Crane rotating speed monitoring system and crane

Abstract

The invention discloses a crane rotating speed monitoring system and a crane, the crane rotating speed monitoring system comprises a permanent magnet ratchet ring and a double-sensor assembly, the double-sensor assembly is installed on a winding drum and comprises a first magneto-dependent sensor and a second magneto-dependent sensor, and when the winding drum rotates, the first magneto-dependent sensor and the second magneto-dependent sensor are connected; the first magneto-dependent sensor and the second magneto-dependent sensor respectively output a first square wave signal and a second square wave signal with constant phase difference, so that the rotation direction of the winding drum is represented through the phase relationship between the first square wave signal and the second square wave signal; and the direction distinguishing module is used for generating a direction signal and a counting pulse signal based on pure digital logic circuit processing. Therefore, the crane rotating speed monitoring system realizes real-time judgment of forward and reverse rotation and quadruplicated frequency counting through orthogonal signal output of the permanent magnet ratchet ring and the double magneto-dependent sensors in combination with a pure hardware direction judgment module, and the position monitoring resolution is improved.

Description

Technical Field

[0001] This invention relates to the field of crane technology, and more particularly to a crane speed monitoring system and a crane. Background Technology

[0002] As a core piece of equipment in industrial material handling, the rotational status monitoring of cranes is directly related to operational safety and efficiency, and they are used in many fields. However, in the current technology, the rotational speed of a crane is mainly calculated by the movement of the equipment it carries. The crane rotational speed is calculated by collecting data on the lifting and lowering height and speed of the crane's lifting devices.

[0003] Existing technologies also include systems that directly detect rotational speed. For example, patent CN114735593A discloses a data acquisition system for the operation of a bridge crane trolley. This system uses a permanent magnet group that rotates with the trolley wheels and a fixed coil that cuts magnetic lines of force to generate an electrical signal. By analyzing the trend and direction of the electrical signal amplitude changes, the system can calculate the operating speed, distance, and direction of rotation. However, this method of detecting rotational speed using magnetic induction still has room for improvement. Summary of the Invention

[0004] The purpose of this invention is to overcome at least one technical problem of the prior art and to provide a crane speed monitoring system and a crane.

[0005] To solve the above technical problems, the present invention is achieved through the following technical solution:

[0006] In a first aspect, this application discloses a crane speed monitoring system, comprising: a permanent magnet ratchet ring, fixed to the inner wall of an electric hoist housing, including N ratchet teeth with permanent magnets evenly spaced along the circumferential direction, where N is an integer greater than or equal to 4; a dual-sensor assembly, mounted on a drum, the dual-sensor assembly including a first magnetic sensor and a second magnetic sensor, wherein when the drum rotates, the first magnetic sensor and the second magnetic sensor respectively output a first square wave signal and a second square wave signal with a constant phase difference, so as to characterize the rotation direction of the drum through the phase relationship between the first square wave signal and the second square wave signal; and a direction discrimination module, the signal input terminal of which is connected to the output terminals of the first magnetic sensor and the second magnetic sensor respectively, for receiving the first square wave signal and the second square wave signal, and generating a direction signal and a counting pulse signal based on pure digital logic circuit processing, wherein the level state of the direction signal uniquely corresponds to the real-time rotation direction of the drum, and each pulse of the counting pulse signal corresponds to a transition edge of the first square wave signal or the second square wave signal.

[0007] Furthermore, the first magnetic sensor and the second magnetic sensor are spaced apart by a predetermined mechanical angle along the circumferential direction of the drum. Arrangement, and meet the requirements , where N is the number of the permanent magnets.

[0008] Furthermore, the direction discrimination module includes: a first D flip-flop and a second D flip-flop, used to latch the edge information of the first square wave signal and the second square wave signal respectively; an XOR gate, whose two inputs are respectively connected to the first square wave signal and the second square wave signal, used to generate a fourth-harmonic pulse signal; and an AND gate, whose first input is connected to the output of the XOR gate, whose second input is connected to the direction signal, and whose output is the counting pulse signal.

[0009] Furthermore, it also includes: a pulse subdivision module, whose input terminal is connected to the output terminal of the direction discrimination module, for receiving the counting pulse signal, and multiplying the frequency of the counting pulse signal by M times before outputting it, where M is an integer greater than 1.

[0010] Furthermore, the pulse subdivision module includes: a phase-locked loop circuit, which includes a phase detector, a loop filter, and a voltage-controlled oscillator; a programmable frequency divider, whose input is connected to the output of the voltage-controlled oscillator, and whose output is connected to one input of the phase detector and the output of the pulse subdivision module; the counting pulse signal is input to the other input of the phase detector, which compares the phase difference between the counting pulse signal and the feedback signal output by the programmable frequency divider and outputs an error voltage. The error voltage is filtered by the loop filter and then controls the output frequency of the voltage-controlled oscillator. The division ratio of the programmable frequency divider is set to M, such that the output frequency of the voltage-controlled oscillator is M times the frequency of the counting pulse signal, thereby obtaining the subdivided pulse signal at the output of the programmable frequency divider.

[0011] Furthermore, the pulse subdivision module also includes a shaping circuit connected between the output terminal of the programmable frequency divider and the output terminal of the pulse subdivision module, used to shape the subdivided pulse signal into a TTL level square wave signal.

[0012] Furthermore, it also includes: an output interface module, which is connected to the output terminals of the direction discrimination module and the pulse subdivision module respectively, for outputting at least one of the direction signal, the counting pulse signal or the subdivision pulse signal.

[0013] Secondly, this application also discloses a crane, including an electric hoist housing and a drum disposed inside the electric hoist housing, and further comprising the aforementioned crane speed monitoring system and controller, wherein the controller is equipped with the aforementioned direction discrimination module, and the crane speed monitoring system is used to monitor the speed of the drum.

[0014] Its effectiveness lies in the fact that the crane speed monitoring system, through the orthogonal signal output of the permanent magnet ratchet ring and dual magnetic sensors, combined with the pure hardware direction discrimination module, realizes real-time forward and reverse rotation discrimination and quadruple frequency counting without software intervention, significantly improving the position monitoring resolution; furthermore, through the phase-locked loop frequency multiplication circuit, subpulse-level position subdivision can be achieved, providing support for high-precision positioning; at the same time, the system outputs direction level, counting pulse and bus interface, which is compatible with mainstream PLC high-speed counting modules, making it easy to integrate auxiliary braking. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of a crane speed monitoring system according to some embodiments of this application;

[0016] Figure 2 This is a cross-sectional schematic diagram of a crane according to some embodiments of this application;

[0017] Figure 3 This is a cross-sectional schematic diagram of a crane according to some embodiments of this application;

[0018] Figure 4 yes Figure 3 Enlarged view of a portion of region A in the middle;

[0019] In the picture:

[0020] 100 - Electric hoist cover, 110 - Ratchet;

[0021] 200-Drum, 210-Drum body, 211-Helical rope groove, 212-Hole, 220-Drum shaft;

[0022] 300-Brake arm, 310-Telescopic contact, 311-Dual sensor assembly, 312-Clamping ball, 320-First elastic element, 330-Clamping element, 331-Wedge block, 332-Second elastic element, 333-Electromagnet, 340-Inductor coil;

[0023] 400-Controller. Detailed Implementation

[0024] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] like Figures 1 to 4 As shown, the crane in the embodiment of this application is understood.

[0026] According to the present application, a crane speed monitoring system is combined with Figure 1The system includes: a permanent magnet ratchet ring, fixed to the inner wall of the electric hoist housing 100, comprising N ratchet teeth 110 evenly spaced along the circumferential direction and each equipped with a permanent magnet, where N is an integer greater than or equal to 4; a dual-sensor assembly 311, mounted on the drum 200, comprising a first magnetic sensor and a second magnetic sensor, wherein when the drum rotates, the first magnetic sensor and the second magnetic sensor respectively output a first square wave signal and a second square wave signal with a constant phase difference of 90 degrees, so as to characterize the rotation direction of the drum through the phase relationship between the first square wave signal and the second square wave signal; and a direction discrimination module, whose signal input terminals are respectively connected to the output terminals of the first magnetic sensor and the second magnetic sensor, for receiving the first square wave signal and the second square wave signal, and generating a direction signal and a counting pulse signal based on pure digital logic circuit processing, wherein the level state of the direction signal uniquely corresponds to the real-time rotation direction of the drum, and each pulse of the counting pulse signal corresponds to a transition edge of the first square wave signal or the second square wave signal.

[0027] Specifically, the permanent magnet ratchet ring consists of N permanent magnets uniformly fixed on the inner wall of the electric hoist casing, with the magnetic poles aligned (e.g., the N pole facing the sensor), and the included angle between adjacent magnets being [missing information]. The dual-sensor assembly 311 is mounted on the brake arm that rotates with the drum, and is equipped with the aforementioned two magnetic sensors, which can be Hall elements or magnetoresistive sensors, denoted as H1 and H2. The direction determination module consists of digital logic chips such as D flip-flops, XOR gates, and AND gates, receiving two sensor signals and outputting a direction level DIR and a counting pulse CLK. When the drum rotates, H1 and H2 pass through each permanent magnet in sequence, outputting two square wave signals. Due to the installation angle... Each permanent magnet corresponds to a complete electrical cycle (360° electrical angle), therefore the phase difference between the square waves output by H1 and H2 is always 90° (one-quarter of a cycle). Thus, the two orthogonal signals are directly output without software direction determination. The period of this orthogonal signal is inversely proportional to the drum rotation speed, and the phase relationship uniquely corresponds to the rotation direction: if H1's phase leads H2, it's forward rotation; otherwise, it's reverse rotation. For each revolution of the drum, each sensor outputs N pulses, and the two orthogonal signals generate a total of 2N rising edges and 2N falling edges (i.e., 4N transition edges).

[0028] Thus, the mechanical displacement corresponding to each transition edge is Where D is the winding diameter of the wire rope on the drum (m). The hardware direction determination module converts the two orthogonal signals into: a direction signal DIR: a high level indicates forward rotation, and a low level indicates reverse rotation; and a counting pulse CLK: each pulse corresponds to a transition edge, and the number of pulses is linearly related to the number of rotations, with the direction indicated by DIR. Specifically, two D flip-flops (such as 74HC74) are used to latch the edges of H1 and H2 respectively. H1 and H2 are connected to the clock terminals of the two flip-flops respectively, and the outputs of the other flip-flops are cross-connected to determine the phase. The direction determination result is held by an RS flip-flop or a JK flip-flop, and the DIR signal is output. H1 and H2 are XORed by an XOR gate and then combined with their own delayed signal to generate a 4x frequency pulse, that is, 4 pulses are generated in each original cycle. An AND gate is used to combine the 4x frequency pulse with the DIR signal to form the final output: when DIR=1, CLK outputs a forward pulse; when DIR=0, CLK outputs a reverse pulse.

[0029] For example, chips such as LS7184 and LS7366R can be directly selected, with the addition of a few resistors and capacitors. Output signal characteristics: DIR is a static level, reflecting the current rotation direction; CLK outputs a signal with a width of [missing information] after each transition edge. The pulse output is adjustable; CLK outputs 4N pulses per revolution of the drum. For example, when N=4, it outputs 16 pulses per revolution, with each pulse corresponding to a displacement. (7.85cm when D=0.4m). Compared to the single-sensor solution (4 pulses per revolution), the hardware frequency multiplication directly increases the resolution by 4 times.

[0030] Therefore, for ease of explanation, the first magnetic sensor is referred to as sensor A and the second magnetic sensor as sensor B. The two sensors are installed at different mechanical angles θ along the circumference of the drum, so that when the drum rotates at a constant speed, the pulse signals output by phase A and phase B are 90° out of phase (i.e., a quarter pulse period).

[0031] In this embodiment, the direction determination module includes: a first D flip-flop and a second D flip-flop, used to latch the edge information of the first square wave signal and the second square wave signal respectively; an XOR gate, whose two inputs are respectively connected to the first square wave signal and the second square wave signal, used to generate a fourth-harmonic pulse signal; and an AND gate, whose first input is connected to the output of the XOR gate, whose second input is connected to the direction signal, and whose output is the counting pulse signal. Specifically, the standard direction determination method of a quadrature encoder is adopted.

[0032] Subsequently, taking the example that both A and B signals in the direction discrimination module are digital, the rising and falling edges of each channel are captured. A signed position counter is set with an initial value of 0 (corresponding to the lifting device being at the upper limit or reference zero point).

[0033] The direction determination rule (taking the rising edge of phase A as an example) is as follows: When the rising edge of phase A is detected, the current level of phase B is read: if phase B is low (0), it is determined to be forward rotation (lifting), and the counter is incremented by 1; if phase B is high (1), it is determined to be reverse rotation (falling), and the counter is decremented by 1. Similarly, direction counting can also be performed at the falling edge of phase A, the rising edge of phase B, and the falling edge of phase B, thereby achieving a fourfold frequency resolution, that is, four counting edges can be generated per pulse cycle, further improving the position resolution to [missing information]. .

[0034] Specifically, assume the total number of counting edges generated per revolution of the drum is 4N (because each ratchet corresponds to a complete pulse cycle, and each cycle has two effective edges: a rising edge and a falling edge; a dual-channel system has a total of four edges). The displacement increment corresponding to each counting edge is... Then the cumulative displacement of the lifting device is:

[0035]

[0036] Where M is the signed cumulative count (increment by 1 for forward rotation, subtract by 1 for reverse rotation). This is the initial position.

[0037] In some optional embodiments, the crane speed monitoring system further includes a pulse subdivision module, whose input is connected to the output of the direction discrimination module. This module receives the counting pulse signal and multiplies the frequency of the counting pulse signal by a factor of M before outputting it, where M is an integer greater than 1. Specifically, the pulse subdivision module includes a phase-locked loop (PLL), a voltage-controlled oscillator (VCO), and a programmable counter, multiplying the original pulse by a factor of M (e.g., 256) to achieve subpulse-level position subdivision.

[0038] Specifically, the pulse subdivision module includes: a phase-locked loop circuit, which includes a phase detector, a loop filter, and a voltage-controlled oscillator (VCO); a programmable frequency divider, whose input is connected to the output of the VCO, and whose output is connected to one input of the phase detector and the output of the pulse subdivision module; the counting pulse signal is connected to the other input of the phase detector, which compares the phase difference between the counting pulse signal and the feedback signal output by the programmable frequency divider and outputs an error voltage. The error voltage is filtered by the loop filter and then controls the output frequency of the VCO. The division ratio of the programmable frequency divider is set to M, such that the output frequency of the VCO is M times the frequency of the counting pulse signal, thereby obtaining a subdivided pulse signal at the output of the programmable frequency divider.

[0039] In addition, the pulse subdivision module further includes a shaping circuit connected between the output terminal of the programmable frequency divider and the output terminal of the pulse subdivision module, used to shape the subdivided pulse signal into a TTL level square wave signal. The output interface provides a direction signal (high / low level) and a subdivision pulse signal (TTL level).

[0040] The system further includes an output interface module, which is connected to the output terminals of the direction discrimination module and the pulse subdivision module, respectively, for outputting at least one of the direction signal, the counting pulse signal, or the subdivision pulse signal. For example, the output interface provides an SPI / I²C bus interface, compatible with mainstream PLC high-speed counting modules.

[0041] The crane according to an embodiment of this application includes an electric hoist housing 100 and a drum 200 disposed within the electric hoist housing 100. It also includes a crane speed monitoring system as described in any of the above-mentioned embodiments and a controller 400. The controller 400 is equipped with a direction determination module, a pulse subdivision module, and an output interface module. The crane speed monitoring system is used to monitor the speed of the drum 200. In this embodiment, the crane also includes a brake arm 300. The controller 400 of this embodiment is installed near the electric hoist gearbox end, and N ratchet teeth 110 with built-in magnets are evenly distributed on the inner wall of the electric hoist housing 100.

[0042] Based on the aforementioned crane, a brake arm 300 is also included; the drum 200 includes a cylinder 210 for winding and storing wire rope and a drum shaft 220 disposed at the drum axis. The outer surface of the cylinder 210 has a spiral rope groove 211 and a hole 212. The brake arm 300 is a hollow straight cylinder connected within the hole 212, with one end fixed to the drum shaft 220. A cylindrical telescopic contact 310, a first elastic element 320, a fastener 330, and an inductor coil 340 are disposed within the hollow cavity of the brake arm 300. The telescopic contact 310 is connected to the drum shaft 220 via the first elastic element 320 to extend and retract within the brake arm 300, and the extended end of the telescopic contact 310 is provided with a dual sensor assembly 311 and a retaining bead 312. The dual sensor assembly 311 includes a first magnetic sensor and a second magnetic sensor. Specifically, the brake arm 300 is a hollow straight cylinder connected to the hole 212, with one end fixed to the drum shaft 220. The hollow cavity of the brake arm 300 is provided with a cylindrical telescopic contact 310, a first elastic element 320, a fastener 330, and an inductor coil 340. The telescopic contact 310 is connected to the drum shaft 220 through the first elastic element 320 to extend and retract within the brake arm 300. The extended end of the telescopic contact 310 is provided with a dual sensor assembly 311 and a retaining bead 312.

[0043] refer to Figure 2 and Figure 3 For example, the holes 212 are symmetrically arranged on the cylinder 210, and the holes 212 are located near the electric hoist gearbox. The outer surface area of ​​the cylinder 210 where the holes 212 are located is not machined with rope grooves and there is no wire rope winding, so that the telescopic contact 310 inside the brake arm 300 can extend. The brake arm 300 is fixed on the drum shaft 220 and rotates synchronously with the drum 200. The brake arm 300 contains a telescopic contact 310 made of magnetic material, and its root is connected to a first elastic element 320 (such as a spring) so that it remains in the retracted state under normal conditions. A retaining bead 312 is provided on the top side of the telescopic contact 310. A semi-circular groove is constructed on the inner wall of the brake arm 300 to fit with the retaining bead 312, so that the retaining bead 312 locks the telescopic contact 310 after matching with the semi-circular groove. In this embodiment, the locking device 330 includes a wedge block 331, a second elastic element 332, and an electromagnet 333. This is used to lock the telescopic contact 310 when it extends. In this embodiment, the telescopic contact 310 is a cylinder made of magnetic metal, with one end near the drum shaft 220 connected to the first elastic element 320, and a dual sensor assembly 311 embedded in the top of the extended end. The top of the telescopic contact 310 is provided with locking beads 312 on both sides.

[0044] For example, the fastener 330 includes a wedge block 331, a second elastic element 332, and an electromagnet 333; the brake arm 300 has the semi-circular groove and the wedge groove on its inner sidewall, the small end of the wedge block 331 is hinged to the wedge groove on the inner wall of the brake arm 300, and the groove is located near the hole 212. During this process, the briefly energized electromagnet 333 attracts the wedge block 331, overcoming the thrust of the second elastic element 332, causing the wedge block 331 to retract into the wedge-shaped groove. This allows the retaining ball 312 to engage with the semi-circular groove on the inner wall of the brake arm 300 when the telescopic contact 310 extends, thus achieving structural locking. Subsequently, the electromagnet 333 is de-energized, and the wedge block 331 resets under the thrust of the second elastic element 332 to cooperate with the retaining ball 312 for locking. When troubleshooting requires device reset, the controller 400 briefly energizes the electromagnet 333, and the retaining element 330 cooperates with the retaining ball 312 to disengage from the locked state. The telescopic contact 310 retracts into the brake arm 300 under the pulling force of the first elastic element 320. It is understandable that when in auxiliary braking state, the locking ball 312 is locked in the semi-circular groove on the inner wall of the brake arm 300 by the fastener 330, thereby locking the telescopic contact 310 in the extended state, so that the telescopic contact 310 will not retract when it abuts against the ratchet 110 for braking. In addition, the locking ball 312 can provide guidance for the telescopic movement of the telescopic contact 310 inside the brake arm 300, and also plays a role in converting sliding friction into rolling friction to reduce motion resistance.

[0045] In some embodiments, the device further includes a controller 400; the controller 400 is electrically connected to the dual-sensor assembly 311. According to the crane speed monitoring system described in the foregoing embodiments, the controller 400 acquires and counts the signals detected by the dual-sensor assembly 311 at the ratchet 110 to calculate and obtain the lifting height displacement value, descent depth displacement value, lifting speed value, and descent speed value of the lifting device. Then, it compares these values ​​with preset protection limits to determine whether to activate the protection action. Furthermore, an inductor coil 340 is embedded and fixed in the inner wall of the brake arm 300 near the drum shaft 220. When the processing module of the controller 400 determines that the brake force is insufficient or that the brake is faulty, it sets to trigger auxiliary braking. At this time, the controller 400 cuts off the power supply to the lifting mechanism and simultaneously supplies power to the inductor coil 340. The resulting electromagnetic force drives the telescopic contact 310 to move towards the ratchet 110.

[0046] In some embodiments, the controller 400 is installed on the outside of the housing for easy observation and includes a processing module and a display module. The display module is configured to display in real-time information such as the lifting height displacement value, descent depth displacement value, lifting speed value, descent speed value, whether the lifting height limit protection is activated, whether the descent depth limit protection is activated, whether the overspeed protection is activated, whether the auxiliary brake is activated, and whether the system is in normal working condition. The processing module is configured to process and calculate the data collected by the ratchet 110 and the dual sensor assembly 311, and to determine whether to activate the overspeed protection and limit protection. When the brake force is insufficient, causing the spreader to fail to stop before falling or overshooting, or when the brake fails and the braking torque cannot be transmitted to the drum 200 due to a coupling failure, the auxiliary brake is triggered.

[0047] Therefore, in this example, based on the aforementioned crane speed monitoring system linked with the brake arm, telescopic contact, and controller, electromagnetic-centrifugal auxiliary braking can be triggered when the brake force is insufficient or malfunctions, thereby achieving overspeed protection, limit protection, and fault self-reset, which greatly improves the operational safety and reliability of the crane.

[0048] The device in this embodiment can perform the following workflows: When the drum 200 rotates and the lifting device is raised (lowered), the dual sensor assembly 311 sequentially detects the ratchet 110 signal, and the controller 400 calculates the displacement and speed values ​​of the lifting device, which are then displayed in real time on the display module of the controller 400. During normal operation, under the tension of the first elastic element 320 inside the brake arm 300 and the supporting force of the coiled state, the telescopic contact 310 remains in a non-extended state, retracted inside the brake arm 300, and the telescopic contact 310 will not come into contact with the ratchet 110.

[0049] Specifically, the lifting or lowering displacement value S of the lifting device = the length of the wire rope = the circumference of the drum C = π × D, where C is the circumference of the drum, π is pi (approximately 3.14), and D is the calculated diameter of the wire rope winding on the drum. When the drum 200 rotates, as in the crane speed monitoring system of the aforementioned embodiment, the magnetic ratchet 110 is detected by the embedded dual-sensor assembly 311 at the top of the telescopic contact 310. The controller 400 calculates the lifting or lowering displacement value S of the lifting device based on the signals collected by the dual-sensor assembly 311. For example, in... Figure 3 In the example, the number of ratchet teeth N is set to 4. In some embodiments, other methods may also be used, such as the controller 400 obtaining the drum rotation speed n through the dual sensor assembly 311 and the ratchet 110, and converting and calculating the lifting or lowering speed value v of the lifting device using the formula v=πDn (where v is the lifting or lowering speed of the lifting device, π is pi approximately equal to 3.14, D is the calculated diameter of the wire rope winding on the drum, and n is the drum rotation speed).

[0050] In some embodiments, limit protection can be implemented. The controller 400 compares the displacement value of the lifting device with the preset displacement protection limit value in real time. When the lifting height displacement value exceeds the lifting height protection limit value, the lifting height limit protection is activated. When the descent depth displacement value exceeds the descent depth protection limit value, the descent depth limit protection is activated. The controller 400 sends a signal to the contactor of the electric hoist control circuit to cut off the power supply to the lifting mechanism. The electric hoist brake is activated, and the lifting device stops lifting or lowering, thus realizing the lifting height or descent depth limit protection function.

[0051] In some embodiments, overspeed protection can be implemented. The controller 400 compares the speed value of the spreader with the preset overspeed protection limit of 1.25V in real time. When the speed value of the spreader exceeds the preset overspeed protection limit of 1.25V (as required by the standard document GB / T3811-2008 Crane Design Specification, the overspeed protection should be activated at 1.25V~1.4V), the controller 400 sends a signal to the contactor of the electric hoist control circuit to cut off the power supply of the hoisting mechanism. The electric hoist brake is activated, and the spreader decelerates during lifting (lowering) until it stops, thus realizing the overspeed protection function.

[0052] In some embodiments, an electromagnetic-centrifugal force triggering mode can also be triggered. When the controller 400 determines that the electric hoist brake has insufficient braking force, resulting in the inability to stop before the hoist falls or overshoots the top, a brake malfunction preventing braking, or a coupling malfunction preventing the braking torque from being transmitted to the drum 200, and the above specific faults occur, the controller 400 sets the auxiliary braking to be triggered. At this time, the controller 400 cuts off the power supply to the hoisting mechanism and supplies power to the inductor coil 340 and the electromagnet 333. The inductor coil 340 generates an electromagnetic force that drives the telescopic contact 310 to move in the direction of the ratchet 110. When the drum 200 rotates, the telescopic contact 310 is also subjected to centrifugal force. Under the combined action of centrifugal force and electromagnetic force, the telescopic contact 310 overcomes the pulling force of the first elastic element 320 (the friction of the retaining ball is negligible) and extends outward towards the port of the brake arm 300. At the same time, the electromagnet 333 attracts the wedge block 331, allowing the retaining ball 312 to run. When it moves to the position where the retaining fastener 330 locks the retaining ball 312, as the drum rotates, the extended telescopic contact 310 will abut against the ratchet 110, and the brake arm 300 will participate in braking, realizing the auxiliary braking function. Thus, when the electromagnet 333 is de-energized, the wedge block 331, under the pushing force of the second elastic element 332, locks with the retaining ball 312. When troubleshooting requires device reset, the controller 400 briefly energizes the electromagnet 333, the retaining fastener 330, and the retaining ball 312 disengage from the locked state, and the telescopic contact 310 retracts into the brake arm 300 under the pulling force of the first elastic element 320. Centrifugal force triggering process: In extreme cases, such as when the main power circuit loses or is undervoltage, the inductor coil 340 cannot provide sufficient electromagnetic force, the weight of the lifting device is too large, or the control system, brake, or coupling fails, the lifting (lowering) speed of the lifting device exceeds the speed limit of 1.4V for a short period of time. The centrifugal force generated by the drum 200 speed corresponding to the lifting (lowering) speed of the lifting device set at 1.4V is greater than the tension of the first elastic element 320 (the friction of the ball bearing can be ignored depending on the situation). At this time, the brake arm 300 does not rely on electromagnetic force but simply relies on the centrifugal force at the speed of 1.4V to directly overcome the tension of the first elastic element 320. The forced telescopic contact 310 extends and triggers the mechanical lock, realizing the passive auxiliary braking effect. After the fault is cleared, the controller 400 briefly powers the electromagnet 333. The electromagnet 333 attracts the wedge block 331, which overcomes the thrust of the second elastic element 332, causing the wedge block 331 to retract into the wedge groove. The locking ball 312 is released from the locked state. Under the pulling force of the first elastic element 320, the telescopic contact 310 retracts into the brake arm 300, and the crane returns to the initial standby state.The retaining ball 312 guides the telescopic contact 310 as it extends and retracts within the brake arm 300. Under pressure from the inner wall of the brake arm 300, the retaining ball 312 partially retracts inside the telescopic contact 310 and does not pop out. When the telescopic contact 310 extends out of the brake arm 300, the retaining ball 312 moves towards the top of the brake arm 300 along with the telescopic contact 310. When the retaining ball 312 reaches a pre-set groove in the brake arm 300, the locking device 330 activates, fixing the retaining ball 312 and the telescopic contact 310 in place. Even when the telescopic contact 310 is braked by the ratchet 110, it cannot retract back into the brake arm 300. Furthermore, the retaining ball 312 transforms the sliding friction between the telescopic contact 310 and the inner wall of the brake arm 300 into rolling friction, reducing frictional resistance during movement.

[0053] The above description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the concept described herein through the above teachings or related technologies or knowledge. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A crane speed monitoring system, characterized in that, include: A permanent magnet ratchet ring is fixed to the inner wall of the electric hoist housing (100), including N ratchet teeth (110) with permanent magnets distributed at equal angular intervals along the circumferential direction, where N is an integer greater than or equal to 4; A dual-sensor assembly (311) is mounted on a drum (200). The dual-sensor assembly (311) includes a first magnetic sensor and a second magnetic sensor. When the drum (200) rotates, the first magnetic sensor and the second magnetic sensor output a first square wave signal and a second square wave signal with a constant phase difference, respectively, so as to characterize the rotation direction of the drum (200) through the phase relationship between the first square wave signal and the second square wave signal. The system also includes a direction discrimination module, whose signal input terminals are connected to the output terminals of the first magnetic sensor and the second magnetic sensor, respectively. The module receives the first square wave signal and the second square wave signal and generates a direction signal and a counting pulse signal based on pure digital logic circuitry. The level state of the direction signal uniquely corresponds to the real-time rotation direction of the drum, and each pulse of the counting pulse signal corresponds to a transition edge of the first square wave signal or the second square wave signal.

2. The crane speed monitoring system according to claim 1, characterized in that, The first magnetic sensor and the second magnetic sensor are spaced apart by a predetermined mechanical angle along the circumferential direction of the drum. Arrangement, and meet the requirements , where N is the number of the permanent magnets.

3. The crane speed monitoring system according to claim 1, characterized in that, The direction determination module includes: The first D flip-flop and the second D flip-flop are used to latch the edge information of the first square wave signal and the second square wave signal, respectively. An XOR gate, whose two inputs are respectively connected to the first square wave signal and the second square wave signal, is used to generate a fourth-harmonic pulse signal; and an AND gate, whose first input is connected to the output of the XOR gate, whose second input is connected to the direction signal, and whose output is the counting pulse signal.

4. The crane speed monitoring system according to claim 1, characterized in that, Also includes: The pulse subdivision module has its input connected to the output of the direction discrimination module. It is used to receive the counting pulse signal and multiply the frequency of the counting pulse signal by M times before outputting it, where M is an integer greater than 1.

5. The crane speed monitoring system according to claim 4, characterized in that, The pulse subdivision module includes: A phase-locked loop circuit, the phase-locked loop circuit including a phase detector, a loop filter and a voltage-controlled oscillator; A programmable frequency divider, the input of which is connected to the output of the voltage-controlled oscillator, and the output of which is connected to one input of the phase detector and the output of the pulse subdivision module respectively; The counting pulse signal is connected to another input terminal of the phase detector. The phase detector is used to compare the phase difference between the counting pulse signal and the feedback signal output by the programmable frequency divider, and outputs an error voltage. The error voltage is filtered by the loop filter and then controls the output frequency of the voltage-controlled oscillator. The division ratio of the programmable frequency divider is set to M, so that the output frequency of the voltage-controlled oscillator is M times the frequency of the counting pulse signal, thereby obtaining a subdivided pulse signal at the output terminal of the programmable frequency divider.

6. The crane speed monitoring system according to claim 5, characterized in that, The pulse subdivision module further includes: A shaping circuit, connected between the output of the programmable frequency divider and the output of the pulse subdivision module, is used to shape the subdivided pulse signal into a TTL level square wave signal.

7. The crane speed monitoring system according to claim 5 or 6, characterized in that, Also includes: The output interface module is connected to the output terminals of the direction discrimination module and the pulse subdivision module respectively, and is used to output at least one of the direction signal, the counting pulse signal or the subdivision pulse signal.

8. A crane, comprising an electric hoist housing (100) and a drum (200) disposed within the electric hoist housing (100), characterized in that, The system also includes a crane speed monitoring system and a controller (400) as described in any one of claims 1-7, wherein the controller (400) is equipped with the direction discrimination module, and the crane speed monitoring system is used to monitor the speed of the drum (200).

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