Aerial work platform and hydraulic control system thereof

Abstract

The application discloses a high-altitude operation platform and a hydraulic control system thereof, and the system comprises a telescopic oil cylinder and a main reversing valve; a one-way balance valve is arranged in a rod cavity working oil path, and a balance valve pilot oil path of the one-way balance valve is connected to a rodless cavity working oil path; a hydraulic control one-way valve is arranged in the rodless cavity working oil path and enables hydraulic oil to flow to the rodless cavity through the hydraulic control one-way valve and reversely cut off, the hydraulic control one-way valve comprises a one-way valve pilot oil path for reversely opening the one-way valve, and the one-way valve pilot oil path is connected to a rod cavity working oil path between the one-way balance valve and the main reversing valve; and an oil cylinder communication oil path is connected between the rodless cavity and the rod cavity and is provided with a communication control valve for controlling on-off of the oil path. The application uses a novel hydraulic balance valve, detects pressure in the balance valve through a pilot oil path, completes automatic regulation of flow, and can automatically control the running speed of the hydraulic oil cylinder.

Description

Technical Field

[0001] This application belongs to the field of high-altitude work technology, specifically, it relates to a high-altitude work platform and its hydraulic control system. Background Technology

[0002] Aerial work platforms often require frequent operation of various booms during use, driven by hydraulic cylinders. The speed of these cylinder movements is typically electrically controlled, though manual control is also possible. These speeds are usually fixed and cannot be adjusted based on factors such as cylinder load.

[0003] In a hydraulic cylinder system, the hydraulic cylinder is supplied with hydraulic oil by a pump. A proportional directional valve controls the current to provide the appropriate flow to the cylinder, thereby controlling its speed. This is the conventional principle for controlling cylinder speed. Sensors can also be added to detect the cylinder chamber pressure and piston position, allowing for timely adjustments to the cylinder speed by changing the current in the proportional directional valve. However, this inevitably requires the introduction of additional detection components such as pressure and stroke sensors, resulting in high cost, poor reliability, high failure rate, and numerous materials, hindering standardization. Summary of the Invention

[0004] The purpose of this application is to provide an aerial work platform and its hydraulic control system, which simplifies the system and enables more automated control of the hydraulic cylinder's movement speed.

[0005] According to one aspect of this application, a hydraulic control system for an aerial work platform is provided, comprising:

[0006] The telescopic cylinder and the main directional valve, wherein the working oil port of the main directional valve is connected to the rod chamber of the telescopic cylinder via a rod chamber working oil circuit and to the rodless chamber via a rodless chamber working oil circuit;

[0007] A one-way balance valve is installed in the working oil circuit of the rod chamber, and the pilot oil circuit of the one-way balance valve is connected to the working oil circuit of the rodless chamber.

[0008] A hydraulically controlled check valve is provided in the working oil circuit of the rodless chamber and allows hydraulic oil to flow to the rodless chamber through the hydraulically controlled check valve and to be cut off in the reverse direction. The hydraulically controlled check valve includes a check valve pilot oil circuit for reversing the opening of the check valve. The check valve pilot oil circuit is connected to the working oil circuit of the rod chamber between the check balance valve and the main directional valve.

[0009] The hydraulic cylinder is connected to the oil circuit, which connects the rodless chamber and the rod chamber, and the oil circuit is equipped with a connection control valve for controlling the opening and closing of the oil circuit.

[0010] In some embodiments, the hydraulic control system includes:

[0011] An overflow valve is connected in parallel with the hydraulically controlled check valve in the rodless chamber working oil circuit.

[0012] In some embodiments, the communication control valve is also a hydraulically controlled check valve and is configured to allow hydraulic oil to flow only from the rod chamber to the rodless chamber and to cut off in the reverse direction. The communication control valve includes a communication valve pilot oil circuit for controlling the opening pressure of the check valve. The pilot oil of the communication valve pilot oil circuit originates from the working oil circuit of the rod chamber between the check balance valve and the main directional valve and is used to drive the valve port of the communication control valve to lock.

[0013] In some embodiments, the connection control valve is a normally closed valve, and the one-way valve opening pressure of the connection control valve is greater than the one-way valve opening pressure of the hydraulically controlled one-way valve.

[0014] In some embodiments, the hydraulic cylinder connecting oil circuit is further provided with an electromagnetic switching valve connected in series with the connecting control valve.

[0015] In some embodiments, the solenoid valve is a normally closed solenoid valve that disconnects the oil circuit under normal conditions.

[0016] In some embodiments, the hydraulic control system includes:

[0017] A pressure sensor is used to detect the oil pressure at the end of the rodless chamber working oil circuit near the main directional valve; and

[0018] A controller is used to control the on / off state of the electromagnetic switching valve.

[0019] In some implementations, the controller is configured to:

[0020] Obtain the oil pressure detection value from the pressure sensor;

[0021] It is determined that the oil pressure detection value is less than the set pressure value;

[0022] Control the electromagnetic switch valve to connect the oil circuit of the oil cylinder;

[0023] The oil pressure detection value is determined to be no less than the set pressure value;

[0024] Control the electromagnetic switch valve to disconnect the oil circuit connecting the oil cylinder.

[0025] In some embodiments, the balancing valve of the one-way balancing valve has an adjustable balancing valve setting pressure that is set to be greater than 1.3 times the load pressure.

[0026] According to another aspect of this application, an aerial work platform is also provided, the aerial work platform including the hydraulic control system of the aerial work platform described above according to this application.

[0027] In the hydraulic control system of the aerial work platform of this application, a hydraulically controlled check valve is used to replace the existing one-way balance valve in the rodless chamber working oil circuit, and an additional cylinder connecting oil circuit with a connecting control valve is set up. This configuration ensures that when the piston rod extends, under low load pressure, the oil pressure in the rodless chamber working oil circuit is low and insufficient to open the one-way balance valve. Therefore, the return oil from the rod chamber can open the connecting control valve, and then return oil to the rodless chamber through the cylinder connecting oil circuit, realizing a differential function. This results in a fast piston extension speed under low load conditions. Under high load pressure, the oil pressure in the rodless chamber working oil circuit is high and can open the one-way balance valve, allowing normal oil return through the one-way balance valve, resulting in a slower piston extension speed. Therefore, the hydraulic system of this application can automatically adjust the cylinder speed.

[0028] Other features and advantages of the embodiments of this application will be described in detail in the following detailed description section. Attached Figure Description

[0029] The accompanying drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the following detailed description to explain the embodiments of this application, but do not constitute a limitation on the embodiments of this application. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without any inventive effort. In the drawings:

[0030] Figure 1 Hydraulic schematic diagram of the hydraulic control system of an existing aerial work platform;

[0031] Figure 2 A hydraulic schematic diagram of a hydraulic control system for an aerial work platform according to a specific embodiment of this application; and

[0032] Figure 3 This is a hydraulic schematic diagram of the hydraulic control system of an aerial work platform according to another specific embodiment of this application.

[0033] Explanation of reference numerals in the attached figures

[0034] 1. Hydraulic oil tank 2. Filter

[0035] 3 Gear pump 4 Pump inlet check valve

[0036] 5. Main directional valve; 6. One-way balance valve

[0037] 7. Hydraulic check valve 8. Relief valve

[0038] 9 Connecting control valve 10 Telescopic cylinder

[0039] 11. Electromagnetic switch valve L0, hydraulic cylinder connected oil circuit.

[0040] L1 Rod chamber working oil circuit L2 Rodless chamber working oil circuit

[0041] X0 One-way valve pilot circuit; X1 Connecting valve pilot circuit

[0042] Y01~Y03 Electromagnets Detailed Implementation

[0043] The specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0044] The aerial work platform and its hydraulic control system according to this application are described below with reference to the accompanying drawings.

[0045] like Figure 1 As shown, in the existing hydraulic control system of aerial work platforms, hydraulic oil passes through a filter to a gear pump. The gear pump then delivers the hydraulic oil to a proportional directional valve. When the electromagnet Y01 shown in the diagram is energized, the flow rate is adjusted by controlling the current of the proportional electromagnet, thereby controlling the operating speed of the hydraulic cylinder. Furthermore, pressure sensors and stroke sensors can be added to the hydraulic system. By judging the pressure and piston stroke, the current is adjusted to control the cylinder's operating speed. Clearly, a simple hydraulic system is insufficient to regulate cylinder speed; additional detection components such as pressure sensors and stroke sensors are required, resulting in high cost, poor reliability, and hindering standardization.

[0046] In view of this, this application discloses a novel hydraulic control system for aerial work platforms. For example... Figure 2 As shown, in one embodiment, the hydraulic control system includes:

[0047] The telescopic cylinder 10 and the main directional valve 5 are connected by a rod chamber working oil circuit L1 between the working oil port of the main directional valve 5 and the rod chamber of the telescopic cylinder 10, and by a rodless chamber working oil circuit L2 between the rodless chamber and the rodless chamber.

[0048] One-way balance valve 6 is installed in the working oil circuit L1 of the rod chamber, and the balance valve pilot oil circuit of one-way balance valve 6 is connected to the working oil circuit L2 of the rodless chamber.

[0049] A hydraulically controlled check valve 7 is installed in the rodless chamber working oil circuit L2, which allows hydraulic oil to flow to the rodless chamber through the hydraulically controlled check valve 7 and to be cut off in the reverse direction. The hydraulically controlled check valve 7 includes a check valve pilot oil circuit X0 for reversing the opening of the check valve. The check valve pilot oil circuit X0 is connected to the rod chamber working oil circuit L1 between the check balance valve 6 and the main directional valve 5.

[0050] The hydraulic cylinder is connected to the oil circuit L0, which connects the rodless chamber and the rod chamber, and the oil circuit is equipped with a connecting control valve 9 for controlling the opening and closing of the oil circuit.

[0051] As can be seen, in the hydraulic system of this application, a hydraulically controlled check valve 7 is used to replace the existing one-way balance valve in the rodless chamber working oil circuit L2, and an additional cylinder connecting oil circuit L0 with a connecting control valve 9 is provided. Compared to Figure 1 The existing hydraulic system has a large opening pressure for the one-way balance valve. Figure 2 The hydraulically controlled check valve 7 has a lower opening pressure and better energy-saving effect; in other words, the hydraulically controlled check valve 7 replaces the existing one-way balance valve, and the opening pressure is lower when the piston rod retracts. In particular, when the piston rod of the telescopic cylinder 10 extends, under low load pressure, the oil return from the rod chamber can return to the rodless chamber through the cylinder connection oil circuit L0, without having to return oil through the main directional valve 5, thus realizing the differential function and the piston extension speed is faster; under high load pressure, the oil can return normally through the one-way balance valve 6, and the piston extension speed is slower, thus automatically realizing the adjustment of the cylinder speed, which will be explained in detail below.

[0052] Furthermore, in this application, a hydraulically controlled check valve is used instead of a one-way balance valve. During the piston rod retraction stroke, the reverse opening pressure of the hydraulically controlled check valve in the rodless chamber working oil circuit is smaller than the opening pressure of the one-way balance valve, which is more conducive to the return oil during piston retraction.

[0053] In this embodiment, the hydraulic control system also includes a relief valve 8, which is connected in parallel with the hydraulically controlled check valve 7 in the rodless chamber working oil circuit L2. When locked, the relief valve 8 can limit the maximum pressure in the rodless chamber, thus protecting the cylinder. Compared to a one-way balance valve, the combination of the relief valve and the hydraulically controlled check valve offers lower cost, lower opening pressure, and greater energy efficiency for the hydraulic system.

[0054] exist Figure 2 In this implementation, the connecting control valve 9 also adopts a hydraulically controlled check valve to achieve more reliable automated hydraulic control without the need for additional electrically controlled valve components. For example... Figure 2 As shown, the connecting control valve 9 is configured to allow hydraulic oil to flow only from the rod chamber to the rodless chamber and to cut off the flow in the reverse direction. The connecting control valve 9 includes a connecting valve pilot oil circuit X1 for controlling the opening pressure of the check valve. The pilot oil of the connecting valve pilot oil circuit X1 originates from the rod chamber working oil circuit L1 between the check balance valve 6 and the main directional valve 5 and is used to drive the valve port of the connecting control valve 9 to lock. Comparatively, the check valve pilot oil circuit X0 is used to open the hydraulically controlled check valve 7 in the reverse direction, while the connecting valve pilot oil circuit X1 is used to drive the valve port of the connecting control valve 9 to lock. It can be seen that both guide the pilot pressure oil to the opposite hydraulically controlled end of the check valve.

[0055] In this embodiment, the valve core of the illustrated connecting control valve 9 is pushed to the locked valve port by a compression spring, meaning the connecting control valve 9 is a normally closed valve. This means that when the pressure of the forward hydraulic oil (i.e., the oil in the rod chamber) does not reach the set value, it is difficult to open the valve port of the connecting control valve 9, and the hydraulic cylinder connection circuit L0 will be cut off. In comparison, the hydraulically controlled check valve 7 does not have a compression spring that pushes the valve core to lock the valve port; therefore, the opening pressure of the connecting control valve 9 is obviously greater than that of the hydraulically controlled check valve 7. Furthermore, it is clear that the opening pressure of the one-way valve of the connecting control valve 9 is also lower than that of the one-way balance valve 6. Therefore, as the cylinder load gradually increases, the load pressure will open the connecting control valve 9 first, connecting the rod chamber and the rodless chamber, resulting in faster piston extension. When the cylinder load is even greater, the inlet pressure of the rodless chamber working oil circuit L2 is higher, opening the one-way balance valve 6, allowing the oil in the rodless chamber to return through the one-way balance valve 6. At this time, the movement of the cylinder piston will slow down, which is more suitable for cylinder stroke control during heavy load extension. Compared to the conventional load lifting return method using the one-way balance valve 6 and the main directional valve 5, which always return oil through the rod chamber working oil circuit L1, the introduction of the cylinder connecting oil circuit L0 and its connecting control valve 9 allows for a differential mode that directly connects the rod chamber and the rodless chamber during light load extension, resulting in faster piston extension, faster response, and a more sensitive and energy-efficient system response.

[0056] Those skilled in the art will understand that the connecting control valve 9 is not limited to a hydraulically controlled check valve, but can also be a hydraulically controlled slide valve with other feasible structures, and can also be replaced by an electrically controlled switch valve, so as to perform corresponding control according to the working conditions to open or close the oil circuit L0 of the cylinder in a timely manner.

[0057] See Figure 3 In another embodiment, the hydraulic cylinder connecting oil circuit L0 is equipped not only with a connecting control valve 9, but also with an electromagnetic switch valve 11 connected in series with the connecting control valve 9. This series combination of the connecting control valve 9 and the electromagnetic switch valve 11 provides a double safety function, allowing for timely switching of the control oil circuit and selection of whether to implement the differential function.

[0058] Optional, Figure 3 The solenoid valve 11 can be designed as a normally closed solenoid valve that disconnects the oil circuit (i.e., the oil cylinder is connected to oil circuit L0) under normal conditions. When the solenoid valve 11 is energized, it interacts with... Figure 2 The implementation method is similar, only controlling the connection of the hydraulic cylinder to the oil circuit L0 through the connecting control valve 9 to achieve automatic adjustment of the hydraulic cylinder speed. However, when necessary, the solenoid switch valve 11 can be de-energized, thereby allowing manual intervention to interrupt the automatic adjustment mode of the hydraulic cylinder speed.

[0059] Specifically, in Figure 3In the illustrated embodiment, the solenoid valve 11 is designed as a normally closed solenoid valve that disconnects the oil circuit (i.e., the oil circuit L0 connected to the cylinder) under normal conditions. In this case, the on / off state of the oil circuit L0 connected to the cylinder can be controlled as needed to achieve automatic adjustment mode of cylinder speed or switching to other control modes.

[0060] For example, in some implementations, the hydraulic control system may include:

[0061] A pressure sensor is used to detect the oil pressure at the end of the rodless chamber working oil circuit L2 near the main directional valve 5; and

[0062] The controller is used to control the on / off state of the solenoid valve 11.

[0063] In this way, by combining the oil pressure detection of the rodless chamber of the cylinder with the pressure sensor, the load size is determined, and then it is determined whether to select the differential mode or the conventional oil return mode, and then the solenoid switch valve 11 is controlled accordingly.

[0064] In other words, the controller can control the opening and closing of the solenoid valve 11, that is, control the opening and closing of the oil circuit L0 connected to the cylinder. However, the hydraulic system can automatically achieve differential operation through pressure detection. The solenoid valve 11 is normally closed by default and cannot achieve differential operation. When energized, it can achieve differential operation. Therefore, it is possible to choose whether to achieve differential operation.

[0065] Specifically, as an example, the controller can be configured as follows:

[0066] Obtain the oil pressure reading from the pressure sensor;

[0067] Confirm that the oil pressure reading is lower than the set pressure value;

[0068] Control the solenoid valve 11 to connect the oil cylinder to the oil circuit L0;

[0069] Ensure that the oil pressure reading is not less than the set pressure value;

[0070] Control the solenoid valve 11 to disconnect the oil circuit L0 connecting the oil cylinder.

[0071] As can be seen, by identifying the pressure internally within the hydraulic system, the opening and closing of the cylinder-connecting oil circuit L0 is controlled to achieve the differential function and adjust the operating speed of the cylinder. When the oil pressure detection value is less than the preset set pressure value, it indicates that the oil pressure in the rodless chamber is not high and the load is not large. At this time, the cylinder-connecting oil circuit L0 can be opened to achieve differential oil return from the rod chamber. When the oil pressure detection value is not less than the preset set pressure value, the cylinder-connecting oil circuit L0 is closed by controlling the solenoid switch valve 11, that is, the electromagnet Y03 shown in the figure is not energized, and the oil in the rodless chamber returns normally through the one-way balance valve 6. In this embodiment, the opening and closing of the cylinder-connecting oil circuit L0 can be controlled and reliable in case the connecting control valve 9 and its connecting valve pilot oil circuit X1 fail.

[0072] In this embodiment, the set pressure of the one-way balance valve 6 is adjustable and set to be greater than 1.3 times the load pressure. Thus, by adjusting the set pressure of the balance valve, the pilot ratio, and the opening pressure of the hydraulic check valve, parameters can be adjusted more rationally to achieve automatic adjustment of the cylinder speed.

[0073] The hydraulic control system of the aerial work platform described above can be applied to various types of aerial work platforms.

[0074] by Figure 2 For example, the hydraulic oil of the aerial work platform passes through filter 2 and reaches gear pump 3. Gear pump 3 delivers the hydraulic oil to the main directional valve 5 through pump port check valve 4, which is used to prevent backflow. The main directional valve 5 is a proportional directional valve. When electromagnet Y01 is energized, the flow rate through the valve port of the main directional valve 5 is adjusted by controlling the current of the proportional electromagnet, pumping hydraulic oil into the rodless chamber of the cylinder, pushing the piston rod to extend, thereby controlling the operating speed of the hydraulic cylinder 10.

[0075] Furthermore, pressure sensors and stroke sensors can be added to the system. By judging the pressure and stroke, the current is adjusted to control the operating speed of the hydraulic cylinder. However, this hydraulic system increases cost, complicates control logic, has a higher failure rate, and increases material quantity due to the addition of electrical components such as pressure and stroke sensors, which is detrimental to after-sales maintainability. In the absence of pressure and stroke sensors, the speed of the hydraulic system is determined by a proportional control valve, resulting in a constant speed throughout the operation. However, in situations requiring differential operation, this can lead to slower speeds.

[0076] When electromagnet Y01 is energized, hydraulic oil enters the rodless chamber of the cylinder after entering the pilot control chamber of the hydraulically controlled check valve 7. Simultaneously, pilot oil enters the pilot control chamber of the one-way balance valve 6. Assuming the balance valve 6 has a set pressure of 300 bar and a pilot ratio of 4:1, the pilot opening pressure is 75 bar. When the pressure entering the hydraulically controlled check valve 7 is less than 75 bar, the one-way balance valve 6 does not open, and the return oil from the rod chamber of the cylinder returns to the rodless chamber via the hydraulically controlled check valve 7, forming a differential mode. When the oil pressure entering the hydraulically controlled check valve 7 is greater than 75 bar, the one-way balance valve 6 opens, and the return oil from the rod chamber of the cylinder returns to the hydraulic oil tank 1 via the one-way balance valve 6 and the main directional valve 5.

[0077] When electromagnet Y02 is energized, the pumped hydraulic oil passes through the main directional valve 5 and then enters the check valve in the one-way balance valve 6, eventually reaching the rod chamber of the cylinder. Simultaneously, pilot oil enters the hydraulically controlled check valve 7, which opens in the reverse direction, allowing the hydraulic oil in the rodless chamber of the cylinder to return to the hydraulic oil tank 1 via the main directional valve 5. The relief valve 8 limits the maximum load pressure in the locked state, protecting the cylinder.

[0078] This application, through optimized design of the internal structure of the hydraulic system, can automatically adjust the cylinder speed without requiring additional pressure and stroke sensors in the electrical control system, achieving simplicity, economy, and reliability. Specifically, by identifying the internal pressure of the hydraulic system, differential function is activated when the pressure is low, and normal function is activated when the speed is high and the pressure is high, thus automatically adjusting the cylinder speed.

[0079] Meanwhile, the one-way balance valve in the rodless chamber of the hydraulic cylinder is replaced with a combination of a hydraulically controlled one-way valve 7 and a relief valve 8, resulting in lower cost, lower opening pressure, and greater energy efficiency in the hydraulic system. The opening pressure of the one-way balance valve 6 is equal to the balance valve set pressure divided by the pilot ratio, and the opening pressure of the hydraulically controlled one-way valve 7 is equal to the load pressure divided by the pilot ratio.

[0080] In the description of this application, it should be understood that 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. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0081] In this application, unless otherwise expressly 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 part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0082] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. 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. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0083] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A hydraulic control system for an aerial work platform, characterized in that, The hydraulic control system includes: Telescopic cylinder (10) and main directional valve (5), wherein the working port of the main directional valve (5) is connected to the rod chamber of the telescopic cylinder (10) via a rod chamber working oil passage (L1) and to the rodless chamber via a rodless chamber working oil passage (L2). A one-way balance valve (6) is provided in the working oil circuit (L1) of the rod chamber, and the balance valve pilot oil circuit of the one-way balance valve (6) is connected to the working oil circuit (L2) of the rodless chamber. A hydraulically controlled check valve (7) is provided in the rodless chamber working oil circuit (L2) and allows hydraulic oil to flow through the hydraulically controlled check valve (7) to the rodless chamber and to be cut off in the reverse direction. The hydraulically controlled check valve (7) includes a check valve pilot oil circuit (X0) for reversing the opening of the check valve. The check valve pilot oil circuit (X0) is connected to the rod chamber working oil circuit (L1) between the check valve (6) and the main directional valve (5). The cylinder connecting oil circuit (L0) connects the rodless chamber and the rod chamber and is provided with a connecting control valve (9) for controlling the opening and closing of the oil circuit and an electromagnetic switch valve (11) connected in series with the connecting control valve (9). The connecting control valve (9) is also a hydraulic control check valve and is configured to allow hydraulic oil to flow from the rod chamber to the rodless chamber only and to cut off in the reverse direction. The connecting control valve (9) includes a connecting valve pilot oil circuit (X1) for controlling the opening pressure of the check valve. The pilot oil of the connecting valve pilot oil circuit (X1) originates from the rod chamber working oil circuit (L1) between the check balance valve (6) and the main directional valve (5) and is used to drive the valve port of the connecting control valve (9) to lock. A pressure sensor is used to detect the oil pressure at one end of the rodless chamber working oil passage (L2) near the main directional valve (5); and A controller is used to control the on / off state of the electromagnetic switching valve (11); The connecting control valve (9) is a normally closed valve. The one-way valve opening pressure of the connecting control valve (9) is greater than the one-way valve opening pressure of the hydraulic control one-way valve (7) and less than the one-way balance valve (6).

2. The hydraulic control system of the aerial work platform according to claim 1, characterized in that, The hydraulic control system includes: An overflow valve (8) is connected in parallel with the hydraulic check valve (7) in the rodless chamber working oil circuit (L2).

3. The hydraulic control system of the aerial work platform according to claim 1, characterized in that, The solenoid switch valve (11) is a normally closed solenoid valve that disconnects the oil circuit under normal conditions.

4. The hydraulic control system of the aerial work platform according to claim 3, characterized in that, The controller is configured to: Obtain the oil pressure detection value from the pressure sensor; It is determined that the oil pressure detection value is less than the set pressure value; Control the electromagnetic switch valve (11) to connect the oil circuit (L0) of the oil cylinder. The oil pressure detection value is determined to be no less than the set pressure value; Control the electromagnetic switch valve (11) to disconnect the oil circuit (L0) connecting the oil cylinder.

5. The hydraulic control system of the aerial work platform according to claim 1, characterized in that, The balancing valve (6) has an adjustable balancing valve setting pressure, which is set to be greater than 1.3 times the load pressure.

6. An aerial work platform, characterized in that, The aerial work platform includes a hydraulic control system for the aerial work platform according to any one of claims 1 to 5.

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