Safety dual-loop emergency stop system for truck-mounted crane

Abstract

The utility model discloses a kind of safety double-loop emergency stop systems for truck crane, belong to engineering machinery safety control field, including the controller signal loop and unloading valve power loop of shunt arrangement, multiple double-path normally closed emergency stop buttons, system controller, hydraulic total unloading valve and pressure sensor in two circuits are connected in series.When any emergency stop button triggers, its double-path normally closed contact synchronously disconnects, makes two circuits simultaneously lose power, and then through controller control engine flameout, simultaneously drive hydraulic total unloading valve unloading, power source and hydraulic execution system synchronous cut-off. Through pressure sensor real-time monitoring hydraulic pressure, if system pressure is not reduced to safety threshold after emergency stop, unloading failure alarm is sent through man-machine interface. The system is through double-loop redundancy design and closed-loop state verification mechanism, effectively solve the reliability deficiency and security risk existing in traditional emergency stop scheme, improve the emergency safety performance of equipment.

Description

Technical Field

[0001] This utility model relates to the field of safety control of engineering machinery, specifically a dual-circuit emergency stop system for truck-mounted cranes. Background Technology

[0002] As a widely used lifting equipment, the operational safety of truck-mounted cranes is of paramount importance. In complex working conditions, the ability to quickly and reliably execute emergency stops in situations such as boom loss of control, hydraulic line rupture, or personnel danger directly impacts the safety of the equipment itself, as well as the safety of personnel and property on site. An effective emergency stop system is the last line of defense against escalating accidents and the protection of life and property. Cranes lacking a complete emergency stop system or with a malfunctioning system will be unable to quickly cut off power in emergencies, potentially leading to catastrophic consequences such as continued uncontrolled boom movement, falling loads, vehicle instability, or even overturning, posing significant safety risks.

[0003] Currently, several solutions exist in existing technologies that attempt to address the safe shutdown of cranes. For example, some solutions use a single electrical control circuit to shut down the engine by cutting off the engine circuit via an emergency stop button. However, this method suffers from response delays, a slow engine shutdown process, and the hydraulic system may still maintain pressure during engine inertia, making instantaneous safe braking impossible. Another solution focuses on the hydraulic system itself, releasing system pressure by controlling an unloading valve. However, this single hydraulic unloading method has a hidden danger: if the unloading valve itself fails to operate due to jamming or circuit failure, the entire emergency stop function will be completely ineffective, and reliability cannot be guaranteed.

[0004] Furthermore, some more advanced systems employ the concept of dual braking to enhance safety. However, these existing technologies generally suffer from the following common defects: Firstly, their dual braking is often limited to redundancy within the same technical field (such as two electric brakes or two hydraulic valves), failing to achieve cross-domain coordinated disconnection of the vehicle's power source and hydraulic actuator system, resulting in a single dimension of safety assurance; secondly, most of these systems are "open-loop" controls, meaning that after an emergency stop command is issued, the system assumes a safe state has been achieved, lacking a mechanism to verify and provide feedback on the effectiveness of the emergency stop action (such as whether the hydraulic system has truly and successfully unloaded). This leads to operators being unable to know whether the equipment has truly entered a safe state, and this "false safety" hazard can easily trigger secondary accidents during subsequent handling.

[0005] Therefore, existing emergency stop solutions have significant shortcomings in terms of reliability, response speed, and state awareness. Utility Model Content

[0006] This invention provides a dual-circuit emergency stop system for truck-mounted cranes. The core of the system lies in achieving dual safety assurance through a single trigger command, simultaneously cutting off the power source and depressurizing the actuator. A status feedback mechanism is introduced to form a closed-loop control. By simultaneously cutting off power and hydraulic pressure and verifying in real time whether a safe state has been achieved, it solves the problems of slow response, single point of failure, and safety hazards in existing technologies.

[0007] To achieve the above objectives, this utility model provides the following technical solution: a dual-circuit emergency stop system for truck-mounted cranes, comprising: an emergency stop command input mechanism, including several emergency stop buttons located at different operating positions of the crane, each emergency stop button having a dual-circuit normally closed contact via mechanical linkage; a safety control mechanism, which is a dual-circuit emergency stop control circuit, including a controller signal circuit and an unloading valve power circuit connected in parallel, the two circuits sharing a DC power supply but being electrically isolated, the first normally closed contact of the several emergency stop buttons being connected in series in the controller signal circuit, and the second normally closed contact being connected in series in the unloading valve power circuit; an execution mechanism, including an engine shutdown unit controlled by the controller signal circuit and a hydraulic unloading unit directly driven by the unloading valve power circuit; a monitoring mechanism, including a pressure sensor installed on the main pressure pipeline of the hydraulic system for real-time monitoring of the system pressure status; and an alarm display mechanism, including a display screen and an audible and visual alarm.

[0008] Further technical solutions are as follows: The emergency stop command input mechanism includes at least four emergency stop buttons located at key operating positions such as the left side of the upper and lower sections of the crane, the right side of the lower section, and the lower section's electrical distribution box. Each emergency stop button uses a safety element conforming to the IEC 60947-5-5 standard, and integrates two sets of independent normally closed contacts that are mechanically linked to ensure that a single operation can simultaneously control both sets of contacts. The first set of normally closed contacts of these emergency stop buttons is connected in series to the controller signal circuit, and the second set of normally closed contacts is connected in series to the unloading valve power circuit, forming a complete emergency stop triggering chain.

[0009] The safety control mechanism consists of a dual-loop emergency stop control circuit formed by a controller signal loop and an unloading valve power loop connected in parallel. The two loops share a DC 24V power supply but maintain electrical isolation, and each has an independent overcurrent protection device. The output of the controller signal loop is connected to the controller's digital input port to transmit the emergency stop command signal; the output of the unloading valve power loop is directly connected to the electromagnet of the hydraulic master unloading valve to directly drive the unloading valve. This dual-loop design achieves physical separation between signal transmission and power drive.

[0010] The actuator comprises an engine control unit and a hydraulic unloading unit. The engine is connected to the controller via a CAN bus and receives the J1939 standard shutdown command issued by the controller based on the emergency stop signal. The hydraulic unloading unit uses a two-position, normally closed solenoid directional valve as the main unloading valve, installed in the main pressure line of the hydraulic system. Its solenoid is directly controlled by the unloading valve's power circuit and automatically switches to the unloading position when the circuit loses power.

[0011] The core component of the monitoring mechanism is a shock-resistant hydraulic pressure transmitter, installed in the main pressure pipeline of the hydraulic system and located downstream of the main unloading valve. It is used to accurately reflect the actual pressure state of the system after unloading. The pressure sensor outputs a 4-20mA analog signal or a digital bus signal to the analog input port of the controller to monitor system pressure changes in real time.

[0012] The alarm display mechanism includes a display screen and an audible and visual alarm. The display screen is connected to the controller via a communication interface and is used to display system status and detailed alarm information. The audible and visual alarm is directly driven by the controller's digital output port to provide audible and visual warnings. The controller is configured to determine "unloading failure" and simultaneously activate both alarm devices if the pressure value fed back by the pressure sensor does not drop to the safety threshold (0-10 Bar) within a set time after an emergency stop is triggered.

[0013] The system works as follows: When any emergency stop button is triggered, its mechanically linked dual normally closed contacts simultaneously open, de-energizing both the controller signal circuit and the unloading valve power circuit. Upon detecting the power loss in the signal circuit, the controller immediately sends a shutdown command to the engine ECU via the CAN bus, cutting off the power source. Simultaneously, the power loss in the unloading valve power circuit causes the hydraulic master unloading valve to automatically switch to the unloading position under spring action, releasing system pressure. Pressure sensors monitor the hydraulic system pressure in real time. If the pressure fails to drop to the safe threshold within a specified time after the emergency stop, the controller determines that unloading has failed, immediately displays specific alarm information on the screen, and activates the audible and visual alarms, thus achieving closed-loop control from emergency stop triggering to safety status verification.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. Significantly improved system reliability. By constructing completely independent controller signal circuits and unloading valve power circuits, coordinated action of engine shutdown and hydraulic unloading is achieved. The two circuits serve as backups for each other; if either circuit fails, the other can still independently perform safety functions, effectively avoiding complete failure of emergency stop due to a single point of failure.

[0015] 2. Safety status is perceptible and controllable. Status feedback from pressure sensors constitutes a closed-loop safety control system. The system not only executes emergency stop commands but also verifies the unloading effect in real time. When unloading fails, the system immediately issues a warning, preventing secondary accidents that might occur due to personnel intervening based on misjudgments of the safety status.

[0016] 3. Faster and more thorough emergency stop response. Traditional single-stage shutdown or single-stage unloading solutions suffer from response delays or incomplete actions. This invention, through dual-circuit synchronous triggering, achieves simultaneous power source cutoff and actuator unloading, enabling the system to enter a safe state more quickly.

[0017] 4. Improved fault diagnosis and maintenance efficiency. The system's alarm prompts can accurately locate the fault range, directly pointing the problem to the hydraulic unloading circuit and its control circuit, providing maintenance personnel with a clear direction for troubleshooting, shortening fault handling time, and reducing maintenance costs. Attached Figure Description

[0018] Figure 1 Schematic diagram of the dual-circuit emergency stop system for truck-mounted cranes; Figure 2 : Dual-circuit emergency stop circuit diagram.

[0019] Explanation of annotations in the image: 3#: DC24V power supply; 94#: Controller signal circuit; 186#: Unloading valve power circuit; SB1: Emergency stop button for loading; SB2: Emergency stop button on the left side for unloading; SB3: Emergency stop button on the right side for unloading; SB4: Emergency stop button for the unloading distribution box. Detailed Implementation

[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model. Example 1:

[0021] See appendix Figure 1The present invention provides a dual-circuit emergency stop system for a truck-mounted crane, comprising: an emergency stop command input mechanism, including several emergency stop buttons located at different operating positions of the crane, each emergency stop button having a dual-circuit normally closed contact via mechanical linkage; a safety control mechanism, which is a dual-circuit emergency stop control circuit, including a controller signal circuit and an unloading valve power circuit connected in parallel, the two circuits sharing a DC power supply but being electrically isolated, the first normally closed contact of the several emergency stop buttons being connected in series in the controller signal circuit, and the second normally closed contact being connected in series in the unloading valve power circuit; an execution mechanism, including an engine shutdown unit controlled by the controller signal circuit and a hydraulic unloading unit directly driven by the unloading valve power circuit; a monitoring mechanism, including a pressure sensor installed on the main pressure pipeline of the hydraulic system for real-time monitoring of the system pressure status; and an alarm display mechanism, including a display screen and an audible and visual alarm.

[0022] The emergency stop command input mechanism includes four emergency stop buttons located on the left side of the upper and lower sections of the crane, the right side of the lower section, and the lower section's electrical distribution box. Each emergency stop button is equipped with a double-circuit normally closed contact that is mechanically linked.

[0023] The safety control mechanism is a dual-circuit emergency stop control circuit, including a controller signal circuit and an unloading valve power circuit connected in parallel. The two circuits share a DC 24V power supply but maintain electrical isolation. The first normally closed contact of each emergency stop button is connected in series in the controller signal circuit, and the second normally closed contact is connected in series in the unloading valve power circuit.

[0024] The actuators include an engine shutdown unit controlled by the controller signal circuit and a hydraulic unloading unit directly driven by the unloading valve power circuit. The controller is connected to the engine ECU via a CAN bus, and the main unloading valve of the hydraulic unloading unit is installed on the main pressure line of the hydraulic system.

[0025] The monitoring mechanism includes a pressure sensor installed on the main pressure pipeline of the hydraulic system, located downstream of the main unloading valve, for real-time monitoring of the system pressure status.

[0026] The alarm display mechanism includes a display screen and an audible and visual alarm, both of which are controlled by the output port of the controller.

[0027] The system operates as follows: When any emergency stop button is triggered, its dual normally closed contacts simultaneously open, de-energizing both circuits. Upon detecting the power loss in the signal circuit, the controller shuts off the engine via the CAN bus; simultaneously, the unloading valve's power circuit is de-energized, causing the main unloading valve to switch to the unloading position. Pressure sensors monitor the system pressure in real time. If the pressure fails to drop to the safe threshold within a specified time after the emergency stop, the controller activates the alarm display mechanism to issue an unloading failure warning.

[0028] Example 2: See Figure 1-2Based on Example 1, this example provides a more specific circuit structure and component selection scheme.

[0029] The dual-circuit emergency stop control circuit adopts a topology of parallel independent power supply and series triggering. Signal circuit #94 is led out from the positive terminal of the power supply and connected in series with the first normally closed contacts of emergency stop buttons SB1, SB2, SB3, and SB4, ending at the digital input port of the controller. A 2A fuse is connected in series at the beginning of the circuit. Power circuit #186 is connected in series with the second normally closed contacts of emergency stop buttons SB1, SB2, SB3, and SB4, ending at the electromagnet coil of the main unloading valve. A 4A fuse is connected in series at the beginning of the circuit. A freewheeling diode is connected in parallel across the electromagnet coil for protection.

[0030] The emergency stop button is a mushroom-shaped self-locking button conforming to IEC 60947-5-5 standard, with an IP67 protection rating. It has two sets of independent and mechanically linked normally closed contacts, and its rated parameters are DC24V / 2A.

[0031] The controller is an industrial-grade PLC that supports the SAE J1939 protocol. It has at least one digital input, one analog input (4-20mA), and two digital outputs, with an operating voltage range of DC18-32V.

[0032] The main unloading valve is a two-position normally closed electromagnetic directional valve with a nominal diameter of NG10, a rated pressure of 350 Bar, an electromagnet operating voltage of DC24V, and a power consumption of 15-30W.

[0033] The pressure sensor is a shock-resistant metal diaphragm pressure transmitter with a range of 0-400 Bar, an output signal of 4-20mA, an accuracy of ±0.5%FS, an electrical interface of M12×1, and a mechanical interface of G1 / 4.

[0034] In the display alarm unit, the display screen is a TFT LCD screen, which communicates with the controller via a CAN bus; the audible and visual alarm is a DC24V integrated device with a sound intensity of not less than 85dB, which is directly driven by the digital output of the controller.

[0035] This embodiment provides a complete and feasible implementation plan through specific circuit design and component selection, ensuring the reliability and security of the system.

[0036] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A dual-circuit emergency stop system for truck-mounted cranes, characterized in that, include: The emergency stop command input mechanism includes several emergency stop buttons located at different operating positions of the crane, each emergency stop button having a double normally closed contact via mechanical linkage; the safety control mechanism includes a controller signal circuit and an unloading valve power circuit connected in parallel, the two circuits sharing a DC power supply but being electrically isolated, the first normally closed contact of the emergency stop button being connected in series in the controller signal circuit, and the second normally closed contact being connected in series in the unloading valve power circuit; the execution mechanism includes an engine shutdown unit controlled by the controller signal circuit and a hydraulic unloading unit directly driven by the unloading valve power circuit; the monitoring mechanism includes a pressure sensor installed on the main pressure pipeline of the hydraulic system; and the alarm display mechanism includes a display screen and an audible and visual alarm.

2. The dual-circuit emergency stop system for truck-mounted cranes according to claim 1, characterized in that, The emergency stop command input mechanism includes four emergency stop buttons located on the left side of the upper and lower sections of the crane, the right side of the lower section, and the lower section's electrical distribution box. Each emergency stop button integrates two sets of independent normally closed contacts that are mechanically linked. The first set of normally closed contacts is connected in series to the controller signal circuit, and the second set of normally closed contacts is connected in series to the unloading valve power circuit.

3. The dual-circuit emergency stop system for truck-mounted cranes according to claim 1, characterized in that, In the safety control mechanism, the controller signal circuit and the unloading valve power circuit are each equipped with an independent overcurrent protection device. The output end of the controller signal circuit is connected to the digital input port of the controller, and the output end of the unloading valve power circuit is directly connected to the electromagnet of the hydraulic main unloading valve.

4. The dual-circuit emergency stop system for truck-mounted cranes according to claim 1, characterized in that, In the actuator, the engine is connected to the controller via a CAN bus, and the hydraulic unloading unit uses a two-position normally closed electromagnetic directional valve as the main unloading valve.

5. The dual-circuit emergency stop system for truck-mounted cranes according to claim 1, characterized in that, The pressure sensor of the monitoring mechanism is installed in the main pressure pipeline of the hydraulic system and is located downstream of the main unloading valve. The pressure sensor establishes a signal connection with the analog input port of the controller.

6. The dual-circuit emergency stop system for truck-mounted cranes according to claim 1, characterized in that, The display screen of the alarm display mechanism is connected to the controller via a communication interface, and the audible and visual alarm is driven by the digital output port of the controller.

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