Double-flow control balance valve, control method and engineering machinery

Abstract

The invention discloses a double-flow control balance valve in the technical field of engineering machinery, which comprises a pilot oil port K and a throttle valve core used for controlling the reverse opening of the double-flow control balance valve, and the pilot oil port K inputs pilot oil to act on the throttle valve core and is used for controlling the opening degree of the throttle valve core. The pressure reducing valve and the reversing valve are arranged between the pilot oil port K and the balance valve in parallel; the output pressure value of the pressure reducing valve is lower than the maximum pilot pressure value received by the pilot oil port K; the reversing valve is used for adjusting the maximum value of the opening degree of the throttling valve element. Through balance valve double-flow control, the maximum variable-amplitude falling speed can be freely switched according to requirements, a pressure reducing valve and an electromagnetic reversing valve are arranged on a balance valve pilot oil way in parallel, and under the condition that the maximum pilot pressure of the balance valve is not changed, balance valve double-flow control can be achieved according to whether the electromagnetic reversing valve is powered on or not; and therefore, free switching of the maximum variable-amplitude falling speed is realized, and the control principle is simple.

Description

Technical Field

[0001] The present invention relates to a dual-flow control balancing valve, a control method and engineering machinery, and belongs to the technical field of engineering machinery. Background Art

[0002] The hydraulic components of a crane's luffing system usually include a hydraulic oil pump, a multi-way valve, a luffing cylinder, and a balancing valve. The multi-way valve is a directional valve that controls the luffing's rising and falling movements, and the balancing valve is a key component that maintains the luffing angle unchanged and adjusts the luffing's lowering speed.

[0003] Currently, the lowering methods of crane luffing systems are generally divided into powered lowering and gravity lowering. Powered lowering relies primarily on the high-pressure oil output of the hydraulic pump to retract the rod chamber of the luffing cylinder to perform the luffing boom movement. The maximum luffing lowering speed is related to the engine speed and is primarily used on small-tonnage cranes. Gravity lowering is primarily used on medium- to large-tonnage cranes and has a wide range of applications. It relies primarily on the weight of the luffing boom and the load to retract the cylinder. A pilot handle is used to control the opening of the luffing counterbalance valve to achieve luffing speed control. The luffing lowering speed is independent of engine speed and is limited by the flow rate of the counterbalance valve, resulting in a narrow controllable range. To ensure work efficiency and hoisting safety during boom luffing, the dropping speed generally needs to be low for heavy loads and high for light loads, which is a great test of the operator's skills. Different users have different requirements for the boom luffing dropping speed. The existing boom luffing system's gravity dropping method has a single dropping speed, which cannot meet the needs of different users and working conditions. It is usually necessary to manually adjust the opening pressure of the balancing valve, but the adjusted speed still cannot meet all working conditions, and may also cause faults such as oil leakage and internal leakage.

[0004] The dual flow control of the balancing valve in the existing technology has high energy consumption and poor product applicability and versatility. In addition, the dual flow control of the balancing valve in the existing technology adopts two technical routes: variable pilot pressure and variable control damping network. The variable pilot pressure is directly related to the engine speed. When the balancing valve is controlled to have a large flow opening, the engine has high energy consumption at high speed. The variable control damping network affects the control characteristics, response characteristics, opening stability, etc. of the balancing valve, and cannot have good adaptability to different vehicle models. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the prior art and provide a dual flow control balancing valve, a control method and engineering machinery.

[0006] In order to solve the above technical problems, the present invention is implemented by adopting the following technical solutions.

[0007] In a first aspect, the present invention discloses a dual-flow control balancing valve, comprising: a pilot oil port K, and a throttle valve core for controlling the reverse opening of the dual-flow control balancing valve. The pilot oil port K inputs pilot oil to act on the throttle valve core of the balancing valve to control the opening size of the throttle valve core. It also includes a pressure reducing valve and a reversing valve arranged in parallel between the pilot oil port K and the balancing valve; The output pressure value of the pressure reducing valve is lower than the maximum pilot pressure value received by the pilot oil port K; The reversing valve is used to adjust the maximum opening of the throttle valve core.

[0008] Furthermore, it also includes a filter screen arranged at the pilot oil port K, and the pilot oil flows to the throttle valve core, the pressure reducing valve and the reversing valve through the filter screen.

[0009] Furthermore, it also includes a control damper arranged after the parallel pressure reducing valve and the reversing valve.

[0010] Furthermore, it also includes: a bypass damper, one end of which is connected between the control damper and the throttle valve core, and the other end of which is connected to the oil drain port L.

[0011] Furthermore, it also includes a one-way valve core, which is used to control the forward opening of the dual-flow control balancing valve and prevent the working oil from flowing in the reverse direction when the dual-flow control balancing valve is not working.

[0012] Furthermore, the reversing valve is an electromagnetic reversing valve, which is closed when power is lost and opened when power is supplied. The opening of the throttle valve core is increased or decreased by controlling the power supply and de-powering of the electromagnetic reversing valve.

[0013] Furthermore, the reversing valve is a normally open hydraulically controlled reversing valve, which is provided with a pressure reversing valve value, and is used for driving the hydraulically controlled reversing valve to reverse when the hydraulic oil pressure input into the working oil port B of the balancing valve increases to the pressure reversing valve value. The pilot oil output by the pilot handle does not pass through the hydraulically controlled reversing valve, but only drives the throttle valve core to move through the pressure reducing valve.

[0014] In a second aspect, the present invention further discloses a control method for the dual flow control balancing valve according to the first aspect, wherein the reversing valve is an electromagnetic reversing valve, comprising the following steps: Control the forward conduction and luffing action of the balancing valve, including: The pilot handle is used to output pilot pressure to control the multi-way valve to switch to one side, controlling the working oil source to be connected to the working oil port A of the balancing valve through the high-pressure oil port P of the multi-way valve. The high-pressure oil source automatically opens the one-way valve core of the balancing valve and enters the rodless chamber of the luffing cylinder through the working oil port B of the balancing valve, driving the piston rod of the luffing cylinder to extend. The balancing valve is the dual-flow control balancing valve. Control the reverse conduction and luffing action of the balancing valve, including: The pilot handle outputs pilot pressure to control the multi-way valve to switch to the other side, controlling the connection between the return oil port T of the multi-way valve and the working oil port A of the balancing valve. The pilot handle outputs pilot pressure and controls the reversal of the throttle valve core at the same time. The throttle valve core opening increases with the increase of pilot pressure, controlling the reverse opening of the balancing valve, so that the rodless chamber of the variable amplitude cylinder is connected to the return oil port T of the multi-way valve through the throttle valve core that is connected in the opposite direction. When heavy load working condition or long arm working condition requires slow luffing and falling speed, the control solenoid reversing valve shall not be energized and the throttle valve core shall be freely adjusted within the first maximum opening, limited by the output pressure of the pressure reducing valve; When the load is light or a fast falling speed is required, the electromagnetic reversing valve is energized, the pilot pressure is not limited by the output pressure of the pressure reducing valve, and the throttle valve core is freely adjusted within the second maximum opening, and the second maximum opening is greater than the first maximum opening; Control the load holding action of the balancing valve, including: When the pilot handle is not in action, the high-pressure oil source in the working oil port B of the balancing valve connected to the rodless chamber of the luffing cylinder is blocked by the one-way valve core and the throttle valve core and is not connected to the working oil port A of the balancing valve.

[0015] In a third aspect, the present invention further discloses a control method for the dual-flow control balancing valve according to the first aspect, characterized in that the reversing valve is a normally open hydraulically controlled reversing valve, and the hydraulically controlled reversing valve is provided with a pressure reversing threshold value, comprising the following steps: When the pressure of the working oil port B of the balancing valve is lower than the pressure reversing valve value, the pilot handle is used to output the pilot pressure to drive the throttle valve core to move through the hydraulically controlled reversing valve. The opening of the throttle valve core increases with the increase of the pilot pressure, and the throttle valve core is controlled to be freely adjusted within the first maximum opening; When the pressure of the working oil port B of the balancing valve reaches the pressure reversing valve value, the pressure of the working oil port B of the balancing valve drives the hydraulically controlled reversing valve to reverse, and the pilot oil output by the pilot handle does not pass through the hydraulically controlled reversing valve, but only drives the throttle valve core to move through the pressure reducing valve, thereby controlling the throttle valve core to freely adjust within the second maximum opening, and the second maximum opening is smaller than the first maximum opening.

[0016] In a fourth aspect, the present invention further discloses an engineering machine, comprising the dual flow control balancing valve described in the first aspect.

[0017] The beneficial effects achieved by the present invention are: The present invention realizes free switching of the maximum speed of variable amplitude falling according to demand through dual flow control of the balancing valve: a pressure reducing valve and an electromagnetic reversing valve are arranged in parallel in the pilot oil circuit of the balancing valve. When the maximum pilot pressure of the balancing valve remains unchanged, the dual flow control of the balancing valve can be realized according to whether the electromagnetic reversing valve is energized, thereby realizing free switching of the maximum speed of variable amplitude falling, and the control principle is simple. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the principle of a dual flow control balancing valve corresponding to Example 1; Figure 2 This is a schematic diagram of the principle of a dual flow control balancing valve corresponding to Example 2; Figure 3 It is a schematic diagram of the amplitude variation principle of a dual flow control balancing valve corresponding to Example 1 of the embodiment.

[0019] In the figure: 1. Pilot handle; 2. Balancing valve; 3. Oil tank; 4. Luffing cylinder; 5. Multi-way valve; 21. Solenoid reversing valve; 22. Filter; 23. Pressure reducing valve; 24. Control damping; 25. Bypass damping; 26. Throttle valve core; 27. Check valve core; 28. Hydraulic control reversing valve. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0022] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0023] Example 1, as Figure 1 As shown, this embodiment introduces a dual-flow control balancing valve, including: a pilot oil port K, a throttle valve core 26 for controlling the reverse opening of the dual-flow control balancing valve, the pilot oil input by the pilot oil port K acts on the flat throttle valve core 26 to control the opening size of the throttle valve core 26, and also includes a pressure reducing valve 23 and a reversing valve arranged in parallel between the pilot oil port K and the balancing valve; the output pressure value of the pressure reducing valve 23 is lower than the maximum pilot pressure value received by the pilot oil port K; the reversing valve is used to adjust the maximum value of the opening of the throttle valve core 26.

[0024] It also includes a filter screen 22 provided at the pilot oil port K, through which the pilot oil flows to the throttle valve core 26, the pressure reducing valve 23 and the reversing valve.

[0025] It also includes a control damper 24 (d1) and a bypass damper 25 (d2). The control damper 24 is arranged after the parallel pressure reducing valve 23 and the reversing valve; one end of the bypass damper 25 is connected between the control damper 24 and the throttle valve core 26, and the other end is connected to the oil drain port L.

[0026] The dual flow control balancing valve further includes a one-way valve core 27 , which is used to control the forward opening of the dual flow control balancing valve and prevent the working oil from flowing in the reverse direction when the dual flow control balancing valve is not working.

[0027] A pressure reducing valve 23 and an electromagnetic reversing valve 21 are arranged in parallel between the filter screen 22 and the control damper 24 in the balancing valve 2 (dual flow control balancing valve). The output pressure value set by the pressure reducing valve 23 is lower than the maximum pilot pressure value received by the pilot oil port K of the balancing valve. The electromagnetic reversing valve 21 is a normally closed two-position two-way electromagnetic valve. When the maximum pilot pressure received by the pilot port K of the balancing valve 2 is constant, the opening of the throttle valve core 26 can be increased or decreased by energizing or de-energizing the electromagnetic reversing valve 21, thereby realizing dual flow control of large flow and small flow of the balancing valve 2, and then realizing free switching of the maximum falling speed of the variable amplitude.

[0028] Example 2 is based on the same inventive concept as Example 1. Figure 2As shown, this embodiment introduces a dual-flow control balancing valve. The difference from Example 1 is that the electromagnetic reversing valve 21 is replaced by a normally open hydraulically controlled reversing valve 28. The hydraulically controlled reversing valve 28 is provided with a pressure reversing valve value, which is used to drive the hydraulically controlled reversing valve 28 to reverse when the hydraulic oil pressure input to the working oil port B of the balancing valve increases to the pressure reversing valve value. The pilot oil output by the pilot handle 1 does not pass through the hydraulically controlled reversing valve 28, but only drives the throttle valve core 26 to operate through the pressure reducing valve 23, thereby automatically achieving heavy-load and low-speed working requirements.

[0029] Example 3, as Figure 1 and Figure 2 As shown, based on the same inventive concept as Example 1, this embodiment introduces a control method for a dual flow control balancing valve, including the following steps: Working State 1: Balancing valve 2 (i.e., the dual-flow control balancing valve in Example 1) is forward-conducting and luffing is actuated. Pilot handle 1 outputs pilot pressure to control the direction of multi-way valve 5, switching it to one side. This controls the flow of working oil through high-pressure port P of multi-way valve 5 and working port A of balancing valve 2. The high-pressure oil automatically opens the check valve spool 27 of balancing valve 2 and enters the rodless chamber of luffing cylinder 4 through working port B of the balancing valve, driving the piston rod of luffing cylinder 4 to extend, achieving luffing control.

[0030] Working state 2: The balance valve 2 is reversely conducted and the boom is lowered. The pilot handle 1 outputs pilot pressure to control the multi-way valve 5 to switch to the other side, and controls the return oil port T of the multi-way valve 5 to be connected with the working oil port A of the balance valve 2. The pilot handle 1 outputs pilot pressure and drives the throttle valve core 26 of the balance valve 2 to switch at the same time. The opening of the throttle valve core 26 increases with the increase of the pilot pressure, and controls the balance valve 2 to open in the reverse direction, so that the rodless cavity of the boom cylinder 4 is connected with the return oil port T of the multi-way valve 5 through the balance valve 2, realizing the boom lowering action. The boom lowering speed is directly related to the opening of the throttle valve core 26 in the balance valve 2. When the crane is lifting heavy loads or the long arm and long working conditions require a slow boom lowering speed, the electromagnetic reversing valve 21 shall not be energized and is affected by The output pressure of the pressure reducing valve 23 is limited, and the throttle valve core 26 can be controlled to be freely adjusted within the first maximum opening. When the working condition is light load or a fast falling speed is required, the electromagnetic reversing valve 21 is controlled to be energized, and the pilot pressure is not affected by the pressure reducing valve 23. The throttle valve core 26 can be controlled to be freely adjusted within the second maximum opening, and the second maximum opening of the throttle valve core 26 is greater than the first maximum opening, realizing the dual flow control of the balancing valve 2, and easily achieving the heavy load low speed and light load high speed variable amplitude falling speed requirements. Therefore, the operator can choose whether to energize the electromagnetic reversing valve 21 according to the load and variable amplitude falling speed requirements, and realize the free switching of the maximum variable amplitude falling speed.

[0031] Working state three: load holding. When the pilot handle 1 is not actuated, the high-pressure oil source in the working oil port B of the balancing valve 2, which is connected to the rodless chamber of the luffing cylinder 4, is blocked by the one-way valve core 27 and the throttle valve core 26 and cannot communicate with the working oil port A, achieving load holding.

[0032] Example 4, as Figure 3 As shown, based on the same inventive concept as Example 2, this embodiment introduces a control method for a dual flow control balancing valve, including the following steps: Working State 1: The forward conduction and luffing start operations of balancing valve 2 (i.e., the dual-flow control balancing valve in Example 1) are the same as those in Example 3. Pilot handle 1 outputs pilot pressure to control the switching of multi-way valve 5 to one side, controlling the flow of working oil through high-pressure port P of multi-way valve 5 and working port A of balancing valve 2. The high-pressure oil automatically opens the one-way valve core 27 of balancing valve 2 and enters the rodless chamber of luffing cylinder 4 through working port B of the balancing valve, driving the piston rod of luffing cylinder 4 to extend, thus achieving luffing start control.

[0033] Working state two: the balancing valve 2 is reversely conducted and the boom-drop action occurs. When the crane is operating under light load conditions, the pressure of the working oil port B of the balancing valve 2 does not reach the set value of the hydraulically controlled reversing valve 28. The pilot handle 1 outputs the pilot pressure to control the multi-way valve 5 to reverse to the other side, and controls the return oil port T of the multi-way valve 5 to be conducted with the working oil port A of the balancing valve 2. The pilot handle 1 outputs the pilot oil source and is simultaneously connected with the pilot oil port K of the balancing valve 2. The throttle valve core 26 of the balancing valve 2 is driven to reverse through the pressure reducing valve 23 and the hydraulically controlled reversing valve 28. The opening of the throttle valve core 26 increases with the increase of the pilot pressure. The throttle valve core 26 is controlled to be freely adjusted and controlled within the first maximum opening. The balancing valve 2 is opened in the reverse direction, so that the rodless chamber of the boom-drop cylinder 4 is conducted with the return oil port T of the multi-way valve 5 through the balancing valve 2, and the boom-drop is achieved. action, the boom lowering speed is directly related to the opening of the throttle valve core 26 in the balancing valve 2; when the crane is operating under heavy load conditions, the pressure of the working oil port B of the balancing valve 2 reaches the set value of the hydraulically controlled reversing valve, and the pressure of the working oil port B of the balancing valve 2 drives the hydraulically controlled reversing valve 28 to reverse, and the pilot oil output by the pilot handle 1 does not pass through the hydraulically controlled reversing valve 28, but only drives the throttle valve core 26 to move through the pressure reducing valve 23, controlling the throttle valve core 26 to freely adjust within the second maximum opening, and the second maximum opening is smaller than the first maximum opening, realizing automatic switching of the boom lowering speed under heavy load conditions of boom length variation, and the balancing valve 2 can automatically switch between two flow control modes according to the pressure in the rodless chamber of the boom cylinder 4, realizing dual flow path control.

[0034] Working state three: load holding, which is the same as embodiment 3. When the pilot handle 1 is not actuated, the high-pressure oil source in the working oil port B of the balancing valve 2 connected to the rodless chamber of the luffing cylinder 4 is blocked by the one-way valve core 27 and the throttle valve core 26 and cannot communicate with the working oil port A, thus achieving load holding.

[0035] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0036] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0037] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0038] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0039] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A dual flow control balancing valve, comprising: The pilot oil port K is used to control the throttle valve core (26) of the dual flow control balancing valve to open in reverse. The pilot oil input into the pilot oil port K acts on the throttle valve core (26) to control the opening size of the throttle valve core (26). It is characterized in that: It also includes a pressure reducing valve (23) and a reversing valve arranged in parallel between the pilot oil port K and the throttle valve core (26); The output pressure value of the pressure reducing valve (23) is lower than the maximum pilot pressure value received by the pilot oil port K; The reversing valve is used to adjust the maximum opening value of the throttle valve core (26).

2. The dual flow control balancing valve according to claim 1, characterized in that: It also includes a filter screen (22) arranged at the pilot oil port K, and the pilot oil flows through the filter screen (22) to the throttle valve core (26), the pressure reducing valve (23) and the reversing valve.

3. The dual flow control balancing valve according to claim 2, characterized in that: It also includes a control damper (24) arranged after the parallel pressure reducing valve (23) and the reversing valve.

4. The dual flow control balancing valve according to claim 3, characterized in that: Also includes: A bypass damper (25), one end of which is connected between the control damper (24) and the throttle valve core (26), and the other end of which is connected to the oil drain port L.

5. The dual flow control balancing valve according to claim 1, characterized in that: It also includes a one-way valve core (27), which is used to control the forward opening of the dual-flow control balancing valve and prevent the working oil from flowing in the reverse direction when the dual-flow control balancing valve is not working.

6. The dual flow control balancing valve according to claim 1, characterized in that: The reversing valve is an electromagnetic reversing valve (21), which is closed when power is lost and opened when power is gained. The opening of the throttle valve core (26) is increased or decreased by controlling the power gain and power loss of the electromagnetic reversing valve (21).

7. The dual flow control balancing valve according to claim 1, characterized in that: The reversing valve is a normally open hydraulically controlled reversing valve (28). The hydraulically controlled reversing valve (28) is provided with a pressure reversing valve value. When the pressure of the hydraulic oil inputted into the working oil port B of the balancing valve increases to the pressure reversing valve value, the hydraulic oil at the working oil port B drives the hydraulically controlled reversing valve (28) to reverse direction. The pilot oil outputted by the pilot handle (1) does not pass through the hydraulically controlled reversing valve (28), but only drives the throttle valve core (26) to operate through the pressure reducing valve (23).

8. A control method for a dual flow control balancing valve according to any one of claims 1 to 5, characterized in that: The reversing valve is a solenoid reversing valve (21), comprising the following steps: Control the forward conduction and amplitude-changing action of the balancing valve (2), including: The pilot handle (1) is used to output the pilot pressure to control the multi-way valve (5) to switch to one side, thereby controlling the working oil source to be connected to the working oil port A of the balance valve (2) through the high-pressure oil port P of the multi-way valve (5). The high-pressure oil source automatically opens the one-way valve core (27) of the balance valve (2) and enters the rodless chamber of the variable amplitude oil cylinder (4) through the working oil port B of the balance valve (2), thereby driving the piston rod of the variable amplitude oil cylinder (4) to extend. The balance valve (2) is the dual-flow control balance valve. Control the reverse conduction and luffing action of the balancing valve (2), including: The pilot handle (1) is used to output the pilot pressure to control the multi-way valve (5) to switch to the other side, thereby controlling the oil return port T of the multi-way valve (5) to be connected to the working oil port A of the balance valve (2). The pilot handle (1) outputs the pilot pressure and simultaneously controls the switching of the throttle valve core (26). The opening of the throttle valve core (26) increases as the pilot pressure increases, thereby controlling the reverse opening of the balance valve (2), so that the rodless chamber of the variable amplitude oil cylinder (4) is connected to the oil return port T of the multi-way valve (5) through the throttle valve core (26) that is connected in the opposite direction. When the heavy load working condition or the long arm working condition requires the luffing and falling speed to be slow, the control electromagnetic reversing valve (21) shall not be energized, and the throttle valve core (26) shall be controlled to be freely adjusted within the first maximum opening by the output pressure of the pressure reducing valve (23); When the load is light or a fast falling speed is required, the electromagnetic reversing valve (21) is energized, the pilot pressure is not limited by the output pressure of the pressure reducing valve (23), and the throttle valve core (26) is controlled to be freely adjusted within the second maximum opening, and the second maximum opening is greater than the first maximum opening; Control the load holding action of the dual flow control balancing valve (2), including: When the pilot handle (1) is not in motion, the high-pressure oil source in the working oil port B of the balancing valve (2) connected to the rodless chamber of the luffing cylinder (4) is blocked by the one-way valve core (27) and the throttle valve core (26) and is not connected to the working oil port A of the balancing valve (2).

9. A control method for a dual flow control balancing valve according to any one of claims 1 to 5, characterized in that: The reversing valve is a normally open hydraulically controlled reversing valve (28), and the hydraulically controlled reversing valve (28) is provided with a pressure reversing valve value, comprising the following steps: When the pressure of the working oil port B of the balancing valve (2) is lower than the pressure reversing valve value, the pilot handle (1) outputs the pilot pressure to drive the throttle valve core (26) to operate through the hydraulic control reversing valve (28), and the opening of the throttle valve core (26) increases as the pilot pressure increases, and the throttle valve core (26) is controlled to be freely adjusted within the first maximum opening; When the pressure of the working oil port B of the balancing valve (2) reaches the pressure reversing valve value, the pressure of the working oil port B of the balancing valve (2) drives the hydraulic control reversing valve (28) to reverse, and the pilot oil output by the pilot handle (1) does not pass through the hydraulic control reversing valve (28), but only drives the throttle valve core (26) to move through the pressure reducing valve (23), thereby controlling the throttle valve core (26) to freely adjust within a second maximum opening, and the second maximum opening is smaller than the first maximum opening.

10. An engineering machine, characterized in that: The invention comprises the dual flow control balancing valve according to any one of claims 1 to 7.

Images