Hydraulic self-weight control system and aerial work vehicle

Abstract

The utility model discloses a kind of hydraulic self-weight control system and aerial work vehicle. Hydraulic self-weight control system includes oil cylinder and oil circuit;Oil cylinder includes rod cavity and rodless cavity;Oil circuit is connected to oil cylinder, including active power oil circuit and emergency control oil circuit, and two-position two-way switch valve is set on active power oil circuit;Active power oil circuit includes first oil circuit and second oil circuit, and first oil circuit is used to supply oil to rodless cavity, to control jib boom amplitude rise or stretch out, and second oil circuit is used to control oil from the outflow in rodless cavity, to control jib boom self-weight amplitude drop or retract;Proportional solenoid valve is set on second oil circuit;Emergency control oil circuit is independently set relative to active power oil circuit, and control jib boom emergency self-weight amplitude drop or retract;Emergency control oil circuit is provided with balance valve. When active power oil circuit fails, emergency control oil circuit can be opened by balance valve, ensure jib boom self-weight amplitude drop or retract, thereby reduce potential safety hazard, improve the safety of aerial work vehicle.

Description

Technical Field

[0001] This utility model relates to the field of engineering machinery technology, and in particular to a hydraulic self-weight control system and an aerial work platform. Background Technology

[0002] Currently, aerial work platforms typically use balance valves to achieve smooth control of boom luffing or extension. Using a balance valve relies on an oil pump in the main power system for oil supply. Through the control of the hydraulic valve assembly, a pilot oil circuit is drawn from the main oil circuit to open the balance valve, thereby enabling the boom luffing or extension movement.

[0003] In existing technologies, when the main power system malfunctions (such as valve jamming or main pump failure), the aerial work platform enters an emergency working state. At this time, the emergency pump needs to operate continuously at high pressure, supplying oil to the rod chamber of the hydraulic cylinder to allow the boom to be lowered or retracted. However, for high-altitude vehicles or equipment using smaller emergency pumps, the high-pressure, high-flow-rate oil supply leads to rapid oil consumption. Therefore, there is a safety risk that the boom cannot be fully lowered or retracted in an emergency, potentially causing serious safety hazards. Utility Model Content

[0004] To solve the above-mentioned technical problems, the purpose of this utility model is to provide a hydraulic self-weight control system and an aerial work platform.

[0005] The technical solution provided by this utility model is as follows:

[0006] A hydraulic self-weight control system, comprising:

[0007] Hydraulic cylinder, including rod chamber and rodless chamber;

[0008] The hydraulic circuit, connected to the hydraulic cylinder, includes a main power hydraulic circuit and an emergency control hydraulic circuit. The main power hydraulic circuit is equipped with a two-position two-way switching valve. The main power hydraulic circuit includes a first hydraulic circuit and a second hydraulic circuit. The first hydraulic circuit is used to supply oil to the rodless chamber to control the boom's luffing or extension. The second hydraulic circuit is used to control the flow of oil out of the rodless chamber to control the boom's weight-based luffing or retraction. A proportional solenoid valve is installed on the second hydraulic circuit. The emergency control hydraulic circuit is independently set relative to the main power hydraulic circuit and controls the boom's emergency weight-based luffing or retraction. A balance valve is installed on the emergency control hydraulic circuit.

[0009] Furthermore, the hydraulic self-weight control system also includes:

[0010] tank;

[0011] The first check valve has its inlet connected to the return oil circuit of the oil circuit and its outlet connected to the oil tank.

[0012] A second check valve is installed in the emergency control oil circuit. The inlet of the second check valve is connected to the balance valve, and the outlet of the second check valve is connected to the return oil circuit of the oil circuit.

[0013] A third check valve is installed in the first oil circuit. The oil inlet of the third check valve is connected to the oil outlet of the main pump, and the oil outlet of the third check valve is connected to the two-position two-way switch valve.

[0014] Furthermore, the hydraulic self-weight control system also includes a hydraulically controlled check valve, which is disposed in the oil outlet or oil supply line of the rod chamber;

[0015] When the first oil circuit controls the boom to rise or extend, the rod chamber, the hydraulic check valve and the first check valve are connected in sequence to control the oil to flow from the rod chamber to the oil tank.

[0016] When the second oil circuit controls the boom to descend or retract under its own weight, the proportional solenoid valve, the hydraulic check valve and the rod chamber are connected in sequence, allowing oil to be replenished to the rod chamber.

[0017] When the emergency control oil circuit controls the boom to descend or retract under emergency self-weight, the second check valve, the hydraulic check valve, and the rod chamber are connected in sequence, allowing oil to be replenished to the rod chamber.

[0018] Furthermore, when the first oil circuit controls the boom to rise or extend, the two-position two-way switch valve is in the left position, and the third check valve, the two-position two-way switch valve and the rodless chamber are connected in sequence, controlling the oil to flow from the main pump outlet to the rodless chamber;

[0019] When the second oil circuit controls the boom to descend or retract due to its own weight, the two-position two-way switch valve is energized and in the right position. The rodless chamber, the two-position two-way switch valve, and the proportional solenoid valve are connected in sequence, controlling the oil to flow from the rodless chamber to the proportional solenoid valve.

[0020] Furthermore, a compensation valve is also provided in the second oil circuit. The oil outlet of the proportional solenoid valve is connected to the oil inlet of the compensation valve, and the oil outlet of the compensation valve is connected to the hydraulic control check valve and the first check valve, respectively.

[0021] Furthermore, a main force pilot oil circuit is connected between the oil outlet of the third check valve and the oil inlet of the two-position two-way switch valve. A portion of the oil flowing out of the oil outlet of the third check valve flows along the main force pilot oil circuit to the hydraulic control check valve to open the hydraulic control check valve.

[0022] Furthermore, the emergency control oil circuit is connected to an emergency pilot oil circuit at the balance valve. The emergency pilot oil circuit is externally connected to an emergency pump. The emergency pump drives the oil to flow along the emergency pilot oil circuit to the balance valve to open the balance valve.

[0023] Furthermore, a damping orifice with a diameter of 0.6 mm is provided on the emergency pilot oil line.

[0024] Furthermore, a damping orifice with a diameter of 0.8 mm is provided between the oil inlet of the second one-way valve and the oil outlet of the balance valve.

[0025] On the other hand, this utility model also provides an aerial work platform vehicle, including the hydraulic self-weight control system described in any of the above embodiments.

[0026] Compared with the prior art, the hydraulic self-weight control system and aerial work platform provided by this utility model embodiment have at least the following technical effects:

[0027] The hydraulic self-weight control system includes a cylinder and an oil circuit. The cylinder includes a rod chamber and a rodless chamber. The oil circuit, connected to the cylinder, includes a main power circuit and an emergency control circuit. The main power circuit is equipped with a two-position, two-way switching valve. The main power circuit includes a first circuit and a second circuit. The first circuit supplies oil to the rodless chamber to control the boom's luffing or extension, while the second circuit controls the flow of oil out of the rodless chamber to control the boom's self-weight luffing or retraction. A proportional solenoid valve is installed on the second circuit. The emergency control circuit is independently set up relative to the main power circuit and is used to control the boom's emergency self-weight luffing or retraction when the main power circuit fails. A balance valve is installed in the emergency control circuit. This design allows the emergency control circuit and the main power circuit to be set up independently. Under normal operating conditions, the main power circuit controls the boom's self-weight luffing or retraction via the two-position, two-way switching valve and the proportional solenoid valve. The emergency control circuit controls the boom's emergency self-weight luffing or retraction by opening the balance valve. In the event of a main power hydraulic circuit failure (such as a stuck valve or main pump malfunction), there is no need for the emergency pump to continuously supply high-pressure hydraulic fluid to the rod chamber of the cylinder. Instead, the emergency pump only needs to supply a small amount of pilot oil to open the balance valve in the emergency control hydraulic circuit. This allows for weight-based lowering or retraction of the boom, ensuring the boom is fully lowered or retracted, thereby reducing potential safety hazards and improving the safety of the aerial work platform. Furthermore, because the balance valve in the emergency control hydraulic circuit only requires a small flow of pilot oil to open, its energy consumption is low, extending the service life of the emergency pump and making it more energy-efficient, thus reducing operating costs. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the hydraulic self-weight control system according to an embodiment of the present invention.

[0030] Reference numerals: 10, hydraulic cylinder; 20, two-position two-way switch valve; 30, proportional solenoid valve; 40, balance valve; 50, first check valve; 60, second check valve; 70, third check valve; 80, hydraulically controlled check valve; 90, compensation valve; 100, pressure sensor. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solutions of this utility model, the technical solutions in the embodiments of this utility model will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0032] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly set on the other component; when a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to the other component.

[0033] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" 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 utility model 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 utility model.

[0034] 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. In the description of this utility model, "a plurality of" or "several" means two or more, unless otherwise explicitly specified.

[0035] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings of this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which this utility model can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and purposes that this utility model can produce, should still fall within the scope of the technical content disclosed in this utility model.

[0036] Please see the appendix Figure 1 As shown, one embodiment of this utility model provides a hydraulic self-weight control system, including a cylinder 10 and an oil circuit; the cylinder 10 includes a rod chamber and a rodless chamber; the oil circuit connected to the cylinder 10 includes a main power oil circuit and an emergency control oil circuit, and a two-position two-way switching valve 20 is provided on the main power oil circuit; the main power oil circuit includes a first oil circuit and a second oil circuit, the first oil circuit is used to supply oil to the rodless chamber to control the boom luffing upward or extending, and the second oil circuit is used to control the oil to flow out of the rodless chamber to control the boom self-weight luffing downward or retracting; a proportional solenoid valve 30 is provided on the second oil circuit; the emergency control oil circuit is set independently relative to the main power oil circuit to control the emergency self-weight luffing downward or retracting of the boom; a balance valve 40 is provided on the emergency control oil circuit.

[0037] In this embodiment, the hydraulic self-weight control system includes a cylinder 10 and an oil circuit; the cylinder 10 includes a rod chamber and a rodless chamber; the oil circuit is connected to the cylinder 10 and includes a main power oil circuit and an emergency control oil circuit. A two-position two-way switching valve 20 is provided on the main power oil circuit; the main power oil circuit includes a first oil circuit and a second oil circuit. The first oil circuit is used to supply oil to the rodless chamber to control the boom luffing upward or extending, and the second oil circuit is used to control the oil to flow out of the rodless chamber to control the boom self-weight luffing downward or retracting; a proportional solenoid valve 30 is provided on the second oil circuit; the emergency control oil circuit is set independently relative to the main power oil circuit and is used to control the emergency self-weight luffing downward or retracting of the boom when the main power oil circuit fails; a balance valve 40 is provided on the emergency control oil circuit. This design separates the emergency control hydraulic circuit and the main power hydraulic circuit. Under normal operating conditions, the main power hydraulic circuit controls the boom's self-weight luffing or retraction via a two-position two-way valve 20 and a proportional solenoid valve 30. The emergency control hydraulic circuit, however, controls the boom's emergency self-weight luffing or retraction by opening the balance valve 40. In the event of a main power hydraulic circuit malfunction (e.g., valve jamming or main pump failure), the emergency pump does not need to continuously supply high-pressure hydraulic fluid to the rod chamber of the cylinder. Only a small amount of pilot oil from the emergency pump is needed to open the balance valve 40 in the emergency control hydraulic circuit, allowing the boom to luff or retract under its own weight. This ensures the boom is fully lowered or retracted, reducing potential safety hazards and improving the safety of the aerial work platform. Furthermore, since the balance valve 40 in the emergency control hydraulic circuit only requires a small flow of pilot oil to open, its energy consumption is low, extending the emergency pump's operating time and making it more energy-efficient, thus reducing operating costs. In addition, the boom maintains stable operation regardless of whether the main power hydraulic circuit or the emergency control hydraulic circuit is in use.

[0038] In some optional embodiments, the hydraulic self-weight control system further includes an oil tank, a first check valve 50, a second check valve 60, and a third check valve 70; wherein the inlet of the first check valve 50 is connected to the return oil circuit of the oil circuit, and the outlet of the first check valve 50 is connected to the oil tank; the second check valve 60 is disposed on the emergency control oil circuit, the inlet of the second check valve 60 is connected to the balance valve 40, and the outlet of the second check valve 60 is connected to the return oil circuit of the oil circuit; the third check valve 70 is disposed on the first oil circuit, the inlet of the third check valve 70 is connected to the main pump outlet, and the outlet of the third check valve 70 is connected to the two-position two-way switch valve 20.

[0039] In some optional embodiments, the hydraulic self-weight control system further includes a hydraulically controlled check valve 80, which is disposed in the oil outlet or oil supply line of the rod chamber. Specifically, when the boom is raised or extended during luffing, the hydraulically controlled check valve 80 is disposed in the oil outlet line of the rod chamber to return oil; when the boom is lowered or retracted during luffing due to self-weight, the hydraulically controlled check valve 80 is disposed in the oil supply line of the rod chamber to prevent the boom from slipping out when the vehicle stops, thus providing a safety protection function. When the first hydraulic circuit controls the boom to rise or extend, the rod chamber, hydraulic check valve 80, and first check valve 50 are connected in sequence, controlling the flow of hydraulic fluid from the rod chamber to the oil tank. When the second hydraulic circuit controls the boom to descend or retract due to its own weight, the proportional solenoid valve 30, hydraulic check valve 80, and rod chamber are connected in sequence, allowing hydraulic fluid to be replenished to the rod chamber. When the emergency control hydraulic circuit controls the boom to descend or retract due to its emergency own weight, the second check valve 60, hydraulic check valve 80, and rod chamber are connected in sequence, allowing hydraulic fluid to be replenished to the rod chamber.

[0040] In some optional embodiments, when the first hydraulic circuit controls the boom to rise or extend, the two-position two-way switch valve 20 is in the left position, and the third check valve 70, the two-position two-way switch valve 20, and the rodless chamber are connected in sequence, controlling the oil to flow from the main pump outlet to the rodless chamber; when the second hydraulic circuit controls the boom to descend or retract due to its own weight, the two-position two-way switch valve 20 is energized and is in the right position, and the rodless chamber, the two-position two-way switch valve 20, and the proportional solenoid valve 30 are connected in sequence, controlling the oil to flow from the rodless chamber to the proportional solenoid valve 30.

[0041] In some optional embodiments, a compensation valve 90 is also provided in the second oil circuit, the oil outlet of the proportional solenoid valve 30 is connected to the oil inlet of the compensation valve 90, and the oil outlet of the compensation valve 90 is connected to the hydraulic control check valve 80 and the first check valve 50 respectively.

[0042] In some optional embodiments, a main force pilot oil circuit is connected between the oil outlet of the third check valve 70 and the oil inlet of the two-position two-way switch valve 20. A portion of the oil flowing out of the oil outlet of the third check valve 70 flows along the main force pilot oil circuit to the hydraulic control check valve 80 to open the hydraulic control check valve 80.

[0043] In some optional embodiments, the emergency control oil circuit is connected to an emergency pilot oil circuit at the balance valve 40. The emergency pilot oil circuit is externally connected to an emergency pump. The emergency pump drives the oil to flow along the emergency pilot oil circuit to the balance valve 40 to open the balance valve 40.

[0044] In some optional embodiments, a damping orifice with a diameter of 0.6 mm is provided in the emergency pilot oil line.

[0045] In some optional embodiments, a damping orifice with a diameter of 0.8 mm is provided between the oil inlet of the second check valve 60 and the oil outlet of the balance valve 40.

[0046] In some alternative embodiments, the hydraulic self-weight control system sets a pressure measuring point at port M1, and a pressure sensor 100 is set at the pressure measuring point to monitor the pressure in the rodless chamber of cylinder 10.

[0047] The working principle of the hydraulic self-weight control system provided in the above embodiments is as follows:

[0048] When the boom needs to luff or extend, the main pump delivers hydraulic fluid from port P to the hydraulic self-weight control system. During this process, the fluid first enters the third check valve 70, then flows through it to the left-hand position of the two-position two-way switch valve 20, and finally enters the rodless chamber of cylinder 10. Simultaneously, a pilot oil path through the third check valve 70 flows along the main power pilot oil path to the hydraulically controlled check valve 80, opening it and thus pushing cylinder 10 to achieve boom luffing or extension. During boom luffing or extension, the fluid flows out from the rod chamber of cylinder 10, passes through the hydraulically controlled check valve 80, and then through the first check valve 50, finally returning to the oil tank. It is important to note that during this process, the second check valve 60 effectively prevents fluid from backflowing to port P, thus avoiding differential reactions and other adverse phenomena. In other words, the fluid can only flow through the hydraulically controlled check valve 80 to the first check valve 50, and finally back to the oil tank.

[0049] When the boom needs to be lowered or retracted, the weight of the cylinder 10 enables the boom to be lowered or retracted. During this process, the electromagnets of the two-position two-way switch valve 20 and the proportional solenoid valve 30 are simultaneously energized, causing the two-position two-way switch valve 20 to be in the right-hand position and the proportional solenoid valve 30 to be in the upper-hand position. The gravity of the cylinder 10 causes the piston rod to move towards the rodless chamber, causing oil to flow out of the rodless chamber of the cylinder 10, enter the right-hand position of the two-position two-way switch valve 20, and then flow into the upper-hand position of the proportional solenoid valve 30. Some oil flows through the proportional solenoid valve 30 into the hydraulic check valve 80, and finally into the rod chamber of the cylinder 10 to prevent a vacuum from occurring in the rod chamber of the cylinder 10. The remaining excess oil flows back to the oil tank through the first check valve 50. This circuit forms a complete gravity circuit. It should be noted that the first check valve 50 generates a slight back pressure, and there is a certain pressure loss in the oil tank pipeline. This causes the oil, after passing through the proportional solenoid valve 30, to preferentially replenish the rod chamber of the cylinder 10. The proportional solenoid valve 30 adjusts the opening size by adjusting the current value, thereby controlling the flow rate and regulating the speed of boom luffing or retraction. Simultaneously, because the proportional solenoid valve 30 is equipped with a post-valve compensation valve 90, it ensures that the speed of self-weight luffing or retraction remains stable. During the boom's self-weight luffing or retraction process, the third check valve 70 prevents oil from flowing back to the oil tank through port P.

[0050] When the boom needs to perform emergency luffing or retraction, the weight of cylinder 10 causes the boom to complete the luffing or retraction. During this process, the emergency pump drives hydraulic fluid from the Pil port along the emergency pilot oil circuit into the hydraulic self-weight control system, and opens the balance valve 40 through a damping orifice (Φ0.6) with a diameter of 0.6 mm. Under the weight of cylinder 10, the piston rod of cylinder 10 moves towards the rodless chamber, causing hydraulic fluid to flow out of the rodless chamber of cylinder 10, enter the balance valve 40, and flow to the second check valve 60 after passing through a damping orifice (Φ0.8) with a diameter of 0.8 mm. Part of the hydraulic fluid enters the rod chamber of cylinder 10 through the hydraulically controlled check valve 80 to prevent a vacuum from occurring in the rod chamber of cylinder 10. The remaining excess hydraulic fluid flows back to the oil tank through the first check valve 50. This circuit forms a complete self-weight circuit. The first check valve 50 generates a slight back pressure, and there is a certain pressure loss in the oil tank pipeline. This causes the oil, after passing through the second check valve 60, to preferentially replenish the rod chamber of the oil cylinder 10. The Φ0.6 damping orifice acts as a buffer to prevent abnormal phenomena such as shaking when the balance valve 40 suddenly opens. The Φ0.8 damping orifice acts as a speed limiter, thereby controlling the speed of the self-weight amplitude reduction or retraction, and preventing stalling during emergency self-weight amplitude reduction or retraction.

[0051] It should be further noted that the hydraulic self-weight control system is specifically designed for self-weight operation and can be applied to models such as AB42RJPlus (diesel-electric hybrid) and AB35RJ Plus (diesel-electric hybrid).

[0052] The hydraulic self-weight control system provided in the above embodiments has the following advantages:

[0053] 1) Independence of emergency self-weight control and main power self-weight control: The emergency control oil circuit and the main power oil circuit are set up independently to avoid mutual influence between the two. Thus, when the main power oil circuit fails, there is no need for the emergency pump to continuously supply high-pressure oil to the rod chamber of the cylinder. The emergency pump only needs to supply pilot oil at a lower pressure to open the balance valve in the emergency control oil circuit, so that the boom self-weight luffing or retraction can be realized, ensuring that the boom is fully lowered or retracted.

[0054] 2) Smooth boom operation: A damping orifice is installed in the emergency control oil circuit to limit the speed of the self-weight, thereby controlling the speed of the self-weight luffing or retraction and preventing stalling during emergency self-weight luffing or retraction.

[0055] 3) Reduced energy consumption: Since the balance valve in the emergency control oil circuit only requires a small flow of pilot oil to open, its energy consumption is low, thereby extending the service life of the emergency pump, making it more energy-efficient and reducing the cost of use.

[0056] 4) Preventing arm slippage and abnormal oil replenishment: The hydraulic check valve and ordinary check valve effectively prevent arm slippage and solve the problem of abnormal oil replenishment that may occur during the self-weight control process.

[0057] On the other hand, one embodiment of this utility model provides an aerial work platform vehicle, including the hydraulic self-weight control system of any of the above embodiments. Since the aerial work platform vehicle includes the hydraulic self-weight control system of any of the above embodiments, it possesses the technical effects of the hydraulic self-weight control system of any of the above embodiments, which will not be elaborated further here.

[0058] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A hydraulic self-weight control system, characterized in that, include: Hydraulic cylinder, including rod chamber and rodless chamber; The hydraulic circuit, connected to the hydraulic cylinder, includes a main power hydraulic circuit and an emergency control hydraulic circuit. A two-position, two-way switching valve is installed on the main power hydraulic circuit. The main power hydraulic circuit includes a first hydraulic circuit and a second hydraulic circuit. The first hydraulic circuit supplies oil to the rodless chamber to control the boom's luffing or extension. The second hydraulic circuit controls the flow of oil out of the rodless chamber to control the boom's weight-based luffing or retraction. A proportional solenoid valve is installed on the second hydraulic circuit. The emergency control oil circuit is set independently from the main power oil circuit, and controls the emergency self-weight luffing descent or retraction of the boom; the emergency control oil circuit is equipped with a balance valve.

2. The hydraulic self-weight control system according to claim 1, characterized in that, Also includes: tank; The first check valve has its inlet connected to the return oil circuit of the oil circuit and its outlet connected to the oil tank. A second check valve is installed in the emergency control oil circuit. The inlet of the second check valve is connected to the balance valve, and the outlet of the second check valve is connected to the return oil circuit of the oil circuit. A third check valve is installed in the first oil circuit. The oil inlet of the third check valve is connected to the oil outlet of the main pump, and the oil outlet of the third check valve is connected to the two-position two-way switch valve.

3. The hydraulic self-weight control system according to claim 2, characterized in that, It also includes a hydraulically controlled check valve, which is disposed in the oil outlet or oil replenishment line of the rod chamber; When the first oil circuit controls the boom to rise or extend, the rod chamber, the hydraulic check valve and the first check valve are connected in sequence to control the oil to flow from the rod chamber to the oil tank. When the second oil circuit controls the boom to descend or retract under its own weight, the proportional solenoid valve, the hydraulic check valve and the rod chamber are connected in sequence, allowing oil to be replenished to the rod chamber. When the emergency control oil circuit controls the boom to descend or retract under emergency self-weight, the second check valve, the hydraulic check valve, and the rod chamber are connected in sequence, allowing oil to be replenished to the rod chamber.

4. The hydraulic self-weight control system according to claim 3, characterized in that, When the first oil circuit controls the boom to rise or extend, the two-position two-way switch valve is in the left position, and the third check valve, the two-position two-way switch valve and the rodless chamber are connected in sequence, controlling the oil to flow from the main pump outlet to the rodless chamber. When the second oil circuit controls the boom to descend or retract due to its own weight, the two-position two-way switch valve is energized and in the right position. The rodless chamber, the two-position two-way switch valve, and the proportional solenoid valve are connected in sequence, controlling the oil to flow from the rodless chamber to the proportional solenoid valve.

5. The hydraulic self-weight control system according to claim 3, characterized in that, The second oil circuit is also equipped with a compensation valve. The oil outlet of the proportional solenoid valve is connected to the oil inlet of the compensation valve, and the oil outlet of the compensation valve is connected to the hydraulic control check valve and the first check valve respectively.

6. The hydraulic self-weight control system according to claim 3, characterized in that, A main force pilot oil circuit is connected between the oil outlet of the third check valve and the oil inlet of the two-position two-way switch valve. A portion of the oil flowing out of the oil outlet of the third check valve flows along the main force pilot oil circuit to the hydraulic control check valve to open the hydraulic control check valve.

7. The hydraulic self-weight control system according to claim 2, characterized in that, The emergency control oil circuit is connected to the balance valve via an emergency pilot oil circuit. The emergency pilot oil circuit is externally connected to an emergency pump. The emergency pump drives the oil to flow along the emergency pilot oil circuit to the balance valve to open the balance valve.

8. The hydraulic self-weight control system according to claim 7, characterized in that, The emergency pilot oil line is equipped with a damping orifice with a diameter of 0.6 mm.

9. The hydraulic self-weight control system according to claim 7 or 8, characterized in that, A damping orifice with a diameter of 0.8 mm is provided between the oil inlet of the second check valve and the oil outlet of the balance valve.

10. An aerial work platform vehicle, characterized in that, Includes the hydraulic self-weight control system as described in any one of claims 1 to 9.

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