A mobile crawler crane mast jacking hydraulic drive system and a control method thereof

Abstract

This invention provides a hydraulic drive system for mast lifting on a mobile crawler crane and its control method. The system includes a luffing winch and a mast lifting cylinder; the luffing winch is equipped with a high / low tension switching structure; this structure switches between a high tension mode and a low tension mode; when the luffing winch is in operating mode, the high / low tension switching structure keeps it in high tension mode; when the luffing winch is in disassembly / assembly mode, after the boom is lowered and supported, the high / low tension switching structure switches the luffing winch to low tension mode. During mast raising or lowering, by rationally setting the design parameters of the mast lifting cylinder and the interactive control logic of the luffing winch system, the operation of the mast system, whether manual or automatic, is relatively simple, eliminating the need for the operator to observe system pressure to adjust the operation and avoid system overload.

Description

Technical Field

[0001] This invention belongs to the field of crane technology, specifically relating to a hydraulic drive system for lifting the mast of a mobile crawler crane and its control method. Background Technology

[0002] The luffing control system of a mobile crawler crane is implemented through a mast and a luffing winch. The mast is connected to the boom via a fixed tie rod, and to the turntable pulley block via the luffing winch, which controls the luffing angle. For ease of relocation and transport, the boom, mast, and luffing winch typically employ a modular design. During transport, they need to be disassembled into several modules for easier transport. After relocation, the modules are reassembled and lifting operations can begin.

[0003] In operation, the mast is connected to the boom via a fixed tie rod and to the turntable pulley block via a luffing winch, which controls the luffing angle. During assembly and disassembly, the mast needs to be lifted to a certain angle by a secondary telescopic cylinder before it can be connected to the boom via the tie rod. The lifting process can be controlled manually or automatically (one-button lift). During disassembly, the secondary telescopic cylinder controls the mast to return to its original position.

[0004] During mast assembly and disassembly, due to their interconnected motion, the mast lifting cylinder and the luffing winch must be controlled synchronously. The detailed control logic is as follows:

[0005] The mast rises:

[0006] The mast speed is controlled by the mast lifting reversing valve. During the mast lifting process, the luffing winch synchronously follows the rope release.

[0007] like Figure 1 As shown, the cylinder pressure is detected by cylinder pressure sensors B621 and B622. When the cylinder pressure exceeds the programmed value, the cylinder and luffing movements are stopped, and operation resumes after the pressure returns to a safe value.

[0008] Once the mast reaches the set angle, its position is controlled by the luffing winch and boom tie rod, and the mast lifting cylinder is controlled by the reversing valve to return to the initial position (fully retracted).

[0009] The mast fell back:

[0010] The mast lifting cylinder is fully extended, and the mast is pulled back to the switching position by the luffing winch, so that the mast load falls onto the lifting cylinder.

[0011] Continue to slowly control the luffing winch to pull back the mast. The mast extension cylinder is pushed back by the winch's pulling force, and the oil pressure overflows through the cylinder balance valve.

[0012] During the mast's descent, pressure sensors B621 and B622 detect the hydraulic cylinder pressure. When the cylinder pressure exceeds the programmed value, the luffing action stops, and resumes once the pressure drops below the set value.

[0013] The following problems exist in the current system operation:

[0014] Due to size limitations, the mast lifting cylinder employs a two-stage telescopic design. The lifting force of the first-stage cylinder is twice that of the second-stage cylinder.

[0015] During mast raising, the hydraulic cylinder pressure must be monitored constantly. Especially when the first-stage hydraulic cylinder is operating, overpressure in the cylinder can easily cause mast overload. Therefore, the operator must carefully observe the hydraulic cylinder pressure and simultaneously adjust the luffing winch's rope release speed to prevent excessively slow winch speeds from causing mast overload.

[0016] For the same reason, during the mast's descent, the hydraulic cylinder pressure must be constantly monitored to prevent overload damage to the mast during the operation of the primary hydraulic cylinder.

[0017] In actual operation, the operator needs to observe the hydraulic cylinder pressure to control the mast and luffing winch. A slow operator reaction time increases the risk of system overload and damage. Summary of the Invention

[0018] The purpose of this invention is to overcome the shortcomings of the prior art and provide a hydraulic drive system for lifting the mast of a mobile crawler crane and its control method, so as to avoid system overload.

[0019] To achieve the above objectives, the present invention is implemented using the following technical solution:

[0020] This invention provides a hydraulic drive system for lifting the mast of a mobile crawler crane, including a luffing winch and a mast lifting cylinder;

[0021] The variable-amplitude winch is equipped with a high / low tension switching structure;

[0022] The high-low tension switching structure is used to switch between the high tension mode and the low tension mode of the luffing winch. When the luffing winch is in working mode, the high-low tension switching structure keeps the luffing winch in high tension mode. When the luffing winch is in disassembly / assembly mode, after the boom is lowered and supported, the high-low tension switching structure switches the luffing winch to low tension mode.

[0023] Furthermore, the luffing winch employs an open hydraulic system;

[0024] The high / low tension switching structure includes a solenoid valve V15, a main relief valve V14, a pilot relief valve V16, a mast lifting cylinder control directional valve Y20B, a luffing winch directional valve Y11, and a luffing winch control pump P10.

[0025] The luffing winch control pump P10 is used to power the luffing winch drive hydraulic motor M13.

[0026] The luffing winch switching valve Y11 is used to control the rotation direction of the luffing winch.

[0027] The main relief valve V14 is used to limit the maximum pressure of the luffing motor M13, thereby controlling the tension of the hoisting wire rope.

[0028] Solenoid valve V15 is used to control the secondary pressure of the main relief valve V14. When solenoid valve V15 is closed, the maximum pressure of the main relief valve V14 is the high pressure set by its own spring. When solenoid valve V15 is powered on and opened, the maximum pressure of the main relief valve V14 is the low pressure set by the pilot relief valve V16.

[0029] Hydraulic pump P20 provides power to the mast lifting cylinder, and controls the extension and retraction of the mast lifting cylinder by controlling the reversing valve Y20.

[0030] When the luffing winch is in working mode, solenoid valve V15 is de-energized, and the luffing winch remains in high-tension mode. The maximum pressure of the luffing motor is set by the main relief valve V14. In disassembly / assembly mode, after the boom is lowered and supported, solenoid valve V15 is energized, the luffing winch switches to low-tension mode, and the pressure of the luffing motor's main relief valve V14 is limited to low-pressure mode by the pilot relief valve V16.

[0031] Furthermore, during the mast raising process, the control method for the high / low tension switching structure includes:

[0032] i. When solenoid valve V15 is energized, the luffing winch switches to low tension mode;

[0033] ii. Power on the reversing valve Y11A, and then slowly increase the flow rate of the luffing winch control pump P10 to 20%, so that the luffing winch wire rope is in a low tension state;

[0034] iii. When the Y20B control valve of the mast lifting cylinder is energized, the cylinder extends and the mast begins to be lifted.

[0035] iv. After the hydraulic cylinder is fully extended, the luffing winch reversing valve Y11A is de-energized; the mast is held by the luffing winch, and the hydraulic cylinder no longer bears the weight of the mast;

[0036] v. When the mast extension cylinder control directional valve Y20A is energized, the mast lifting cylinder retracts, and the mast raising process is completed.

[0037] During the mast's descent, the control method for the high / low tension switching structure includes:

[0038] i. When solenoid valve V15 is energized, the luffing winch switches to low tension mode;

[0039] ii. When the Y20B reversing valve of the mast lifting cylinder is energized, the cylinder extends fully;

[0040] iii. The reversing valve Y11A is energized, and then the flow rate of the luffing winch control pump P10 is slowly increased. The luffing winch pulls the mast back close to the extension cylinder. Then the flow rate of the luffing winch control pump P10 is increased to the maximum.

[0041] iv. When the Y20A reversing valve of the mast extension cylinder is energized, the mast begins to descend until it reaches the fully lowered state.

[0042] Furthermore, the luffing winch employs a closed hydraulic system;

[0043] The high and low tension switching structure includes a solenoid valve V11, a pilot relief valve V12, a relief valve V13, a mast lifting cylinder control reversing valve Y20, and a luffing winch reversing valve Y11.

[0044] Solenoid valve V11, pilot relief valve V12, and relief valve V13 control the tension of the luffing winch wire rope.

[0045] When the solenoid valve V11 is de-energized and closed, the luffing pump P10 drives the luffing motor M14, and the wire rope tension can reach the maximum tension designed by the system.

[0046] When the solenoid valve V11 is powered on and opened, the pressure of the luffing winch pump P10 is limited to the low pressure set value of the overflow valve V12, thereby limiting the luffing winch wire rope to a low tension state.

[0047] The relief valve V13 is used to provide pressure protection for the variable mechanism of the luffing winch pump P10 by limiting the inherent characteristics of the pump itself.

[0048] In luffing winch operating mode, solenoid valve V11 is de-energized, and the luffing winch remains in high tension mode. The luffing closed pump can output the maximum pressure set by the system. In disassembly / assembly mode, after the boom is lowered and supported, solenoid valve V11 is energized, the luffing winch switches to low tension mode, and the maximum output pressure of the luffing closed pump is limited by pilot relief valve V12.

[0049] Furthermore, during the mast raising process, the control method for the high / low tension switching structure includes:

[0050] i. When solenoid valve V11 is energized, the luffing winch switches to low tension mode;

[0051] ii. The flow rate of the closed-loop pump P10 with luffing winch is slowly increased to the maximum in the direction of rope winding, and the luffing winch wire rope is in a low tension state.

[0052] iii. When the Y20B control valve of the mast lifting cylinder is energized, the cylinder extends and the mast begins to be lifted.

[0053] iv. After the hydraulic cylinder is fully extended, the luffing winch control pump stops rope winding, and the pump displacement returns to zero. The mast is then held in place by the luffing winch, and the hydraulic cylinder no longer bears the weight of the mast.

[0054] v. When the mast extension cylinder control directional valve Y20A is energized, the mast lifting cylinder retracts, and the mast raising process is completed.

[0055] Furthermore, during the mast lowering process, the control method for the high / low tension switching structure includes:

[0056] v. When solenoid valve V11 is energized, the luffing winch switches to low tension mode;

[0057] vi. When the Y20B directional valve of the mast lifting cylinder is energized, the cylinder extends fully.

[0058] vii. The luffing winch closed pump P10 slowly increases the flow rate in the direction of rope winding. The luffing winch pulls the mast back and closes it to the extension cylinder. Then, the flow rate of the control pump P10 is increased to the maximum.

[0059] viii. When the Y20A reversing valve of the mast extension cylinder is energized, the mast begins to descend until it reaches the fully lowered state.

[0060] Furthermore, the design limit for the operating speed of the mast lifting cylinder is such that the resulting follow-up operating speed of the luffing winch cannot exceed the design speed of the luffing winch.

[0061] In a second aspect, the present invention provides a control method for a mobile crawler crane mast lifting hydraulic drive system, based on the mobile crawler crane mast lifting hydraulic drive system as described in the first aspect, comprising the following steps:

[0062] When the luffing winch is in working mode, keep it in high tension mode; when the luffing winch is in disassembly / assembly mode, switch it to low tension mode after the boom is lowered and supported.

[0063] Thirdly, the present invention provides an engineering machinery, including a mobile crawler crane mast lifting hydraulic drive system as described in the first aspect.

[0064] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0065] During the raising or lowering of the mast, the luffing winch is set to a small tension on the mast (enough to maintain the tension of the luffing wire rope and allow the mast to be pulled back within the disassembly / reassembly angle range). The mast will not be subjected to additional bending tension, and the mast structure can be effectively protected from damage due to overload or the risk of overload.

[0066] In assembly / disassembly mode, during mast lifting or lowering, the luffing winch switches to a pre-set low constant tension state. The operator only needs to control the speed of the mast lifting cylinder. The luffing winch automatically follows with low constant tension, greatly reducing control difficulty and the risk of system overload damage caused by human error.

[0067] During the mast raising or lowering process, there is no need to introduce actual hydraulic pressure for control. This eliminates the risk of overload caused by slow system response and operator reaction speed.

[0068] In installation mode, the manual and automatic control (one-button lifting) functions of the mast are combined, greatly simplifying the control mode and operation.

[0069] During the raising or lowering process, by reasonably setting the design parameters of the mast lifting cylinder and the interactive control logic of the luffing winch system, the operation of the mast system is relatively simple, whether manually or automatically controlled (one-button lifting). The operator does not need to observe the system pressure to adjust the operation process to avoid system overload. Attached Figure Description

[0070] Figure 1 This is a schematic diagram of an existing mast lifting cylinder.

[0071] Figure 2 This is a diagram of an open hydraulic system for a luffing winch;

[0072] Figure 3 This is a diagram showing the closed hydraulic system used in the luffing winch.

[0073] Figure 4 This is a schematic diagram of the interference distance.

[0074] In the diagram: M13: In the design of an open hydraulic system, the variable-amplitude winch hydraulic motor (Motor). The numbers are the component serial numbers for easy identification.

[0075] M14: In the design of a closed hydraulic system, a variable-amplitude winch hydraulic motor.

[0076] P20: Hydraulic pump for mast lifting system

[0077] V stands for Valve, and V13 is the safety protection relief valve for the closed-loop pump P10 in low constant tension operating mode. Detailed Implementation

[0078] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0079] In the description of this embodiment, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this embodiment and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this embodiment.

[0080] Example 1:

[0081] This embodiment provides a hydraulic drive system for lifting the mast of a mobile crawler crane, including a luffing winch and a mast lifting cylinder;

[0082] The variable-amplitude winch is equipped with a high / low tension switching structure;

[0083] The high-low tension switching structure is used to switch between the high tension mode and the low tension mode of the luffing winch. When the luffing winch is in working mode, the high-low tension switching structure keeps the luffing winch in high tension mode. When the luffing winch is in disassembly / assembly mode, after the boom is lowered and supported, the high-low tension switching structure switches the luffing winch to low tension mode.

[0084] Preferably, the luffing winch adopts an open hydraulic system;

[0085] The high / low tension switching structure includes a solenoid valve V15, a main relief valve V14, a pilot relief valve V16, a mast lifting cylinder control directional valve Y20B, a luffing winch directional valve Y11, and a luffing winch control pump P10.

[0086] The luffing winch control pump P10 is used to power the luffing winch drive hydraulic motor M13.

[0087] The luffing winch switching valve Y11 is used to control the rotation direction of the luffing winch.

[0088] The main relief valve V14 is used to limit the maximum pressure of the luffing motor M13, thereby controlling the tension of the hoisting wire rope.

[0089] Solenoid valve V15 is used to control the secondary pressure of the main relief valve V14. When solenoid valve V15 is closed, the maximum pressure of the main relief valve V14 is the high pressure set by its own spring. When solenoid valve V15 is powered on and opened, the maximum pressure of the main relief valve V14 is the low pressure set by the pilot relief valve V16.

[0090] Hydraulic pump P20 provides power to the mast lifting cylinder, and controls the extension and retraction of the mast lifting cylinder by controlling the reversing valve Y20.

[0091] When the luffing winch is in working mode, solenoid valve V15 is de-energized, and the luffing winch remains in high-tension mode. The maximum pressure of the luffing motor is set by the main relief valve V14. In disassembly / assembly mode, after the boom is lowered and supported, solenoid valve V15 is energized, the luffing winch switches to low-tension mode, and the pressure of the luffing motor's main relief valve V14 is limited to low-pressure mode by the pilot relief valve V16.

[0092] Preferably, the luffing winch adopts an open hydraulic system;

[0093] The high / low tension switching structure includes a solenoid valve V15, a main relief valve V14, a pilot relief valve V16, a mast lifting cylinder control directional valve Y20B, a luffing winch directional valve Y11, and a luffing winch control pump P10.

[0094] The luffing winch control pump P10 is used to power the luffing winch drive hydraulic motor M13.

[0095] The luffing winch switching valve Y11 is used to control the rotation direction of the luffing winch.

[0096] The main relief valve V14 is used to limit the maximum pressure of the luffing motor M13, thereby controlling the tension of the hoisting wire rope.

[0097] Solenoid valve V15 is used to control the secondary pressure of the main relief valve V14. When solenoid valve V15 is closed, the maximum pressure of the main relief valve V14 is the high pressure set by its own spring. When solenoid valve V15 is powered on and opened, the maximum pressure of the main relief valve V14 is the low pressure set by the pilot relief valve V16.

[0098] Hydraulic pump P20 provides power to the mast lifting cylinder, and controls the extension and retraction of the mast lifting cylinder by controlling the reversing valve Y20.

[0099] When the luffing winch is in working mode, solenoid valve V15 is de-energized, and the luffing winch remains in high-tension mode. The maximum pressure of the luffing motor is set by the main relief valve V14. In disassembly / assembly mode, after the boom is lowered and supported, solenoid valve V15 is energized, the luffing winch switches to low-tension mode, and the pressure of the luffing motor's main relief valve V14 is limited to low-pressure mode by the pilot relief valve V16.

[0100] The basic principle of this invention is that the mast's lifting and lowering processes are controlled by a lifting cylinder. The luffing winch's tension is limited to a level sufficient to tighten the wire rope while simultaneously pulling the mast back. This ensures that the tension exerted by the luffing winch on the mast remains at a relatively low limit, preventing overload of the mast and its cylinders and guaranteeing system safety.

[0101] A. The luffing winch adopts an open hydraulic system:

[0102] like Figure 2The hydraulic schematic diagram shows that the luffing winch adds a high / low tension switching function. In the luffing winch's operating mode, solenoid valve V15 is de-energized, and the luffing winch remains in high tension mode (the maximum pressure of the luffing motor is set by the main relief valve V14). In disassembly / assembly mode, after the boom is lowered and supported (the boom no longer needs tension from the luffing system), solenoid valve V15 is energized, and the luffing winch switches to low tension mode (the pressure of the luffing motor's main relief valve V14 is limited to low pressure mode by the pilot relief valve V16).

[0103] a) The mast raising process:

[0104] i. When solenoid valve V15 is energized, the luffing winch switches to low tension mode;

[0105] ii. Power on the reversing valve Y11A, and then slowly increase the flow rate of the luffing winch control pump P10 to 20%, so that the luffing winch wire rope is in a low tension state;

[0106] iii. When the Y20B control valve of the mast lifting cylinder is energized, the cylinder extends and the mast begins to be lifted.

[0107] iv. After the hydraulic cylinder is fully extended, the luffing winch reversing valve Y11A is de-energized; the mast is held by the luffing winch, and the hydraulic cylinder no longer bears the weight of the mast;

[0108] v. When the mast extension cylinder control directional valve Y20A is energized, the mast lifting cylinder retracts, and the mast raising process is completed.

[0109] b) The process of the mast falling:

[0110] i. When solenoid valve V15 is energized, the luffing winch switches to low tension mode;

[0111] ii. When the Y20B reversing valve of the mast lifting cylinder is energized, the cylinder extends fully;

[0112] iii. The reversing valve Y11A is energized, and then the flow rate of the luffing winch control pump P10 is slowly increased. The luffing winch pulls the mast back close to the extension cylinder. Then the flow rate of the luffing winch control pump P10 is increased to the maximum.

[0113] iv. When the Y20A reversing valve of the mast extension cylinder is energized, the mast begins to descend until it reaches the fully lowered state.

[0114] B. The luffing winch adopts a closed hydraulic system:

[0115] As shown in the hydraulic schematic below, the luffing winch adds a high / low tension switching function. In the luffing winch's operating mode, solenoid valve V11 is de-energized, and the luffing winch remains in high tension mode (the luffing closed-loop pump can output the system's maximum set pressure). In disassembly / assembly mode, after the boom is lowered and supported (the boom no longer needs tension from the luffing system), solenoid valve V11 is energized, and the luffing winch switches to low tension mode (the maximum output pressure of the luffing closed-loop pump is limited by the pilot valve relief valve V12).

[0116] a) The mast raising process:

[0117] i. When solenoid valve V11 is energized, the luffing winch switches to low tension mode;

[0118] ii. The flow rate of the closed-loop pump P10 with luffing winch is slowly increased to the maximum in the direction of rope winding, and the luffing winch wire rope is in a low tension state.

[0119] iii. When the Y20B control valve of the mast lifting cylinder is energized, the cylinder extends and the mast begins to be lifted.

[0120] iv. After the hydraulic cylinder is fully extended, the luffing winch control pump stops rope winding, and the pump displacement returns to zero. The mast is then held in place by the luffing winch, and the hydraulic cylinder no longer bears the weight of the mast.

[0121] v. When the mast extension cylinder control directional valve Y20A is energized, the mast lifting cylinder retracts, and the mast raising process is completed.

[0122] b) The process of the mast falling:

[0123] v. When solenoid valve V11 is energized, the luffing winch switches to low tension mode;

[0124] vi. When the Y20B directional valve of the mast lifting cylinder is energized, the cylinder extends fully.

[0125] vii. The luffing winch closed pump P10 slowly increases the flow rate in the direction of rope winding. The luffing winch pulls the mast back and closes it to the extension cylinder. Then, the flow rate of the control pump P10 is increased to the maximum.

[0126] viii. When the Y20A reversing valve of the mast extension cylinder is energized, the mast begins to descend until it reaches the fully lowered state.

[0127] c) Considerations for related issues when determining system parameters:

[0128] The following issues need to be considered during the system parameter design and matching process:

[0129] The luffing winch's follow-up speed, induced by the mast's lifting speed, must not exceed its design speed. Otherwise, the low constant tension function of the closed hydraulic system will fail due to overspeed during mast raising. Simultaneously, during mast lowering, if the mast falls too quickly, the luffing winch may not have enough time to reel in the rope, causing the wire rope to detach from the turntable pulley block. During mast lifting, the mast speed is controlled by the lifting cylinder, and the luffing winch maintains only a small tension on the mast. If the luffing winch's follow-up speed exceeds its design speed, the passive tension on the mast will increase due to overspeed, causing the lifting force of the lifting cylinder to exceed the mast's own strength limit, thus damaging the mast.

[0130] During the mast lifting process using hydraulic cylinders, acceleration must not be too rapid (the control system limits the cylinder acceleration). Due to the luffing winch's own rotational inertia, the tension in the wire rope will increase to a certain extent during passive acceleration. If the starting speed is too fast when the mast lifting begins, the mast will pull the luffing wire rope outward, applying excessive acceleration to the luffing winch. Because the winch system's rotational inertia is too large, excessive acceleration will cause the wire rope tension to rise, potentially damaging the mast.

[0131] During the raising or lowering of the mast, this invention, by reasonably setting the design parameters of the mast lifting cylinder and the interactive control logic of the luffing winch system, makes the operation of the mast system relatively simple, whether manually or automatically controlled (one-button lifting), without requiring the operator to observe the system pressure to adjust the operation process to avoid system overload.

[0132] Example 2:

[0133] This embodiment provides a control method for a mobile crawler crane mast lifting hydraulic drive system, based on the mobile crawler crane mast lifting hydraulic drive system as described in the first aspect, including the following steps:

[0134] When the luffing winch is in working mode, keep it in high tension mode; when the luffing winch is in disassembly / assembly mode, switch it to low tension mode after the boom is lowered and supported.

[0135] Example 3:

[0136] This embodiment provides an engineering machinery, including a mobile crawler crane mast lifting hydraulic drive system as described in Embodiment 1.

[0137] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature, and in the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0138] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0139] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0140] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0141] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention without departing from the principles and spirit of the present invention.

Claims

1. A hydraulic drive system for lifting the mast of a mobile crawler crane, characterized in that, Including luffing winch and mast lifting cylinder; The variable-amplitude winch is equipped with a high / low tension switching structure; The high-low tension switching structure is used to switch between the high tension mode and the low tension mode of the luffing winch. When the luffing winch is in working mode, the high-low tension switching structure keeps the luffing winch in high tension mode. When the luffing winch is in disassembly / assembly mode, after the boom is lowered and supported, the high-low tension switching structure switches the luffing winch to low tension mode. The luffing winch employs an open hydraulic system; The high / low tension switching structure includes a solenoid valve V15, a main relief valve V14, a pilot relief valve V16, a mast lifting cylinder control directional valve Y20, a luffing winch directional valve Y11, and a luffing winch control pump P10. The luffing winch control pump P10 is used to power the luffing winch drive hydraulic motor M13. The luffing winch switching valve Y11 is used to control the rotation direction and speed of the luffing winch; The main relief valve V14 is used to limit the maximum pressure of the luffing motor M13, thereby controlling the tension of the hoisting wire rope; Solenoid valve V15 is used to control the secondary pressure of main relief valve V14; when solenoid valve V15 is closed, the maximum pressure of main relief valve V14 is the high pressure set by its own spring; when solenoid valve V15 is powered on and opened, the maximum pressure of main relief valve V14 is the low pressure set by pilot relief valve V16. Hydraulic pump P20 is used to provide power to the mast lifting cylinder, and the extension and retraction of the mast lifting cylinder is controlled by controlling the reversing valve Y20; When the luffing winch is in working mode, solenoid valve V15 is de-energized, and the luffing winch remains in high tension mode. The maximum pressure of the luffing motor is set by the main relief valve V14. In disassembly / assembly mode, after the boom is lowered and supported, solenoid valve V15 is energized, the luffing winch switches to low tension mode, and the pressure of the luffing motor main relief valve V14 is limited to low pressure mode by the pilot relief valve V16.

2. The mobile crawler crane mast lifting hydraulic drive system according to claim 1, characterized in that, During the mast raising process, the control method of the high / low tension switching structure includes: When solenoid valve V15 is energized, the luffing winch switches to low tension mode. The reversing valve Y11A is energized, and then the flow rate of the luffing winch control pump P10 is slowly increased to 20%, so that the luffing winch wire rope is in a low tension state. When the Y20B control valve of the mast lifting cylinder is energized, the cylinder extends outward, and the mast begins to be lifted. After the hydraulic cylinder is fully extended, the luffing winch reversing valve Y11A is de-energized; the mast is held in place by the luffing winch, and the hydraulic cylinder no longer bears the weight of the mast. When the mast extension cylinder control valve Y20A is energized, the mast lifting cylinder retracts, and the mast raising process is completed.

3. The mobile crawler crane mast lifting hydraulic drive system according to claim 2, characterized in that, During the mast's descent, the control method for the high / low tension switching structure includes: When solenoid valve V15 is energized, the luffing winch switches to low tension mode. When the Y20B reversing valve of the mast lifting cylinder is energized, the cylinder extends fully. The reversing valve Y11A is energized, and then the flow rate of the luffing winch control pump P10 is slowly increased. The luffing winch pulls the mast back close to the extension cylinder. Then the flow rate of the luffing winch control pump P10 is increased to the maximum. When the Y20A reversing valve of the mast extension cylinder is energized, the mast begins to descend until it reaches the fully lowered position.

4. The mobile crawler crane mast lifting hydraulic drive system according to claim 1, characterized in that, The luffing winch employs a closed hydraulic system; The high and low tension switching structure includes a solenoid valve V11, a pilot relief valve V12, a relief valve V13, a mast lifting cylinder control reversing valve Y20, and a luffing winch reversing valve Y11. Solenoid valve V11, pilot relief valve V12, and relief valve V13 control the tension of the luffing winch wire rope; When the solenoid valve V11 is de-energized and closed, the luffing pump P10 drives the luffing motor M14, and the wire rope tension can reach the maximum tension designed by the system. When the solenoid valve V11 is powered on and opened, the pressure of the luffing winch pump P10 is limited to the low pressure set value of the overflow valve V12, thereby limiting the luffing winch wire rope to a low tension state. The relief valve V13 is used to provide pressure protection based on the characteristics of the luffing winch pump P10 by limiting the pressure of the variable mechanism of the luffing winch pump P10. In the luffing winch operating mode, the solenoid valve V11 is de-energized, the luffing winch remains in high tension mode, and the luffing closed pump can output the maximum pressure set by the system; in the disassembly and assembly mode, after the boom is lowered and supported, the solenoid valve V11 is energized, the luffing winch switches to low tension mode, and the maximum pressure output by the luffing closed pump is limited by the pilot relief valve V12.

5. The mobile crawler crane mast lifting hydraulic drive system according to claim 4, characterized in that, During the mast raising process, the control method of the high / low tension switching structure includes: When solenoid valve V11 is energized, the luffing winch switches to low tension mode. The luffing winch closed pump P10 slowly increases the flow rate to the maximum in the direction of rope winding, and the luffing winch wire rope is in a low tension state. When the Y20B control valve of the mast lifting cylinder is energized, the cylinder extends outward, and the mast begins to be lifted. After the hydraulic cylinder is fully extended, the luffing winch control pump stops rope winding control, and the pump displacement returns to zero; the mast is held in place by the luffing winch, and the hydraulic cylinder no longer bears the weight of the mast; When the mast extension cylinder control valve Y20A is energized, the mast lifting cylinder retracts, and the mast raising process is completed.

6. The mobile crawler crane mast lifting hydraulic drive system according to claim 5, characterized in that, The control method for the high / low tension switching structure during the mast descent process includes: When solenoid valve V11 is energized, the luffing winch switches to low tension mode. When the Y20B reversing valve of the mast lifting cylinder is energized, the cylinder extends fully. The luffing winch closed pump P10 slowly increases the flow rate in the direction of rope winding. The luffing winch pulls the mast back and closes it to the extension cylinder. Then, the flow rate of the control pump P10 is increased to the maximum. When the Y20A reversing valve of the mast extension cylinder is energized, the mast begins to descend until it reaches the fully lowered position.

7. The mobile crawler crane mast lifting hydraulic drive system according to claim 1, characterized in that, The operating speed of the luffing winch caused by the operation of the mast lifting cylinder must not exceed the design speed of the luffing winch.

8. A control method for a hydraulic drive system for lifting the mast of a mobile crawler crane, characterized in that, Based on the mobile crawler crane mast lifting hydraulic drive system as described in any one of claims 1-7, the system includes the following steps: When the luffing winch is in working mode, keep it in high tension mode; when the luffing winch is in disassembly / assembly mode, switch it to low tension mode after the boom is lowered and supported.

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