Hydraulic control system and aerial work machine

Abstract

The present application relates to hydraulic equipment of construction machinery, and provides a hydraulic control system, which comprises an oil inlet oil way, an oil return oil way, an oil inlet joint and a plurality of working joints. The oil inlet oil way is connected with the oil inlet joint and each working joint to supply oil. The oil return oil way is connected with the oil inlet joint and each working joint to return oil. Two working oil ports of a main valve core of part or all working joints are connected with an actuator through a working oil way to supply and return oil to the actuator. When the oil supply pressure of the actuator is lower than a set value, the actuator does not act. An unloading valve is arranged between the two working oil ways. When the main valve core of the working joint receives a neutral control instruction, the unloading valve can control the two working oil ways of the working joint to be communicated with each other through the unloading valve. The hydraulic control system of the present application can avoid the hydraulic oil from being delivered to the actuator by the stuck valve core when the valve core is stuck and not in the neutral position, prevent the actuator from producing uncontrollable action, and improve the safety of the hydraulic system. The present application also provides a high-altitude working machine.

Description

Technical Field

[0001] This invention relates to hydraulic equipment for engineering machinery, specifically to a hydraulic control system. It also relates to aerial work platform machinery. Background Technology

[0002] Aerial work machinery typically needs to lift people and objects to a certain height for tasks such as maintenance and equipment installation. Since the work is carried out at height, the stable operation of aerial work machinery is particularly important.

[0003] Existing aerial work platforms all use hydraulic systems to control various boom movements, typically including tower boom, main boom, main boom telescopic boom, jib boom, and leveling boom. The main hydraulic valve connects the valve cores of the tower boom, main boom, main boom telescopic boom, jib boom, and leveling boom in parallel to deliver hydraulic oil to different valve cores and control the actuator movements. However, due to the impact of hydraulic system cleanliness, valve jamming frequently occurs. For example, when the tower boom valve core reverses and the tower boom moves, if the main boom valve core is stuck and not in the neutral position, hydraulic oil will flow to both the tower boom and main boom valve cores simultaneously, causing both the tower boom and main boom to move at the same time. This poses a life-threatening danger to personnel on the aerial work platform.

[0004] Therefore, how to prevent safety accidents when the valve core is stuck is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a hydraulic control system that can prevent the stuck valve core from delivering hydraulic oil to the actuator when the valve core is stuck and not in the neutral position, thereby preventing the actuator from producing uncontrollable actions and improving the safety of the hydraulic system.

[0006] The technical problem that this invention also aims to solve is to provide an aerial work platform that, when the valve core is stuck and not in the neutral position, prevents the actuators from producing uncontrollable movements, thus ensuring the safety of aerial work.

[0007] To address the aforementioned technical problems, this invention provides a hydraulic control system, including an oil inlet circuit, an oil return circuit, an oil inlet link, and multiple working links. The oil inlet circuit connects the oil inlet link to each of the working links to supply oil, and the oil return circuit connects the oil inlet link to each of the working links to return oil. Two working ports of the main valve core of some or all of the working links are respectively connected to an actuator through a working oil circuit, enabling the actuator to supply and return oil. When the oil supply pressure of the actuator is lower than a set value, the actuator does not operate. An unloading valve is provided between the two working oil circuits. When the main valve core of the working link is in the neutral position, the unloading valve controls the two working oil circuits of the working link to connect to each other through the unloading valve.

[0008] Preferably, some or all of the working links are provided with a bidirectional balancing valve, the two working oil circuits are respectively connected to the two oil inlets of the bidirectional balancing valve, and the two oil outlets of the bidirectional balancing valve are respectively connected to the actuator.

[0009] Specifically, it includes a pilot oil circuit, which is connected to the control end of the main valve core of each working link. The oil inlet link is connected to the oil supply unit through the main oil circuit. The oil inlet circuit is connected to the main oil circuit. The pilot oil circuit is connected to the main oil circuit through a three-way pressure reducing valve.

[0010] Preferably, it includes a load feedback oil circuit, the output pressure of the main valve core of each working link can be introduced into the load feedback oil circuit, the oil inlet link is provided with a differential pressure reducing valve, the main oil circuit is connected to the return oil circuit through the differential pressure reducing valve, and the load feedback oil circuit is connected to the spring end of the differential pressure reducing valve.

[0011] Preferably, the oil inlet is equipped with a load feedback unloading valve, and the load feedback oil circuit is connected to the unloading oil circuit through the load feedback unloading valve.

[0012] Specifically, the load feedback unloading valve is a solenoid valve.

[0013] Specifically, each of the working links includes a telescopic link, a main boom link, and a tower boom link, and each of the telescopic link, the main boom link, and the tower boom link is equipped with the bidirectional balancing valve and the unloading valve.

[0014] Specifically, the telescopic linkage includes a telescopic main valve core, which includes a telescopic inlet, a telescopic return port, a first telescopic working port, and a second telescopic working port. The inlet oil circuit is connected to the telescopic inlet via a telescopic pressure compensation valve. The telescopic main valve core includes at least a first working position, a second working position, and a neutral position. When the telescopic main valve core is in the first working position, the telescopic inlet is connected to the first telescopic working port, and the telescopic return port is connected to the second telescopic working port. When the telescopic main valve core is in the second working position, the telescopic inlet is connected to the second telescopic working port, and the telescopic return port is connected to the first telescopic working port. The telescopic main valve core has a Y-shaped neutral position function.

[0015] Specifically, the control end of the telescopic main valve core is connected to the pilot oil circuit and the unloading oil circuit. The telescopic main valve core is equipped with a first telescopic electromagnet and a second telescopic electromagnet. When the first telescopic electromagnet is energized, the oil pressure in the pilot oil circuit pushes the telescopic main valve core to move to the first working position. When the second telescopic electromagnet is energized, the oil pressure in the pilot oil circuit pushes the telescopic main valve core to move to the second working position.

[0016] Furthermore, the present invention provides an aerial work platform, including the hydraulic control system described in any one of the above technical solutions.

[0017] The beneficial effects of the present invention through the above solution are as follows:

[0018] This invention's hydraulic control system incorporates an unloading valve between the two working oil circuits of the actuator and the main valve core of the working link. When the main valve core receives a control command, it moves to the neutral position, opening the unloading valve. This allows the two working oil circuits of the working link to be directly connected. Therefore, even if the main valve core is stuck and not in the neutral position, hydraulic oil passing through the stuck valve core can return directly to the return oil circuit via the unloading valve for pressure relief. This prevents the hydraulic oil from building sufficient pressure to supply the actuator, thus avoiding uncontrollable actions by the actuator in this working link. Conversely, when the working link needs to control the actuator, the main valve core is in the working position, and the unloading valve is closed. This prevents the two working oil circuits of the working link from being directly connected, allowing the inlet oil circuit to generate sufficient pressure to supply the actuator, enabling it to move oil in and out and complete its actions.

[0019] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0020] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0021] Figure 1 This is a hydraulic schematic diagram of a specific embodiment of the hydraulic control system of the present invention;

[0022] Figure 2 yes Figure 1 Enlarged view of section H in the middle.

[0023] Explanation of reference numerals in the attached figures

[0024] 1. Oil inlet connection 11. Main oil circuit

[0025] 12 Three-way pressure reducing valve 13 Differential pressure reducing valve

[0026] 14 Load feedback unloading valve 15 Main relief valve

[0027] 2 telescopic joint 21 telescopic main valve core

[0028] 22 Telescopic pressure compensation valve; 23 Telescopic first electromagnet

[0029] 24 Telescopic second electromagnet 25 Telescopic first overflow valve

[0030] 26 Telescopic second relief valve 27 First shuttle valve

[0031] 28 Telescopic bidirectional balancing valve 29 Telescopic unloading valve

[0032] 210 Telescopic first working oil circuit; 211 Telescopic second working oil circuit

[0033] 3 main boom link 31 main boom main valve core

[0034] 32 Main boom pressure compensation valve; 33 Second shuttle valve

[0035] 4-tower arm connection with 41-tower arm main valve core

[0036] 42 Tower arm pressure compensation valve; 43 Third shuttle valve

[0037] 5 fuel supply units

[0038] 100 oil inlet circuit, 200 oil return circuit

[0039] 300 pilot oil circuit 400 load feedback oil circuit

[0040] 500 oil unloading circuit

[0041] p telescopic oil inlet t telescopic oil return outlet

[0042] a. Extend / retract the first working oil port; b. Extend / retract the second working oil port.

[0043] c. Telescopic first oil port; d. Telescopic first overflow oil port

[0044] e retracts the second oil port; f retracts the third oil port.

[0045] g retractable second overflow port h retractable fourth port

[0046] i retracts the fifth oil port; j retracts the sixth oil port.

[0047] k telescopic seventh oil port Detailed Implementation

[0048] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only for illustration and explanation of the present invention, and the scope of protection of the present invention is not limited to the specific embodiments described below.

[0049] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "forming," "having," "setting," and "connecting," etc., should be interpreted broadly. For example, a connection can be a direct connection or an indirect connection through an intermediate medium; it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection or an indirect connection through an intermediate connector; it can be the internal communication of two elements or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0050] In this invention, unless otherwise specified, the directional terms "upper" and "lower" used to indicate the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to 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 invention. The directional terms of this invention should be understood in conjunction with the actual installation state.

[0051] This invention provides a hydraulic control system, see [link to relevant documentation]. Figure 1As a specific embodiment of the hydraulic control system of the present invention, it includes an oil inlet circuit 100, an oil return circuit 200, an oil inlet link 1, and multiple working links. The oil inlet circuit 100 connects the oil inlet link 1 to each working link to supply oil. The oil return circuit 200 connects the oil inlet link 1 to each working link to return oil. The two working ports of the main valve core of some or all working links are respectively connected to the actuator through a working circuit to enable the actuator to supply and return oil. When the oil supply pressure of the actuator is lower than the set value, the actuator does not operate. An unloading valve is provided between the two working circuits. When the working link... When the main valve core receives the neutral position control command, the unloading valve can control the two working oil circuits of the working link to connect with each other through the unloading valve. Therefore, even if the main valve core of a working link is stuck and does not move to the neutral position, while other working links are running, the hydraulic oil passing through the main valve core of the working link with the stuck main valve core will directly return to the return oil circuit 200 for pressure relief, so that the hydraulic oil will not build up enough pressure (oil pressure less than the set value) to be delivered to the actuator, avoiding the actuator of the working link from producing uncontrollable actions, thereby ensuring the smooth operation of the hydraulic control system and improving the safety of the hydraulic system. In addition, when the main valve core of the working link is in the working position, the unloading valve is closed, which prevents the two working oil circuits of the working link from being directly connected. This allows the working oil circuit supplying oil to the actuator to generate sufficient pressure (oil pressure greater than the set value) to deliver oil to the actuator, enabling the actuator to supply and return oil and complete the action. The unloading valve in the closed state also has a certain safety function. If the oil pressure supplied to the actuator is too high and exceeds the safety value, the oil supply working oil circuit can overflow directly to the oil return working oil circuit through the unloading valve, avoiding damage to the actuator caused by excessive oil pressure.

[0052] See Figure 1In a preferred embodiment of the hydraulic control system of the present invention, a bidirectional balancing valve is provided in part or all of the working connections. Two working oil circuits are connected one-to-one to the two inlets of the bidirectional balancing valve, and the two outlets of the bidirectional balancing valve are connected to the actuators. The bidirectional balancing valve comprises two identical parts, each consisting of a check valve and a pressure valve piloted by a reverse pipeline. The check valve allows oil to flow into the actuator with low pressure loss and remains closed in the reverse direction. When oil flows through the first working oil circuit of the working link and its pressure reaches the set value, the pressure valve of the corresponding second working oil circuit opens under the pilot control of the oil in the first working oil circuit. This allows the actuator to return oil through the pressure valve of the second working oil circuit. At the same time, the first working oil circuit supplies oil to the actuator through the check valve, causing the actuator to move. Therefore, the set value mentioned above is the oil pressure pilot controlled by the pressure valve in the bidirectional balance valve. When the oil pressure in the first working oil circuit is less than the set value, the pressure valve of the second working oil circuit will not open, and the check valve of the second working oil circuit will remain closed. With the main valve core of the working link in the neutral position, the corresponding actuator load is maintained, and there is no movement. When the main valve core of the working link becomes stuck, the unloading valve corresponding to the working link opens due to the mid-position control command. Therefore, even if oil flows into the first working oil circuit of the working link, the oil will be directly unloaded through the unloading valve and cannot build up sufficient oil pressure. Under the action of the bidirectional balance valve, the actuator will not produce uncontrollable actions, ensuring the safe operation of the hydraulic system.

[0053] See Figure 1 The hydraulic control system of this invention also includes a pilot oil circuit 300, which is connected to the control end of the main valve core of each working link, so as to control the main valve core of each working link to move to different positions, thereby controlling the corresponding actuator to perform actions. In order to supply oil, the oil inlet link 1 is connected to the oil supply unit 5 through the main oil circuit 11. The oil supply unit 5 delivers hydraulic oil to the main oil circuit 11. The oil inlet circuit 100 is connected to the main oil circuit 11 to supply oil to the main valve core of each working link. The pilot oil circuit 300 is connected to the main oil circuit 11 through a three-way pressure reducing valve 12 to reduce the oil pressure of the main oil circuit 11 to the required pilot oil pressure. At the same time, the three-way pressure reducing valve 12 is also connected to the return oil circuit 200, so as to overflow when the pressure reduction capacity is insufficient, avoiding excessive pilot oil pressure and causing safety hazards. In a preferred embodiment, the oil supply unit 5 consists of a gear pump and a check valve. The gear pump draws oil from the hydraulic oil tank, and the hydraulic oil enters the main oil circuit 11 in the oil inlet link 1 through the check valve.

[0054] As a preferred embodiment of the hydraulic control system of the present invention, see [link to relevant documentation]. Figure 1It also includes a load feedback oil circuit 400. The output pressure of the main valve core of each working link can be introduced into the load feedback oil circuit 400. The oil inlet link 1 is equipped with a differential pressure reducing valve 13. The main oil circuit 11 is connected to the return oil circuit 200 through the differential pressure reducing valve 13. The load feedback oil circuit 400 is connected to the spring end of the differential pressure reducing valve 13, so that the maximum load pressure of each working link can act on the spring end of the differential pressure reducing valve 13. When the load pressure increases, the oil flow diverted from the main oil circuit 11 by the differential pressure reducing valve 13 decreases, thereby allowing the main oil circuit 11 to flow into the oil inlet link 1. When the oil flow rate increases, it ensures that the oil flow rate in the inlet oil circuit 100 meets the requirements of the working circuit, allowing each actuator to operate normally. Conversely, when the load pressure decreases, the oil flow rate required by the working circuit decreases. To prevent excess oil flow from flowing into the inlet oil circuit 100 and causing losses, the differential pressure reducing valve 13 increases the oil flow rate diverted from the main oil circuit 11, thus reducing the flow rate in the inlet oil circuit 100. This reduced flow rate in the inlet oil circuit 100 is directly returned to the return oil circuit 200 through the differential pressure reducing valve 13, reducing losses and achieving energy saving. It should be noted that the main oil circuit 11 is also equipped with a main relief valve 15 connected to the return oil circuit 200 to ensure that the oil pressure in the inlet oil circuit 100 is always within a safe range.

[0055] Further, see Figure 1 The inlet link 1 is equipped with a load feedback unloading valve 14. The load feedback oil circuit 400 is connected to the unloading oil circuit 500 through the load feedback unloading valve 14. When the working links are not working, the load feedback unloading valve 14 is opened, and the load feedback unloading valve 14 is directly connected to the unloading oil circuit 500 for unloading. The spring end of the differential pressure reducing valve 13 is not subjected to load pressure, so that the oil in the main oil circuit 11 can directly return to the return oil circuit 200 through the differential pressure reducing valve 13, reducing the oil loss in the inlet oil circuit 100. When the working links are working, the load feedback unloading valve 14 is closed. The load pressure of each working link can be fed back to the spring end of the differential pressure reducing valve 13 through the load feedback oil circuit 400 to regulate the flow of the inlet oil circuit 100. When the oil pressure in the load feedback oil circuit 400 is too high and exceeds the safety value, it can directly overflow to the unloading oil circuit 500 through the load feedback unloading valve 14 for unloading, ensuring the safe operation of the hydraulic system of this invention. It should be noted that the load feedback unloading valve 14 is preferably a solenoid valve. When the electromagnet is energized, the load feedback unloading valve 14 closes; when the electromagnet is de-energized, the load feedback unloading valve 14 opens.

[0056] Taking aerial work platforms as an example, see Figure 1Each working link includes telescopic link 2, main boom link 3, and tower boom link 4. Telescopic link 2, main boom link 3, and tower boom link 4 are all equipped with bidirectional balance valves and unloading valves. In case the main valve core of the working link gets stuck and cannot return to the neutral position, the corresponding actuator will not produce uncontrollable movements, thus preventing the boom from colliding with other objects and ensuring the safety of personnel working at height.

[0057] Specifically, see Figure 1 and Figure 2 The telescopic linkage 2 includes a telescopic main valve core 21, which includes a telescopic inlet p, a telescopic return port t, a first telescopic working port a, and a second telescopic working port b. The inlet oil circuit 100 is connected to the telescopic inlet p via a telescopic pressure compensation valve 22 to compensate for the differential pressure of the hydraulic oil output from the telescopic main valve core 21. The telescopic return port t is connected to the return oil circuit 200. The first telescopic working port a and the second telescopic working port b are respectively connected to the first telescopic working circuit 210 and the second telescopic working circuit 211. The first telescopic working circuit 210 and the second telescopic working circuit 211 are respectively connected to the rodless chamber and the rod chamber of the telescopic cylinder (actuator of the telescopic linkage 2) via a telescopic bidirectional balance valve 28. A telescopic unloading valve 29 is provided between the first telescopic working circuit 210 and the second working circuit 211. The telescopic main valve core 21 includes at least a first working position, a second working position, and a neutral position. When the telescopic main valve core 21 is in the first working position (…),… Figure 1 In the middle and lower position state, the telescopic inlet p is connected to the first telescopic working port a, the telescopic return port t is connected to the second telescopic working port b, the telescopic unloading valve 29 is in the closed state, the oil pressure of the first telescopic working oil circuit 210 can reach the set value, the first telescopic working oil circuit 210 can supply oil to the rodless chamber through the telescopic bidirectional balance valve 28, and the rod chamber can return oil to the second telescopic working oil circuit 211 through the telescopic bidirectional balance valve 28; when the telescopic main valve core 21 is in the second working position state ( Figure 1In the upper-middle position, the telescopic inlet p is connected to the telescopic second working port b, and the telescopic return port t is connected to the telescopic first working port a. The telescopic unloading valve 29 is closed, and the oil pressure of the telescopic second working oil circuit 211 can reach the set value. The telescopic second working oil circuit 211 can supply oil to the rod chamber through the telescopic bidirectional balance valve 28, and the rodless chamber can return oil to the telescopic first working oil circuit 210 through the telescopic bidirectional balance valve 28. The telescopic main valve core 21 has a Y-shaped neutral position function, that is, when the telescopic main valve core 21 is in the neutral position, both the telescopic first working port a and the telescopic second working port b are connected to the telescopic return port t, so that the oil in the first working oil circuit 210 and the second working oil circuit 211 is unloaded, which cooperates with the telescopic... The bidirectional balance valve 28 maintains the load of the telescopic cylinder. When it receives a control command to move the telescopic main valve core 21 to the neutral position, it simultaneously controls the telescopic unloading valve 29 to open, thus connecting the first telescopic working oil circuit 210 and the second telescopic working oil circuit 211. Therefore, even if the telescopic main valve core 21 gets stuck and does not return to the neutral position, when the telescopic main valve core 21 supplies hydraulic oil to one of the telescopic first working oil circuit 210 or the second telescopic working oil circuit 211, it can unload to the other oil circuit through the telescopic unloading valve 29. The oil pressure will not accumulate to exceed the set value, and the telescopic cylinder cannot return oil through the bidirectional balance valve 28, thus preventing uncontrollable actions and ensuring the safety of high-altitude operations.

[0058] It should be noted that, see Figure 1 The main boom link 3 includes a main boom main valve core 31, a main boom pressure compensation valve 32 that compensates for the oil pressure output of the main boom main valve core 31, and a second shuttle valve 33. The tower boom link 4 includes a tower boom main valve core 41, a tower boom pressure compensation valve 42 that compensates for the oil pressure output of the tower boom main valve core 41, and a third shuttle valve 43. The telescopic link 2 is equipped with a first shuttle valve 27. The load pressure in the telescopic link 2, the main boom link 3, and the tower boom link 4 is compared through the first shuttle valve 27, the second shuttle valve 33, and the third shuttle valve 43, so that the maximum load pressure in the three working links can be introduced into the load feedback oil circuit 400 for load feedback.

[0059] Additionally, see Figure 2The telescopic main valve core 21 also includes a telescopic first oil port c, a telescopic first overflow oil port d, a telescopic second oil port e, a telescopic third oil port f, a telescopic second overflow oil port g, a telescopic fourth oil port h, a telescopic fifth oil port i, a telescopic sixth oil port j, and a telescopic seventh oil port k. The telescopic fifth oil port i and the telescopic sixth oil port j are respectively connected to the telescopic second working oil port b and the telescopic first working oil port a. The telescopic second oil port e and the telescopic third oil port f are both connected to the same comparison oil port of the first shuttle valve 27. The control end of the telescopic pressure compensation valve 22 is also connected through the same oil circuit. The sixth telescopic oil port j and the third telescopic oil port f are connected when the telescopic main valve core 21 is in the first working position, and the fifth telescopic oil port i and the second telescopic oil port e are connected when the telescopic main valve core 21 is in the second working position. This allows the load pressure of the telescopic link 2 to be applied to the first shuttle valve 27 and compared with the load pressure of other working links. It also allows the telescopic pressure compensation valve 22 to compare the input and output oil of the telescopic main valve core 21, thereby compensating for and ensuring a constant pressure difference. The second telescopic port e and the third telescopic port f are also connected to the first telescopic port c and the fourth telescopic port h through the same oil circuit. The first telescopic overflow port d is connected to the first telescopic overflow valve 25, and the second telescopic overflow port g is connected to the second telescopic overflow valve 26. The fourth telescopic port h and the first telescopic overflow port d are connected when the telescopic main valve core 21 is in the first working position. When the oil inlet pressure of the first telescopic working oil circuit 210 exceeds the safety value, it can overflow and unload to the unloading oil circuit 500 through the first telescopic overflow valve 25. When the telescopic main valve core 21 is in the second working position, the first oil port c and the telescopic second overflow oil port g are connected. When the oil inlet pressure of the telescopic second working oil circuit 211 exceeds the safety value, the pressure can be relieved by overflowing to the unloading oil circuit 500 through the telescopic second overflow valve 26. When the telescopic main valve core 21 is in the neutral position, the telescopic fourth oil port h is connected to the telescopic seventh oil port k, which is directly connected to the return oil circuit 200, so that the control end of the telescopic pressure compensation valve 22 is directly unloaded by connecting to the return oil circuit 200 in the neutral position. It should be noted that, in the preferred case, the telescopic second oil port e and the telescopic third oil port f are connected to the control end of the telescopic pressure compensation valve 22, and a throttling orifice is provided on the same oil circuit as the telescopic first oil port c and the telescopic fourth oil port h to filter the oil pressure fluctuations in the oil circuit.

[0060] As a preferred embodiment of the hydraulic control system of the present invention, see [link to previous document]. Figure 1The control end of the telescopic main valve core 21 is connected to the pilot oil circuit 300 and the unloading oil circuit 500. The telescopic main valve core 21 is electromagnetically controlled. Preferably, the telescopic unloading valve 29 is also electromagnetically controlled. The telescopic main valve core 21 is equipped with a first telescopic electromagnet 23 and a second telescopic electromagnet 24. When the telescopic main valve core 21 needs to move to the first working position, the first telescopic electromagnet 23 is energized, and the oil pressure in the pilot oil circuit 300 pushes the telescopic main valve core 21 to move to the first working position. When the telescopic main valve core 21 needs to move to the second working position, the second telescopic electromagnet 24 is energized, and the oil pressure in the pilot oil circuit 300 pushes the telescopic main valve core 21 to move to the second working position. Simultaneously, when the telescopic main valve core 21 moves to the first or second working position, the electromagnet of the telescopic unloading valve 29 is energized, and the telescopic unloading valve 29 closes, so that the first telescopic working oil circuit 210 and the second telescopic working oil circuit 211 are not interconnected. When the oil supply pressure of the first telescopic working oil circuit 210 or the second telescopic working oil circuit 211 is greater than the set value, the telescopic cylinder can extend or retract. When the oil supply pressure of the first telescopic working oil circuit 210 or the second telescopic working oil circuit 211 exceeds the safety value, the telescopic unloading valve 29 can be opened by oil pressure, so that the two working oil circuits are directly connected to enable overflow unloading. When the telescopic main valve core 21 receives the neutral position command, both the first telescopic electromagnet 23 and the second telescopic electromagnet 24 are de-energized. The telescopic main valve core 21 moves to the neutral position under the action of the reset spring at the control end. At the same time, the electromagnet of the telescopic unloading valve 29 is de-energized, and the telescopic unloading valve 29 opens. The first telescopic working oil circuit 210 and the second telescopic working oil circuit 211 are directly connected through the telescopic unloading valve 29. Therefore, even if the telescopic main valve core 21 is stuck and does not move to the neutral position, the main boom linkage 3 and the tower boom linkage 4 will operate. The oil passing through the stuck telescopic main valve core 21 can directly return from the telescopic main valve core 21 to the return oil circuit 200, so that the oil pressure in the first telescopic working oil circuit 210 or the second telescopic working oil circuit 211 does not exceed the set value. Under the action of the telescopic bidirectional balance valve 28, the telescopic cylinder will not produce uncontrollable movements.

[0061] This invention's hydraulic control system incorporates an unloading valve between the two working oil circuits of the actuator and the main valve core of the working link. When the main valve core receives a control command, it moves to the neutral position, opening the unloading valve. This allows the two working oil circuits of the working link to be directly connected. Therefore, even if the main valve core is stuck and not in the neutral position, hydraulic oil passing through the stuck valve core can return directly to the return oil circuit via the unloading valve for pressure relief. This prevents the hydraulic oil from building sufficient pressure to supply the actuator, thus avoiding uncontrollable actions by the actuator in this working link. Conversely, when the working link needs to control the actuator, the main valve core is in the working position, and the unloading valve is closed. This prevents the two working oil circuits of the working link from being directly connected, allowing the inlet oil circuit to generate sufficient pressure to supply the actuator, enabling it to move oil in and out and complete its actions.

[0062] Furthermore, the present invention also provides an aerial work platform, which includes the hydraulic control system of the present invention. Therefore, it possesses all the beneficial effects of the hydraulic control system of the present invention, which will not be elaborated here.

[0063] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0064] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0065] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A hydraulic control system, characterized in that, It includes an oil inlet circuit (100), an oil return circuit (200), a pilot circuit (300), a load feedback circuit (400), an oil inlet link (1), and multiple working links. The oil inlet circuit (100) connects the oil inlet link (1) to each of the working links to supply oil. The oil return circuit (200) connects the oil inlet link (1) to each of the working links to return oil. The two working ports of the main valve core of some or all of the working links are connected to the actuator through a working circuit to enable the actuator to supply and return oil. When the oil supply pressure of the actuator is lower than the set value, the actuator does not operate. An unloading valve is provided between the two working circuits. When the main valve core of the working link receives the mid-position control command, the unloading valve can control the two working circuits of the working link to be interconnected through the unloading valve. Some or all of the working links are equipped with a bidirectional balance valve, and the two working oil circuits are respectively connected to the two oil inlets of the bidirectional balance valve, and the two oil outlets of the bidirectional balance valve are respectively connected to the actuator. The pilot oil circuit (300) is connected to the control end of the main valve core of each working link. The oil inlet link (1) is connected to the oil supply unit (5) through the main oil circuit (11). The oil inlet circuit (100) is connected to the main oil circuit (11). The pilot oil circuit (300) is connected to the main oil circuit (11) through the three-way pressure reducing valve (12). The output pressure of the main valve core of each working link can be introduced into the load feedback oil circuit (400). The oil inlet link (1) is equipped with a differential pressure reducing valve (13). The main oil circuit (11) is connected to the return oil circuit (200) through the differential pressure reducing valve (13). The load feedback oil circuit (400) is connected to the spring end of the differential pressure reducing valve (13). The oil inlet line (1) is equipped with a load feedback unloading valve (14), and the load feedback oil circuit (400) is connected to the unloading oil circuit (500) through the load feedback unloading valve (14).

2. The hydraulic control system according to claim 1, characterized in that, The load feedback unloading valve (14) is a solenoid valve.

3. The hydraulic control system according to claim 1, characterized in that, Each of the aforementioned working links includes a telescopic link (2), a main boom link (3), and a tower boom link (4). The telescopic link (2), the main boom link (3), and the tower boom link (4) are all equipped with the bidirectional balancing valve and the unloading valve.

4. The hydraulic control system according to claim 3, characterized in that, The telescopic link (2) includes a telescopic main valve core (21), which includes a telescopic inlet (p), a telescopic return port (t), a first telescopic working port (a), and a second telescopic working port (b). The oil inlet circuit (100) is connected to the telescopic inlet (p) through a telescopic pressure compensation valve (22). The telescopic main valve core (21) includes at least a first working position, a second working position, and a neutral position. When the telescopic main valve core (21) is in the first working position, the telescopic inlet (p) is connected to the first telescopic working port (a), and the telescopic return port (t) is connected to the second telescopic working port (b). When the telescopic main valve core (21) is in the second working position, the telescopic inlet (p) is connected to the second telescopic working port (b), and the telescopic return port (t) is connected to the first telescopic working port (a). The telescopic main valve core (21) has a Y-shaped neutral position function.

5. The hydraulic control system according to claim 4, characterized in that, The control end of the telescopic main valve core (21) is connected to the pilot oil circuit (300) and the unloading oil circuit (500). The telescopic main valve core (21) is equipped with a first telescopic electromagnet (23) and a second telescopic electromagnet (24). When the first telescopic electromagnet (23) is energized, the oil pressure in the pilot oil circuit (300) pushes the telescopic main valve core (21) to the first working position. When the second telescopic electromagnet (24) is energized, the oil pressure in the pilot oil circuit (300) pushes the telescopic main valve core (21) to the second working position.

6. An aerial work platform, characterized in that, The hydraulic control system includes any one of claims 1-5.

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