Telescopic sand-proof crawling ladder for hoisting large wind turbine generator

Abstract

The utility model provides a telescopic sand-proof ladder stand for hoisting a large wind turbine generator, which relates to the technical field of hoisting of large fans and comprises a first ladder stand, a second ladder stand is slidably connected onto the first ladder stand, a third ladder stand is slidably connected onto the second ladder stand, a stabilizing structure is arranged on the first ladder stand, and the stabilizing structure is arranged on the third ladder stand. The stable structure is mainly composed of four sliding grooves, every two of the four sliding grooves are formed in the inner walls of the two sides of the first crawling ladder body and the inner walls of the two sides of the second crawling ladder body respectively, sliding blocks are slidably connected into the sliding grooves, the two sliding blocks are fixedly connected with the second crawling ladder body, and the two sliding blocks are fixedly connected with the third crawling ladder body. According to the utility model, the problem that the pull rope is easy to be unstable due to the influence of external factors when the height of the crawling ladder is adjusted because the pull rope swings along with wind in a hoisting site with strong wind power because most of large fans are arranged in areas with strong wind is solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to large -scale fan hoisting technical field especially relates to a telescopic sand prevention ladder for large -scale wind turbine generator system hoisting. BACKGROUND

[0002] Large -scale fan is because its huge size and weight, hoisting process is a highly complex and dangerous operation, in the hoisting process, need accurately install each component (such as tower drum, cabin, blade etc.) to predetermined position, this requires relevant auxiliary equipment, such as ladder, can adapt to different installation height and operation environment requirement, fan tower drum height is usually higher, from dozens of meters to hundreds of meters, in different hoisting stage, staff need to operate at different heights of tower drum, therefore, the height adjustment function of ladder is very important.

[0003] Telescopic ladder is widely used in large -scale fan hoisting operation to meet the demand of different height operation, and traditional telescopic ladder mostly adopts pull rope adjustment mechanism, and large -scale fan is mostly set in the area where the wind is big, and in the hoisting site where the wind is big, pull rope will swing with the wind, so that pull rope is easy to be unstable when adjusting the height of ladder due to the influence of external factors. UTILITY MODEL CONTENTS

[0004] The utility model aims at solving the shortcomings in the prior art and provides a telescopic sand prevention ladder for large -scale wind turbine generator system hoisting.

[0005] In order to realize the above-mentioned purpose, the utility model adopts the following technical scheme: a telescopic sand prevention ladder for large -scale wind turbine generator system hoisting, including first ladder, the first ladder is slidably connected with second ladder, the second ladder is slidably connected with third ladder, the first ladder is provided with stabilizing structure, the stabilizing structure mainly comprises four sliding grooves, four sliding grooves are set up on the two side inner walls of first ladder and second ladder respectively in pairs, the sliding groove is slidably connected with sliding block, two sliding blocks are fixedly connected with second ladder, two sliding blocks are fixedly connected with third ladder, the sliding groove is fixedly connected with first motor, the sliding groove is rotatably connected with lead screw through bearing, the lead screw is threadedly connected with sliding block, and the lead screw is driven to rotate through first motor.

[0006] The effects achieved by the above components are that the surfaces of the first, second and third ladders are sprayed with zinc-aluminum coating, which can form a dense protective film on the surface of the frame, preventing wind and sand erosion and resisting corrosion in the desert environment. The first ladder is placed at a suitable position, and then the two first motors on the first ladder are started simultaneously to drive the lead screws to rotate, thereby driving the second ladder to slide upwards. Similarly, for higher installation points, the two first motors on the second ladder are started simultaneously to drive the lead screws to rotate, thereby driving the third ladder to slide upwards, and then the third ladder is adjusted to a suitable position. The power module has multiple outputs and can ensure that the outputs are synchronized. The power module is internally designed with a special circuit that can ensure that each output port provides stable voltage simultaneously when the output is started, thereby synchronously starting the two motors connected to different output ports. The lead screw is a mechanical element that converts rotary motion into linear motion, and its structural characteristics ensure that it does not sway or elastically deform during force transmission, thereby avoiding the situation that the rope sways with the wind in windy areas, and thus the rope is easily affected by external factors when adjusting the height of the ladder.

[0007] Preferably, the first ladder is rotatably connected to two inclined supports through bearings, and the two inclined supports are rotatably connected to a support plate through bearings.

[0008] The effects achieved by the above components are that after the position of the first ladder is determined, the inclined support is rotated to support the support plate on the ground, and the inclined support cooperates with the support plate to support the first ladder, further improving the stability.

[0009] Preferably, the second and third ladders are each fixedly connected to two fixed blocks, and the fixed blocks are rotatably connected to two shafts through bearings. One of the shafts is fixedly connected to a limiting block.

[0010] The effects achieved by the above components are that when the second and third ladders move upwards, the pedal on the first or second ladder pushes the limiting block to rotate, and then the lower end of the limiting block abuts against the pedal below. The limiting block cannot rotate in the opposite direction due to the limitation of the fixed block, thereby limiting the second or third ladder to prevent it from sliding downwards in an unexpected situation, further improving the stability.

[0011] Preferably, two first springs are sleeved on one of the shafts, one end of the first spring is fixedly connected to the limiting block, and the other end of the first spring is fixedly connected to the fixed block.

[0012] The effect achieved by the above components is that when the pedal pushes the limiting block to rotate, the two first springs are in a twisted state, so that the limiting block is reset under the action of the elastic force of the first spring, and then is clamped on the next pedal when the extension is stopped.

[0013] Preferably, a limiting rod is fixedly connected to one of the rotating shafts, two second springs are sleeved on the rotating shaft, one end of the second spring is fixedly connected to the limiting rod, and the other end of the second spring is fixedly connected to the fixed block.

[0014] The effect achieved by the above components is that when the extension ladder is retracted, the second extension ladder or the third extension ladder is first moved upward, so that the limiting rod and the limiting block are between the two pedals, then the second extension ladder or the third extension ladder is moved downward, the pedal pushes the limiting rod to rotate upward, the end of the limiting rod pushes the limiting block to rotate inward, thereby releasing the limiting of the pedal, so that the downward movement is more smooth, and in the stop state, the pedal is between the limiting block and the limiting rod, the limiting rod can rotate in two directions, and when rotating, the second spring is in a twisted state, and then the limiting rod is reset under the action of the elastic force of the second spring.

[0015] Preferably, a sand prevention structure is arranged in the sliding groove, the sand prevention structure mainly comprises a storage groove, the storage groove is arranged below the sliding groove, a winding rod is rotatably connected in the storage groove through a bearing, a sand cloth is fixedly connected to the winding rod, one end of the sand cloth is fixedly connected to a fixed plate, the fixed plate is fixedly connected with the sliding block, a rectangular groove is arranged on the inner bottom wall of the sliding groove, and the storage groove and the sliding groove are connected in communication through the rectangular groove.

[0016] The effect achieved by the above components is that rotating the winding rod can drive the rectangular groove to be wound or unwound, the fixed plate is moved during the movement of the second extension ladder, so that the sand cloth is gradually opened through the rectangular groove, and the sand cloth can play a barrier role on the sliding groove to prevent sand from entering the sliding groove and damaging the screw rod.

[0017] Preferably, limiting grooves are respectively arranged on the inner walls of the two sides of the sliding groove, and the limiting grooves are slidably connected with the fixed plate.

[0018] The effect achieved by the above components is that the fixed plate is limited to slide in the two limiting grooves, so that the movement of the fixed plate is more stable.

[0019] Preferably, two second motors are respectively fixedly connected to the first extension ladder and the second extension ladder, and the winding rod is driven to rotate by the second motor.

[0020] The effects achieved by the above components are that the output end of the second motor is connected with the winding rod through the speed reducer and the shaft, the winding rod is driven to rotate by starting the second motor, and the sand prevention cloth is wound and unwound, the encoders are installed on the first motor and the second motor, the encoders can monitor the rotating speed, position and other information of the motors in real time, the output signals of the encoders are connected to the controller, appropriate control algorithms such as the PID control algorithm are adopted in the controller, in the starting stage, the controller calculates the control amount of the two motors according to the initial state information of the motors fed back by the encoders, and in the running process after the motors are started, the adjustment is continuously made according to the feedback of the encoders, so that the first motor drives the second ladder and the third ladder to slide, and the second motor can drive the winding rod to rotate appropriately to enable the sand prevention cloth to be wound and unwound.

[0021] Compared with the prior art, the advantages and positive effects of the utility model lie in that, in the utility model, the stable structure is arranged, the zinc-aluminum coating is sprayed on the surfaces of the first ladder, the second ladder and the third ladder, it can form a dense protective film on the surface of the frame, can prevent wind sand erosion and resist the corrosion in the desert environment, the first ladder is placed at a suitable position, then the two first motors on the first ladder are started at the same time, drive the screw rod to rotate, drive the second ladder to slide upwards, the two first motors on the second ladder are started at the same time for the installation point of higher height, drive the screw rod to rotate, drive the third ladder to slide upwards, and then adjust it to a suitable position, the power module with multiple outputs and capable of ensuring the synchronization of each output is used, the special circuit is designed in the power module, can ensure that each output port provides stable voltage at the time of output starting, thereby enabling the two motors connected to different output ports to start synchronously, the screw rod is a mechanical element for converting rotary motion into linear motion, its structural characteristics determine that it will not produce swing or elastic deformation like a pull rope in the process of force transmission, thereby avoiding the situation that the pull rope swings with the wind in the hoisting site with large wind force, and the pull rope is easily affected by external factors and unstable when adjusting the height of the ladder. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 A perspective structural schematic view of the telescopic sand prevention ladder for hoisting the large wind turbine generator is provided for the utility model;

[0023] Figure 2 Another perspective structural schematic view of the telescopic sand prevention ladder for hoisting the large wind turbine generator is provided for the utility model;

[0024] Figure 3 A partial schematic view of the stable structure of the telescopic sand prevention ladder for hoisting the large wind turbine generator is provided for the utility model;

[0025] Figure 4 This utility model proposes a retractable sand-proof ladder for hoisting large wind turbine units. Figure 2 Enlarged view of part A in the middle.

[0026] Legend: 1. First ladder; 2. Second ladder; 3. Third ladder; 4. Stabilizing structure; 41. Slide groove; 42. Slider; 43. First motor; 44. Lead screw; 45. Diagonal brace; 46. Support plate; 47. Rubber pad; 48. Fixing block; 49. Rotating shaft; 410. Limiting block; 411. Limiting rod; 412. First spring; 413. Second spring; 5. Sandproof structure; 51. Storage groove; 52. Winding rod; 53. Sandproof cloth; 54. Fixing plate; 55. Rectangular groove; 56. Limiting groove; 57. Second motor. Detailed Implementation

[0027] Example 1, as Figure 1 As shown, a retractable sand-proof ladder for hoisting large wind turbine units includes a first ladder 1, a second ladder 2 slidably connected to the first ladder 1, and a third ladder 3 slidably connected to the second ladder 2.

[0028] Reference Figures 2 to 4The first ladder 1 is provided with a stabilizing structure 4, the stabilizing structure 4 is mainly composed of four sliding grooves 41, the four sliding grooves 41 are arranged on the inner walls of the two sides of the first ladder 1 and the second ladder 2 respectively, sliding blocks 42 are slidably connected in the sliding grooves 41, two sliding blocks 42 are fixedly connected with the second ladder 2, two sliding blocks 42 are fixedly connected with the third ladder 3, a first motor 43 is fixedly connected in the sliding groove 41, a lead screw 44 is rotatably connected in the sliding groove 41 through a bearing, the lead screw 44 is threadedly connected with the sliding block 42, the lead screw 44 is driven to rotate by the first motor 43, a zinc-aluminum coating is sprayed on the surfaces of the first ladder 1, the second ladder 2 and the third ladder 3, which can form a dense protective film on the surface of the frame, which can prevent wind and sand erosion and resist the corrosion in the desert environment, the first ladder 1 is placed at a suitable position, then the two first motors 43 on the first ladder 1 are started at the same time, the lead screw 44 is driven to rotate, so that the second ladder 2 is driven to slide upwards, and the third ladder 3 is driven to slide upwards at the same time, and then the third ladder 3 is adjusted to a suitable position, a power module with multiple outputs and capable of ensuring that the outputs are synchronized is used, the power module is internally designed with a special circuit, which can ensure that each output port provides stable voltage at the same time when the output is started, so that two motors connected to different output ports are started synchronously, the lead screw 44 is a mechanical element for converting rotary motion into linear motion, and its structural characteristics determine that it will not sway or elastically deform during force transmission, thereby avoiding the situation that the rope sways with the wind in the hoisting site with strong wind, so that the rope is easily affected by external factors and unstable when adjusting the height of the ladder, two inclined supports 45 are rotatably connected to the first ladder 1 through bearings, two support plates 46 are rotatably connected to the two inclined supports 45 through bearings, rubber pads 47 are fixedly connected to the support plates 46, after the position of the first ladder 1 is determined, the inclined supports 45 are rotated, so that the support plates 46 support the ground and cooperate with the inclined supports 45 to support the first ladder 1, further improving the stability, two fixed blocks 48 are fixedly connected to the second ladder 2 and the third ladder 3, two rotating shafts 49 are rotatably connected in the fixed blocks 48 through bearings, a limiting block 410 is fixedly connected to one rotating shaft 49, when the second ladder 2 and the third ladder 3 move upwards, the limiting block 410 is rotated by the pedal on the first ladder 1 or the second ladder 2, and then the lower end of the limiting block 410 abuts against the pedal below, the limiting block 410 cannot be reversely rotated under the limitation of the fixed block 48, thereby limiting the second ladder 2 or the third ladder 3, preventing the second ladder 2 or the third ladder 3 from sliding downwards in an accidental situation, further improving the stability, two first springs 412 are sleeved on one rotating shaft 49, one end of the first spring 412 is fixedly connected to the limiting block 410,The other end of the first spring 412 is fixedly connected to the fixed block 48. When the pedal pushes the limiting block 410 to rotate, the two first springs 412 are in a twisted state, so that the limiting block 410 is reset under the action of the elastic force of the first spring 412, and then clamped on the next pedal when the telescopic operation is stopped. A limiting rod 411 is fixedly connected to a rotating shaft 49. Two second springs 413 are sleeved on the rotating shaft 49. One end of the second spring 413 is fixedly connected to the limiting rod 411, and the other end of the second spring 413 is fixedly connected to the fixed block 48. When the telescopic ladder is retracted, the second ladder 2 or the third ladder 3 is first moved upward, so that the limiting rod 411 and the limiting block 410 are between the two pedals. Then the second ladder 2 or the third ladder 3 is moved downward, the pedal pushes the limiting rod 411 to rotate upward, the end of the limiting rod 411 pushes the limiting block 410 to rotate inward, thereby releasing the limiting of the pedal, so that the downward movement is more smooth, and in the stop state, the pedal is between the limiting block 410 and the limiting rod 411. The limiting rod 411 can rotate in two directions, and the second spring 413 is in a twisted state when rotating. Then the limiting rod 411 is reset under the action of the elastic force of the second spring 413.

[0029] With reference to Figure 1 and Figure 3The sand prevention structure 5 is mainly composed of a receiving groove 51, the receiving groove 51 is arranged below the sliding groove 41, the receiving groove 51 is rotationally connected with a winding rod 52 through a bearing, the winding rod 52 is fixedly connected with a sand cloth 53, one end of the sand cloth 53 is fixedly connected with a fixed plate 54, the fixed plate 54 is fixedly connected with the sliding block 42, a rectangular groove 55 is arranged on the inner bottom wall of the sliding groove 41, the receiving groove 51 is communicated with the sliding groove 41 through the rectangular groove 55, the winding rod 52 can drive the rectangular groove 55 to be wound or unwound, the fixed plate 54 is driven to move in the movement of the second ladder 2, so that the sand cloth 53 is gradually opened through the rectangular groove 55, the sand cloth 53 can play a barrier role on the sliding groove 41, preventing sand from entering the sliding groove 41 and causing damage to the lead screw 44, limit grooves 56 are respectively arranged on the inner walls of the two sides of the sliding groove 41, the limit grooves 56 are slidably connected with the fixed plate 54, the fixed plate 54 is limitedly slid in the two limit grooves 56, so that the movement of the fixed plate 54 is more stable, two second motors 57 are respectively fixedly connected on the first ladder 1 and the second ladder 2, the winding rod 52 is driven to rotate through the second motor 57, the output end of the second motor 57 is connected with the winding rod 52 through a speed reducer and a shaft coupling, the winding rod 52 is driven to rotate by starting the second motor 57, and then the sand cloth 53 is wound or unwound, encoders are installed on the first motor 43 and the second motor 57, the encoders can monitor the speed, position and other information of the motors in real time, the output signals of the encoders are connected to a controller, appropriate control algorithms are adopted in the controller, such as a PID control algorithm, in the starting stage, the controller calculates the control amount of the two motors according to the initial state information of the motor fed back by the encoder, and in the running process after the motor is started, the adjustment is continuously made according to the feedback of the encoder, so as to ensure that the first motor 43 drives the second ladder 2 and the third ladder 3 to slide, and the second motor 57 drives the winding rod 52 to rotate appropriately, so that the sand cloth 53 is wound or unwound.

[0030] The working principle is that the surfaces of the first ladder 1, the second ladder 2 and the third ladder 3 are sprayed with a zinc-aluminum coating, which can form a dense protective film on the surface of the frame, can prevent wind and sand erosion, and can resist the corrosion in the desert environment. The first ladder 1 is placed at a suitable position, and then the two first motors 43 on the first ladder 1 are started at the same time to drive the lead screw 44 to rotate, so as to drive the second ladder 2 to slide upwards. Similarly, for the installation point of higher height, the two first motors 43 on the second ladder 2 are started at the same time to drive the lead screw 44 to rotate, so as to drive the third ladder 3 to slide upwards, and then the third ladder 3 is adjusted to a suitable position. A power module with multiple outputs and capable of ensuring that the outputs are synchronized is used. The power module is internally designed with a special circuit, which can ensure that stable voltage is provided at each output port at the same time when the output is started, so that the two motors connected to different output ports are started synchronously. The lead screw 44 is a mechanical element that converts rotary motion into linear motion. Its structural characteristics determine that it will not produce swing or elastic deformation in the process of force transmission, thereby avoiding the situation that the rope will swing with the wind in the hoisting site with strong wind, and the rope is easily affected by external factors and unstable when adjusting the height of the ladder. After the position of the first ladder 1 is determined, the diagonal brace 45 is rotated to make the supporting plate 46 support on the ground and cooperate with the diagonal brace 45 to support the first ladder 1, thereby further improving the stability. When the second ladder 2 and the third ladder 3 move upwards, the tread plate on the first ladder 1 or the second ladder 2 pushes the limiting block 410 to rotate, and then the lower end of the limiting block 410 abuts against the tread plate below. The limiting block 410 cannot be reversely rotated under the limiting of the fixed block 48, thereby limiting the second ladder 2 or the third ladder 3, preventing the second ladder 2 or the third ladder 3 from sliding downwards in the case of accident, and further improving the stability. When the tread plate pushes the limiting block 410 to rotate, the two first springs 412 are in a twisted state, so that the limiting block 410 is reset under the action of the elastic force of the first spring 412, and then is clamped on the next tread plate when the extension is stopped. When the ladder is retracted, the second ladder 2 or the third ladder 3 is first moved upwards, so that the limiting rod 411 is between the two tread plates. Then the second ladder 2 or the third ladder 3 is moved downwards, the tread plate pushes the limiting rod 411 to rotate upwards, the end of the limiting rod 411 pushes the limiting block 410 to rotate inwards, thereby releasing the limiting of the tread plate, so that the downward movement is more smooth. In the stop state, the tread plate is between the limiting block 410 and the limiting rod 411. The limiting rod 411 can rotate in two directions, and the second spring 413 is in a twisted state when the limiting rod 411 rotates. Then the limiting rod 411 is reset under the action of the spring elastic force of the second spring 413. The rotating rod 52 can drive the rectangular groove 55 to be wound or unwound. The fixed plate 54 is moved during the movement of the second ladder 2, so that the sandproof cloth 53 is gradually opened through the rectangular groove 55. The sandproof cloth 53 can play a barrier role on the sliding groove 41.The sand-proof cloth 53 is prevented from entering the sliding groove 41 to damage the lead screw 44, the fixed plate 54 is limited to slide in the two limiting grooves 56, the movement of the fixed plate 54 is more stable, the output end of the second motor 57 is connected with the winding rod 52 through a speed reducer and a shaft coupling, the winding rod 52 is driven to rotate by starting the second motor 57, and then the sand-proof cloth 53 is wound and unwound, the first motor 43 and the second motor 57 are both provided with encoders, the encoders can monitor the rotating speed, position and other information of the motors in real time, the output signals of the encoders are connected to a controller, and a suitable control algorithm, such as a PID control algorithm, is adopted in the controller, in the starting stage, the controller calculates the control amount of the two motors according to the initial state information of the motors fed back by the encoders, and in the running process after the motors are started, the adjustment is continuously made according to the feedback of the encoders, so that when the first motor 43 drives the second ladder 2 and the third ladder 3 to slide, the second motor 57 can drive the winding rod 52 to rotate appropriately to wind and unwind the sand-proof cloth 53.

[0031] The above is only a preferred embodiment of the present application, and is not intended to limit the present application in other forms. Any skilled person in the art can modify or change the above disclosed technical content to equivalent embodiments applied to other fields, but any simple modification, equivalent change and modification of the above embodiments made without departing from the technical solution of the present application, according to the technical essence of the present application, still belong to the protection scope of the present application. In the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "mounting", "connection" and "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication between two elements. For ordinary skilled persons in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

Claims

1. A telescopic sand protection ladder for hoisting a large wind turbine, comprising a first ladder (1), characterized in that: The first ladder (1) is slidably connected with a second ladder (2), the second ladder (2) is slidably connected with a third ladder (3), the first ladder (1) is provided with a stabilizing structure (4), the stabilizing structure (4) is mainly composed of four sliding grooves (41), the four sliding grooves (41) are respectively and pairwise arranged on the inner walls of the two sides of the first ladder (1) and the second ladder (2), the sliding grooves (41) are slidably connected with sliding blocks (42), two sliding blocks (42) are fixedly connected with the second ladder (2), and two sliding blocks (42) are fixedly connected with the third ladder (3), the sliding grooves (41) are fixedly connected with first motors (43), the sliding grooves (41) are rotatably connected with lead screws (44) through bearings, the lead screws (44) are threadedly connected with the sliding blocks (42), and the lead screws (44) are driven to rotate by the first motors (43).

2. A telescopic sand prevention ladder for hoisting a large wind turbine generator according to claim 1, characterized in that: The first ladder (1) is rotatably connected with two inclined supports (45) through bearings, and the two inclined supports (45) are rotatably connected with a supporting plate (46) through bearings.

3. A telescopic sand protection ladder for hoisting a large wind turbine generator according to claim 2, characterized in that: The second ladder (2) and the third ladder (3) are fixedly connected with two fixed blocks (48), the fixed blocks (48) are rotatably connected with two rotating shafts (49) through bearings, and one rotating shaft (49) is fixedly connected with a limiting block (410).

4. A telescopic sand protection ladder for hoisting a large wind turbine generator according to claim 3, characterized in that: One rotating shaft (49) is sleeved with two first springs (412), one end of the first spring (412) is fixedly connected to the limiting block (410), and the other end of the first spring (412) is fixedly connected to the fixed block (48).

5. A telescopic sand protection ladder for hoisting a large wind turbine generator according to claim 4, characterized in that: One rotating shaft (49) is fixedly connected with a limiting rod (411), one rotating shaft (49) is sleeved with two second springs (413), one end of the second spring (413) is fixedly connected to the limiting rod (411), and the other end of the second spring (413) is fixedly connected to the fixed block (48).

6. A telescopic sand protection ladder for hoisting a large wind turbine generator according to claim 5, characterized in that: The sliding groove (41) is provided with a sand prevention structure (5), the sand prevention structure (5) is mainly composed of a receiving groove (51), the receiving groove (51) is arranged below the sliding groove (41), the receiving groove (51) is rotatably connected with a winding rod (52) through a bearing, the winding rod (52) is fixedly connected with a sand prevention cloth (53), one end of the sand prevention cloth (53) is fixedly connected with a fixed plate (54), the fixed plate (54) is fixedly connected with the sliding block (42), a rectangular groove (55) is arranged on the inner bottom wall of the sliding groove (41), and the receiving groove (51) and the sliding groove (41) are communicated through the rectangular groove (55).

7. A telescopic sand protection ladder for hoisting a large wind turbine generator according to claim 6, characterized in that: Limiting grooves (56) are respectively arranged on the inner walls of the two sides of the sliding groove (41), and the limiting grooves (56) are slidably connected with the fixed plate (54).

8. A telescopic sand protection ladder for hoisting a large wind turbine generator according to claim 7, characterized in that: The first ladder (1) and the second ladder (2) are respectively fixedly connected with two second motors (57), and the winding rod (52) is driven to rotate by the second motor (57).

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