An energy-saving device and control method for an electric rock grabber.

Abstract

This invention discloses an energy-saving device and control method for an electric rock grabber, belonging to the field of rock grabber equipment for vertical shaft construction. It includes a hoisting mechanism, a power generation device, a control device, and an energy storage device. The hoisting mechanism includes a grab bucket controlled by a hoisting winch driving a steel wire rope. The power generation device includes at least two generators that rotate synchronously via the steel wire rope, including a high-power electromagnetic torque generator for generating power under heavy load and a low-power electromagnetic torque generator for generating power under light load. By using the high-power and low-power electromagnetic torque generators to achieve graded recovery of gravitational potential energy according to the light or heavy load of the material being grabbed, energy utilization efficiency is improved, resulting in energy saving. Simultaneously, the high-power electromagnetic torque generator provides protection for the hoisting mechanism when the grab bucket stalls, enabling coordinated control of efficient and rapid drive of heavy equipment and reliable and safe energy recovery.

Description

Technical Field

[0001] This invention relates to an energy-saving device and control method for an electric rock grabber, belonging to the field of rock grabber equipment for vertical shaft construction. Background Technology

[0002] Rock grabbers are important pieces of machinery in the construction of mine shafts. They are mainly used to grab loose rock fragments after blasting, place the grabbed rock fragments in a bucket, and then use the bucket to lift the rock fragments out of the shaft.

[0003] Rock grabbers consume a lot of energy and have low energy utilization. For rock grabber lifting equipment, recovering gravitational potential energy during the lowering of heavy objects is a good energy-saving method. However, the energy recovery efficiency varies under different working conditions, which limits the improvement of energy utilization. At the same time, rock grabbers experience drastic load changes, and the grab bucket swings in different directions during compound actions at high speeds and with frequent reversals, resulting in huge impacts when lifting heavy objects. Conventional energy recovery methods are unsafe and unreliable. There are currently no kinetic energy recovery devices and control methods specifically for electric rock grabbers. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides an energy-saving device and control method for an electric rock grabber. Based on the weight of the material being grabbed by the grabber, a power generation device is used to achieve graded recovery of gravitational potential energy, and to achieve coordinated control of efficient and rapid driving of heavy equipment and reliable and safe energy recovery.

[0005] To achieve the above technical objectives, the present invention provides an energy-saving device for an electric rock grabber, comprising a lifting mechanism, a power generation device, a control device, and an energy storage device connected to each other; the lifting mechanism includes a control grabber that drives a wire rope via a lifting winch, and the power generation device includes at least two generators that rotate synchronously via the wire rope, including a high-power electromagnetic torque generator for generating electricity under heavy load on the grabber and a low-power electromagnetic torque generator for generating electricity under light load on the grabber.

[0006] Furthermore, the lifting mechanism includes a platform, a boom, and a grab bucket. The top of the grab bucket is equipped with a movable pulley. The platform is connected to a rotating body, and a lifting winch is connected to the rotating body via a winch base. A frame is connected below the rotating body, and a buffer device is movably connected to the frame. The buffer device is equipped with a buffer device fixed pulley. The frame is movably connected to the boom, and one end of the boom is equipped with a boom fixed pulley a. The boom is coaxially connected to the frame via the boom fixed pulley a, and the other end of the boom is equipped with a boom fixed pulley b. The wire rope extends from the lifting winch and passes sequentially through the buffer device fixed pulley, the boom fixed pulley a, the boom fixed pulley b, and the movable pulley before being fixed to the boom via a tie rod.

[0007] Furthermore, the hoisting winch includes a drum mounted on a drum support, a wire rope wound around the drum, a rope-blocking sleeve on the hoisting winch, a permanent magnet synchronous motor coaxially mounted on the left and right sides of the drum as a power source, and a hoisting winch generator as a high-power electromagnetic torque generator. The hoisting winch generator is an internal rotor generator.

[0008] Furthermore, the buffer device includes a damping mechanism. The tail end of the damping mechanism is connected to the frame via a buffer device mounting base. The end of the damping mechanism is connected to a buffer device fixed pulley and a buffer device generator via a rope wheel seat and a pulley shaft. The buffer device fixed pulley is connected to the pulley shaft via a bearing. The buffer device generator is an external rotor generator. The stator of the buffer device generator is mounted on the pulley shaft. The external rotor is synchronously connected to an outer casing. The buffer device fixed pulley is connected to the outer casing of the external rotor via a left end cover provided on the left side, thereby synchronously connecting the buffer device fixed pulley with the rotor of the buffer device generator and driving the rotor to rotate synchronously with the buffer device fixed pulley.

[0009] Furthermore, the control device and energy storage device are mounted on the hoisting platform. The control device includes an interconnected hoisting winch MCU, a host computer, and an excitation regulator. The hoisting winch MCU is connected to the permanent magnet synchronous motor in the hoisting winch via a line. The host computer is connected to the excitation main circuit installed on the hoisting winch generator or the buffer device generator via the excitation regulator. The excitation main circuit includes an excitation circuit, an excitation branch, and a de-excitation branch. When the hoisting winch stalls, the host computer controls the excitation regulator on the hoisting winch generator or the buffer device generator to increase the excitation current of the excitation main circuit to achieve braking. The energy storage device includes a battery connected to an inverter. The electrical energy converted from gravitational potential energy is stored in the battery, and the stored electrical energy is transmitted to the power-consuming device through the inverter.

[0010] Furthermore, the excitation main circuit includes an excitation circuit, an excitation branch, and a demagnetizing branch; the excitation circuit includes an excitation transformer, a rectifier, and an excitation switch; the excitation branch includes an excitation power supply and an excitation switch; and the demagnetizing branch includes a demagnetizing device and a demagnetizing switch.

[0011] The excitation transformer is connected in parallel with the power output terminal of a high-power electromagnetic torque generator or a low-power electromagnetic torque generator. The excitation transformer is connected to a rectifier, which is connected to the excitation power supply via an excitation switch. The rectifier is also connected to the power input terminal of a hoisting winch generator or a buffer device generator. The power input terminal of the hoisting winch generator or the buffer device generator is also connected to a demagnetizing device via a demagnetizing switch. The excitation regulator is connected to and controls the excitation switch, the rectifier, and the demagnetizing switch via separate lines.

[0012] The excitation transformer draws energy from the voltage generated by the hoisting winch generator or the buffer device generator itself. The rectifier receives the AC power provided by the excitation transformer, converts it into DC power, and enters the hoisting winch generator or the buffer device generator to excite the generator. The excitation switch controls the on / off state of the excitation circuit. The excitation power supply of the starting excitation branch enables the generator to establish an initial voltage from a static state. The starting excitation switch controls whether the starting excitation power supply is connected to the rectifier. The demagnetizing device of the demagnetizing branch consumes the magnetic field energy stored in the hoisting winch generator or the buffer device generator after the excitation switch is opened. The demagnetizing switch controls whether the demagnetizing device is connected to the excitation circuit. After demagnetization, the hoisting winch generator or the buffer device generator rotates but does not generate electricity.

[0013] A control method for an energy-saving device of an electric rock grabber is disclosed. When the grab bucket lowers a heavy object, the steel wire rope drives the fixed pulley of the buffer device and the drum of the hoisting winch to rotate under the influence of gravity. At this time, the hoisting winch generator or the buffer device generator generates electricity, converting gravitational potential energy into electrical energy. The generator power of the hoisting winch generator is greater than that of the buffer device generator. Different masses of the heavy objects lowered by the grab bucket result in different amounts of energy to be recovered. When the grab bucket lowers a heavy object, if the real-time torque of the permanent magnet synchronous motor is less than the set value, the load condition is judged as a light load condition, and the buffer device generator is used to recover small kinetic energy. If the real-time torque of the permanent magnet synchronous motor is greater than the set value, the load condition is judged as a heavy load condition, and the hoisting winch generator is used to recover large kinetic energy, thereby realizing graded kinetic energy recovery by the hoisting winch generator and the buffer device generator.

[0014] Furthermore, the hoist MCU can determine whether the electric rock grabber is under heavy or light load and whether it is lifting or lowering based on the speed and torque feedback from the built-in rotary transformer of the permanent magnet synchronous motor.

[0015] When the electric rock grabber is in the working state of lifting heavy objects, the host computer controls the excitation regulator, and at this time, neither the hoisting winch generator nor the buffer device generator works; when the electric rock grabber is in the working state of lowering heavy objects, the excitation regulator is controlled by the host computer based on the current working condition.

[0016] The host computer controls the main excitation circuit through the excitation regulator according to the working conditions and working status. The excitation regulator controls the switching status of the excitation switch, demagnetization switch and excitation start switch through switching signals.

[0017] The excitation regulator adjusts the magnitude of the excitation current through the rectifier and determines whether there is a risk of stalling when the grab bucket is lowered. In turn, it adjusts the electromagnetic torque of the hoisting winch generator or the buffer device generator to increase the torque and play a protective role.

[0018] When the hoisting winch generator or the buffer device generator needs to work, the excitation regulator controls the excitation switch to open, and the excitation power supply is connected to the rectifier. When the voltage at the hoisting winch generator terminal is established to the preset level, the excitation switch is opened. Then, the excitation regulator controls the excitation switch to open, and the excitation transformer is connected in parallel to the power output terminal to draw energy from the voltage generated by the hoisting winch generator or the buffer device generator itself. The rectifier receives the AC power provided by the excitation transformer and converts it into DC power to enter the hoisting winch generator as the excitation current.

[0019] When the hoisting winch generator or the buffer device generator is not working, the excitation regulator controls the excitation switch to open, and at the same time the demagnetizing switch opens and the demagnetizing device is connected, which consumes the energy stored in the magnetic field after the excitation current is disconnected, so that the hoisting winch generator or the buffer device generator does not generate electricity.

[0020] Furthermore, the host computer controls the rectifier to adjust the excitation current through the excitation regulator. When the host computer detects that the real-time acceleration of the permanent magnet synchronous motor exceeds the set maximum acceleration, and thus determines that a stall has occurred, it increases the excitation current and increases the electromagnetic torque of the hoisting winch generator or the buffer device generator to make the real-time angular acceleration of the permanent magnet synchronous motor lower than the set maximum angular acceleration, thereby protecting the hoisting mechanism.

[0021] The criteria for determining stall are as follows:

[0022] ,

[0023] In the formula, For real-time acceleration, The maximum angular acceleration is set.

[0024] The formula for the electromagnetic torque required to be generated by the hoisting generator or buffer device generator is as follows:

[0025] ,

[0026] The formulas for the electromagnetic torque and excitation current generated by the hoisting generator or buffer device generator are as follows:

[0027] ,

[0028] ,

[0029] In the formula, The electromagnetic torque of a permanent magnet synchronous motor. To increase the electromagnetic torque of the winch generator or buffer device generator, Let be the moment of inertia of the drum. Stator terminal voltage, For the excitation current The no-load potential induced by the generated air gap magnetic flux It is a direct-axis synchronous reactance. For quadrature axis synchronous reactance, To synchronize mechanical angular velocity, The angle between the rotor magnetic field axis and the stator combined magnetic field axis. The linearity coefficient is the coefficient when the magnetic circuit is saturated. and The relationship is non-linear and is determined based on the no-load characteristic curve obtained through experiments. For load torque, , These represent direct-axis synchronous reactance and quadrature-axis synchronous reactance, respectively.

[0030] Beneficial effects: Compared with the prior art, this invention, without affecting the normal operation of the electric rock grabber's lifting mechanism, installs a generator in the lifting winch and buffer device. When lowering heavy objects, the generator drives the generator to generate electricity. When the grab bucket is empty or the material is light, the generator in the buffer device works. According to the weight of the material, the gravitational potential energy is recovered in stages, which improves the energy utilization rate and achieves the effect of energy saving. The high-power electromagnetic torque generator provides protection for the lifting mechanism when the grab bucket stalls, which can realize the coordinated control of efficient and fast driving of heavy equipment and reliable and safe energy recovery. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the electric rock grabber in an embodiment of the present invention.

[0032] Figure 2 This is a schematic diagram of the lifting and hoisting power generation device of the electric rock grabber in an embodiment of the present invention.

[0033] Figure 3 This is a schematic diagram of the buffer device structure in an embodiment of the present invention.

[0034] Figure 4 This is a flowchart of the energy-saving control method for an electric rock grabber in an embodiment of the present invention.

[0035] In the diagram: 1. Hoisting winch; 2. Winch base; 3. Rotating body; 4. Buffer device; 5. Boom fixed pulley a; 6. Wire rope; 7. Boom fixed pulley b; 8. Moving pulley; 9. Tie rod; 10. Frame; 11. Hanging platform; 101. Permanent magnet synchronous motor; 102. Drum support; 103. Drum; 104. Hoisting winch generator; 105. Rope retainer; 401. Buffer device fixed pulley; 402. Outer casing; 403. Buffer device generator; 404. Pulley shaft; 405. Rope wheel seat; 406. Buffer device fixing seat; 407. Left end cover of fixed pulley. Detailed Implementation

[0036] The embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0037] This invention discloses an energy-saving device for an electric rock grabber, comprising a lifting mechanism, a power generation device, a control device, and an energy storage device;

[0038] like Figure 1 As shown, the lifting mechanism includes a control grab bucket driven by a lifting winch 1 and a wire rope 6. Specifically, it includes a hoisting platform 11, a boom, and a grab bucket. A movable pulley 8 is provided at the top of the grab bucket. A rotating body 3 is connected to the hoisting platform 11. The lifting winch 1 is connected to the rotating body 3 via a winch base 2. A frame 10 is connected below the rotating body 3. A buffer device 4 is movably connected to the frame 10. A buffer device fixed pulley 401 is provided on the buffer device 4. A boom is movably connected to the frame 10. A boom fixed pulley a5 is provided at one end of the boom. The boom is coaxially connected to the frame 10 via the boom fixed pulley a5. A boom fixed pulley b7 is provided at the other end of the boom. The wire rope 6 extends from the lifting winch 1 and passes sequentially through the buffer device fixed pulley 401, the boom fixed pulley a5, the boom fixed pulley b7, and the movable pulley 8 before being fixed to the boom via a tie rod 9. The hoisting winch 1 includes a drum 103 mounted on a drum support 102, with a wire rope 6 wound around the drum 103. The hoisting winch 1 is equipped with auxiliary wire rope 6 neatly arranged on the drum 103, and a rope-blocking sleeve 105 for the auxiliary wire rope 6. A permanent magnet synchronous motor 101 is connected to the left side of the drum 103, and a hoisting winch generator 104 is connected to the right side. Figure 2 As shown.

[0039] like Figure 3 As shown, the buffer device 4 includes a damping mechanism. The tail end of the damping mechanism is connected to the frame 10 via a buffer device fixing seat 406. The end of the damping mechanism is connected to a buffer device fixed pulley 401 and a buffer device generator 403 via a rope wheel seat 405 and a pulley shaft 404. The buffer device fixed pulley 401 is connected to the pulley shaft 404 via a bearing. The buffer device generator 403 is an external rotor generator. The stator of the buffer device generator 403 is mounted on the pulley shaft 404. The external rotor is synchronously connected to an outer housing 402. The buffer device fixed pulley 401 is connected to the outer housing 402 of the external rotor via a fixed pulley left end cover 407 provided on the left side. This allows the buffer device fixed pulley 401 to be synchronously connected to the rotor of the buffer device generator 403, and drives the rotor to rotate synchronously with the buffer device fixed pulley 401.

[0040] The power generation device includes a hoisting winch generator 104 and a buffer device generator 403; the hoisting winch generator 104 is a high-power electromagnetic torque generator used when the grab bucket is heavily loaded, and the buffer device generator 403 is a low-power electromagnetic torque generator used when the grab bucket is lightly loaded.

[0041] The control device and energy storage device are installed on the hoisting platform 11. The control device includes a hoisting MCU, a host computer and an excitation regulator that are connected to each other. The hoisting MCU is connected to the permanent magnet synchronous motor 101 in the hoisting hoist 1 through a line.

[0042] The energy storage device includes a battery connected to an inverter. The electrical energy converted from gravitational potential energy is stored in the battery, and the stored electrical energy is transmitted to the electrical device through the inverter.

[0043] The host computer connects to the main excitation circuit installed on the hoisting winch generator 104 or the buffer device generator 403 via the excitation regulator. The main excitation circuit includes an excitation circuit, an excitation branch, and a de-excitation branch. When the hoisting winch 1 stalls, the host computer increases the excitation current of the main excitation circuit by controlling the excitation regulator on the hoisting winch generator 104 or the buffer device generator 403 to achieve braking.

[0044] The power generation logic control system is used to control both high-power and low-power electromagnetic torque generators. The system includes a host computer, a hoisting MCU, an excitation regulator, and the main excitation circuit.

[0045] like Figure 4 As shown, the excitation main circuit includes an excitation circuit, an excitation branch, and a demagnetizing branch; the excitation circuit includes an excitation transformer, a rectifier, and an excitation switch; the excitation branch includes an excitation power supply and an excitation switch; and the demagnetizing branch includes a demagnetizing device and a demagnetizing switch.

[0046] The excitation transformer is connected in parallel with the power output terminal of a high-power electromagnetic torque generator or a low-power electromagnetic torque generator. The excitation transformer is connected to a rectifier. The rectifier is connected to the excitation power supply through an excitation switch. The rectifier is also connected to the power input terminal of the hoisting winch generator 104 or the buffer device generator 403. The power input terminal of the hoisting winch generator 104 or the buffer device generator 403 is also connected to a demagnetizing device through a demagnetizing switch. The excitation regulator is connected to and controls the excitation switch, the rectifier, and the demagnetizing switch through lines.

[0047] The excitation transformer draws energy from the voltage generated by the hoisting winch generator 104 or the buffer device generator 403. The rectifier receives the AC power provided by the excitation transformer and converts it into DC power, which enters the hoisting winch generator 104 or the buffer device generator 403 to excite the generator. The excitation switch controls the on / off state of the excitation circuit. The excitation power supply of the starting excitation branch enables the generator to establish an initial voltage from a static state. The starting excitation switch controls whether the starting excitation power supply is connected to the rectifier. The demagnetizing device of the demagnetizing branch consumes the magnetic field energy stored in the hoisting winch generator 104 or the buffer device generator 403 after the excitation switch is turned off. The demagnetizing switch controls whether the demagnetizing device is connected to the excitation circuit. After demagnetization, the hoisting winch generator 104 or the buffer device generator 403 rotates but does not generate electricity.

[0048] The working process is as follows: The control method of the energy-saving device for the electric rock grabber is as follows: When the grab bucket lowers a heavy object, under the influence of gravity, the wire rope 6 drives the buffer device 4's fixed pulley 401 and the hoisting winch 1's drum 103 to rotate. At this time, the hoisting winch generator 104 or the buffer device generator 403 generates electricity, converting gravitational potential energy into electrical energy. The generator power of the hoisting winch generator 104 is greater than that of the buffer device generator 403. Different masses of the lowered object result in different amounts of energy to be recovered. When the grab bucket lowers a heavy object, if the real-time torque of the permanent magnet synchronous motor 101 is less than the set value, the load condition is judged as a light load condition, and the buffer device generator 403 is used to recover small kinetic energy. If the real-time torque of the permanent magnet synchronous motor 101 is greater than the set value, the load condition is judged as a heavy load condition, and the hoisting winch generator 104 is used to recover large kinetic energy, thus achieving graded kinetic energy recovery by the hoisting winch generator 104 and the buffer device generator 403.

[0049] Among them, the hoisting MCU determines whether the electric rock grabber is under heavy load or light load, and whether the working state is lifting or lowering, based on the speed and torque feedback from the built-in rotary transformer of the permanent magnet synchronous motor 101.

[0050] Specifically, when the electric rock grabber is in the working state of lifting heavy objects, the host computer controls the excitation regulator, and at this time, neither the hoisting winch generator 104 nor the buffer device generator 403 works. When the electric rock grabber is in the working state of lowering heavy objects, the excitation regulator is controlled by the host computer based on the current working condition. The host computer controls the excitation main circuit through the excitation regulator according to the working condition and working state. The excitation regulator controls the switching state of the excitation switch, demagnetization switch and excitation start switch through switch signals. The excitation regulator adjusts the magnitude of the excitation current through the rectifier device and judges whether there is a risk of stalling when the grab is lowered, and then adjusts the electromagnetic torque of the hoisting winch generator 104 or the buffer device generator 403 to increase the torque for protection.

[0051] When the hoisting winch generator 104 or the buffer device generator 403 needs to work, the excitation regulator controls the excitation switch to open, and the excitation power supply is connected to the rectifier. When the voltage at the hoisting winch generator 104 reaches the preset level, the excitation switch is opened. Then, the excitation regulator controls the excitation switch to open, and the excitation transformer is connected in parallel to the power output terminal to draw energy from the voltage generated by the hoisting winch generator 104 or the buffer device generator 403 itself. The rectifier receives the AC power provided by the excitation transformer and converts it into DC power to enter the hoisting winch generator 104 as the excitation current. When the hoisting winch generator 104 or the buffer device generator 403 is not working, the excitation regulator controls the excitation switch to open, and at the same time, the demagnetizing switch is opened, and the demagnetizing device is connected to consume the energy stored in the magnetic field after the excitation current is disconnected, so that the hoisting winch generator 104 or the buffer device generator 403 does not generate electricity.

[0052] The excitation current is adjusted by controlling the rectifier through the excitation regulator. When the host computer detects that the real-time acceleration of the permanent magnet synchronous motor 101 exceeds the set maximum acceleration, and thus determines that a stall situation has occurred, the excitation current is increased to increase the electromagnetic torque of the hoisting winch generator 104 or the buffer device generator 403 so that the real-time angular acceleration of the permanent magnet synchronous motor 101 is lower than the set maximum angular acceleration, thereby protecting the hoisting mechanism.

[0053] The criteria for determining stall are as follows:

[0054] ,

[0055] In the formula, For real-time acceleration, The maximum angular acceleration is set.

[0056] The formula for the electromagnetic torque required to be generated by the hoisting generator 104 or the buffer device generator 403 is as follows:

[0057] ,

[0058] The formulas for the electromagnetic torque and excitation current generated by the hoisting generator 104 or the buffer device generator 403 are as follows:

[0059] ,

[0060] ,

[0061] In the formula, The electromagnetic torque of the permanent magnet synchronous motor 101, To increase the electromagnetic torque of the winch generator 104 or the buffer device generator 403, The moment of inertia of roller 103, Stator terminal voltage, For the excitation current The no-load potential induced by the generated air gap magnetic flux It is a direct-axis synchronous reactance. For quadrature axis synchronous reactance, To synchronize mechanical angular velocity, The angle between the rotor magnetic field axis and the stator combined magnetic field axis. The linearity coefficient is the coefficient when the magnetic circuit is saturated. and The relationship is non-linear and is determined based on the no-load characteristic curve obtained through experiments. For load torque, , These represent direct-axis synchronous reactance and quadrature-axis synchronous reactance, respectively.

[0062] The above description is merely one embodiment of the present invention and is not intended to limit the present invention. Any minor modifications, equivalent substitutions, and improvements made to the above embodiment based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. An energy-saving device for an electric rock grabber, characterized in that, It includes an interconnected lifting mechanism, a power generation device, a control device, and an energy storage device; the lifting mechanism includes a control grab bucket that drives a wire rope (6) via a lifting winch (1); the power generation device includes at least two generators that rotate synchronously via the wire rope (6), including a high-power electromagnetic torque generator for heavy-load power generation of the grab bucket and a low-power electromagnetic torque generator for light-load power generation of the grab bucket. The lifting mechanism includes a lifting platform (11), a boom and a grab bucket. A movable pulley (8) is provided at the top of the grab bucket. A rotating body (3) is connected to the lifting platform (11). A lifting winch (1) is connected to the rotating body (3) through a winch base (2). A frame (10) is connected below the rotating body (3). A buffer device (4) is movably connected to the frame (10). A buffer device fixed pulley (401) is provided on the buffer device (4). The hoisting winch (1) includes a drum (103) mounted on a drum support (102), a wire rope (6) wound around the drum (103), a rope-blocking sleeve (105) on the hoisting winch (1), a permanent magnet synchronous motor (101) coaxially mounted on the left and right sides of the drum (103) as a power source, and a hoisting winch generator (104) as a high-power electromagnetic torque generator. The hoisting winch generator (104) is an internal rotor generator. The buffer device (4) includes a damping mechanism. The tail of the damping mechanism is connected to the frame (10) through the buffer device fixing seat (406). The end of the damping mechanism is connected to the buffer device fixed pulley (401) and the buffer device generator (403) through the rope wheel seat (405) and the pulley shaft (404). The buffer device fixed pulley (401) is connected to the pulley shaft (404) through the bearing. The buffer device generator (403) is an external rotor generator. The stator of the buffer device generator (403) is set on the pulley shaft (404). The external rotor is synchronously connected to the outer casing (402). The buffer device fixed pulley (401) is connected to the outer casing (402) of the external rotor through the fixed pulley left end cover (407) set on the left side. This makes the buffer device fixed pulley (401) synchronously connected to the rotor of the buffer device generator (403) and drives the rotor to rotate synchronously with the buffer device fixed pulley (401).

2. The energy-saving device for the electric rock grabber according to claim 1, characterized in that, The frame (10) is movably connected to the boom. One end of the boom is provided with a fixed pulley a (5). The boom is coaxially connected to the frame (10) through the fixed pulley a (5). The other end of the boom is provided with a fixed pulley b (7). The wire rope (6) extends from the hoisting winch (1) and passes through the buffer device fixed pulley (401), the boom fixed pulley a (5), the boom fixed pulley b (7) and the movable pulley (8) in sequence, and is then fixed to the boom through the tie rod (9).

3. The energy-saving device for the electric rock grabber according to claim 2, characterized in that, The control device and energy storage device are installed on the hoisting platform (11). The control device includes a hoisting MCU, a host computer and an excitation regulator that are connected to each other. The hoisting MCU is connected to the permanent magnet synchronous motor (101) in the hoisting hoist (1) through a line. The host computer is connected to the excitation main circuit installed on the hoisting hoisting generator (104) or the buffer device generator (403) through the excitation regulator. The excitation main circuit includes an excitation circuit, an excitation branch and a demagnetization branch. When the hoisting hoist (1) stalls, the host computer increases the excitation current of the excitation main circuit by controlling the excitation regulator on the hoisting hoisting generator (104) or the buffer device generator (403) to achieve braking. The energy storage device includes a battery. The battery is connected to an inverter. The electrical energy converted from gravitational potential energy is stored in the battery. The stored electrical energy is transmitted to the electrical device through the inverter.

4. The energy-saving device for the electric rock grabber according to claim 3, characterized in that, The main excitation circuit includes an excitation circuit, an excitation branch, and a demagnetizing branch; the excitation circuit includes an excitation transformer, a rectifier, and an excitation switch; the excitation branch includes an excitation power supply and an excitation switch; and the demagnetizing branch includes a demagnetizing device and a demagnetizing switch. The excitation transformer is connected in parallel with the power output terminal of the high-power electromagnetic torque generator or the low-power electromagnetic torque generator. The excitation transformer is connected to the rectifier. The rectifier is connected to the excitation power supply through the excitation switch. The rectifier is also connected to the power input terminal of the hoisting winch generator (104) or the buffer device generator (403). The power input terminal of the hoisting winch generator (104) or the buffer device generator (403) is also connected to the demagnetizing device through the demagnetizing switch. The excitation regulator is connected to and controls the excitation switch, the rectifier and the demagnetizing switch through lines respectively. The excitation transformer draws energy from the voltage generated by the hoisting winch generator (104) or the buffer device generator (403). The rectifier receives the AC power provided by the excitation transformer and converts it into DC power to enter the hoisting winch generator (104) or the buffer device generator (403) for generator excitation. The excitation switch controls the opening and closing of the excitation circuit. The excitation power supply of the excitation branch enables the generator to establish an initial voltage from a static state. The excitation switch controls whether the excitation power supply is connected to the rectifier. The demagnetizing device of the demagnetizing branch consumes the magnetic field energy stored in the hoisting winch generator (104) or the buffer device generator (403) after the excitation switch is opened. The demagnetizing switch controls whether the demagnetizing device is connected to the excitation circuit. After demagnetization, the hoisting winch generator (104) or the buffer device generator (403) rotates but does not generate electricity.

5. A control method for the energy-saving device of the electric rock grabber according to claim 4, characterized in that, When the grab bucket lowers the heavy object, the grab bucket is under the influence of gravity, and the wire rope (6) drives the buffer device (4) fixed pulley (401) and the lifting winch (1) drum (103) to rotate. At this time, the lifting winch generator (104) or the buffer device generator (403) generates electricity, converting the gravitational potential energy into electrical energy. The power of the hoisting winch generator (104) is greater than that of the buffer device generator (403); the different masses of the loads lowered by the grab bucket result in different amounts of energy to be recovered; when the grab bucket lowers the load, if the real-time torque of the permanent magnet synchronous motor (101) is less than the set value, the load condition is judged to be a light load condition, and the buffer device generator (403) is used to recover small kinetic energy; if the real-time torque of the permanent magnet synchronous motor (101) is greater than the set value, the load condition is judged to be a heavy load condition, and the hoisting winch generator (104) is used to recover large kinetic energy, thereby realizing graded kinetic energy recovery of the hoisting winch generator (104) and the buffer device generator (403).

6. The control method according to claim 5, characterized in that, The hoisting MCU determines whether the electric rock grabber is under heavy load or light load, and whether it is lifting or lowering, based on the speed and torque feedback from the built-in rotary transformer of the permanent magnet synchronous motor (101). When the electric rock grabber is in the working state of lifting heavy objects, the host computer controls the excitation regulator. At this time, the hoisting winch generator (104) and the buffer device generator (403) are not working. When the electric rock grabber is in the working state of lowering heavy objects, the excitation regulator is controlled by the host computer based on the current working condition. The host computer controls the main excitation circuit through the excitation regulator according to the working conditions and working status. The excitation regulator controls the switching status of the excitation switch, demagnetization switch and excitation start switch through switching signals. The excitation regulator adjusts the magnitude of the excitation current through the rectifier and determines whether there is a risk of stalling when the grab bucket is lowered. In turn, it adjusts the electromagnetic torque of the hoisting winch generator (104) or the buffer device generator (403) to increase the torque and play a protective role. When the hoisting winch generator (104) or the buffer device generator (403) needs to work, the excitation regulator controls the excitation switch to open, and the excitation power supply is connected to the rectifier. When the voltage at the hoisting winch generator (104) reaches the preset level, the excitation switch is opened. Then, the excitation regulator controls the excitation switch to open, and the excitation transformer is connected in parallel to the power output terminal. Energy is taken from the voltage generated by the hoisting winch generator (104) or the buffer device generator (403). The rectifier receives the AC power provided by the excitation transformer and converts it into DC power to enter the hoisting winch generator (104) as the excitation current. When the hoisting winch generator (104) or the buffer device generator (403) is not working, the excitation regulator controls the excitation switch to be disconnected, and at the same time the demagnetization switch is opened and the demagnetization device is connected, which consumes the energy stored in the magnetic field after the excitation current is disconnected, so that the hoisting winch generator (104) or the buffer device generator (403) does not generate electricity.

7. The control method according to claim 6, characterized in that, The host computer controls the rectifier to adjust the excitation current through the excitation regulator. When the host computer detects that the real-time acceleration of the permanent magnet synchronous motor (101) exceeds the set maximum acceleration, and thus judges that a stall situation has occurred, it increases the excitation current and increases the electromagnetic torque of the regulating hoisting generator (104) or the buffer device generator (403) so that the real-time angular acceleration of the permanent magnet synchronous motor (101) is lower than the set maximum angular acceleration, thereby protecting the hoisting mechanism. The criteria for determining stall are as follows: ， In the formula, For real-time acceleration, The maximum angular acceleration is set. The formula for the electromagnetic torque required to be generated by the hoisting generator (104) or the buffer device generator (403) is as follows: ， The formulas for the electromagnetic torque and excitation current generated by the hoisting generator (104) or the buffer device generator (403) are as follows: ， ， In the formula, The electromagnetic torque of the permanent magnet synchronous motor (101) is... To increase the electromagnetic torque of the winch generator (104) or the buffer device generator (403), The moment of inertia of the roller (103) Stator terminal voltage, For the excitation current The no-load potential induced by the generated air gap magnetic flux It is a direct-axis synchronous reactance. For quadrature axis synchronous reactance, To synchronize mechanical angular velocity, The angle between the rotor magnetic field axis and the stator combined magnetic field axis. The linearity coefficient is the coefficient when the magnetic circuit is saturated. and The relationship is non-linear and is determined based on the no-load characteristic curve obtained through experiments. For load torque, , These represent direct-axis synchronous reactance and quadrature-axis synchronous reactance, respectively.

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