A lightweight solar tower heliostat capable of removing dust from the mirror surface and changing the area

Abstract

A lightweight solar tower heliostat capable of removing dust from the mirror surface and changing the mirror area, comprising a plurality of mirror units mounted on a main frame, a mechanism or device for enabling the main frame to track the sun, a traction device, a cleaning brush device, a cleaning brush B, a linear slide, and a locking device; the main frame adopts a lightweight grid structure, with two static mirror units fixed to two upper grids of the main frame, and two moving mirror units mounted to the lower two grids via a linear slide; a cleaning brush device for contacting and wiping the moving mirror unit for removing dust is mounted above the moving mirror unit, and a cleaning brush B for wiping and removing dust from the static mirror unit is provided on the back of the moving mirror unit; the moving mirror unit is pulled back and forth by a rope of the traction device to achieve both variable lighting area by blocking the static mirror unit and wiping and removing dust from the entire reflective mirror surface; the mirror unit adopts a plurality of thin-walled core tube structures fixedly connected in an array between the back of the reflector and a support plate with raised reinforcing ribs on the surface, having the advantages of light weight and high rigidity.

Description

Technical Field

[0001] The present invention belongs to the field of solar concentrating thermal power generation and new energy utilization, and in particular relates to a lightweight solar tower heliostat capable of mirror dust removal and area change. Background Art

[0002] Tower solar thermal power generation technology uses thousands of heliostats to focus low-density solar radiation onto a small receiver (or absorber). This high-density radiation heats the working fluid within the receiver, which in turn drives a heat engine / generator to generate electricity. This solar power technology has the potential to become a baseload power source. As a new favorite in the clean energy landscape, it plays a crucial role in future energy development and is a key path to upgrading the energy mix. It is attracting widespread attention and is being actively implemented.

[0003] However, tower heliostats, the core energy concentrators, operate in open areas, with large frontal areas and poor air permeability. Their optical performance is highly sensitive to wind loads, which can degrade energy flux distribution on the absorber surface, posing significant challenges to their safe and efficient operation. To minimize deformation in the heliostat's frame structure and ensure accurate focusing, a heavy, rigid, and expensive steel truss structure is typically used. This, however, increases costs associated with structural materials, manufacturing, transportation, installation, and operational power consumption. Therefore, minimizing material requirements and overall quality is beneficial for reducing heliostat production costs.

[0004] On the other hand, tower-type solar thermal power plants are built in Gobi plains or desert fringes with abundant sunlight. Dust and other tiny particles inevitably accumulate on the heliostats, affecting their reflectivity and reducing the overall optical efficiency of the plant. Cleaning the heliostats has always been a key issue in the solar thermal power generation industry. Currently, the cleaning method for heliostat fields in operation primarily relies on mechanical cleaning, featuring the use of mechanized cleaning vehicles. The cleaning process typically involves water spraying followed by contact scrubbing. However, the main drawbacks are the manual operation required, high technical requirements, and high water consumption, making it unsuitable for the water-scarce and cold climate of Northwest China. In particular, for large tower power plants with tens of thousands of heliostats, cleaning speed is slow and costly, making it difficult to clean all the mirrors in a short period of time. Furthermore, the uneven terrain of the site creates a high risk of damage during the cleaning process, and the mechanical equipment requires regular maintenance. Therefore, the ability to install cleaning devices on individual heliostats that can autonomously wipe the mirrors is crucial, reducing cleaning costs while maintaining the power generation of the plant.

[0005] Furthermore, during the operation of a tower-type solar thermal power station, the energy requirements projected onto the heat absorber vary at different operating stages. For example, less energy is required during the preheating stage of the heat absorber, and when cloud occlusion occurs in the mirror field, the energy projected onto the heat absorber needs to be reduced to prevent a drastic change in the energy on the heat absorber after the cloud passes. When the heat absorber is operating normally, when the direct solar radiation in the mirror field is high and the energy projected onto the heat absorber exceeds the design requirements of the heat absorber, energy scheduling is required to reduce the energy on the heat absorber. The above-mentioned requirements for energy adjustment in the mirror field are generally achieved by controlling the movement of the heliostats in the current tower-type solar mirror field. When energy needs to be projected, the target point is set to a certain point on the heat absorber; when energy needs to be withdrawn, the target point is set to a safe position outside the heat absorber. In this kind of mirror field energy scheduling, not only is it necessary to frequently control the operation of the heliostats, which consumes a large amount of high-quality electric energy and reduces the normal service life of the precision drive components for two-axis tracking. To address this problem, the existing Chinese patent technology 201910257355.1 provides a belt conveying structure composed of a flexible reflecting surface and a flexible photovoltaic panel, which can achieve the adjustment of light-reflected energy. However, in actual operation, the flexible reflecting surface is difficult to cope with wind-induced vibration deformation, and its light concentration accuracy cannot be guaranteed. Summary of the Invention

[0006] The present invention provides a lightweight solar tower-type heliostat capable of mirror dust removal and variable area. It adopts a simple and lightweight main frame with a cross-shaped structure having four rectangular grids. Two static mirror units are fixedly installed on the upper two grids, and the other two moving mirror units are installed on the lower two grids through linear slides. The moving mirror units are pulled back and forth by a traction device rope to block the static mirror units to achieve variable light collection area; a cleaning brush A that contacts and wipes for dust removal is installed above the moving mirror unit, and a cleaning brush B is installed on the back of the moving mirror unit to achieve wiping and dust removal of the static mirror unit; the mirror unit adopts a lightweight core tube support structure.

[0007] The technical solution adopted by the present invention is: a lightweight solar tower heliostat capable of mirror dust removal and area change, comprising a plurality of rectangular mirror units mounted on the front side of a main frame, an articulated seat fixed to the center position of the rear side of the main frame and extending rearward with a hinge ear, a column fixed vertically to the ground plane, an azimuth tracking device with a worm gear mechanism and a worm gear rotation axis coaxial with the column, a support body with a lower end coaxially fixedly connected to the rotating worm gear in the azimuth tracking device, a hinge ear with an axis perpendicular to the worm gear rotation axis at the top of the support body, the hinge ear being coaxially articulated with the hinge ear of the articulated seat, an electric push rod with two ends articulated to the lower side of the support body and the rear side of the main frame respectively; a planar mechanism formed by the main frame, the support body and the electric push rod realizes the main frame The height pitch movement of the frame; it also includes a traction device, a cleaning brush device, a cleaning brush B, several linear slides and a locking device for locking the slider in the linear slide; the main frame is a field structure with four rectangular grids fixed by three horizontal main beams and three vertical main beams, and the upper and lower horizontal main beams of the field structure are parallel to the hinge ear axis of the hinge seat and the ground plane; the mirror unit includes two static mirror units and two dynamic mirror units with the same structure, and the mirror unit includes a high-reflectivity reflector, a thin-walled core tube with several arrays fixed to the back of the reflector at one end, and a support plate with raised surface reinforcement ribs fixed to the other end of the core tube. The two static mirror units are fixed to the two upper grids of the main frame's field structure with a number of bolts through their support plates. The linear slide comprises four linear guide rails parallel to each other, which are fixed to the vertical main beams of the two grids below the main frame after being raised by pads, a number of sliders slidingly matched with the linear guide rails, and buffer pads installed at both ends of the guide rails to prevent the sliders from falling out. The linear guide rails extend upward from the lower horizontal main beam of the main frame close to the ground, and the direction of the guide rails is perpendicular to the hinge ear axis of the hinge seat. The part of the linear guide rails located in the two grids above the main frame is higher than the static mirror unit; the two moving mirror units are respectively fixed on the sliders of the two linear guide rails through their support plates, and the two moving mirror units are fixed to their respective support plates through connecting plates to achieve left and right parallel fixed connection. When the area is changed or dust is removed, the two moving mirror units move upward synchronously along the linear guide rails and can reach the same level as the one located below them. The static mirror units of the two sides completely overlap, and when the area is not variable or dust is not removed, the dynamic mirror unit is located on the two grids in the lower middle of the main frame and has a gap with the lower edge of the static mirror unit; the cleaning brush device is a gantry structure fixed to the main frame by a connecting plate and located above the reflector of the dynamic mirror unit and perpendicular to the movement direction of its slider, and a cleaning brush A is fixed downward along the crossbeam of the gantry structure, which can contact the reflector surface of the dynamic mirror unit and wipe and remove dust when sliding with the dynamic mirror unit, and the gantry structure is located at the lower edge of the static mirror unit; a cleaning brush B is fixed to the upper edge of the back of the support plate in each dynamic mirror unit along the direction perpendicular to its sliding direction, and the cleaning brush B can keep in contact with the reflector surface of the static mirror unit to wipe and remove dust during the sliding process of the dynamic mirror unit;The traction device comprises a support arm fixed to the uppermost transverse main beam of the main frame and protruding from the front of the main frame; a rotating shaft engaging a plurality of coaxial holes on the support arm and having an axis perpendicular to the linear guide rail; a motor driving the rotating shaft; and two parallel traction ropes with one end wound around the rotating shaft. The other end of each traction rope is fixed to the uppermost edge of a moving mirror unit and, through the movement of the rotating shaft, pulls the mirror unit to achieve linear sliding.

[0008] In the aforementioned lightweight solar tower heliostat capable of mirror dust removal and area variation, a plurality of cleaning brushes B are arranged in a parallel array on the back of the support plate of the moving mirror unit; the cleaning brushes A and B are made of weather-resistant rubber or silicone coating material, and the end surfaces that contact and wipe the reflector surface for dust removal are provided with a plurality of serrated dirt-receiving structures perpendicular to the sliding direction of the moving mirror unit.

[0009] In the aforementioned lightweight solar tower heliostat capable of mirror dust removal and area variation, the dynamic and static mirror units have the same structural form, but the optical geometric surface of each reflector must meet the heliostat focusing design requirements. The core barrel is a cylindrical or conical barrel made of weather-resistant plastic or Bakelite. The support plate is also made of weather-resistant plastic or Bakelite. The core barrel and support plate are integrally injection-molded, and the other end of the core barrel is bonded to the reflector surface. Small holes are provided in the side walls of some core barrels, and through holes connecting the core barrel interior are provided at the connection between the support plate and the core barrel with the small holes, allowing air to enter the core barrel interior and accelerate its flow out of the small holes in the side walls to cool the mirror units. A suitable amount of particles or liquid is filled inside several closed core barrels to suppress wind vibration energy consumption.

[0010] In the aforementioned lightweight solar tower heliostat capable of mirror dust removal and area variation, the locking device includes a latch with a conical head at one end that coaxially slides with a cylindrical hole in a connecting plate fixed to a main frame, a return spring located between the latch's conical head and the connecting plate and coaxially sleeved on the latch, and an electromagnet for attracting a fixed iron plate at the other end of the latch and fixing it to a connecting seat fixed to the main frame. The conical head of the latch engages with a conical hole provided on the side of a slider to be locked. When the electromagnet is energized to attract the latch, the slider is unlocked. Conversely, when the movable mirror unit on the slider moves to a non-variable area or non-dust removal operating position, the electromagnet is de-energized, and the conical head of the latch falls into the cooperating conical hole in the slider to lock it. At least one locking device is configured for each movable mirror unit.

[0011] In the above-mentioned lightweight solar tower heliostat capable of mirror dust removal and variable area, a mass block is provided at the bottom of each movable mirror unit to prevent the movable mirror unit from being unable to slide down to the bottom of the main frame by its own weight due to excessive dust removal and wiping resistance.

[0012] In the above-mentioned lightweight solar tower heliostat capable of mirror dust removal and variable area, core tubes are provided at the connection positions between the support plate of the moving mirror unit and the slider in the linear slide for support and force transmission; after the traction rope is tensioned, it is located above the static mirror unit and does not contact it; the upper end of the linear guide rail is fixedly connected to the support arm of the traction device to enhance its cantilever stiffness.

[0013] The aforementioned lightweight solar tower heliostat capable of dust removal and area change also includes a controller for controlling a motor to drive the mirror unit to slide, and for controlling an azimuth tracking device and an electric push rod to enable the heliostat to track the sun's position.

[0014] In the above-mentioned lightweight solar tower heliostat capable of removing dust from the mirror surface and varying the area, connecting rods are provided at two diagonally opposite corners of each grid in the field structure of the main frame to enhance its structural rigidity.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) The present invention adopts a main frame with a simple and lightweight structure and a field structure with four rectangular grids, and fixes two static mirror units on the upper two grids, while the other two moving mirror units are installed on the lower two grids through a linear slide. The moving mirror units are pulled back and forth by a traction device rope to block the static mirror units to achieve a variable lighting area.

[0017] (2) A cleaning brush A is installed above the moving mirror unit to wipe and remove dust, and a cleaning brush B is installed on the back of the moving mirror unit to wipe and remove dust from the static mirror unit. The traction device makes the moving mirror unit slide to wipe and remove dust from the surface of all mirrors.

[0018] (3) The mirror unit adopts a lightweight core tube support structure, which consists of a high-reflectivity reflector, a plurality of arrays of thin-walled core tubes fixed at one end to the back of the reflector, and a support plate with surface raised reinforcement ribs fixed to the other end of the core tube; the core tube is made of weather-resistant plastic or bakelite lightweight high-strength material, and some of the core tube side walls are provided with small through holes. A through hole connecting the core tube is provided at the connection position between the support plate and the core tube with the small hole, so that air enters the core tube and flows out from the small hole on its side wall to cool the mirror unit, thereby reducing the influence of its thermal deformation during service on the focusing accuracy; a suitable amount of particles or liquid is filled inside several closed core tubes to dissipate wind vibration energy and suppress its structural vibration. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a front view of the solar tower heliostat of the present invention with the movable mirror unit located at the lowest position.

[0020] Figure 2 for Figure 1 A 3D axonometric view of the heliostats on a solar tower.

[0021] Figure 3 This is an axial side view of the movable mirror unit of the solar tower heliostat of the present invention being pulled to a certain position.

[0022] Figure 4 for Figure 3 Axonometric view of a solar tower heliostat with the moving and static mirror units hidden.

[0023] Figure 5 It is a schematic structural diagram of the dynamic or static mirror unit in the solar tower heliostat of the present invention.

[0024] Figure 6 It is a cross-sectional view of the movable mirror unit in the solar tower heliostat of the present invention.

[0025] Figure 7 It is a structural schematic diagram of the locking device of the movable mirror unit in the present invention.

[0026] In the figure: 1-column; 2-controller; 3-azimuth tracking device; 4-support body; 5-electric push rod; 6-articulated seat; 7-traction device; 701-motor; 702-rotating shaft; 703-traction rope; 704-support arm; 8-main frame; 9-static mirror unit; 10-cleaning brush device; 11-cleaning brush B; 12-moving mirror unit; 121-core barrel; 122-reflector; 123-support plate; 13-linear slide; 131-slider; 132-linear guide rail; 133-buffer pad; 134-pad; 14-locking device; 141-latch; 142-reset spring; 143-electromagnet; 144-connecting plate; 145-connecting seat. DETAILED DESCRIPTION

[0027] The present invention will be further described below with reference to the accompanying drawings.

[0028] like Figures 1-4As shown, a lightweight solar tower heliostat capable of dust removal and changing mirror area comprises a plurality of rectangular mirror units (9 and 12) mounted on the front side of a main frame 8, a hinged seat 6 fixed to the center of the rear side of the main frame 8 and having hinge ears extending backward, a column 1 fixed vertically to the ground plane, an azimuth tracking device 3 with a worm gear mechanism and a rotating axis of the worm gear coaxial with the column, and a support body 4 with a lower end coaxially fixedly connected to the rotating worm gear in the azimuth tracking device 3. A hinge ear with an axis perpendicular to the worm gear rotation axis is provided at the top of the body 4. The hinge ear is coaxially hinged with the hinge ear of the hinge seat 6, and the two ends of the electric push rod 5 are respectively hinged to the lower side of the support body 4 and the rear side of the main frame 8; the planar mechanism formed by the main frame 8, the support body 4 and the electric push rod 5 realizes the height pitch movement of the main frame 8; it also includes a traction device 7, a cleaning brush device 10, a cleaning brush B11, a plurality of linear slides 13 and a locking device 14 for locking the slider 131 in the linear slide 13.

[0029] like Figures 1-4 As shown, the main frame 8 is a field structure with four rectangular grids formed by fixing three horizontal main beams and three vertical main beams. The upper and lower horizontal main beams of the field structure are parallel to the hinge ear axis of the hinge seat 6 and the ground plane. The mirror unit includes two static mirror units 9 and two dynamic mirror units 12 with the same structure. The mirror units (9 and 12) include a high-reflectivity reflector 122, a plurality of arrays of thin-walled core tubes 121 with one end fixed to the back of the reflector 122, and a support plate 123 with raised surface reinforcement ribs fixedly connected to the other end of the core tube 121 (see Figure 5 and Figure 6 ), the two static mirror units 9 are fixed to the two upper grids of the main frame 8 in the field structure by a number of bolts through their support plates 123; the linear slide 13 includes four linear guide rails 132 parallel to each other, which are fixed to the vertical main beams of the two grids below the main frame 8 after being raised by pads 134, a number of sliders 131 slidingly matched with the linear guide rails 132, and buffer pads 133 installed at both ends of the guide rails to prevent the sliders from falling out. The linear guide rail 132 extends upward from the lower horizontal main beam of the main frame 8 close to the ground, and the direction of the guide rail is perpendicular to the hinge ear axis of the hinge seat 6. The part of the linear guide rail 132 located in the two grids above the main frame 8 is higher than the static mirror unit 9, and this part can be cantilevered, but it is necessary to avoid contact with the reflector of the static mirror unit 9 and crushing the mirror (see Figure 4The two moving mirror units 12 are fixed on the sliders 131 of the two linear guide rails 132 respectively through their support plates 123, and the two moving mirror units 12 are fixed to their respective support plates through the connecting plates to achieve left and right parallel fixed connection. Here, each moving mirror unit 12 is fixedly connected to the sliders on the two linear guide rails; when in the variable area or dust removal working condition, the two moving mirror units 12 move upward synchronously along the linear guide rails 132 and can reach a position that completely overlaps with the static mirror unit 9 located below it, that is, at this time, the moving mirror unit position On the top of the static mirror unit; and in the non-variable area or non-dust removal working condition, the dynamic mirror unit 12 is located on the two grids below the main frame 8 and has a gap with the lower edge of the static mirror unit 9. This gap is to avoid light blocking; the cleaning brush device 10 is a gantry structure fixed to the main frame 8 by a connecting plate and located above the reflector of the dynamic mirror unit 12 and perpendicular to the movement direction of its slider. A cleaning brush is fixed downward along the crossbeam of the gantry structure, which can contact the reflector surface of the dynamic mirror unit 12 when sliding and wipe the dust. Cleaning brush A, the gantry structure is located at the lower edge of the static mirror unit 9; the upper edge of the back of the support plate 123 in each moving mirror unit 12 is fixed with a cleaning brush B11 along the vertical sliding direction thereof, and the cleaning brush B11 can be in contact with the reflective mirror surface of the static mirror unit 9 during the sliding process of the moving mirror unit 12 to wipe and remove dust, that is, when the moving mirror unit 12 slides upward, the cleaning brush B11 can wipe and remove dust from the static mirror unit 9; the traction device 7 includes a device fixed to the topmost horizontal main beam of the main frame 8 and moving toward the front of the main frame 8 A support arm 704 with a side projection, a rotating shaft 702 with a plurality of coaxial holes in the support arm 704 and an axis perpendicular to the linear guide, a motor 701 that drives the rotating shaft 702, and two parallel traction ropes 703 with one end wrapped around the rotating shaft 702. The other end of each traction rope 703 is fixed to the topmost edge of a moving mirror unit 12. Thus, the rotating shaft 702 rotates to pull the moving mirror unit 12 to achieve linear sliding. However, to lower the mirror unit, the rotating shaft rotates in the opposite direction, allowing the mirror unit to slide downward under its own gravity. The present invention also includes a controller 2 for controlling the motor 701 to pull and drive the moving mirror unit 12 to slide, and for controlling the azimuth tracking device 3 and the electric push rod 5 to enable the heliostat to track the sun's position.

[0030] Preferably, the cleaning brushes B11 are arranged in parallel array on the back of the support plate 123 of the moving mirror unit 12; the cleaning brushes A and B11 are made of weather-resistant rubber or silicone coating materials, and the end surfaces that contact the surface of the reflector for wiping and removing dust are provided with a plurality of serrated dirt-receiving structures perpendicular to the sliding direction of the moving mirror unit, such as Figure 6 shown.

[0031] Preferably, the moving mirror unit 12 and the static mirror unit 9 have the same structural form, but the optical geometric surface of each reflector must meet the heliostat focusing design requirements; the core tube 121 is a cylindrical tube or a conical tube made of weather-resistant plastic or bakelite; the support plate 123 is made of weather-resistant plastic or bakelite; the core tube 121 and the support plate 123 are integrally injection-molded, and the other end of the core tube 121 is bonded and fixed to the reflector 122; Figure 5 and Figure 6 As shown, small holes are provided on the side walls of some core tubes 121, and a through hole connected to the inside of the core tube is provided at the connection position between the support plate 123 and the core tube with the small holes, so that air enters the core tube and is accelerated to flow out from the small holes on its side walls to cool the mirror unit; a proper amount of particles or liquid is filled inside several closed core tubes 121 to dissipate energy under wind load and suppress its structural vibration, thereby ensuring the accuracy of wind-disturbed focusing.

[0032] Limited, such as Figure 1 and Figure 7 As shown, the locking device 14 includes a pin 141 with a conical head at one end and coaxially slidingly engaged with a cylindrical hole of a connecting plate 144 fixed to the main frame 8, a return spring 142 located between the conical head of the pin 141 and the connecting plate 144 and coaxially sleeved on the pin 141, and an electromagnet 143 for attracting the iron plate fixed at the other end of the pin 141 and fixing it to a connecting seat 145 fixed to the main frame 8; the conical head of the pin 141 is in contact with the cylindrical hole to be locked. The conical hole set on the side of the slider 131 cooperates. When the electromagnet 143 is energized to attract the pin 141, the slider 131 is unlocked. On the contrary, when the movable mirror unit 12 on the slider 131 moves to the non-variable area or non-dust removal working position, the electromagnet 143 is de-energized, and the conical head of the pin 141 falls into the conical hole of the matching slider to lock it. The locking device 14 is configured with at least one for each movable mirror unit 12, which is used to lock its position during normal focusing service.

[0033] Preferably, a mass block is provided at the bottom of the moving mirror unit 12 to prevent the moving mirror unit 12 from being unable to slide down to the bottom of the main frame 8 by its own weight due to excessive resistance to mirror dust removal and wiping, that is, returning to the normal focusing state. The moving mirror unit 12 is located 2 grid positions below the main frame 8.

[0034] Preferably, the support plate 123 of the moving mirror unit 12 and the position where the slider in the linear slide 13 is connected are both provided with a core tube 121 for supporting and transmitting force; after the traction rope 703 is tensioned, it is located above the static mirror unit 9 and does not contact it, so as to avoid damage to the reflector; the upper end of each linear guide rail 132 is fixedly connected to the support arm 704 of the traction device 7, so as to enhance the bearing stiffness of the part of the linear guide rail 132 suspended above the static mirror unit 9.

[0035] Preferably, connecting rods are provided at two diagonally opposite corners of each grid in the chevron structure of the main frame 8 to enhance its structural rigidity.

Claims

1. A lightweight solar tower heliostat capable of dust removal and area change of the mirror, comprising a plurality of rectangular mirror units mounted on the front side of a main frame, an articulated seat fixed to the center position of the rear side of the main frame and having a hinge ear extending backward, a column fixed vertically to the ground plane, an azimuth tracking device with a worm gear mechanism and a housing fixed to the top of the column, the worm gear rotation axis being coaxial with the column, a support body with a lower end coaxially fixedly connected to the rotating worm gear in the azimuth tracking device, the top of the support body being provided with a hinge ear with an axis perpendicular to the rotation axis of the worm gear, the hinge ear being coaxially articulated with the hinge ear of the articulated seat, an electric push rod with both ends articulated to the lower side surface of the support body and the rear side of the main frame respectively; a planar mechanism formed by the main frame, the support body and the electric push rod realizes the height pitch movement of the main frame; and it is characterized in that It also includes a traction device, a cleaning brush device, a cleaning brush B, several linear slides and a locking device for locking the slider in the linear slide; the main frame is a field structure with four rectangular grids fixed by three horizontal main beams and three vertical main beams, and the upper and lower horizontal main beams of the field structure are parallel to the hinge ear axis of the hinge seat and the ground plane; the mirror unit includes two static mirror units and two dynamic mirror units with the same structure, and the mirror unit includes a high-reflectivity reflector, a thin-walled core tube with several arrays fixed to the back of the reflector at one end, and a support plate with raised surface reinforcement ribs fixed to the other end of the core tube. The two static mirror units are supported by their support plates. The dry bolts are respectively fixed to the two grids above the main frame's field structure; the linear slide includes four linear guides parallel to each other, which are fixed to the vertical main beams of the two grids below the main frame after being raised by pads, a number of sliders sliding with the linear guides, and buffer pads installed at both ends of the guides to prevent the sliders from falling out. The linear guide extends upward from the lower horizontal main beam of the main frame close to the ground, and the direction of the guide is perpendicular to the hinge ear axis of the hinge seat. The part of the linear guide located in the two grids above the main frame is higher than the static mirror unit; the two moving mirror units are respectively fixed to the sliders of the two linear guides through their support plates, and the two moving mirror units are fixed through the connecting plate The respective support plates are fixedly connected in parallel on the left and right sides. When the area is changed or dust is removed, the two moving mirror units move upward synchronously along the linear guide rail and can completely overlap with the static mirror unit below them. When the area is not changed or dust is not removed, the moving mirror unit is located on the two grids in the lower middle of the main frame and there is a gap with the lower edge of the static mirror unit; the cleaning brush device is a gantry structure fixed to the main frame by a connecting plate and located above the reflector of the moving mirror unit and perpendicular to the movement direction of its slider. A cleaning brush A is fixed downward along the crossbeam of the gantry structure, which can contact the surface of the reflector when sliding with the moving mirror unit and wipe and remove dust. The gantry structure is located above the static mirror unit. The lower edge position of the element; a cleaning brush B is fixed to the upper edge of the back of the support plate in each moving mirror unit along a direction perpendicular to its sliding direction, and the cleaning brush B can keep in contact with the reflective mirror surface of the static mirror unit to wipe and remove dust during the sliding of the moving mirror unit; the traction device includes a support arm fixed to the uppermost horizontal main beam of the main frame and protruding from the front side of the main frame, a rotating shaft that cooperates with a plurality of coaxial holes on the support arm and whose axis is perpendicular to the direction of the linear guide rail, a motor that drives the rotating shaft to rotate, and two parallel traction ropes with one end wound around the rotating shaft; the other end of each traction rope is fixed to the uppermost edge of a moving mirror unit and pulls the mirror unit through the movement of the rotating shaft to achieve linear sliding.

2. The lightweight solar tower heliostat capable of mirror surface dust removal and area change according to claim 1, characterized in that: Several cleaning brushes B are arranged in a parallel array on the back of the support plate of the moving mirror unit; the cleaning brushes A and B are made of weather-resistant rubber or silicone coating materials, and the end faces that contact the surface of the reflector to wipe and remove dust are provided with several serrated dirt-receiving structures perpendicular to the sliding direction of the moving mirror unit.

3. The lightweight solar tower heliostat capable of mirror surface dust removal and area change according to claim 1, characterized in that: The dynamic mirror unit and the static mirror unit have the same structural form, but the optical geometric surface of each reflector must meet the design requirements for heliostat focusing. The core barrel is a cylindrical or conical barrel made of weather-resistant plastic or Bakelite. The support plate is also made of weather-resistant plastic or Bakelite. The core barrel and the support plate are integrally injection-molded, and the other end of the core barrel is bonded and fixed to the reflector surface. Some core barrel sidewalls are provided with small holes, and through holes connecting to the interior of the core barrel are provided at the connection point between the support plate and the core barrel with the small holes. This allows air to enter the core barrel and accelerate its flow out of the small holes in the sidewalls to cool the mirror unit. A suitable amount of particles or liquid is filled inside several closed core barrels to suppress wind vibration energy consumption.

4. The lightweight solar tower heliostat capable of mirror surface dust removal and area change according to claim 1, characterized in that: The locking device includes a pin with a conical head at one end and coaxially slidingly engaged with a cylindrical hole of a connecting plate fixed to the main frame, a return spring located between the conical head of the pin and the connecting plate and coaxially sleeved on the pin, and an electromagnet for attracting a fixed iron plate at the other end of the pin and fixing it to a connecting seat fixed to the main frame; the conical head of the pin cooperates with a conical hole provided on the side of the slider to be locked, and when the electromagnet is energized to attract the pin, the slider is released from lock. Conversely, when the moving mirror unit on the slider moves to a non-variable area or non-dust removal working position, the conical head of the pin falls into the matching conical hole of the slider after the electromagnet is de-energized to lock it; at least one locking device is configured for each moving mirror unit.

5. The lightweight solar tower heliostat capable of mirror surface dust removal and area change according to claim 1, characterized in that: The bottom of the moving mirror unit is provided with a mass block, which is used to prevent the moving mirror unit from being unable to slide down to the bottom of the main frame by its own weight due to excessive dust removal and wiping resistance.

6. The lightweight solar tower heliostat capable of mirror surface dust removal and area change according to claim 1, characterized in that: The support plate of the moving mirror unit and the slider in the linear slide are connected with core tubes for supporting and transmitting force; after the traction rope is tensioned, it is located above the static mirror unit and does not contact it; the upper end of the linear guide rail is fixedly connected to the support arm of the traction device to enhance its cantilever stiffness.

7. The lightweight solar tower heliostat capable of mirror surface dust removal and area change according to claim 1, characterized in that: It also includes a controller for controlling a motor to drive the mirror unit to slide, and controlling an azimuth tracking device and an electric push rod to enable the heliostat to track the sun's position.

8. The lightweight solar tower heliostat capable of mirror surface dust removal and area change according to claim 1, characterized in that: Two diagonally opposite corners of each grid in the field structure of the main frame are provided with connecting rods to enhance the structural rigidity.

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