Main drive system and grab dredger

Abstract

The present invention provides a main drive system and a grab dredger, relating to the technical field of dredgers. The main drive system for a grab dredger includes a support drum drive system for driving the grab bucket to raise and lower, and an opening and closing drum drive system for driving the grab bucket to open and close. The support drum drive system and the opening and closing drum drive system each include an engine, a magnetorheological clutch, a gearbox, and a drum. The engine is connected to the input end of the gearbox via the magnetorheological clutch, and the output end of the gearbox is connected to the drum, which is used to connect to the grab bucket. The present invention can greatly simplify the structure and control points of the drive system.

Description

Technical Field

[0001] The present invention relates to the technical field of dredgers, and in particular to a main drive system and a grab dredger. Background Art

[0002] Grab dredgers are the core operating equipment on dredgers. They utilize two main drive systems: a support drum and an opening and closing drum. These drums suspend the grab bucket via booms and ropes, controlling its lowering, hovering, opening, closing, and raising. During the lowering of an empty bucket, the hovering of a closed bucket to grab mud, and the lifting of a full bucket, the drive system must provide significant torque to the grab bucket. The grab bucket moves at very high speeds, requiring frequent speed adjustments. Existing drive systems primarily utilize hydraulic and electrical main drives. These require complex design of hydraulic and electrical components, resulting in complex structures, and the need to manipulate multiple control points to achieve output torque changes. Summary of the Invention

[0003] The problem solved by the present invention is how to greatly simplify the structure and control points of the drive system.

[0004] On the one hand, the present invention provides a main drive system for a grab dredger, comprising a supporting drum drive system for driving the lifting and lowering of the grab dredger and an opening and closing drum drive system for driving the opening and closing of the grab, the supporting drum drive system and the opening and closing drum drive system respectively comprising an engine, a magnetorheological clutch, a gearbox and a drum, the engine being connected to the input end of the gearbox through the magnetorheological clutch, the output end of the gearbox being connected to the drum, and the drum being used to be connected to the grab.

[0005] Optionally, the supporting reel driving system and the opening and closing reel driving system further include a transmission mechanism, and the output end of the gear box is connected to the reel through the transmission mechanism.

[0006] Optionally, the transmission mechanism includes a first gear assembly connected to the output end of the gear box and a second gear assembly connected to the reel, the first gear assembly includes a first gear, the second gear assembly includes a second gear, and the first gear and the second gear are engaged with each other.

[0007] Optionally, the diameter of the first gear is smaller than the diameter of the second gear.

[0008] Optionally, the supporting reel driving system and the opening and closing reel driving system further include couplings, respectively, and both ends of the couplings are detachably connected to the output end of the gear box and the first gear assembly, respectively.

[0009] Optionally, the first gear assembly further includes a connecting shaft, the connecting shaft is connected to the coupling, and the first gear is sleeved on the connecting shaft.

[0010] Optionally, the reel includes a rotating shaft, and the second gear is sleeved on the connecting shaft and connected to the rotating shaft.

[0011] Optionally, the engine is a diesel engine or a gasoline engine.

[0012] In a second aspect, the present invention provides a grab dredger comprising the main drive system as described above.

[0013] Optionally, the grab dredger further includes a controller, each of which is electrically connected to the magnetorheological clutch of the main drive system, and the controller is used to:

[0014] During the grab bucket lowering phase, a first control current is input to the magnetorheological clutch supporting the drum drive system within a first preset time period to cause the grab bucket to hover, and then the first control current is gradually reduced to a second control current to accelerate the grab bucket lowering. The second control current is maintained constant within a second preset time period to cause the grab bucket to lower at a uniform speed, and then the second control current is gradually increased to the first control current to decelerate the grab bucket to a hovering state.

[0015] During the lowering phase of the grab bucket, the current supplied to the magnetorheological clutch of the opening and closing drum drive system is always zero, so that the grab bucket is opened;

[0016] During the grab bucket dredging stage, inputting the first control current into the magnetorheological clutch of the support drum drive system to cause the grab bucket to suspend;

[0017] During the grab bucket dredging stage, the input current of the magnetorheological clutch of the opening and closing drum drive system is gradually increased from 0 to a third control current to accelerate the closing of the grab bucket. The third control current is maintained unchanged within a third preset time to allow the grab bucket to close at a uniform speed. Subsequently, the third control current is gradually reduced to the first control current to decelerate the closing of the grab bucket until it is fully closed and occluded.

[0018] During the rising stage of the grab, the input currents of the magnetorheological clutch of the supporting drum drive system and the magnetorheological clutch of the opening and closing drum drive system are gradually increased from the first control current to the third control current, so that the grab after closing is gradually accelerated to rise from a static state. The third control current is maintained unchanged within a fourth preset time, so that the grab after closing is raised at a uniform speed. Subsequently, the input currents of the magnetorheological clutch of the supporting drum drive system and the magnetorheological clutch of the opening and closing drum drive system are gradually reduced from the third control current to the first control current, so that the grab after closing is decelerated and runs to a hovering state.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The main drive system's support drum drive system and opening and closing drum drive system are two independent drive systems. The support drum drive system is used to drive the grab bucket of the grab dredger to raise and lower, while the opening and closing drum drive system is used to drive the grab bucket to open and close. The support drum drive system and the opening and closing drum drive system each include an engine, a magnetorheological clutch, a gearbox, and a drum. The engine is connected to the input end of the gearbox via the magnetorheological clutch, and the output end of the gearbox is connected to the drum, which is used to connect to the grab bucket. Compared to traditional hydraulic and electric main drives, this system does not require complex hydraulic or electrical components and has a simpler structure. The engine transmits power to the gearbox via the magnetorheological clutch, and then to the drum from the gearbox, thereby driving the grab bucket to raise and lower, or open and close. Furthermore, during operation, the main drive system of the present invention can change the input current of the magnetorheological clutch, thereby changing the strength of the magnetic field within the magnetorheological clutch to modify the physical and chemical properties of the magnetorheological fluid, ultimately changing the output torque. This system only requires controlling the input current of the magnetorheological clutch, greatly simplifying the control points. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic structural diagram of an embodiment of the main drive system of the present invention;

[0022] Figure 2 This is a schematic diagram of the connection between the gear box and the reel in one embodiment of the present invention;

[0023] Figure 3 It is a structural schematic diagram of an embodiment of the grab dredger of the present invention;

[0024] Figure 4 Schematic diagram of the main driving system for rope winding and the rope winding of the grab bucket in the present invention.

[0025] Description of reference numerals:

[0026] 1. Support drum drive system; 2. Opening and closing drum drive system; 3. Engine; 4. Magnetorheological clutch; 5. Gearbox; 6. Coupling; 7. Drum; 71. Rotating shaft; 72. Drum body; 8. Transmission mechanism; 81. First gear assembly; 811. First gear; 812. Connecting shaft; 82. Second gear; 9. Grab bucket; 10. Guide pulley; 11. Boom pulley; 12. Opening and closing pulley; 13. Wire rope. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0028] It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, such that the embodiments of the present invention described herein can be practiced in an order other than that illustrated or described herein.

[0029] like Figure 1 As shown, an embodiment of the present invention provides a main drive system for a grab dredger, including a supporting drum drive system 1 for driving the grab 9 of the grab dredger to lift and lower, and an opening and closing drum drive system 2 for driving the grab 9 to open and close. The supporting drum drive system 1 and the opening and closing drum drive system 2 respectively include an engine 3, a magnetorheological clutch 4, a gearbox 5 and a drum 7. The engine 3 is connected to the input end of the gearbox 5 through the magnetorheological clutch 4, and the output end of the gearbox 5 is connected to the drum 7. The drum 7 is used to be connected to the grab 9.

[0030] In this embodiment, the support drum drive system 1 and the opening and closing drum drive system 2 of the main drive system are two independent drive systems. The support drum drive system 1 is used to drive the grab bucket 9 of the grab excavator to rise and fall, and the opening and closing drum drive system 2 is used to drive the grab bucket 9 to open and close.

[0031] In this embodiment, the supporting drum drive system 1 and the opening and closing drum drive system 2 have the same structure, and each includes an engine 3, a magnetorheological clutch 4, a gearbox 5, and a drum 7. The engine 3 is connected to the input end of the gearbox 5 through the magnetorheological clutch 4, and the output end of the gearbox 5 is connected to the drum 7, which is used to connect to the grab bucket 9. Figure 1 、 3 As shown, the drum 7 of the supporting drum driving system 1 is connected to the grab bucket 9 through a wire rope 13, and the drum 7 of the opening and closing drum driving system 2 is connected to the opening and closing pulley 12 group in the grab bucket 9 through a wire rope 13.

[0032] In this way, compared with traditional hydraulic main drive and electric main drive, it does not require the design of complex hydraulic or electrical components and has a simple structure. The engine 3 transmits power to the gearbox 5 through the magnetorheological clutch 4, and then the gearbox 5 transmits it to the reel 7, thereby driving the grab bucket 9 to rise and fall or open and close. At the same time, when the main drive system of the present invention is working, it can change the input current of the magnetorheological clutch 4, and then change the strength of the magnetic field inside the magnetorheological clutch 4 to change the physical and chemical properties of the magnetorheological fluid, and finally change the size of the output torque. It only needs to control the input current of the magnetorheological clutch 4, which greatly simplifies the control point.

[0033] Optionally, the supporting reel driving system 1 and the opening and closing reel driving system 2 further include a transmission mechanism 8 , respectively, and the output end of the gear box 5 is connected to the reel 7 via the transmission mechanism 8 .

[0034] Specifically, the transmission mechanism 8 includes a first gear assembly 81 connected to the output end of the gear box 5 and a second gear assembly connected to the reel 7. The first gear assembly 81 includes a first gear 811, and the second gear assembly includes a second gear 82. The first gear 811 and the second gear 82 are engaged with each other.

[0035] like Figure 2 As shown, in the supporting reel drive system 1, the output end of the gearbox 5 is connected to a first gear assembly 81, and the reel 7 is connected to a second gear assembly. The first gear assembly 81 includes a first gear 811, and the second gear assembly includes a second gear 82. After assembly, the first gear 811 and the second gear 82 are meshed with each other. In this way, the gearbox 5 can transmit power to the reel 7 through the first gear 811 and the second gear 82. The rotation center of the reel 7 does not need to be coaxial with the output end of the gearbox 5, which facilitates the reasonable placement of the reel 7 and the gearbox 5.

[0036] Since the structures of the supporting reel driving system 1 and the opening and closing reel driving system 2 are the same, they will not be described in detail here.

[0037] In other embodiments, the output end of the gear box 5 may be directly connected to the reel 7 . In this case, the rotation center of the reel 7 is coaxially arranged with the output end of the gear box 5 , and the gear box 5 directly drives the reel 7 to rotate.

[0038] Furthermore, the diameter of the first gear 811 is smaller than the diameter of the second gear 82. In this way, the first gear 811 drives the second gear 82 to form a deceleration motion, which is more labor-saving.

[0039] Optionally, the supporting reel driving system 1 and the opening and closing reel driving system 2 further include a coupling 6 , respectively. Both ends of the coupling 6 are detachably connected to the output end of the gear box 5 and the first gear assembly 81 , respectively.

[0040] like Figure 1 、 2 As shown, in the supporting reel driving system 1, the output end of the gear box 5 is detachably connected to the first gear assembly 81 through the coupling 6. The coupling 6 is a rigid coupling 6 or a flexible coupling 6. Preferably, the coupling 6 is a flexible coupling 6.

[0041] In this way, under the action of the coupling 6, the first gear assembly 81 can not only maintain synchronous movement with the output end of the gear box 5, but also reduce the risk of separation between the two.

[0042] Optionally, the first gear assembly 81 further includes a connecting shaft 812 , the connecting shaft 812 is connected to the coupling 6 , and the first gear 811 is sleeved on the connecting shaft 812 .

[0043] like Figure 2 As shown, the first gear assembly 81 includes a connecting shaft 812 and a first gear 811. The first gear 811 is sleeved on the connecting shaft 812 and fixedly connected to the connecting shaft 812. One end of the connecting shaft 812 is inserted into the slot of the coupling 6, thereby achieving a detachable connection with the coupling 6. In this way, a stable connection between the first gear assembly 81 and the coupling 6 is achieved.

[0044] In this embodiment, the connection method between the first gear 811 and the connecting shaft 812 includes but is not limited to bonding, welding or screw fixing.

[0045] Optionally, the reel 7 includes a rotating shaft 71 , and the second gear 82 is sleeved on the connecting shaft 812 and connected to the rotating shaft 71 .

[0046] In this embodiment, the reel 7 includes a reel body 72 and a rotating shaft 71. The rotating shafts 71 are provided at both ends of the reel body 72. The rotating shafts 71 at both ends of the reel body 72 are rotatably mounted on a bracket. The second gear 82 is sleeved on the connecting shaft 812 and fixedly connected to the rotating shaft 71. In this way, a stable connection between the second gear 82 and the reel 7 is achieved.

[0047] In this embodiment, the connection method between the second gear 82 and the rotating shaft 71 includes but is not limited to bonding, welding or screw fixing.

[0048] In other embodiments, the circular baffle on one side of the barrel body 72 may be thickened, and latch teeth may be provided on the circumferential side wall of the circular baffle to form the second gear 82 .

[0049] Optionally, the engine 3 is a diesel engine or a gasoline engine. There is no restriction here and it depends on actual needs. Preferably, the engine 3 is a diesel engine.

[0050] like Figure 3 As shown, a grab dredger according to another embodiment of the present invention includes the main drive system as described above.

[0051] In this embodiment, a guide pulley 10 is provided on the frame of the grab dredger, and an arm head pulley 11 is provided on the arm head of the boom. Figure 4 As shown, two steel wire ropes 13 are provided on the drum 7 supporting the drum drive system 1, and the two steel wire ropes 13 are respectively wound around the corresponding guide pulleys 10 and the arm head pulley 11 and then connected to the lifting lugs on the top wall of the grab 9. Two steel wire ropes 13 are also provided on the drum 7 of the opening and closing drum drive system 2, and the two steel wire ropes 13 are respectively wound around the corresponding guide pulleys 10 and the arm head pulley 11 and then connected to the opening and closing pulley 12 arranged opposite to the grab 9.

[0052] Optionally, the grab dredger further includes a controller, which is electrically connected to the magnetorheological clutch 4 of the main drive system, and is used to:

[0053] During the lowering phase of the grab 9, a first control current is input to the magnetorheological clutch 4 supporting the drum drive system 1 within a first preset time to cause the grab 9 to hover, and then the first control current is gradually reduced to a second control current to accelerate the lowering of the grab 9. The second control current is maintained constant within a second preset time to cause the grab 9 to descend at a uniform speed, and then the second control current is gradually increased to the first control current to decelerate the grab 9 to hover.

[0054] During the lowering phase of the grab bucket 9, the current supplied to the magnetorheological clutch 4 of the opening and closing drum drive system 2 is always zero, so that the grab bucket 9 is opened;

[0055] During the dredging phase of the grab bucket 9, a first control current is input to the magnetorheological clutch 4 supporting the drum drive system 1 to make the grab bucket 9 hover;

[0056] During the dredging phase of the grab 9, the input current of the magnetorheological clutch 4 of the opening and closing drum drive system 2 is gradually increased from 0 to the third control current to accelerate the closing of the grab 9. The third control current is maintained unchanged within a third preset time to ensure that the grab 9 closes at a uniform speed. Subsequently, the third control current is gradually reduced to the first control current to decelerate the closing of the grab 9 until it is fully closed and locked.

[0057] During the rising stage of the grab 9, the input current of the magneto-rheological clutch 4 supporting the drum drive system 1 and the magneto-rheological clutch 4 supporting the opening and closing drum drive system 2 is gradually increased from the first control current to the third control current, so that the closed grab 9 gradually accelerates to rise from a static state. The third control current is maintained unchanged within the fourth preset time, so that the closed grab 9 rises at a uniform speed. Subsequently, the input current of the magneto-rheological clutch 4 supporting the drum drive system 1 and the magneto-rheological clutch 4 supporting the opening and closing drum drive system 2 is gradually reduced from the third control current to the first control current, so that the closed grab 9 decelerates and runs to a hovering state.

[0058] In this embodiment, the core operating process of the grab dredger is as follows: lowering the empty bucket to the dredging position → suspending the grab 9 → closing the grab 9 to grab the dredged material → raising the full bucket. During both the lowering and raising of the empty bucket, the opening and closing drum drive system 2 and the drum 7 of the supporting drum drive system 1 act together via the wire rope 13 on the grab 9 to raise or lower the grab 9. Suspending the grab 9 is achieved by the drum 7 of the supporting drum drive system 1 pulling the grab 9. Closing the grab 9 to grab the dredged material is achieved by the drum 7 of the opening and closing drum drive system 2 controlling the closing of the grab 9 via the opening and closing pulley 12.

[0059] Changing the input current alters the torque transmitted by the magneto-rheological clutch 4. Since the magneto-rheological clutch 4 is located in the transmission path between the support drum drive system 1 and the opening and closing drum drive system 2, this also changes the output torque of both. When the sum of the output torques exceeds the weight of the grab bucket 9, the grab bucket 9 ascends or decelerates downward. When the sum of the output torques is less than the weight of the grab bucket 9, the grab bucket 9 descends or decelerates upward. When the sum of the output torques equals the weight of the grab bucket 9, the grab bucket 9 hovers. Thus, by varying the input current of the magneto-rheological clutch 4, it is possible to switch between lowering, hovering, and ascending modes of the grab bucket 9, as well as adjust the speed of the lowering and ascending operations.

[0060] The following analysis uses a 40m³ grab dredger as the analysis object, detailing the process flow of the grab bucket 9 during a cycle of lowering, dredging, and ascending. Each cycle lasts 80 seconds. For ease of description, the magnetorheological clutch 4 of the support drum drive system 1 will be referred to as the support clutch, the drum 7 of the support drum drive system 1 will be referred to as the support drum, the magnetorheological clutch 4 of the opening and closing drum drive system 2 will be referred to as the opening and closing clutch, and the drum 7 of the opening and closing drum drive system 2 will be referred to as the opening and closing drum.

[0061] The empty bucket of a 40m³ grab dredger weighs 40 tons, and the mud weight is 40 tons when it is full of mud. The expected maximum lowering speed of the empty bucket is 65m / min, and the maximum rising speed of the full bucket is 50m / min when it is full of mud.

[0062] Grab bucket 9 lowering: Initially, a control current of 12A is input to the support clutch. The output torque of the support drum equals the weight of the grab bucket 9, causing the grab bucket 9 to hover. The input current to the support clutch is then gradually reduced to 6A. At this stage, because the output torque of the support drum is less than the weight of the grab bucket 9, the grab bucket 9 accelerates downward, gradually increasing its speed from 0 to 65 m / min. The input current of 6A is maintained, and the grab bucket 9 descends at a speed of 65 m / min. The current is then gradually increased from 6A to 12A. The output torque of the support drum increases, eventually balancing with the weight of the grab bucket 9 again, and the grab bucket 9 decelerates and gradually stops. Throughout the entire process of lowering the grab bucket 9, the current input to the opening and closing clutch remains zero, and the opening and closing clutch does not output torque. This effectively disconnects the power transmission between the diesel engine and the opening and closing drum. The opening and closing drum is pulled against the grab bucket 9 and idles, maintaining its speed consistent with the support drum. The grab bucket 9 is controlled solely by the support drum, achieving a downward motion in which the grab bucket 9 accelerates, maintains a constant speed, and finally decelerates to a standstill.

[0063] Grab bucket 9 dredging: In this stage, the current input to the support clutch is kept constant at 12A, the output torque of the support drum is equal to the gravity of the grab bucket 9, the grab bucket 9 remains suspended, and the input current of the opening and closing clutch is gradually increased from 0 to 20A. The output torque of the opening and closing drum is greater than the resistance that the grab bucket 9 needs to overcome to close and dredge. The grab bucket 9 accelerates to close and dredge, and the speed gradually increases from 0 to 65m / min. The current of 20A is kept constant, and the grab bucket 9 continues to close at a uniform speed of 65m / min. Then the current gradually decreases from 20A to 12A, and the grab bucket 9 decelerates and closes until it is completely closed and tightened.

[0064] Grab bucket 9 rises: In this stage, the same electrical signal is input to the support clutch and the opening and closing clutch, causing the support drum and the opening and closing drum to move synchronously, lifting the grab bucket 9 filled with mud to the designated position. The input current of the support clutch and the opening and closing clutch is gradually increased from 12A to 20A at the same time. The sum of the output torques of the support drum and the opening and closing drum is greater than the total weight of the grab bucket 9 filled with mud. The grab bucket 9 gradually accelerates from a stationary state to a speed of 50m / min. Then, the input current of the two clutches is maintained at 20A, and the grab bucket 9 continues to rise at a constant speed of 50m / min. Subsequently, the input current of the support clutch and the opening and closing clutch is gradually reduced from 20A to 12A. The sum of the output torques of the support drum and the opening and closing drum is less than the total weight of the grab bucket 9, and the grab bucket 9 decelerates to a standstill.

[0065] The reader should understand that in the description of this specification, reference to the terms "one embodiment", "some embodiments", "examples", "specific examples" or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, different embodiments or examples described in this specification and features of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0066] Although the present disclosure is disclosed as above, the protection scope of the present disclosure is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A main drive system for a grab dredger, characterized in that: The invention comprises a support drum drive system (1) for driving the lifting and lowering of the grab bucket (9) of the grab dredger and an opening and closing drum drive system (2) for driving the opening and closing of the grab bucket (9), wherein the support drum drive system (1) and the opening and closing drum drive system (2) respectively comprise an engine (3), a magnetorheological clutch (4), a gear box (5) and a drum (7), wherein the engine (3) is connected to the input end of the gear box (5) through the magnetorheological clutch (4), and the output end of the gear box (5) is connected to the drum (7), and the drum (7) is used to be connected to the grab bucket (9); During the lowering phase of the grab (9), a first control current is input to the magnetorheological clutch (4) of the support drum drive system (1) within a first preset time, so that the grab (9) is suspended, and then the first control current is gradually reduced to a second control current, so that the grab (9) is accelerated to lower, and the second control current is maintained constant within a second preset time, so that the grab (9) is lowered at a uniform speed, and then the second control current is gradually increased to the first control current, so that the grab (9) is decelerated to hover; the current of the magnetorheological clutch (4) of the opening and closing drum drive system (2) is always 0, so that the grab (9) is opened; During the dredging phase of the grab bucket (9), the first control current is input into the magnetorheological clutch (4) of the support drum drive system (1) to cause the grab bucket (9) to suspend; gradually increasing the input current of the magnetorheological clutch (4) of the opening and closing drum drive system (2) from 0 to a third control current to accelerate the closing of the grab (9), maintaining the third control current constant within a third preset time to allow the grab (9) to close at a uniform speed, and then gradually reducing the third control current to the first control current to allow the grab (9) to decelerate and close until it is completely closed and tightly engaged; During the rising stage of the grab (9), the input currents of the magnetorheological clutch (4) of the supporting drum drive system (1) and the magnetorheological clutch (4) of the opening and closing drum drive system (2) are gradually increased from the first control current to the third control current, so that the closed grab (9) gradually accelerates from a static state to rise, and the third control current is maintained unchanged within a fourth preset time, so that the closed grab (9) rises at a uniform speed, and then the input currents of the magnetorheological clutch (4) of the supporting drum drive system (1) and the magnetorheological clutch (4) of the opening and closing drum drive system (2) are gradually reduced from the third control current to the first control current, so that the closed grab (9) decelerates and runs to a hovering state.

2. The main drive system according to claim 1, characterized in that: The supporting reel drive system (1) and the opening and closing reel drive system (2) further include a transmission mechanism (8), and the output end of the gear box (5) is connected to the reel (7) via the transmission mechanism (8).

3. The main drive system according to claim 2, characterized in that: The transmission mechanism (8) comprises a first gear assembly (81) connected to the output end of the gear box (5) and a second gear assembly connected to the reel (7), wherein the first gear assembly (81) comprises a first gear (811), and the second gear assembly comprises a second gear (82), and the first gear (811) and the second gear (82) are meshed with each other.

4. The main drive system according to claim 3, characterized in that: The diameter of the first gear (811) is smaller than the diameter of the second gear (82).

5. The main drive system according to claim 3, characterized in that: The supporting reel drive system (1) and the opening and closing reel drive system (2) further include a coupling (6), respectively, and both ends of the coupling (6) are detachably connected to the output end of the gear box (5) and the first gear assembly (81), respectively.

6. The main drive system according to claim 5, characterized in that: The first gear assembly (81) further includes a connecting shaft (812), the connecting shaft (812) being connected to the coupling (6), and the first gear (811) being sleeved on the connecting shaft (812).

7. The main drive system according to claim 6, characterized in that: The reel (7) comprises a rotating shaft (71), and the second gear (82) is sleeved on the connecting shaft (812) and connected to the rotating shaft (71).

8. The main drive system according to claim 1, characterized in that: The engine (3) is a diesel engine or a gasoline engine.

9. A grab dredger, characterized in that: Comprising the main drive system according to any one of claims 1 to 8.

10. The grab dredger according to claim 9, characterized in that: It also includes a controller, which is electrically connected to the magnetorheological clutch (4) of the main drive system, and is used to: During the lowering phase of the grab (9), a first control current is input to the magnetorheological clutch (4) supporting the drum drive system (1) within a first preset time, so that the grab (9) is suspended, and then the first control current is gradually reduced to a second control current, so that the grab (9) is accelerated to lower, and the second control current is maintained constant within a second preset time, so that the grab (9) is lowered at a uniform speed, and then the second control current is gradually increased to the first control current, so that the grab (9) is decelerated to hover; During the lowering phase of the grab bucket (9), the current supplied to the magnetorheological clutch (4) of the opening and closing drum drive system (2) is always zero, so that the grab bucket (9) is opened; During the dredging phase of the grab bucket (9), the first control current is input into the magnetorheological clutch (4) of the support drum drive system (1) to cause the grab bucket (9) to suspend; During the dredging stage of the grab (9), the input current of the magnetorheological clutch (4) of the opening and closing drum drive system (2) is gradually increased from 0 to a third control current, so that the grab (9) is accelerated to close, the third control current is maintained unchanged within a third preset time, so that the grab (9) is closed at a uniform speed, and then the third control current is gradually reduced to the first control current, so that the grab (9) is decelerated to close until it is completely closed and tightly engaged; During the rising stage of the grab (9), the input currents of the magnetorheological clutch (4) of the supporting drum drive system (1) and the magnetorheological clutch (4) of the opening and closing drum drive system (2) are gradually increased from the first control current to the third control current, so that the closed grab (9) gradually accelerates from a static state to rise, and the third control current is maintained unchanged within a fourth preset time, so that the closed grab (9) rises at a uniform speed, and then the input currents of the magnetorheological clutch (4) of the supporting drum drive system (1) and the magnetorheological clutch (4) of the opening and closing drum drive system (2) are gradually reduced from the third control current to the first control current, so that the closed grab (9) decelerates and runs to a hovering state.

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