Hydraulic control system and aerial work platform

Abstract

The present application relates to hydraulic equipment of construction machinery, and provides a hydraulic control system, which comprises an oil inlet oil path, an oil return oil path, an oil discharge oil path, an oil inlet joint and multiple working joints. The main valve core of the working joint comprises an oil inlet port, an oil return port and two working oil ports connected with actuators respectively. When the oil supply pressure of the actuator is lower than a set value, the actuator does not act. Part or all of the working joints are provided with control valves. The control valves are connected with the main valve core of the working joint and the oil discharge oil path respectively. When the main valve core of the working joint is moved to connect one working oil port of the main valve core with the oil inlet port, the control valve can be connected with the oil inlet port. When the main valve core of the working joint receives a neutral control instruction, the control valve can control the main valve core to communicate with the oil discharge oil path. The hydraulic control system of the present application can avoid the valve core stuck in the neutral position from delivering hydraulic oil to the actuator, 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 inlet oil circuit, a return oil circuit, an unloading oil circuit, an inlet coupling, and multiple working couplings. The inlet oil circuit connects the inlet coupling to each of the working couplings to supply oil, and the return oil circuit connects the inlet coupling to each of the working couplings to return oil. The main valve core of each working coupling includes an inlet port connected to the inlet oil circuit, a return oil port connected to the return oil circuit, and two working ports respectively connected to an actuator. When the oil supply pressure of the actuator is lower than a set value, the actuator does not operate. Some or all of the working couplings are equipped with control valves, which are respectively connected to the main valve core of the working coupling and the unloading oil circuit. When the main valve core of the working coupling moves so that one of its working ports connects to the inlet port, the control valve can connect to the inlet port. Furthermore, when the main valve core of the working coupling receives a neutral position control command, the control valve can control the main valve core to connect to the unloading oil circuit.

[0008] 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 control valve.

[0009] Specifically, the boom assembly includes a boom main valve core and a boom control valve. The boom control valve is connected to the boom main valve core and the unloading oil circuit. The boom main valve core includes a boom inlet, a boom return port, a boom first working port, and a boom second working port. The boom main valve core includes at least a first working position, a second working position, and a neutral position. When the boom main valve core is in the first working position, the boom inlet is connected to the boom first working port, and the boom return port is connected to the boom second working port. Working oil port; when the main boom valve core is in the second working position, the main boom oil inlet is connected to the second working oil port of the main boom, and the main boom oil return port is connected to the first working oil port of the main boom; the main boom valve core has a Y-shaped center position function; wherein, when the main boom valve core is in the first or second working position, the main boom control valve is connected to the main boom oil inlet, and when the main boom valve core receives a center position command, the main boom control valve can control the main boom valve core to connect to the unloading oil circuit.

[0010] Preferably, the boom is equipped with a boom pressure compensation valve, and the oil inlet circuit is connected to the boom oil inlet through the boom pressure compensation valve. The boom main valve core includes a boom second oil port, a boom third oil port, a boom fifth oil port, and a boom sixth oil port. The boom fifth oil port is connected to the boom second working oil port, and the boom sixth oil port is connected to the boom first working oil port. The boom second oil port and the boom third oil port are connected to the control terminal of the boom pressure compensation valve through the boom first oil circuit. The boom sixth oil port and the boom third oil port are connected when the boom main valve core is in the first working position, and the boom fifth oil port and the boom second oil port are connected when the boom main valve core is in the second working position.

[0011] 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, and the oil inlet link is provided with a differential pressure reducing valve, which can control the oil flow rate of the oil inlet line according to the oil pressure in the load feedback oil circuit.

[0012] Specifically, the telescopic link includes a telescopic main valve core and a first shuttle valve, the main boom link includes a second shuttle valve, and the tower boom link includes a tower boom main valve core and a third shuttle valve. The comparison port of the third shuttle valve is connected to the output port of the tower boom main valve core. The two comparison ports of the second shuttle valve are respectively connected to the first oil circuit of the main boom and the output port of the third shuttle valve. The two comparison ports of the first shuttle valve are respectively connected to the output port of the second shuttle valve and the output port of the telescopic main valve core. The output port of the first shuttle valve is connected to the load feedback oil circuit.

[0013] Specifically, the main boom control valve includes a first main boom control valve and a second main boom control valve. The main boom valve core includes a first main boom port, a fourth main boom port, a seventh main boom port, a first main boom control port, and a second main boom control port. The first and fourth main boom ports are both connected to the first main boom oil circuit. The first main boom control port is connected to the unloading oil circuit through the second main boom oil circuit. The second main boom control port is connected to the unloading oil circuit through the third main boom oil circuit. The first main boom control valve is located in the second main boom oil circuit, and the second main boom control valve is located in the third main boom oil circuit. The first and fourth main boom ports are connected when the main boom valve core is in the first working position. The second main boom control port is connected to the first main boom port when the main boom valve core is in the second working position. The seventh main boom port and the fourth main boom port, which are connected to the return oil circuit, are connected when the main boom valve core is in the neutral position.

[0014] Preferably, the boom assembly is provided with a first boom overflow valve and a second boom overflow valve. The first boom overflow valve is connected in parallel with the first boom control valve in the second boom oil circuit, and the second boom overflow valve is connected in parallel with the second boom control valve in the third boom oil circuit.

[0015] Preferably, some or all of the working links are provided with a bidirectional balancing valve, and the two working oil ports of the working link 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.

[0016] Furthermore, the present invention also 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] The hydraulic control system of this invention connects the main valve core of the working link and the unloading oil circuit via a control valve. When the main valve core of the working link moves, connecting one of its working ports to the inlet port, the control valve connects to the inlet port, thus connecting the inlet port of the main valve core to the unloading oil circuit. The control valve only opens when the main valve core receives a neutral position control command. Therefore, even if the main valve core is stuck and does not move to the neutral position, the hydraulic oil supplied from the inlet port to the main valve core can still flow directly to the unloading oil circuit for pressure relief through the control valve. This prevents the hydraulic oil from building up sufficient pressure to be supplied to the actuator from the working port, avoiding uncontrollable actions by the actuator in this working link. When the working link needs to control the actuator to move, the main valve core is in the working position. At this time, the control valve is closed, blocking the inlet port from the unloading oil circuit. This ensures that the hydraulic oil supplied from the working port of the main valve core to the actuator has sufficient pressure, allowing the actuator to perform oil inflow and outflow, and thus complete its action.

[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 First shuttle valve

[0029] 3 main boom link 31 main boom main valve core

[0030] 311 Main arm first electromagnet; 312 Main arm second electromagnet

[0031] 32 Main boom control valve 321 Main boom first control valve

[0032] 322 Main boom second control valve; 33 Main boom pressure compensation valve

[0033] 34 Main boom first oil circuit 35 Second shuttle valve

[0034] 36 Main boom second oil circuit 37 Main boom third oil circuit

[0035] 38 Main boom first overflow valve 39 Main boom second overflow valve

[0036] 4-tower arm connection with 41-tower arm main valve core

[0037] 42 Third shuttle valve

[0038] 5 fuel supply units

[0039] 100 oil inlet circuit, 200 oil return circuit

[0040] 300 pilot oil circuit 400 load feedback oil circuit

[0041] 500 oil unloading circuit

[0042] p Main boom oil inlet t Main boom oil return outlet

[0043] a. Main boom first working oil port b. Main boom second working oil port

[0044] c. Main boom first oil port; d. Main boom first control oil port

[0045] e Main arm second oil port f Main arm third oil port

[0046] g Main boom second control oil port h Main boom fourth oil port

[0047] i Main arm fifth oil port j Main arm sixth oil port

[0048] K main arm seventh oil port Detailed Implementation

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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 discharge circuit 500, 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 main valve core of each working link includes an oil inlet port connected to the oil inlet circuit 100, an oil return port connected to the oil return circuit 200, and two working ports respectively connected to the actuator. The main valve core can realize the oil supply and return of the actuator through the two working ports. When the oil supply pressure of the actuator is lower than the set value, the actuator does not operate. Part or all of the working links are equipped with control valves, which are respectively connected to the main valve core of the working link and the oil discharge circuit 500. When the main valve core of the working link moves, it causes... When one working port of the main valve core in the working link is connected to the inlet, the control valve can connect to the inlet, thereby connecting the inlet of the main valve core to the unloading oil circuit 500 through the control valve. When the main valve core in the working link receives a neutral position control command, the control valve can open to control the main valve core to connect to the unloading oil circuit 500. Therefore, even if the main valve core is stuck and has not moved to the neutral position, while other working links are running, the hydraulic oil supplied from the inlet to the stuck main valve core by the inlet oil circuit 100 can also flow directly to the unloading oil circuit 500 through the control valve for pressure relief. This prevents the hydraulic oil from building up sufficient pressure (oil pressure less than the set value) to be supplied to the actuator, avoiding uncontrollable actions of the actuator in this working link, thereby ensuring the stable 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 control valve is closed, which blocks the oil inlet and the oil discharge circuit 500. This ensures that the hydraulic oil delivered from the working port to the actuator has sufficient pressure (the oil pressure is greater than the set value), enabling the actuator to supply and return oil, and thus complete the action.

[0053] It should be noted that, in order to ensure that the actuator does not operate when the oil supply pressure is lower than the set value, preferably, a two-way balancing valve is installed in part or all of the working links. The two working ports of the working links are connected one-to-one with the two inlets of the two-way balancing valve, and the two outlets of the two-way balancing valve are connected to the actuator. The two-way balancing valve consists of two identical parts, both of which are composed of a check valve and a pressure valve piloted by a reverse pipeline. The check valve allows oil to flow into the actuator with a 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 control valve corresponding to the working link opens due to the receipt of the neutral position control command. Therefore, the hydraulic oil flowing from the oil inlet 100 to the oil inlet of the main valve core of the working link will flow directly through the control valve. The oil will also be directly unloaded through the unloading valve, and sufficient oil pressure cannot be built up. Under the action of the bidirectional balance valve, the actuator will not produce uncontrollable actions, ensuring the safe operation of the hydraulic system.

[0054] Taking aerial work platforms as an example, see Figure 1 Each 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 control valves to prevent the corresponding actuators from making uncontrollable movements if the main valve core of the working link gets stuck and cannot return to the neutral position, thereby preventing the boom from colliding with other objects and ensuring the safety of personnel working at height.

[0055] Specifically, see Figure 1 and Figure 2 The main boom linkage 3 includes a main boom main valve core 31 and a main boom control valve 32. The main boom control valve 32 is connected to the main boom main valve core 31 and the unloading oil circuit 500. The main boom main valve core 31 includes a main boom oil inlet p, a main boom oil return port t, a main boom first working oil port a, and a main boom second working oil port b. The main boom first working oil port a is connected to the rodless chamber of the main boom cylinder (the actuator of the main boom linkage 3), and the main boom second working oil port b is connected to the rod chamber of the main boom cylinder. The main boom main valve core 31 includes at least a first working position, a second working position, and a neutral position. When the main boom main valve core 31 is in the first working position (…), Figure 1In the lower position, the main boom oil inlet p is connected to the first working oil port a of the main boom, and the main boom oil return port t is connected to the second working oil port b of the main boom, so that the main boom cylinder can extend. When the main boom valve core 31 is in the second working position, the main boom oil inlet p is connected to the second working oil port b of the main boom, and the main boom oil return port t is connected to the first working oil port a of the main boom, so that the main boom cylinder can retract. When the main boom valve core 31 is in the first or second working position, the main boom control valve 32 is connected to the main boom oil inlet p. When the main boom valve core receives the first or second working position command, the main boom control valve 32 is closed, blocking the connection between the main boom oil inlet p and the unloading oil circuit 500. The hydraulic oil supplied from the main boom oil inlet p to the main boom valve core 31 through the oil inlet circuit 100 reaches the set value, allowing the hydraulic oil flowing from the first working oil port a or the second working oil port b of the main boom to the actuator to open the bidirectional balance valve, enabling the main boom cylinder to extend or retract. When the main boom valve core 31 receives the neutral position command... When the main boom control valve 32 opens, it can control the main boom main valve core 31 to connect to the unloading oil circuit 500. Therefore, even if the main boom main valve core 31 is stuck and does not return to the neutral position, the main boom oil inlet p can still connect to the unloading oil circuit 500 through the main boom control valve 32. When the oil inlet circuit 100 delivers hydraulic oil to the main boom oil inlet p, it can flow directly to the unloading oil circuit 500 to unload, so that the oil pressure in the working oil circuits connected to the actuators of the main boom first working oil port a and the main boom second working oil port b will not accumulate to exceed the set value. The main boom cylinder cannot return oil through the two-way balance valve, thus preventing uncontrollable actions and ensuring the safety of high-altitude operations. In addition, the main boom valve core 31 has a Y-shaped neutral position function, that is, when the main boom valve core 31 is in the neutral position, the first working oil port a and the second working oil port b of the main boom are both connected to the main boom return oil port t, so that the oil in the working oil circuit connected to the main boom cylinder by the first working oil port a and the second working oil port b of the main boom is unloaded, and the load of the main boom cylinder is maintained in conjunction with the two-way balance valve.

[0056] In a preferred embodiment of the hydraulic control system of the present invention, the main boom assembly 3 is equipped with a main boom pressure compensation valve 33. The oil inlet circuit 100 is connected to the main boom oil inlet p through the main boom pressure compensation valve 33, so as to compensate for the differential pressure of the hydraulic oil output by the main boom main valve core 31. The main boom main valve core 31 includes a main boom second oil port e, a main boom third oil port f, a main boom fifth oil port i, and a main boom sixth oil port j. The main boom fifth oil port i is connected to the main boom second working oil port b, and the main boom sixth oil port j is connected to the main boom first working oil port a. The main boom second oil port e and the main boom third oil port f together... The control terminal of the main boom pressure compensation valve 33 is connected via the first oil passage 34 of the main boom. The sixth oil port j and the third oil port f of the main boom are connected when the main boom main valve core 31 is in the first working position. The fifth oil port i and the second oil port e of the main boom are connected when the main boom main valve core 31 is in the second working position. This allows the output oil pressure of the main boom main valve core 31 in either the first or second working position to act on the control terminal of the main boom pressure compensation valve 33. This enables the main boom pressure compensation valve 33 to compare the input and output oil pressures of the main boom main valve core 31, thereby compensating for and ensuring a constant pressure difference. Preferably, the first oil passage 34 of the main boom is equipped with a throttling orifice to filter oil pressure fluctuations in the oil passage.

[0057] See Figure 1 The hydraulic control system of this invention includes a pilot oil circuit 300, which is connected to the control end of the main valve core of each working link, enabling control of the main valve core of each working link to move to different positions, thereby controlling the corresponding actuator to perform actions. For oil supply, the inlet link 1 is connected to the oil supply unit 5 via the main oil circuit 11. The oil supply unit 5 delivers hydraulic oil to the main oil circuit 11. The inlet oil 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 via a three-way pressure reducing valve 12, reducing the oil pressure in the main oil circuit 11 to the required pilot oil pressure. Simultaneously, the three-way pressure reducing valve 12 is also connected to the return oil circuit 200, allowing overflow in case of insufficient pressure reduction, preventing excessive pilot oil pressure from causing safety hazards. Preferably, 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 inlet link 1 through the check valve.

[0058] It should be noted that the hydraulic control system of the present invention 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, which can control the oil flow rate of the oil inlet oil circuit 100 according to the oil pressure in the load feedback oil circuit 400. Specifically, see Figure 1The main oil circuit 11 is connected to the return oil circuit 200 via a differential pressure reducing valve 13, and the load feedback oil circuit 400 is connected to the spring end of the differential pressure reducing valve 13. This allows the maximum load pressure of each working link to 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 increasing the oil flow from the main oil circuit 11 into the inlet oil circuit 100. This ensures that the oil flow in the inlet oil circuit 100 meets the requirements of the working links, and the actuators operate normally. Conversely, when the load pressure decreases, the oil flow required by the working links decreases. To prevent excess oil flow from flowing into the inlet oil circuit 100 and causing losses, the oil flow diverted from the main oil circuit 11 by the differential pressure reducing valve 13 increases, reducing the flow in the inlet oil circuit 100. The reduced flow in the inlet oil circuit 100 is then 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 that connects to the return oil circuit 200, so as to ensure that the oil pressure of the inlet oil circuit 100 is always within a safe range.

[0059] 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.

[0060] In order to input the maximum load pressure between each working link into the load feedback oil circuit 400, see Figure 1 and Figure 2The telescopic link 2 includes a telescopic main valve core 21 and a first shuttle valve 22; the main boom link 3 includes a second shuttle valve 35; and the tower boom link 4 includes a tower boom main valve core 41 and a third shuttle valve 42. The comparison port of the third shuttle valve 42 is connected to the output port of the tower boom main valve core 41. The two comparison ports of the second shuttle valve 35 are respectively connected to the first oil circuit 34 of the main boom and the output port of the third shuttle valve 42. The two comparison ports of the first shuttle valve 22 are respectively connected to the output port of the second shuttle valve 35 and the output port of the telescopic main valve core 21. The output port of the first shuttle valve 22 is connected to the load feedback oil circuit 400.

[0061] As a preferred embodiment of the hydraulic control system of the present invention, see [link to previous document]. Figure 1 and Figure 2The main boom control valve 32 includes a first main boom control valve 321 and a second main boom control valve 322. The main boom valve core 31 includes a first main boom oil port c, a fourth main boom oil port h, a seventh main boom oil port k, a first main boom control oil port d, and a second main boom control oil port g. The first main boom oil port c and the fourth main boom oil port h are both connected to the first main boom oil passage 34. The first main boom control oil port d is connected to the unloading oil passage 500 through the second main boom oil passage 36. The second main boom control oil port g is connected to the unloading oil passage 500 through the third main boom oil passage 37. The main boom first control valve 321 is located on the main boom second oil passage 36, and the main boom second control valve 322 is located on the main boom third oil passage 37. The main boom first control oil port d and the main boom fourth oil port h are connected when the main boom main valve core 31 is in the first working position. Therefore, if the main boom main valve core 31 gets stuck during the process of moving from the first working position to the middle position and does not return to the middle position, the oil flowing from the oil inlet passage 100 to the main boom oil inlet p flows sequentially through the main boom first working oil port a and the main boom sixth oil port. j. The main boom third oil port f, the main boom first oil passage 34, the main boom fourth oil port h, the main boom first control oil port d, and the main boom first control valve 321 unload the oil discharge oil passage 500, so that the working oil passage connecting the main boom first working oil port a to the rodless chamber of the main boom cylinder cannot accumulate oil pressure, thus preventing the main boom cylinder from making uncontrollable extension movements; the main boom second control oil port g and the main boom first oil port c are connected when the main boom main valve core 31 is in the second working position, so that during the process of the main boom main valve core 31 moving from the second working position to the middle position, the oil discharge oil discharge oil is unloaded. Currently, with the main boom valve core 31 not returning to the neutral position, the oil flowing from the inlet oil passage 100 to the main boom inlet p flows sequentially through the main boom second working oil port b, the main boom fifth oil port i, the main boom second oil port e, the main boom first oil passage 34, the main boom first oil port c, the main boom second control oil port g, and the main boom second control valve 322 to unload the oil discharge oil passage 500. This prevents the main boom first working oil port a from accumulating oil pressure in the working oil passage connected to the rod chamber of the main boom cylinder, thus avoiding an unavoidable retraction action of the main boom cylinder. In addition, the main boom seventh oil port k and the main boom fourth oil port h, which are connected to the return oil passage 200, are connected when the main boom valve core 31 is in the neutral position, allowing the control end of the main boom pressure compensation valve 33 to directly unload the oil by connecting to the return oil passage 200 in the neutral position.

[0062] It should be noted that uncontrollable extension and retraction movements of the main boom cylinder can cause safety issues. Therefore, the main boom first control valve 321 and main boom second control valve 322 are set to correspond to the two situations of the main boom main valve core 31 being stuck, respectively. However, the actuator of the working link may cause a safety problem when one movement is uncontrollable, while the other movement may not have an impact. For example, the retraction movement of the telescopic cylinder (the actuator of telescopic link 2) is safe for the aerial work platform. Even if the valve is stuck, it will not cause a safety hazard. However, the extension movement of the telescopic cylinder is dangerous when it is uncontrollable. Therefore, only one control valve can be set in telescopic link 2 to avoid uncontrollable extension movements of the telescopic cylinder.

[0063] To ensure that the oil pressure delivered from the main boom valve core 31 to the main boom cylinder is within a safe range, preferably, the main boom assembly 3 is equipped with a first main boom relief valve 38 and a second main boom relief valve 39. The first main boom relief valve 38 is connected in parallel with the first main boom control valve 321 on the second main boom oil circuit 36. When the main boom valve core 31 is in the first working position, and the oil pressure delivered from the first main boom working port a to the main boom cylinder exceeds the safe value, the hydraulic oil flows sequentially through the sixth main boom port j, the third main boom port f, the first main boom oil circuit 34, the fourth main boom port h, and the first main boom control port. d, thereby opening the valve core of the first relief valve 38 of the main boom to unload the oil unloading circuit 500; the second relief valve 39 of the main boom and the second control valve 322 of the main boom are connected in parallel on the third oil circuit 37 of the main boom. When the main valve core 31 of the main boom is in the second working position, and the oil pressure delivered to the main boom cylinder by the second working oil port b of the main boom exceeds the safety value, the hydraulic oil flows through the fifth oil port i of the main boom, the second oil port e of the main boom, the first oil circuit 34 of the main boom, the first oil port c of the main boom and the second control oil port g of the main boom in sequence, thereby opening the valve core of the second relief valve 39 of the main boom to unload the oil unloading circuit 500.

[0064] It should be noted that, see Figure 1The control end of the main boom valve core 31 is connected to the pilot oil circuit 300 and the unloading oil circuit 500. The main boom valve core 31 is electromagnetically controlled. Preferably, the first control valve 321 and the second control valve 322 of the main boom are also electromagnetically controlled. The main boom valve core 31 is equipped with a first electromagnet 311 and a second electromagnet 312. When the main boom valve core 31 needs to move to the first working position, the first electromagnet 311 is energized, and the oil pressure in the pilot oil circuit 300 pushes the main boom valve core 31 to move to the first working position. At the same time, the electromagnet of the first control valve 321 is energized, and the first control valve 321 closes, blocking the connection between the main boom oil inlet p and the unloading oil circuit 500. The first working oil port a of the main boom supplies oil to the rodless chamber of the main boom cylinder. When the oil pressure is greater than the set value, the main boom cylinder can extend. When the main boom valve core 31 needs to move to the second working position, the main boom second electromagnet 312 is energized, and the oil pressure in the pilot oil circuit 300 pushes the main boom valve core 31 to move to the second working position. At the same time, the electromagnet of the main boom second control valve 322 is energized, and the main boom second control valve 322 is closed, which blocks the connection between the main boom oil inlet p and the unloading oil circuit 500. The oil supply pressure from the main boom second working oil port b to the rod chamber of the main boom cylinder is greater than the set value, and the main boom cylinder can retract. When the main boom valve core 31 receives the neutral position command, both the first main boom solenoid 311 and the second main boom solenoid 312 are de-energized. The main boom valve core 21 moves to the neutral position under the action of the return spring at the control end. At the same time, the solenoids of the first main boom control valve 321 and the second main boom control valve 322 are de-energized, and both the first main boom control valve 321 and the second main boom control valve 322 are in the open state. Therefore, even if the main boom valve core 31 is stuck and does not move to the neutral position, for example, if it is stuck during the process of moving from the first working position to the neutral position, or if it is stuck during the process of moving from the second working position to the neutral position, the hydraulic oil input at the main boom inlet p can be directly unloaded from the second main boom oil circuit 36 ​​or the third main boom oil circuit 37 to the unloading oil circuit 500. This ensures that the oil pressure in the working oil circuit connected to the main boom cylinder at the first main boom working oil port a or the second main boom working oil port b does not exceed the set value. Under the action of the bidirectional balance valve, the main boom cylinder will not produce uncontrollable movements.

[0065] The hydraulic control system of this invention connects the main valve core of the working link and the unloading oil circuit 500 through a control valve. When the main valve core of the working link moves, connecting one of its working ports to the inlet port, the control valve can connect to the inlet port, thus connecting the inlet port of the main valve core to the unloading oil circuit 500 through the control valve. The control valve will only open when the main valve core of the working link receives a neutral position control command. Therefore, even if the main valve core is stuck and does not move to the neutral position, the hydraulic oil supplied from the inlet port to the main valve core can flow directly to the unloading oil circuit 500 through the control valve for pressure relief, preventing the hydraulic oil from building up sufficient pressure to be supplied to the actuator from the working port, thus avoiding uncontrollable actions of the actuator in the working link. When the actuator needs to be controlled to perform an action in this working link, the main valve core is in the working position. At this time, the control valve is closed, which blocks the oil inlet and the oil discharge circuit 500. This ensures that the hydraulic oil delivered from the working oil port to the actuator has sufficient pressure, allowing the actuator to perform oil inlet and outlet operations and complete the action.

[0066] Furthermore, the present invention provides an aerial work platform that 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.

[0067] 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.

[0068] 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.

[0069] 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), an oil discharge circuit (500), an oil inlet connector (1), and multiple working connectors. The oil inlet circuit (100) connects the oil inlet connector (1) to each of the working connectors to supply oil. The oil return circuit (200) connects the oil inlet connector (1) to each of the working connectors to return oil. The main valve core of each working connector includes an oil inlet connected to the oil inlet circuit (100), an oil return port connected to the oil return circuit (200), and two working ports respectively connected to the actuator. When the oil supply pressure of the actuator is lower than the set value, the actuator does not operate. Among them, some or all of the working links are equipped with control valves. The control valves are respectively connected to the main valve core of the working link and the unloading oil circuit (500). When the main valve core of the working link moves so that one of the working oil ports of the main valve core of the working link is connected to the oil inlet, the control valve can connect to the oil inlet. And when the main valve core of the working link receives a mid-position control command, the control valve can control the main valve core to connect to the unloading oil circuit (500). Each of the aforementioned working links includes a telescopic link (2), a main boom link (3), and a tower boom link (4). Each of the telescopic link (2), the main boom link (3), and the tower boom link (4) is equipped with a control valve. The main boom link (3) includes a main boom main valve core (31) and a main boom control valve (32). The main boom control valve (32) is connected to the main boom main valve core (31) and the unloading oil circuit (500). The main boom main valve core (31) includes a main boom oil inlet (p), a main boom oil return port (t), a first main boom working oil port (a), and a second main boom working oil port (b). The valve core (31) includes at least a first working position, a second working position, and a neutral position. When the main boom valve core (31) is in the first working position, the main boom oil inlet (p) is connected to the main boom first working oil port (a), and the main boom oil return port (t) is connected to the main boom second working oil port (b). When the main boom valve core (31) is in the second working position, the main boom oil inlet (p) is connected to the main boom second working oil port (b), and the main boom oil return port (t) is connected to the main boom first working oil port (a). The main boom valve core (31) has a Y-shaped neutral position function. When the main boom valve core (31) is in the first working position or the second working position, the main boom control valve (32) is connected to the main boom oil inlet (p). When the main boom valve core (31) receives the mid-position command, the main boom control valve (32) can control the main boom valve core (31) to connect to the unloading oil circuit (500).

2. The hydraulic control system according to claim 1, characterized in that, The main boom assembly (3) is equipped with a main boom pressure compensation valve (33). The oil inlet circuit (100) is connected to the main boom oil inlet (p) through the main boom pressure compensation valve (33). The main boom main valve core (31) includes a main boom second oil port (e), a main boom third oil port (f), a main boom fifth oil port (i), and a main boom sixth oil port (j). The main boom fifth oil port (i) is connected to the main boom second working oil port (b), and the main boom sixth oil port (j) is connected to the main boom. The first working oil port (a), the second oil port (e) of the main boom and the third oil port (f) of the main boom are connected to the control end of the main boom pressure compensation valve (33) through the first oil circuit (34) of the main boom. The sixth oil port (j) of the main boom and the third oil port (f) of the main boom are connected when the main boom main valve core (31) is in the first working position. The fifth oil port (i) of the main boom and the second oil port (e) of the main boom are connected when the main boom main valve core (31) is in the second working position.

3. The hydraulic control system according to claim 2, characterized in that, 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 provided with a differential pressure reducing valve (13), the differential pressure reducing valve (13) can control the oil flow rate of the oil inlet link (100) according to the oil pressure in the load feedback oil circuit (400).

4. The hydraulic control system according to claim 3, characterized in that, The telescopic link (2) includes a telescopic main valve core (21) and a first shuttle valve (22). The main boom link (3) includes a second shuttle valve (35). The tower boom link (4) includes a tower boom main valve core (41) and a third shuttle valve (42). The comparison port of the third shuttle valve (42) is connected to the output port of the tower boom main valve core (41). The two comparison ports of the second shuttle valve (35) are respectively connected to the first oil circuit (34) of the main boom and the output port of the third shuttle valve (42). The two comparison ports of the first shuttle valve (22) are respectively connected to the output port of the second shuttle valve (35) and the output port of the telescopic main valve core (21). The output port of the first shuttle valve (22) is connected to the load feedback oil circuit (400).

5. The hydraulic control system according to claim 2, characterized in that, The main boom control valve (32) includes a main boom first control valve (321) and a main boom second control valve (322). The main boom main valve core (31) includes a main boom first oil port (c), a main boom fourth oil port (h), a main boom seventh oil port (k), a main boom first control oil port (d), and a main boom second control oil port (g). The main boom first oil port (c) and the main boom fourth oil port (h) are both connected to the main boom first oil passage (34). The main boom first control oil port (d) is connected to the unloading oil passage (500) through the main boom second oil passage (36). The main boom second control oil port (g) is connected to the unloading oil passage (500) through the main boom third oil passage (37). 00) connection, the first control valve (321) of the main boom is set on the second oil circuit (36) of the main boom, the second control valve (322) of the main boom is set on the third oil circuit (37) of the main boom, the first control oil port (d) of the main boom and the fourth oil port (h) of the main boom are connected when the main boom main valve core (31) is in the first working position, the second control oil port (g) of the main boom and the first oil port (c) of the main boom are connected when the main boom main valve core (31) is in the second working position, the seventh oil port (k) of the main boom connected to the return oil circuit (200) and the fourth oil port (h) of the main boom are connected when the main boom main valve core (31) is in the middle position.

6. The hydraulic control system according to claim 5, characterized in that, The main boom assembly (3) is equipped with a first main boom overflow valve (38) and a second main boom overflow valve (39). The first main boom overflow valve (38) and the first main boom control valve (321) are connected in parallel on the second main boom oil circuit (36). The second main boom overflow valve (39) and the second main boom control valve (322) are connected in parallel on the third main boom oil circuit (37).

7. The hydraulic control system according to claim 1, characterized in that, Some or all of the working links are equipped with a bidirectional balancing valve, and the two working oil ports of the working link 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.

8. An aerial work platform, characterized in that, The hydraulic control system includes any one of claims 1-7.

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