will be generated due to the friction of the gears during long-term rotation. The impurities in the lubricating oil can be filtered out by the filter device 16 so that the lubricating oil can be recycled in the future.

[0083] A filter box 27 is fixedly installed inside the cooling box 2. The filter box 27 is fixedly connected to the discharge pipe 5, and the side wall of the filter box 27 is fixedly connected to the circulation pipe 10.

[0084] The filtration device 16 includes:

[0085] The filter screen 17 is fixedly installed inside the filter box 27. The position of the filter screen 17 is higher than the position of the circulation pipe 10 on the filter box 27, and the position of the filter screen 17 is lower than the position of the discharge pipe 5 on the filter box 27.

[0086] A cleaning component 18 is disposed above the filter screen 17 and is used to clean impurities on the filter screen 17.

[0087] The lubricating oil in the discharge pipe 5 enters the filter box 27 and passes through the filter screen 17, where impurities in the lubricating oil are retained. The lubricating oil then enters the circulation pipe 10. The retained impurities will clog the mesh on the filter screen 17, and the cleaning component 18 can clean the impurities on the filter screen 17.

[0088] The cleaning component 18 includes:

[0089] Guide rail 19, the guide rail 19 is fixedly installed on the side wall of filter box 27 along the width direction of filter box 27;

[0090] A cleaning brush 20 is slidably disposed above the filter screen 17. Both ends of the cleaning brush 20 are slidably connected to the guide rail 19, and one end of the cleaning brush 20 is provided with a toothed groove 24.

[0091] Rotating block 21, which is rotatably disposed outside the filter box 27, is provided with a rack 23 corresponding to the cleaning brush 20, and the rack 23 meshes with the tooth groove 24.

[0092] Power source 22 is fixedly installed outside the cooling box 2, and the output shaft of the power source 22 is connected to one end of the rotating block 21.

[0093] When the power source 22 starts to move, it drives the rotating block 21 to rotate. Because the rack 23 and the tooth groove 24 mesh with each other, the cleaning brush 20 slides on the guide rail 19, thereby cleaning the impurities on the filter screen 17.

[0094] The filter screen 17 is detachably provided with an upward-opening collection box 25 on its lower side, and a magnet block 26 is fixedly provided in the collection box 25.

[0095] The cleaning brush 20 sweeps the impurities into the collection box 25, which is fixedly equipped with a magnet 26 to attract metals from the impurities for easy collection.

[0096] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A gearbox for wind power generation, characterized in that ,include: Cooling box (2), on one side of the cooling box (2) is a discharge pipe (5) connected to the discharge port of gearbox (1); Cooling device (3), the cooling device (3) is installed inside the cooling device (3), the cooling device (3) is used to cool the heated lubricating oil; A circulation device (4) is disposed above the cooling box (2) and connected to the gearbox (1). The circulation device (4) is used to resupply the cooled lubricating oil to the gearbox (1).

2. A gearbox for wind power generation according to claim 1, characterized in that The circulation device (4) includes: Oil supply pipe (6), the oil supply pipe (6) is provided at the oil supply port of gearbox (1); An oil pump (7) is installed on top of the cooling tank (2), and one end of the oil pump (7) is fixedly connected to the oil supply pipe (6). The conduit (8) is installed through the upper surface of the cooling box (2). One end of the conduit (8) is connected to the oil pump (7), and the other end of the conduit (8) is connected to the cooling device (3).

3. A gearbox for wind power generation according to claim 1, characterized in that... The cooling device (3) includes: A refrigeration pipe (9) is installed inside the cooling box (2) along the height direction of the cooling box (2), and the refrigeration pipe (9) is fixedly connected to the side wall of the cooling box (2); A circulation pipe (10) is installed inside the cooling tank (2). One end of the circulation pipe (10) is connected to the conduit (8). Coolant (12) is installed in the space between the circulation pipe (10) and the cooling tank (2). A flow assembly (11) is disposed at the bottom of the cooling tank (2) and is used to flow the coolant (12) inside the cooling tank (2).

4. A gearbox for wind power generation according to claim 3, characterized in that... The circulation pipe (10) is made of thermally conductive metal material and is spiral in shape.

5. A gearbox for wind power generation according to claim 3, characterized in that, The flow component (11) includes: A rotating shaft (13) is arranged inside the cooling box (2) along the length direction of the cooling box (2). One end of the rotating shaft (13) passes through the side wall of the cooling box (2) and is rotatably connected to the side wall opposite to the cooling box (2). A stirring block (14) is spirally arranged on a rotating shaft (13) in a circumferential direction, and there is a gap between the top of the stirring block and the bottom of the circulation pipe (10). The motor (15) is fixedly installed outside the cooling box (2), and the output end of the motor (15) is connected to one end of the rotating shaft (13).

6. A gearbox for wind power generation according to claim 1, characterized in that... The cooling box (2) is equipped with a filter device (16), which is connected to the discharge pipe (5). The filter device (16) is used to filter impurities in the high-temperature lubricating oil.

7. A gearbox for wind power generation according to claim 1, characterized in that... A filter box (27) is fixedly installed inside the cooling box (2). The filter box (27) is fixedly connected to the discharge pipe (5). The side wall of the filter box (27) is fixedly connected to the circulation pipe (10).

8. A gearbox for wind power generation according to claim 6, characterized in that... The filter device (16) includes: The filter screen (17) is fixedly installed inside the filter box (27). The position of the filter screen (17) is higher than the position of the circulation pipe (10) on the filter box (27), and the position of the filter screen (17) is lower than the position of the discharge pipe (5) on the filter box (27). A cleaning component (18) is disposed above the filter screen (17) and is used to clean impurities on the filter screen (17).

9. A gearbox for wind power generation according to claim 8, characterized in that... The cleaning component (18) includes: Guide rail (19), the guide rail (19) is fixedly installed on the side wall of filter box (27) along the width direction of filter box (27); A cleaning brush (20) is slidably disposed above a filter screen (17). Both ends of the cleaning brush (20) are slidably connected to a guide rail (19). One end of the cleaning brush (20) is provided with a toothed groove (24). Rotating block (21), the rotating block (21) is rotatably disposed outside the filter box (27), the rotating block (21) is provided with a rack (23) corresponding to the cleaning brush (20), the rack (23) meshes with the tooth groove (24); The power source (22) is fixedly installed outside the cooling box (2), and the output shaft of the power source (22) is connected to one end of the rotating block (21).

10. A gearbox for wind power generation according to claim 8, characterized in that... The filter (17) is detachably provided with an upward-opening collection box (25) on its lower side, and a magnet block (26) is fixedly provided in the collection box (25).

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