A small capacity active filter

Abstract

The present invention relates to the technical field of active filters, and specifically to a small-capacity active filter, comprising a filter body, wherein the filter body generates a compensation current with an amplitude equal to that of the harmonic current of the power grid and an opposite polarity and injects the compensation current into the power grid to compensate or offset the harmonic current, thereby actively eliminating power harmonics; the filter body is provided with an air inlet and an air outlet for ventilation to achieve heat dissipation, and two reels with a motor as a power source are rotatably installed in the filter body, and absorbent cloths are fixedly installed on the two reels, and the two reels are respectively used to roll up and release the absorbent cloth. The present invention prevents moisture in high-humidity air from condensing inside the filter by allowing moisture in the air entering the filter from the air inlet to bypass its internal electronic components.

Description

Technical Field

[0001] The invention relates to the technical field of active filters, in particular to a small-capacity active filter. Background Art

[0002] Active power filter (APF) is a new type of power electronic device that can be used to dynamically suppress harmonics and compensate reactive power. According to the size of the capacity level, active filters can be divided into small-capacity active filters and conventional active filters. Among them, small-capacity filters with a capacity level below 15A are widely used in on-site governance filtering solutions.

[0003] For small-capacity active filters, the operating environment requires a humidity between 5% and 95%, and no condensation. However, in southern coastal cities, the air humidity can reach 100% during the return of the south wind, and condensation will naturally form, which poses a threat to the use of the filter. In addition, the active filter needs to rely on power to work, and the electronic components inside it will generate heat, which needs to be dissipated through air cooling. Therefore, active filters inevitably need to be equipped with air inlets and outlets. However, during the return of the south wind season, the use of air cooling will introduce air with excessive humidity into the filter, causing condensation problems, which may cause short circuits or burn electronic components, affecting the normal use of the filter.

[0004] In this regard, a common solution is to set a water-absorbing filter element, such as activated carbon, water-absorbing cotton, etc., at the air inlet to remove moisture from the air. This method is low-cost and easy to implement. However, as the amount of water absorbed by the water-absorbing filter element increases, its dehumidification effect will gradually decrease, or even completely fail. Therefore, during the return of the south wind season, the filter needs to be inspected frequently to replace the water-saturated filter element in time. However, although the return of the south wind phenomenon occurs mainly from February to May each year, its occurrence depends on the flow of warm air, and the weather forecast can only predict the wind direction and temperature, but cannot directly predict whether the return of the south wind will occur. Therefore, users in southern coastal cities are often unprepared for the return of the south wind, so it is difficult to arrange the inspection of the filter. Although inspections can be arranged every day from February to May to alleviate the problem, it will increase the labor intensity of workers, and if there is no return of the south wind on that day, it will waste manpower. In addition, if the inspection is arranged after the return of the south wind, it will be too late. The inside of the filter is likely to have been affected by condensation. Therefore, the condensation must be cleared before the filter can be used again, which will affect the normal use of the terminal equipment.

[0005] Another solution is to set up a dehumidifier powered by UPS and supplemented by a humidity detector. When the humidity detector detects that the humidity exceeds the standard, the control system can automatically control the dehumidifier to reduce the humidity in the filter. However, the air intake required for active filter air cooling can be as high as 44L / sec, that is, the air flow in the filter is strong and the flow rate is large. Therefore, the dehumidification efficiency of conventional dehumidifiers is difficult to meet the requirements, which may lead to condensation problems. Even if a higher-power dehumidifier is used to improve the dehumidification efficiency, it will increase the cost of the on-site treatment plan, thereby increasing the risk of the treatment project being stranded.

[0006] Therefore, a small-capacity active filter is proposed. Summary of the invention

[0007] The purpose of the present invention is to provide a small-capacity active filter to improve the applicability of the small-capacity active filter in a high-humidity environment. The above purpose is achieved by allowing the moisture in the air entering the filter from the air inlet to bypass the internal electronic components thereof, thereby preventing the moisture in the high-humidity air from condensing inside the filter.

[0008] To achieve the above object, the present invention provides the following technical solutions:

[0009] A small-capacity active filter comprises a filter body, wherein the filter body generates a compensation current with the same amplitude and opposite polarity as the harmonic current of the power grid and injects the compensation current into the power grid to compensate or offset the harmonic current, thereby actively eliminating the power harmonics; the filter body is provided with an air inlet and an air outlet for ventilation to achieve heat dissipation; two motor-driven reels are rotatably installed in the filter body, and absorbent cloths are fixedly installed on the two reels, and the two reels cooperate with each other to ensure that the absorbent cloth is stretched straight between the two reels; the absorbent cloth is arranged at the air inlet of the filter body, and a humidity sensor electrically connected to the motor is fixedly installed at the lower end of the outer side wall of the filter body; The filter body is provided with a drying unit for drying the absorbent cloth by utilizing the hot air from the air outlet, and a plurality of rollers for guiding the absorbent cloth to the drying unit are rotatably installed in the filter body; a partition for isolating the absorbent cloth from the electronic components in the filter body is fixedly installed in the filter body, and a ventilation hole is provided on the partition, and the absorbent cloth is connected with the electronic components in the filter body only at the ventilation hole; two folding and unfolding devices for pneumatically folding or unfolding the absorbent cloth located at the air inlet part are provided in the filter body, and a locking unit for pneumatically locking the folding and unfolding device is provided on the folding and unfolding device and in the filter body, and the locking unit and the folding and unfolding device share the same air supply source.

[0010] When the air humidity reaches 95%, the humidity sensor will send an electrical signal to the control system to control the retracting and unfolding device to open the absorbent cloth and cover the air inlet. In this way, the excess moisture in the humid air entering the filter body will be absorbed by the absorbent cloth. Then, under the action of the two rollers driven by the power supply, the absorbent cloth containing water will be sent from the air inlet to the air outlet. The absorbent cloth containing water will be dried by the relatively high temperature air discharged from the air outlet, and the kinetic energy of the discharged air will be used to blow the evaporated water vapor away from the filter, thereby ensuring that the humidity of the air inside the filter meets the requirements.

[0011] When the absorbent cloth stored at the air inlet is used up, the dried absorbent cloth rolled up at the air outlet is reversed and sent back to the air inlet via two reels for reuse, thus reducing the maintenance requirements of the equipment. When the outside air humidity is lower than 95%, the humidity sensor stops sending electrical signals, and the retracting and unfolding device retracts the absorbent cloth and folds it up to reduce the wind resistance at the air inlet, thus ensuring the air cooling efficiency to the greatest extent.

[0012] It should be noted that air with high water content has a higher density and therefore tends to settle in low places. In order to quickly respond and start the present invention, the probe of the humidity sensor should be located at the lower end of the outer side wall of the filter body. Specifically, the optimal installation position of the humidity sensor should be determined according to the actual installation position of the filter, ensuring that the probe is located at the lowest point on the surface of the filter body and is not close to the surface of any other object. This can ensure the fastest response time and the most accurate humidity control effect.

[0013] In addition, the absorbent cloth moving in the narrow space inside the filter body will inevitably be affected by the heat inside the filter, causing the water on the absorbent cloth to evaporate. This evaporated water may condense again and cause damage to the electronic components inside the filter. Therefore, the present invention provides a partition in the filter body to isolate the water-containing absorbent cloth from the electronic components in the filter to prevent the water from condensing again in the filter and causing damage to the electronic components. When designing the partition, it is necessary to consider the installation position and the choice of materials to ensure the best isolation effect while not interfering with the operation of other components. In this way, the designed filter can operate more healthily and stably, thereby ensuring that the electronic components are in a safe and reliable state to the greatest extent.

[0014] Preferably, the absorbent cloth is made of polyester material, and each polyester fiber is provided with a groove along its own axial direction for diffusing water by utilizing capillary action.

[0015] Among common fabric raw materials, polyester material has the smallest moisture regain, which is only 0.4%. After polyester cloth absorbs water, the water usually only stays on the surface of the fabric fiber and does not penetrate into the fiber, so polyester cloth has the characteristic of fast drying. However, polyester material has poor hydrophilicity, and its water absorption rate is usually less than 1%. In order to improve this situation, axial grooves are made on the surface of polyester fiber when it is manufactured, so that when the polyester cloth made of this is used to absorb water, the water can be quickly absorbed by capillary action and temporarily stored in the grooves, thereby increasing the water absorption rate to 316%. In addition, the grooves can also guide the water to diffuse to other areas on the absorbent cloth, thereby maximizing the use of the surface area and improving the evaporation efficiency. Therefore, the absorbent cloth can be quickly dried in the drying unit.

[0016] Preferably, the retracting and expanding device includes a cross rod fixedly mounted inside the filter body, and the two ends of the cross rod are respectively fixed at the top and bottom ends inside the filter body; a slider, a bamboo tube and a fixing seat are sequentially mounted on the cross rod from top to bottom, the fixing seat is fixedly mounted on the bottom end inside the filter body, the slider and the bamboo tube are both sleeved on the cross rod, and the two ends of the bamboo tube are respectively fixed at the top of the fixing seat and the bottom of the slider, the slider is gap-matched with the cross rod through a cross-shaped through hole opened thereon, the slider, the bamboo tube, the fixing seat and the cross rod together form a chamber, an air pump electrically connected to the humidity sensor is installed in the filter body, the air pump is used to introduce or extract gas into or out of the chamber, a rotating ring is rotatably mounted on the slider and the fixing seat respectively, a clamping wheel is rotatably mounted on the slider and the fixing seat respectively, the rotating ring and the clamping wheel located on the same slider or the same fixing seat are jointly used to clamp the edge of the absorbent cloth.

[0017] Based on this solution, when the air humidity is greater than 95%, the retracting and unfolding device unfolds the absorbent cloth, and the air pump introduces gas into the chamber surrounded by the slider, bamboo tube, fixed seat and cross rod, so that the slider slides from bottom to top along the cross rod. Then, the rotating ring and the clamping wheel clamp the absorbent cloth and unfold it from bottom to top, so that the absorbent cloth covers the air inlet. Therefore, the air entering the filter from the air inlet must pass through the absorbent cloth. During this crossing process, the absorbent cloth absorbs excess moisture in the air. When the air humidity is less than 95%, the retracting and unfolding device folds and retracts the absorbent cloth to reduce the wind resistance of the air inlet and maximize the efficiency of air cooling.

[0018] Several points worth mentioning are: First, the principle of moisture absorption by the absorbent cloth is actually the same as the reason why condensation is formed during the return of the south wind, that is, the moisture in the hot air will condense when it encounters a lower temperature. Specifically, when the humid hot air encounters the lower temperature absorbent cloth, the water vapor in it will cool and condense on the absorbent cloth, so that the absorbent cloth can remove excess moisture in the air by absorbing and storing water vapor. Therefore, the temperature of the absorbent cloth should be consistent with or lower than the temperature of the coldest components inside the filter to ensure that the air passing through the absorbent cloth will not condense on these components, thereby avoiding the formation of condensation inside the filter. For example, install the reel at the air inlet in the corner farthest from the heating element in the filter.

[0019] Secondly, in order to ensure the stable and reliable operation of the retracting and unfolding device, the present invention uses a cross rod to limit the rotation of the slider, so that the slider can only move in translation along the axis of the cross rod. This structure can prevent the bamboo tube from being deformed due to torsion during the extension and retraction process. At the same time, since the cross rod has a special cross-sectional shape, it can withstand a greater load in a specific direction than ordinary rods of the same volume, similar to the principle of I-beams. Since the force exerted on the absorbent cloth when air is blown into the air inlet is fixed, the use of a cross rod can achieve the maximum load-bearing capacity while using the least amount of material, which is beneficial to the miniaturization of the device of the present invention and cost savings.

[0020] Third, in order to ensure that the slider moves smoothly when it is acted upon by the air pump, there should be at least three air holes connected to the air pump on the same fixed seat. These air holes should be evenly distributed on the fixed seat and arranged around the axis of the cross rod. In addition, the gas discharged from these air holes should be directly sprayed onto the bottom of the slider along the normal direction of the bottom of the slider, so that the slider is lifted by at least three thrusts of the same magnitude, so that the slider moves smoothly and is not easily disturbed by tilting, which causes an increase in sliding resistance. In addition, this design can also make the speed of the gas pumped into the chamber decay quickly, thereby preventing the high-speed airflow from causing deformation of the bamboo tube.

[0021] Fourthly, the reason for selecting bamboo tubes is that bamboo tubes have a specific deformation form when expanding and contracting, which helps to reduce interference between components.

[0022] Fifth, a certain matching gap needs to be reserved between the slider and the cross rod, so that the slider can slide freely on the cross rod. At the same time, when the air pump is inflated or exhausted, the air overflowing or entering the chamber can form an air film in the gap, thereby reducing the friction between the slider and the cross rod, which is more conducive to the sliding of the slider. The matching gap should be in the range of 0.5 to 1.5 mm. If the gap is less than 0.5 mm, it will lead to an increase in the manufacturing cost of the component, and a gap that is too small is not conducive to the formation of an air film. If the gap is greater than 1.5 mm, the ability of the cross rod to limit the rotation of the slider will be weakened, which is not conducive to ensuring that the slider has a certain movement, nor is it conducive to the alignment and buckling of the lock block and the lock hole.

[0023] Preferably, the locking unit includes two locking blocks fixedly mounted on the top of the fixing seat and the top of the inner part of the filter body respectively, a locking hole is provided on the slider, a silicone ring is fixedly installed in the locking hole for engaging with the locking block to fix the slider, the silicone ring is gap-fitted with the cross rod, a micro switch cooperating with the slider is provided at the top of the inner part of the filter body, and the micro switch is electrically connected to the air pump.

[0024] Based on this design, when the air pump injects gas into the chamber to move the slider upward along the cross rod to the top, the slider triggers the micro switch to stop the air pump. The lock block on the slider is buckled with the silicone ring to prevent the slider from sliding down along the cross rod, thereby fixing the slider. This design can reduce the working time of the air pump during the working process of the present invention and reduce electricity costs.

[0025] Among them, due to the existence of mechanical vibration and matching clearance, the clamping process of the locking block and the silicone ring is not able to achieve a simple repetition of the same action every time, so it is difficult to ensure their alignment. When the silicone ring is aligned with the locking block, the force on the locking block is only the positive pressure along the axial direction of the cross rod, but if the alignment relationship between the silicone ring and the locking block is offset due to vibration, the silicone ring and the locking block are no longer aligned, resulting in an imbalance of force on the entire top surface of the locking block, which may generate bending stress. Therefore, the locking block may be bent and fail, thereby reducing the connection performance of the locking unit and ultimately affecting the reliability of the entire device. In order to solve this problem, the locking block can be formed into a continuous annular whole in a shape that fits the shape of the side wall of the cross rod, and is fixedly connected to the cross rod by an interference fit to form a continuous annular whole, thereby improving the overall bending strength of the locking block. During use, the interference fit method can also enable the locking block to obtain support from the cross rod, improve its bending resistance, thereby avoiding the bending damage that may occur when the locking block is matched with the lock hole, and ultimately ensuring the reliability of the entire device during use.

[0026] Preferably, two support rods are rotatably mounted on the slider and the fixed seat respectively, and the other ends of the two support rods are rotatably connected to each other. When the slider moves toward the fixed seat, the two support rods cause the absorbent cloth to be folded in half. The hinge point between the slider and the support rods thereon is A, the hinge point between the fixed seat and the support rods thereon is B, and the hinge point between the two support rods is C. When the distance between the slider and the fixed seat along the axis of the cross rod is the largest, the line between A and B is parallel to the axis of the cross rod, and C is not on the line between A and B.

[0027] When the absorbent cloth is in a folded state and the air inlet continues to flow in, the flowing air will form a negative pressure zone, which will generate suction on the absorbent cloth, causing it to sway, and thus may interfere with other components. In order to avoid this situation, the present invention is provided with two support rods. The two support rods are installed on the same folding and unfolding device and are composed of a group of support components. When the folding and unfolding device retracts the absorbent cloth, the two adjacent groups of support components will be pushed out in the direction of the absorbent cloth at the same time, so that the absorbent cloth is folded in half along the line connecting the two vertices, which ensures that the absorbent cloth is in a certain folded state and occupies as little height space as possible, avoids interference between the absorbent cloth and other structures, and prevents the absorbent cloth from being stuck by other components, thereby ensuring that the absorbent cloth can be correctly unfolded each time it is used. At the same time, it should be noted that when the distance between the slider and the fixed seat along the axis of the cross rod is the largest, point C should not be collinear with points A and B to avoid the connecting rod mechanism from falling into a dead point, so as to ensure the reliable movement of the mechanism.

[0028] In addition, in order to realize the folding of the absorbent cloth in half, a preferred design method can be adopted, that is, the two support rods are designed with the same specifications and parameters, so that the two support rods can use exactly the same parts. This design can optimize the processability of the present invention and make it easier to achieve standardization and mass production during the production process.

[0029] Preferably, supports are swingably mounted on the fixed seat and the sliding block, and the two clamping wheels are rotatably mounted on the two supports respectively. When the absorbent cloth moves in the fitting gap between the clamping wheel and the rotating ring, the supports swing along the movement of the absorbent cloth so that the clamping wheel can unfold the absorbent cloth along the axis direction of the cross rod.

[0030] After the absorbent cloth is fully unfolded by the retracting and unfolding device, the two reels will drive the absorbent cloth to move. At this time, when the absorbent cloth passes through the gap between the clamping wheel and the rotating ring, it will apply force to the clamping wheel along its movement direction. This force will drive the clamping wheel to swing, so that the speed direction of the clamping wheel on the cloth surface of the absorbent cloth and the movement speed direction of the absorbent cloth itself form an angle, so that the clamping wheel can provide a force to cause the absorbent cloth to unfold when rotating, so as to ensure that the absorbent cloth will not escape from the gap between the clamping wheel and the rotating ring in its width direction, thereby ensuring that the clamping wheel and the rotating ring can always clamp the absorbent cloth.

[0031] Preferably, the drying unit includes two slots opened on the wall surface of the filter body shell on the same side as the air outlet, and the absorbent cloth passes through the two slots in sequence and has a portion located outside the filter body. A guide pipe is installed on the outside of the filter body, and the guide pipe is used to guide the air discharged from the air outlet to sweep over the portion of the absorbent cloth located outside the filter body.

[0032] The absorbent cloth absorbs moisture from the air inlet of the filter through the driving action of two reels and the guidance of multiple rollers, and then unfolds along the outer side of the filter housing. Then, the hot air at the air outlet is guided by the guide pipe to sweep over the surface of the absorbent cloth, so that the moisture on the absorbent cloth evaporates and is blown away by the air flow, thereby completing the drying of the absorbent cloth.

[0033] Preferably, a plurality of guide rollers for changing the moving direction of the absorbent cloth are rotatably installed in the guide pipe, and the plurality of guide rollers are arranged at corresponding parts of the guide pipe and the absorbent cloth, and are staggered along the extending direction of the guide pipe.

[0034] Based on this design, the absorbent cloth will meander in the guide tube, which means that, under the premise that the distance between the two slots remains unchanged, the length of the absorbent cloth in the guide tube can be extended, thereby obtaining a larger drying area, which is beneficial to improving the drying effect of the absorbent cloth in the drying unit.

[0035] Preferably, the portion of the partition directly facing the air inlet is provided with a protrusion protruding toward the air inlet, the vent is opened on the protrusion, and the absorbent cloth fits exactly with the protrusion and completely covers the vent when unfolded.

[0036] Based on this solution, the vents can be completely covered with absorbent cloth to ensure that the excess moisture in the incoming air can be fully analyzed by the absorbent cloth. This is because the air entering from the air inlet must pass through the vents on the protruding part of the partition to enter the interior of the filter body, and by covering the vents with absorbent cloth, the incoming air can pass through the absorbent cloth to prevent humid air from bypassing the absorbent cloth and entering the filter. At the same time, the wind force of the incoming air can also push the absorbent cloth against the protruding part of the partition to ensure that the absorbent cloth can cover the vents well. In addition, the protrusion can also reduce the contact area between the absorbent cloth and the partition while completely covering the vents, thereby reducing the friction between the two and avoiding excessive wear of the absorbent cloth.

[0037] In summary, compared with the prior art, the present invention has the following advantages:

[0038] 1. Improve the applicability of small-capacity active filters in high-humidity environments. By allowing the moisture in the air entering the filter from the air inlet to bypass its internal electronic components, the moisture in the high-humidity air is prevented from condensing inside the filter, thereby preventing condensation from damaging the electronic components inside the filter. To this end, inside the active filter, the absorbent cloth is driven by electricity to cyclically circulate between the air inlet and outlet of the active filter to absorb the moisture in the air entering from the air inlet and transport it to the drying unit located at the air outlet, so that the moisture will eventually evaporate and leave the filter.

[0039] 2. By setting up a retractable device, the problem of increased ventilation resistance caused by the absorbent cloth blocking the air inlet under normal humidity conditions is solved, thereby ensuring the air cooling efficiency of the small-capacity active filter when used under normal humidity conditions. To this end, the absorbent cloth located at the air inlet is pneumatically driven to expand or fold, so that the absorbent cloth is expanded under high humidity conditions to filter out excess moisture in the air entering the active filter, and the absorbent cloth is folded under normal humidity conditions to reduce the wind resistance of the air inlet to maximize the air cooling efficiency of the active filter.

[0040] 3. By arranging two support rods on the folding and unfolding device, the problem that the absorbent cloth of the present invention is affected by the negative pressure area of ​​the filter air inlet in the folded state, resulting in the risk of interference with other components, is solved, and the stability of the present invention is ensured. At the same time, by using exactly the same parts for the two support rods, the present invention is easier to achieve standardized and mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0042] Figure 2 It is a schematic diagram of the internal structure of the present invention;

[0043] Figure 3 It is a schematic diagram of the overall structure of the stowage and unfolding device;

[0044] Figure 4 It is a schematic diagram of the internal structure of the stowage and expansion device;

[0045] Figure 5 for Figure 4 A magnified view of part D in the middle;

[0046] Figure 6 It is a front plan view of the retractable device when the absorbent cloth is unfolded;

[0047] Figure 7 It is a plan view of the retractable device when folding the absorbent cloth;

[0048] Figure 8Schematic diagram of the swing state of the clamping wheel when the absorbent cloth moves

[0049] Fig. 9 It is a structural schematic diagram of the locking block;

[0050] Fig.10 It is a structural schematic diagram of a drying unit;

[0051] Fig.11 for Figure 2 Top view of section E;

[0052] Fig.12 for Figure 2 Schematic diagram of the structure after removing the absorbent cloth.

[0053] In the figure: 1. filter body; 2. reel; 3. absorbent cloth; 4. retracting and unfolding device; 5. guide pipe; 6. movement direction of absorbent cloth; 101. air inlet; 102. air outlet; 103. partition; 104. humidity sensor; 201. roller; 401. slider; 402. bamboo tube; 403. rotating ring; 404. fixed seat; 405. clamping wheel; 406. support rod; 407. locking hole; 408. locking block; 409. cross rod; 410. silicone ring; 501. guide roller; 1031. vent; 1032. protrusion; 4041. air hole; 4051. support. DETAILED DESCRIPTION

[0054] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0055] Embodiment 1:

[0056] like Figures 1 to 12As shown, the first specific implementation of the present invention is shown. The specific parameters are as follows: the size parameters of the filter body 1 are 400mm*325mm*45mm, the size of the air inlet 101 and the air outlet 102 are both 230mm*25mm, so the total length of the absorbent cloth 3 is 2500mm, the cloth surface width is 35mm, and except for the part that is normally stretched straight in the filter body 1, the rest of the absorbent cloth 3 is rolled up on the reel 2; the absorbent cloth 3 is made of polyester chemical fiber material, and its water absorption rate is 316%, and the capillary test result is 159mm. At the same time, the polyester fiber has a special-shaped cross-sectional structure, and there are axial grooves on the surface of the fiber; The thickness of the absorbent cloth 3 in its natural state is 0.4 mm; two locking holes 407 are respectively provided on the top and bottom ends of the slider 401, both of which are blind holes and are internally installed with silicone rings 410, the thickness of the silicone ring 410 is 1.5 mm and the width is 2.5 mm; the swing angle of the support 4051 of the clamping wheel 405 is 20°; the roller 201 adopts a structure similar to that of the retracting and unfolding device 4, the difference being that the slider 401 is fixedly mounted on the top part of the cross rod 409 by means of an interference fit, and is not provided with a corresponding micro switch, and is not connected to the air pump (not shown in the figure).

[0057] The capacity level of APF is 15A, and an intelligent air cooling system with a rated flow rate of 30L / sec is used. The relative humidity of the working environment of APF is required to be within the range of 5% to 95%. In order to ensure the timely startup of the equipment, the response threshold of the humidity sensor 104 is set to 87%. When the relative humidity of the environment is greater than or equal to 87%, the humidity sensor 104 is triggered and sends an electrical signal to the computer control system, so that the air pump starts to pump air into the chamber surrounded by the slider 401, the fixed seat 404, the cross rod 409 and the bamboo tube 402. Then, through the clamping action of the clamping wheel 405 on the slider 401 and the rotating ring 403 on the absorbent cloth 3, the slider 401 unfolds the absorbent cloth 3 while sliding upward along the cross rod 409, and finally makes the absorbent cloth 3 cover the entire air inlet 101, and at the same time, makes the part of the absorbent cloth 3 covering the air inlet 101 be tensioned, so that the thickness of this part of the absorbent cloth 3 changes from 0.4mm to 0.3mm.

[0058] There is a 1mm fit gap between the annular inner side of the silicone ring 410 and the cross bar 409, and there is also a 1mm fit gap between the slider 401 and the cross bar 409, while the annular inner side of the lock block 408 is in close contact with the outer wall of the cross bar 409. During installation, the cross bar 409 is inserted into the lock block 408 in an interference fit manner. When the slider 401 slides along the cross bar 409, the gas in the chamber escapes outward through the fit gaps between the slider 401 and the cross bar 409, and between the silicone ring 410 and the cross bar 409, and during the escape process, a 1mm thick air film is formed between the slider 401 and the cross bar 409, and between the silicone ring 410 and the cross bar 409, thereby reducing friction and allowing the slider 401 to slide more smoothly on the cross bar 409. When the slider 401 gradually slides upward along the cross rod 409 until the lock block 408 installed at the top of the filter body 1 contacts the silicone ring 410 in the lock hole 407 at the top of the slider 401, the lock block 408 blocks the gap between the silicone ring 410 and the cross rod 409, so that the air can no longer escape, thereby increasing the pressure in the chamber. With the help of this pressure, the slider 401 continues to move upward, causing the lock block 408 and the silicone ring 410 to buckle, thereby fixing the slider 401. At this time, the top of the slider 401 just triggers the micro switch (not shown in the figure) to turn off the air pump.

[0059] After that, the two motors drive the two reels 2 to rotate respectively, so that the absorbent cloth 3 moves at a speed of 25 mm / s, and then the absorbent cloth 3 absorbs excess moisture in the air at the air inlet 101, and then sends the moisture to the drying unit at the air outlet 102 for evaporation and blowing away. In this process, due to the friction between the absorbent cloth 3 and the clamping wheel 405, the clamping wheel 405 swings 10 degrees, so that the clamping wheel 405 can generate a tensioning force on the absorbent cloth 3 along the width direction of the absorbent cloth 3, so that the absorbent cloth 3 remains in a compact and unfolded state.

[0060] When the absorbent cloth 3 moves to the drying unit, under the action of the guide pipe 5, the hot air at 28°C blown out from the air outlet 102 passes over the absorbent cloth 3 in a direction parallel to the cloth surface, maximizing the use of the heat and kinetic energy of the hot air, thereby allowing the moisture on the absorbent cloth 3 with an average temperature of 21°C to be effectively evaporated and blown away from the filter body 1. At the same time, the dried absorbent cloth 3 can be rolled up by the reel 2 near the air outlet 102 for next use.

[0061] When the relative humidity of the air drops below 87%, the humidity sensor 104 stops responding, so that the two reels 2 stop rotating, and then the air pump draws air from the chamber, so that the slider 401 moves downward, and the negative pressure in the chamber causes the locking block 408 at the top of the filter body 1 to release the buckling relationship between the silicone ring 410 at the top of the slider 401, and at the same time, the two support rods 406 push out in the direction of the absorbent cloth 3 to fold the absorbent cloth 3. Until the locking block 408 installed on the fixing seat 404 contacts the silicone ring 410 in the locking hole 407 at the bottom of the slider 401, the locking block 408 blocks the gap between the silicone ring 410 and the cross rod 409, so that the air can no longer escape to the outside, thereby increasing the negative pressure in the chamber, and with the help of this negative pressure, the slider 401 continues to move downward, so that the locking block 408 and the silicone ring 410 are buckled, so that the slider 401 is fixed. At this time, the two support rods 406 are against the outer shell of the filter body 1, so that the overhanging ends of the two support rods 406 obtain the support force from the outer shell, reducing shaking, thereby ensuring that the absorbent cloth 3 can be in a certain position and remain stable when folded.

[0062] It should be noted that the total length of the absorbent cloth 3 and its maximum stroke are recorded in the computer control system. Therefore, during the dehumidification process of the present invention, when the absorbent cloth 3 on the reel 2 near the air inlet 101 is used up, the control system will control the two reels 2 to reverse, so that the absorbent cloth 3 on the reel 2 at the air outlet 102 can be rewound onto the reel 2 at the air inlet 101 at a speed of 75 mm / s, so that the same absorbent cloth 3 can be repeatedly used, reducing the number of manual maintenance times.

[0063] Embodiment 2:

[0064] The difference between this embodiment and the first embodiment is that, in order to increase the friction force of the clamping wheel 405 on the absorbent cloth 3 and thereby ensure its unfolding effect on the absorbent cloth 3, a silicone sleeve is sleeved on the side of the clamping wheel 405, and a transverse tread protruding outward by 0.5 mm is integrally manufactured on the silicone sleeve, and the direction of the tread is the same as the direction of the rotation axis of the clamping wheel 405. The silicone sleeve is made of food-grade silicone by hand-molding, has a certain elasticity, and is bonded to the clamping wheel 405 by quick-drying glue.

[0065] It should be noted that: when the clamping wheel 405 swings to the left extreme position, the size of the matching clearance between the clamping wheel 405 and the rotating ring 403 is L1; when the clamping wheel 405 swings to the right extreme position, the size of the matching clearance between the clamping wheel 405 and the rotating ring 403 is L2; ​​in the process of the clamping wheel 405 swinging from the left extreme position to the right extreme position, since the clamping wheel 405 needs to climb over the rotating ring 403, there is a minimum clearance L3 between the clamping wheel 405 and the rotating ring 403. Among them, L1=L2>L3.

[0066] In order to ensure the clamping effect on the absorbent cloth 3, L1=L2=0.3mm is taken. At this time, L1 is actually the gap between the transverse tread of the silicone sleeve and the side of the rotating ring 403. Obviously, the silicone sleeve is under pressure and elastically deformed at this time, so that the absorbent cloth 3 is clamped. In addition, in the process of the clamping wheel 405 crossing the rotating ring 403, the maximum elastic deformation of the absorbent cloth 3 is considered, and the minimum gap L3=0.1mm is taken. At this time, the silicone sleeve undergoes elastic deformation to prevent the support 4051 or the rotating ring 403 from retreating, so that the support 4051 and the rotating ring 403 are reliably in a stable position, thereby improving the reliability of the equipment.

[0067] Although the beneficial effects of the present invention have been demonstrated in detail and embodiments have been provided in this specification, it is apparent to those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A small-capacity active filter, comprising a filter body (1), wherein the filter body (1) generates a compensation current with an amplitude equal to that of a harmonic current of a power grid and an opposite polarity and injects the compensation current into the power grid to compensate or offset the harmonic current, thereby actively eliminating power harmonics; the filter body is provided with an air inlet (101) and an air outlet (102) for ventilation to achieve heat dissipation; and the filter body is characterized in that: Two motor-driven reels (2) are rotatably mounted in the filter body (1); a water-absorbing cloth (3) is fixedly mounted on the two reels (2); the two reels (2) cooperate with each other to ensure that the water-absorbing cloth (3) is stretched straight between the two reels (2); the water-absorbing cloth (3) is arranged at the air inlet (101) of the filter body (1); a humidity sensor (104) electrically connected to the motor is fixedly mounted at the lower end of the outer side wall of the filter body (1); a drying unit for drying the water-absorbing cloth (3) by using hot air from the air outlet (102) is provided on the filter body (1); a plurality of rollers for guiding the water-absorbing cloth (3) to the drying unit are rotatably mounted in the filter body (1). (201); A partition (103) for isolating the absorbent cloth (3) from the electronic components in the filter body (1) is fixedly installed in the filter body (1); a vent (1031) is provided on the partition (103); the absorbent cloth (3) is connected to the electronic components in the filter body (1) only at the vent (1031); two folding and unfolding devices (4) for pneumatically folding or unfolding the absorbent cloth (3) located at the air inlet (101) are provided in the filter body (1); a locking unit for pneumatically locking the folding and unfolding device (4) is provided on the folding and unfolding device (4) and in the filter body (1); and the locking unit and the folding and unfolding device (4) share the same air supply source; The retractable and unfoldable device (4) comprises a cross rod (409) fixedly mounted inside the filter body (1), and the two ends of the cross rod (409) are respectively fixed at the top and bottom of the filter body (1); a slider (401), a bamboo tube (402) and a fixing seat (404) are sequentially mounted on the cross rod (409) from top to bottom, the fixing seat (404) is fixedly mounted at the bottom of the filter body (1), the slider (401) and the bamboo tube (402) are both sleeved on the cross rod (409), and the two ends of the bamboo tube (402) are respectively fixed at the top of the fixing seat (404) and the bottom of the slider (401), and the slider (401) is inserted through a cross-shaped through hole provided on the slider The slider (401), the bamboo tube (402), the fixed seat (404) and the cross bar (409) are clearance-matched to form a chamber together. An air pump electrically connected to the humidity sensor (104) is installed in the filter body (1). The air pump is used to introduce or extract gas into or out of the chamber. A rotating ring (403) is rotatably installed on the slider (401) and the fixed seat (404). A clamping wheel (405) is rotatably installed on the slider (401) and the fixed seat (404). The rotating ring (403) and the clamping wheel (405) located on the same slider (401) or the same fixed seat (404) are used to clamp the edge of the absorbent cloth (3).

2. A small capacity active filter according to claim 1, characterized in that: The locking unit comprises two locking blocks (408) respectively fixedly mounted on the top of the fixing seat (404) and the top of the filter body (1); a locking hole (407) is provided on the slider (401); a silicone ring (410) is fixedly mounted in the locking hole (407) and is used for engaging with the locking block (408) to fix the slider (401); the silicone ring (410) is loosely engaged with the cross rod (409); a micro switch is provided at the top of the filter body (1) and is engaged with the slider (401); the micro switch is electrically connected to the air pump.

3. A small capacity active filter according to claim 1, characterized in that: Two support rods (406) are rotatably mounted on the slider (401) and the fixed seat (404), respectively, and the other ends of the two support rods (406) are rotatably connected to each other. When the slider (401) moves toward the fixed seat (404), the two support rods (406) cause the absorbent cloth (3) to be folded in half. The hinge point between the slider (401) and the support rods (406) thereon is A, the hinge point between the fixed seat (404) and the support rods (406) thereon is B, and the hinge point between the two support rods (406) is C. When the distance between the slider (401) and the fixed seat (404) along the axis direction of the cross rod (409) is the largest, the line between A and B is parallel to the axis of the cross rod (409), and C is not on the line between A and B.

4. A small capacity active filter according to claim 1, characterized in that: A support (4051) is swingably mounted on both the fixed seat (404) and the sliding block (401), and the two clamping wheels (405) are rotatably mounted on the two supports (4051) respectively. When the water-absorbing cloth (3) moves in the matching gap between the clamping wheel (405) and the rotating ring (403), the support (4051) swings along the movement of the water-absorbing cloth (3) so that the clamping wheel (405) can unfold the water-absorbing cloth (3) along the axial direction of the cross rod (409).

5. A small capacity active filter according to claim 1, characterized in that: The drying unit comprises two slots formed on a wall surface of a housing of a filter body (1) on the same side as the air outlet (102); the absorbent cloth (3) passes through the two slots in sequence and has a portion located outside the filter body (1); a guide pipe (5) is installed outside the filter body (1); the guide pipe (5) is used to guide the air discharged from the air outlet (102) to sweep over the portion of the absorbent cloth (3) located outside the filter body (1).

6. A small capacity active filter according to claim 5, characterized in that: The absorbent cloth (3) is made of polyester material that absorbs and diffuses water by capillary action, and each polyester fiber is provided with a groove along its own axial direction, and the absorbent cloth (3) realizes the capillary action through the groove.

7. A small capacity active filter according to claim 5, characterized in that: A plurality of guide rollers (501) for changing the movement direction of the water-absorbing cloth (3) are rotatably mounted in the guide tube (5); the plurality of guide rollers (501) are arranged at corresponding parts of the guide tube (5) and the water-absorbing cloth (3), and are arranged in a staggered manner along the extension direction of the guide tube (5).

8. A small capacity active filter according to claim 3, characterized in that: The portion of the partition (103) directly facing the air inlet (101) is provided with a protrusion (1032) protruding toward the air inlet (101); the vent (1031) is opened on the protrusion (1032); and when the absorbent cloth (3) is unfolded, it just fits with the protrusion (1032) and completely covers the vent (1031).

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