Luffing mechanism emergency falling system and crane thereof

Abstract

The invention discloses an emergency falling system of a luffing mechanism. The emergency falling system comprises a luffing oil cylinder, an emergency valve, a luffing balance valve, an oil tank, a first control valve, a pressure sensor and a force limiter system, the variable-amplitude oil cylinder, the emergency valve, the variable-amplitude balance valve and the oil tank are connected in sequence; the variable-amplitude oil cylinder and the oil tank are connected with the first control valve; the variable-amplitude oil cylinder is provided with a rodless cavity and a rod cavity; the emergency valve comprises a logic valve, a second control valve and a third control valve; the variable-amplitude balance valve comprises a balance valve, an overflow valve and a throttling valve. The method is suitable for different system cranes such as single-pump cranes and double-pump cranes, and is high in universality; the vehicle oil pump or the emergency oil pump is not needed, only the emergency valve and the corresponding pipeline are added, the structure and the system are simple, and the cost is low; and variable-amplitude emergency falling can be achieved without power, and the emergency valve does not participate in operation in a conventional variable-amplitude rising and falling range.

Description

Technical Field

[0001] This invention relates to the field of cranes, and more particularly to an emergency lowering system for a luffing mechanism and a crane thereof. Background Technology

[0002] When a crane boom is performing lifting operations, the luffing mechanism supporting it is one of the main load-bearing components. Currently, most crane luffing mechanisms on the market are hydraulically driven, with the power component, the oil pump, primarily driven by the chassis engine through the gearbox, or directly by the engine. If there is a power system failure or oil pump damage, the crane boom, while in operation, will be unable to lower or retract, and the vehicle will be unable to be moved for maintenance. This situation is both inconvenient for vehicle repair and poses a significant safety hazard. In an emergency, if the oil pump supplying power to the luffing mechanism or the crane's overall power system fails, the luffing system will be unable to perform normal luffing and lowering operations. In this case, an emergency system is needed to lower the crane boom.

[0003] Existing technology 1, such as the patent "Hydraulic Power Emergency System and Crane" (CN111039183A) of Sany Automobile Crane Machinery Co., Ltd., is applicable to cranes where the telescopic luffing pump and winch motor are controlled separately by two pumps. This solution refers to configuring the winch motor pump as the power component of the crane's hydraulic power emergency system when the telescopic luffing pump fails but the overall vehicle power is not lost. The pump outlet is connected to the solenoid directional valve of the emergency valve group. The emergency valve group port is connected to the luffing cylinder and luffing balance valve through a quick-connect fitting. The emergency valve group is equipped with a pressure reducing valve and a relief valve as safety valves to control the system pressure. At this time, the pump operates to provide power to drive the luffing cylinder to achieve emergency action.

[0004] Existing technology 2, such as the patent "Emergency Hydraulic System and Truck Crane" (CN114476947B) of Zoomlion Heavy Industry Science & Technology Co., Ltd., employs a method of selecting either a normal oil supply circuit or an emergency oil supply circuit to pump system pressure oil into the emergency hydraulic system. In the normal state, the third check valve is opened, and the first and second check valves are closed, allowing the system to be supplied with oil from the original oil supply circuit while shutting off the emergency oil supply circuit. In the emergency state, the third check valve is closed, and the first and second check valves are opened, allowing the system to be supplied with oil from the emergency oil supply circuit while shutting off the original oil supply circuit.

[0005] However, existing technology 1 uses a winch pump instead of a luffing pump to control the luffing system, but some cranes use a single-pump system, limiting its applicability. Existing technology 2 requires an additional emergency oil pump, which necessitates shutting down the original oil supply line and using the emergency line to supply pressurized oil to the system in emergency situations. This results in extremely low utilization of the emergency system and increased costs. Summary of the Invention

[0006] Purpose of the invention: To address the shortcomings and defects of existing technologies, this invention provides an emergency lowering system for a luffing mechanism and its crane, applicable to cranes with different systems such as single-pump and dual-pump cranes, with strong versatility; it does not require the use of the vehicle's own oil pump or emergency oil pump, relying only on the addition of an emergency valve and corresponding pipelines, resulting in a simple structure and system with low cost; it can realize emergency lowering of luffing without power, and the emergency valve does not participate in the operation during the normal luffing lifting process.

[0007] Technical Solution: The present invention provides an emergency drop system for a luffing mechanism, characterized in that it includes a luffing cylinder, an emergency valve, a luffing balance valve, an oil tank, a first control valve, a pressure sensor, and a force limiter system; the luffing cylinder, emergency valve, luffing balance valve, and oil tank are connected in sequence, and the luffing cylinder, oil tank, and first control valve are connected; the luffing cylinder has a rodless chamber and a rod chamber; the emergency valve includes a logic valve, a second control valve, and a third control valve; the luffing balance valve includes a balance valve, an overflow valve, and a throttle valve.

[0008] The first control valve is connected to the rodless chamber via a variable amplitude balancing valve; one end of the emergency valve is connected to the pipeline between the rodless chamber and the variable amplitude balancing valve, and the other end of the emergency valve is connected to the pipeline between the rod chamber and the first control valve.

[0009] The first control valve uses a Y-type center position functional control valve to control the crane luffing cylinder. When there is no movement, the load is unloaded, and the rod chamber of the luffing cylinder is connected to the oil tank.

[0010] The third control valve is an electro-proportional control valve, which controls the valve opening by changing the magnitude of the control current; variable amplitude emergency descent is achieved by controlling the second and third control valves.

[0011] The force limiter system controls the current output to the third control valve solenoid valve Y2 based on the pressure in the rodless chamber, thereby achieving smooth control during variable amplitude emergency descent.

[0012] The rodless cavity is connected to the crane's turntable via a hinge point, and the rod cavity is connected to the crane boom via a hinge point.

[0013] The balance valve is connected to the first control valve at one end and to the oil tank at the other end via a throttle valve and a relief valve. The balance valve is connected to the rodless chamber, and its reversing is controlled by the pilot oil circuit Psi. The logic valve inlet is connected to the rodless chamber, and the logic valve outlet is connected to the rod chamber and the first control valve via a third control valve. The logic valve control port is connected to the second control valve. The second control valve is connected to the rodless chamber at one end, to the logic valve control port at the other end, and its return port is connected to the return port of the third control valve. The pressure sensor is connected to the rodless chamber and sends a signal to the force limiter system.

[0014] The first control valve operates in the neutral position by default, the balance valve operates in the left position by default, the second control valve operates in the left position by default, and the third control valve operates in the upper position by default. At this time, the spring force plus the control port pressure in the logic valve is greater than the pressure before the valve, and the logic valve is in the closed state. When the crane performs luffing operation, the first control valve operates in the right position, and the pressure oil at port P enters the rodless chamber of the luffing cylinder through the right position of the first control valve and the left position of the balance valve. The oil in the rod chamber returns to the hydraulic oil tank through the first control valve. At this time, the luffing cylinder extends, and the boom achieves luffing. When the crane performs luffing lowering operation, the first control valve operates in the left position, and the pressure oil at port P directly enters the rod chamber through the left position of the first control valve. The system pilot pressure pushes the balance valve to switch to the right position, and the oil in the rodless chamber returns to the hydraulic oil tank through the right position of the balance valve and the first control valve. At this time, the luffing cylinder retracts, and the boom achieves luffing lowering.

[0015] When an emergency luffing descent is required, the emergency luffing descent switch is opened in the crane force limiter system. At this time, the solenoid valve Y1 of the second control valve in the emergency valve is energized, and the second control valve is in the right position. At this time, the control pressure of the logic valve is 0, and the pressure in front of the logic valve is greater than the spring force, so the logic valve opens. At this time, the solenoid Y2 of the third control valve is energized, and the third control valve is in the lower position. The pressure oil in the rodless chamber flows into the rod chamber through the logic valve and the third control valve, and the excess oil flows back to the oil tank through the first control valve.

[0016] Due to the weight of the boom, the luffing cylinder is under pressure, and there is pressure buildup in the rodless chamber. At this time, the pressure sensor transmits the pressure signal of the rodless chamber to the crane force limiter system. The force limiter system controls the current of the third directional valve solenoid Y2 according to the pressure. The lower the pressure, the higher the current, and the higher the pressure, the lower the current. This allows for control of the emergency descent speed of the boom at different luffing angles, improving the stability of the emergency descent.

[0017] The present invention relates to a crane, characterized in that: it uses the luffing mechanism emergency descent system of the present invention.

[0018] Beneficial Effects: Compared with the prior art, the present invention has the following significant advantages: The present invention solves the problem of emergency boom luffing and lowering in the event of power system failure of the crane; by adding an emergency valve to the original luffing hydraulic system, it solves the problem of not needing to use the original winch pump as an emergency power source, nor adding an emergency oil pump as a power source, reducing costs and being applicable to various systems such as single pump and dual pump, and the problem of emergency boom lowering can be achieved solely by the weight of the boom itself; and by identifying the rodless chamber pressure of the luffing cylinder at different boom angles through a force limiter, the current of the emergency valve is automatically adjusted to control the valve opening, thereby achieving control of the emergency lowering speed of the boom at different angles, and ensuring a smooth emergency luffing and lowering. Attached Figure Description

[0019] Figure 1This is a schematic diagram of the structure of the present invention;

[0020] Figure 2 This is a schematic diagram of the crane structure of the present invention;

[0021] Figure 3 This is a control diagram of the present invention;

[0022] In the diagram, 1 is the luffing cylinder; 2 is the emergency valve; 3 is the luffing balance valve; 4 is the oil tank; 5 is the first control valve; 6 is the boom; 7 is the turntable; 8 is the pressure sensor; 11 is the rodless chamber; 12 is the rod chamber; 21 is the logic valve; 22 is the second control valve; 23 is the third control valve; 31 is the balance valve; 32 is the relief valve; and 33 is the throttle valve. Detailed Implementation

[0023] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0024] The emergency valve of this invention is an integrated valve assembly for controlling the on / off state of an oil circuit, which controls the on / off state of the oil circuit through a switching valve within the control valve assembly. The crane boom is a telescopic boom composed of multiple nested extension sections, which can support the crane to complete lifting operations by adjusting the working angle. The luffing balance valve is composed of a balance valve and a relief valve connected in parallel, which can maintain the operation of the luffing cylinder.

[0025] The emergency drop system for the luffing mechanism of the present invention includes a luffing cylinder 1, an emergency valve 2, a luffing balance valve 3, an oil tank 4, a first control valve 5, a pressure sensor 8, and a force limiter system. The luffing cylinder 1, emergency valve 2, luffing balance valve 3, and oil tank 4 are connected in sequence, and the luffing cylinder 1 and oil tank 4 are connected to the first control valve 5. The luffing cylinder 1 has a rodless chamber 11 and a rod chamber 12. The emergency valve 2 includes a logic valve 21, a second control valve 22, and a third control valve 23. The luffing balance valve 3 includes a balance valve 31, an overflow valve 32, and a throttle valve 33. The luffing balance valve 3 is connected between the first control valve 5 and the rodless chamber 11. One end of the emergency valve 2 is connected to the pipeline between the rodless chamber 11 and the luffing balance valve 3, and the other end of the emergency valve 2 is connected to the pipeline between the rod chamber 12 and the first control valve 5. The first control valve 5 uses a Y-type neutral position functional control valve to control the crane's luffing cylinder. When not in operation, it unloads, and the rod chamber 12 of the luffing cylinder is connected to the oil tank. The third control valve 23 is an electro-proportional control valve, controlling the valve opening by changing the control current; it controls the emergency descent during luffing by controlling the second control valve 22 and the third control valve 23. The force limiter system controls the current output to the solenoid valve Y2 of the third control valve 23 based on the pressure in the rodless chamber 11, achieving smooth control during emergency descent. The rodless chamber 11 is connected to the crane's turntable 7 via a hinge point, and the rod chamber 12 is connected to the boom 6 via a hinge point.

[0026] In use, one end of the balance valve 31 is connected to the first control valve 5, and the other end is connected to the oil tank 4 through the throttle valve 33 and the overflow valve 32; the balance valve 31 is connected to the rodless chamber 11, and the switching of the balance valve is controlled by the pilot oil circuit Psi; the oil inlet of the logic valve 21 is connected to the rodless chamber 11, and the oil outlet of the logic valve 21 is connected to the rod chamber 12 and the first control valve 5 through the third control valve 23; the control port of the logic valve 21 is connected to the second control valve 22; one end of the second control valve 22 is connected to the rodless chamber 11, the other end is connected to the control port of the logic valve 21, and the other end's oil return port is connected to the oil return port of the third control valve 23; the pressure sensor 8 is connected to the rodless chamber 11 and sends the signal to the force limiter system.

[0027] The first control valve 5 operates in the neutral position by default, the balance valve 31 operates in the left position by default, the second control valve 22 operates in the left position by default, and the third control valve 23 operates in the upper position by default. At this time, the spring force in the logic valve 21 plus the control port pressure is greater than the pressure before the valve, and the logic valve is in the closed state. When the crane performs luffing operation, the first control valve 5 operates in the right position. The pressure oil at port P enters the rodless chamber 11 of the luffing cylinder through the right position of the first control valve 5 and the left position of the balance valve 31. The oil in the rod chamber 12 returns to the hydraulic oil tank through the first control valve 5. At this time, the luffing cylinder 1 extends, and the boom achieves luffing. When the crane performs luffing lowering operation, the first control valve 5 operates in the left position. The pressure oil at port P enters the rod chamber 12 directly through the left position of the first control valve 5. The system pilot pressure pushes the balance valve 31 to switch to the right position. The oil in the rodless chamber 11 returns to the hydraulic oil tank through the right position of the balance valve 31 and the first control valve 5. At this time, the luffing cylinder 1 retracts, and the boom achieves luffing lowering.

[0028] When an emergency luffing descent is required, the emergency luffing descent switch is opened in the crane force limiter system. At this time, the solenoid valve Y1 of the second control valve 22 in the emergency valve 2 is energized, and the second control valve 22 operates in the right position. At this time, the control pressure of the logic valve 21 is 0, and the pressure before the logic valve 21 is greater than the spring force, so the logic valve 21 opens. At this time, the solenoid Y2 of the third control valve 23 is energized, and the third control valve 23 operates in the lower position. The pressure oil in the rodless chamber 11 flows into the rod chamber 12 through the logic valve 21 and the third control valve 23, and the excess oil flows back to the oil tank through the first control valve 5.

[0029] Due to the weight of the boom, the luffing cylinder 1 is under pressure, and the rodless chamber 11 is under pressure. At this time, the pressure sensor 8 transmits the pressure signal of the rodless chamber 11 to the crane force limiter system. The force limiter system controls the current of the third directional valve 23 and the solenoid valve Y2 according to the pressure. The lower the pressure, the greater the current, and the greater the pressure, the smaller the current. This can realize the control of the emergency descent speed of the boom at different luffing angles and improve the stability of the emergency descent.

[0030] The second and third control valves in the emergency valve can be mechanically switched, achieving both luffing emergency descent and control of the descent speed. The connection between the emergency valve and the rodless and rod-side chambers of the luffing cylinder can be a quick-connect type.

[0031] This invention solves the problem of emergency boom lowering in the event of power system failure in cranes. By adding an emergency valve to the original luffing hydraulic system, it eliminates the need for the original winch pump as an emergency power source or a new emergency oil pump, reducing costs and making it applicable to various systems such as single-pump and dual-pump systems. The emergency lowering of the boom can be achieved solely by the weight of the boom itself. Furthermore, by using a force limiter to identify the rodless chamber pressure of the luffing cylinder at different boom angles, it automatically adjusts the current of the emergency valve to control the valve opening, thereby controlling the emergency lowering speed of the boom at different angles and ensuring a smooth emergency luffing descent.

Claims

1. A variable amplitude mechanism emergency drop system, characterized by: The utility model relates to a crane amplitude control system, including amplitude cylinder (1), emergency valve (2), amplitude balance valve (3), oil tank (4), first control valve (5), pressure sensor (8) and force limiter system, amplitude cylinder (1), emergency valve (2), amplitude balance valve (3), oil tank (4) are connected in proper order, and amplitude cylinder (1), oil tank (4) are connected with first control valve (5), amplitude cylinder (1) is equipped with rodless cavity (11) and rod cavity (12), emergency valve (2) includes logic valve (21), second control valve (22) and third control valve (23), amplitude balance valve (3) includes balance valve (31), overflow valve (32) and throttle valve (33).

2. A yoke emergency drop system according to claim 1, wherein: First control valve (5) and rodless cavity (11) are connected with amplitude balance valve (3), and one end of emergency valve (2) is connected with the pipeline between rodless cavity (11) and amplitude balance valve (3), and the other end of emergency valve (2) is connected with the pipeline between rod cavity (12) and first control valve (5).

3. The yoke emergency drop system of claim 2, wherein: First control valve (5) adopts a Y type mid-position function control valve to realize the control of crane amplitude cylinder, unloads when not acting, and rod cavity (12) of amplitude cylinder is communicated with the oil tank.

4. The yoke emergency drop system of claim 1, wherein: Third control valve (23) is an electric proportional control valve, and the valve opening is controlled by changing control current size, and the emergency amplitude drop is realized by controlling second control valve (22) and third control valve (23).

5. The yoke emergency drop system of claim 1, wherein: The force limiter system controls the current output to the electromagnetic valve Y2 of third control valve (23) according to the pressure of rodless cavity (11), and realizes the smooth control of emergency amplitude drop.

6. The yoke emergency drop system of claim 1, wherein: Rodless cavity (11) is connected with the rotating platform (7) of crane through hinge point, and rod cavity (12) is connected with the lifting arm (6) through hinge point.

7. A yoke emergency drop system according to any one of claims 1-6, characterized in that: Balance valve (31) one end is connected with first control valve (5), and the other end is connected with oil tank (4) through throttle valve (33) and overflow valve (32), balance valve (31) is connected with rodless cavity (11), and balance valve reversing is controlled by pilot oil circuit Psi, logic valve (21) oil inlet is connected with rodless cavity (11), logic valve (21) oil outlet is connected with rod cavity (12) and first control valve (5) through third control valve (23), and logic valve (21) control port is connected with second control valve (22), one end of second control valve (22) is connected with rodless cavity (11), one end is connected with logic valve (21) control port, and the other end oil return port is connected with third control valve (23) oil return port, pressure sensor (8) is connected with rodless cavity (11), and sends signal to force limiter system.

8. The yoke emergency drop system of claim 7, wherein: The first control valve (5) is in default neutral position, the balance valve (31) is in default left position, the second control valve (22) is in default left position, the third control valve (23) is in default upper position, at this time the spring force of the logic valve (21) plus the control port pressure is greater than the valve front pressure, and the logic valve is in a closed state; when the crane performs the variable amplitude lifting operation, the first control valve (5) works in the right position, the P port pressure oil enters the rodless chamber (11) of the variable amplitude cylinder through the right position of the first control valve (5) and the left position of the balance valve (31), and the oil in the rod chamber (12) returns to the hydraulic oil tank through the first control valve (5) at this time, the variable amplitude cylinder (1) is extended, and the crane boom realizes variable amplitude lifting; when the crane performs the variable amplitude falling operation, the first control valve (5) works in the left position, the P port pressure oil directly enters the rod chamber (12) through the left position of the first control valve (5), and the system pilot pressure drives the balance valve (31) to reverse to the right position, the oil in the rodless chamber (11) returns to the hydraulic oil tank through the right position of the balance valve (31) and the first control valve (5), at this time, the variable amplitude cylinder (1) is retracted, and the crane boom realizes variable amplitude falling.

9. The yoke emergency drop system of claim 7, wherein: When the variable amplitude emergency falling needs to be performed, the crane limiter system opens the variable amplitude emergency falling switch at this time, the electromagnetic valve Y1 of the second control valve (22) in the emergency valve (2) is electrified, the second control valve (22) works in the right position, at this time, the control pressure of the logic valve (21) is 0, the valve front pressure of the logic valve (21) is greater than the spring force, the logic valve (21) is opened, at this time, the electromagnetic iron Y2 of the third control valve (23) is electrified, the third control valve (23) works in the lower position, the pressure oil in the rodless chamber (11) flows into the rod chamber (12) through the logic valve (21) and the third control valve (23), and the excess oil flows back to the oil tank through the first control valve (5); Due to the self-weight of the crane boom, the variable amplitude cylinder (1) is under pressure, and the rodless chamber (11) is under pressure at this time, the pressure sensor (8) transmits the pressure signal of the rodless chamber (11) to the crane limiter system, the limiter system controls the current of the electromagnetic valve Y2 of the third reversing valve (23) according to the pressure, the smaller the pressure, the greater the current, the greater the pressure, the smaller the current, thereby the variable amplitude emergency falling speed of the crane boom at different angles can be controlled, and the variable amplitude emergency falling stability is improved.

10. A crane characterized by: The variable amplitude mechanism emergency falling system of any one of claims 1-6 is used.

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