Actuator-in-line drive hydraulic system and excavator

Abstract

The application discloses an actuator series drive hydraulic system and a excavator, comprising: a driving actuator, comprising a cylinder body and a piston rod, the cylinder body comprising a rod cavity and a rodless cavity, and the piston rod being used for bearing; a passive actuator; a first switch valve, an oil inlet of which is connected with the rodless cavity; a first check valve, an oil inlet of which is connected with an oil outlet of the first switch valve, and an oil outlet of the first check valve being connected with an oil inlet of the passive actuator; and a controller, connected with the first switch valve, used for controlling the first switch valve to be opened when an action request signal of the passive actuator is received in a piston rod retraction working condition, so that hydraulic oil in the rodless cavity flows to the passive actuator via the first switch valve and the first check valve, series driving of the driving actuator and the passive actuator is realized, energy generated by an external load of the driving actuator is reused, an accumulator does not need to be additionally arranged, equipment investment and maintenance cost are reduced, and flow provided by other oil sources is reduced.

Description

Technical Field

[0001] This invention relates to the field of actuator-driven hydraulic systems, and more specifically, to an actuator-tandem-driven hydraulic system. Furthermore, this invention also relates to an excavator comprising the aforementioned actuator-tandem-driven hydraulic system. Background Technology

[0002] In the field of engineering machinery technology, many engineering equipment are driven by hydraulic systems. For example, hydraulic excavators use hydraulic actuators such as boom cylinders, bucket cylinders, stick cylinders and swing motors to drive the corresponding structural components.

[0003] In related technologies, some actuators bear significant loads, such as hydraulic excavators. Their working devices experience substantial gravity, which acts as a load on the boom cylinder, meaning the working device generates considerable gravitational potential energy. During descent, gravity and other forces propel the boom cylinder, causing it to output return oil from its rodless chamber. To stabilize the working device's speed, the rodless chamber of the boom cylinder needs to generate high return oil pressure as back pressure. The pressurized return oil output from the boom cylinder is then sent to the hydraulic tank via a throttle valve. During this process, the energy of the return oil from the boom cylinder is converted into system heat and dissipated within the system. This not only wastes the gravitational potential energy of the working device but also increases the heat generated by the hydraulic system.

[0004] In related technologies, energy storage devices such as accumulators are added to the hydraulic system to recover the gravitational potential energy of the working device. However, this not only increases equipment costs but also increases the complexity of equipment maintenance.

[0005] Therefore, how to recover energy from hydraulic systems while reducing equipment investment costs and maintenance complexity is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide an actuator series drive hydraulic system that can recover hydraulic system energy while reducing equipment investment costs and maintenance complexity.

[0007] Another objective of this invention is to provide an excavator including the above-mentioned actuator series drive hydraulic system, which can reduce equipment investment costs and maintenance complexity while recovering hydraulic system energy.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A series actuator drive hydraulic system, comprising:

[0010] An active actuator includes a cylinder and a piston rod, the cylinder including a rod chamber and a rodless chamber, and the piston rod being used for bearing loads;

[0011] Passive actuator;

[0012] The first switching valve has its oil inlet connected to the rodless chamber;

[0013] The first check valve has its inlet connected to the outlet of the first switching valve, and the outlet of the first check valve is connected to the inlet of the passive actuator.

[0014] The controller, connected to the first switching valve, is used to control the first switching valve to open when it receives an action request signal from the passive actuator during the piston rod retraction condition, so that the hydraulic oil in the rodless chamber flows to the passive actuator via the first switching valve and the first check valve.

[0015] Optionally, it also includes:

[0016] A one-way switching valve, the oil inlet of which is connected to the rodless chamber, and the oil outlet of which is connected to the rod chamber;

[0017] The third switching valve has its inlet connected to the first oil source, and its outlet connected to the rod chamber.

[0018] The controller is connected to the one-way switching valve and the third switching valve respectively, and the controller is used to control the one-way switching valve and the third switching valve to open or close.

[0019] Optionally, when both the one-way switching valve and the third switching valve are closed, the pressure in the rodless chamber is in a non-pressurized mode;

[0020] When the one-way switch valve is open and the third switch valve is closed, the pressure in the rodless chamber is in a self-pressurizing mode.

[0021] When the third switching valve is open and the one-way switching valve is closed, the pressure in the rodless chamber is in the external pressure mode;

[0022] The pressure in the rodless chamber during the externally pressurized mode is greater than the pressure in the non-pressurized mode, but less than the pressure in the rodless chamber during the self-pressurized mode.

[0023] Optionally, the oil outlet of the first switching valve is equipped with a pressure sensor, which is connected to the controller. The controller is used to control the one-way switching valve and the third switching valve to open or close according to the pressure detected by the pressure sensor.

[0024] Optionally, the pressure detected by the pressure sensor is defined as Pb, and the controller is configured to:

[0025] When Pb < P1, both the one-way switching valve and the third switching valve are closed.

[0026] When P2 < Pb < P3, the third switching valve is opened and the one-way switching valve is closed.

[0027] When Pb > P4, the one-way switch valve is opened and the third switch valve is closed.

[0028] When P1≤Pb≤P2, when the pressure of the rodless chamber was in the non-pressurized mode, both the one-way valve and the third valve are closed; when the pressure of the rodless chamber was in the external pressurized mode, the third valve is opened and the one-way valve is closed.

[0029] When P3≤Pb≤P4, when the pressure of the rodless chamber was in the external pressure mode, the third switch valve is opened and the one-way switch valve is closed; when the pressure of the rodless chamber was in the self-pressure mode, the one-way switch valve is opened and the third switch valve is closed.

[0030] Among them, P1, P2, P3 and P4 are preset pressure values, where 0 < P1 < P2 < P3 < P4.

[0031] Optionally, the passive actuator includes a first passive actuator, a second passive actuator, and a third passive actuator. The oil inlet pressure of the first passive actuator meets a first preset threshold, the oil inlet pressure of the second passive actuator meets a second preset threshold, and the oil inlet pressure of the third passive actuator meets a third preset threshold. The highest value of the first preset threshold is less than the lowest value of the second preset threshold, and the highest value of the second preset threshold is less than the lowest value of the third preset threshold.

[0032] The controller is configured to:

[0033] When the piston rod is retracted, upon receiving an action request signal from the first passive actuator, both the one-way switching valve and the third switching valve are controlled to close.

[0034] When the piston rod is retracted, upon receiving an action request signal from the second passive actuator, or simultaneously receiving action request signals from both the first and second passive actuators, the third switching valve is controlled to open and the one-way switching valve is controlled to close.

[0035] When the piston rod is retracted, upon receiving an action request signal from the third passive actuator, or simultaneously receiving action request signals from the first passive actuator and the third passive actuator, or simultaneously receiving action request signals from the second passive actuator and the third passive actuator, or simultaneously receiving action request signals from the first passive actuator, the second passive actuator, and the third passive actuator, the one-way switching valve is controlled to open and the third switching valve is controlled to close.

[0036] Optionally, it also includes:

[0037] The second switching valve has its oil inlet connected to the rodless chamber;

[0038] The oil replenishment circuit includes a back pressure valve and an oil tank. The oil inlet of the back pressure valve is connected to the oil outlet of the second switching valve, and the oil outlet of the back pressure valve is connected to the oil tank. The oil inlet of the back pressure valve is also connected to the oil outlet of the rod chamber and the passive actuator, respectively. A second check valve is provided between the back pressure valve and the rod chamber, and the oil inlet of the second check valve is connected to the oil inlet of the back pressure valve.

[0039] Optionally, the controller is configured to:

[0040] When only the action request signal of the active actuator is received, the first switching valve, the one-way switching valve and the third switching valve are all closed, and the second switching valve is opened.

[0041] Optionally, the oil inlet of the passive actuator is also connected to a second oil source; the controller is configured to:

[0042] When only the action request signal of the passive actuator is received, the second oil source is controlled to supply oil to the passive actuator;

[0043] And / or, the controller is connected to an operating handle, which is used to send action request signals of the active actuator and the passive actuator to the controller.

[0044] An excavator includes a boom cylinder, a bucket cylinder, a stick cylinder, a swing motor, and a series-connected actuator hydraulic system. The active actuator of the series-connected actuator hydraulic system is the boom cylinder, and the number of passive actuators in the series-connected actuator hydraulic system is three, namely the bucket cylinder, the stick cylinder, and the swing motor.

[0045] The actuator-connected series drive hydraulic system provided by the present invention has at least the following beneficial effects:

[0046] The first switching valve and the first check valve are connected between the active actuator and the passive actuator, forming a series oil circuit between them. The first switching valve controls the opening and closing of this series oil circuit. When the first switching valve is a first throttle valve, the flow rate through it can be controlled by adjusting its opening. The first check valve allows oil to flow into the passive actuator's inlet through its outlet, but prohibits reverse flow. When the piston rod of the active actuator retracts, when the controller receives a motion request signal from the passive actuator, it opens the first switching valve, allowing the return oil from the rodless chamber of the active actuator to flow into the passive actuator's inlet through the first switching valve and the first check valve, thereby driving the passive actuator to move and enabling the active and passive actuators to drive each other in series.

[0047] By utilizing the return oil from the active actuator to drive the passive actuator simultaneously, a series drive between the active and passive actuators is achieved. During series drive, the work done by the load G1 on the active actuator is converted into hydraulic energy for the system, which is then used to drive the passive actuator. This reuses the energy generated by the external load G1, achieving energy saving or speed increase. This makes the energy-saving system simpler and more reliable, while also reducing system heat generation. Compared to related technologies, there is no need to add energy storage devices such as accumulators for energy recovery and reuse. Therefore, while recovering hydraulic system energy, it reduces equipment investment costs and maintenance complexity. Furthermore, during series drive, the need for other oil sources to provide flow can be reduced or eliminated, thus significantly reducing the passive actuator's demand on the main pump's flow and power.

[0048] The excavator provided by the present invention includes the above-mentioned actuator series drive hydraulic system, and has at least the beneficial effects of the above-mentioned actuator series drive hydraulic system. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0050] Figure 1 A system schematic diagram of an actuator-connected hydraulic system provided in a specific embodiment of the present invention;

[0051] Figure 2 A flowchart illustrating the controller's control of the rodless chamber pressure mode of the active actuator based on the pressure Pb detected by the pressure sensor.

[0052] Figure 3This is a flowchart illustrating how the controller controls the pressure mode of the rodless chamber of the active actuator based on the correspondence between the action request command of the passive actuator and the pressure mode of the rodless chamber of the active actuator.

[0053] Figure 4 This is a schematic diagram of the structure of an excavator provided in a specific embodiment of the present invention.

[0054] Figure label:

[0055] 1-Active actuator; 2-Passive actuator; 21-First passive actuator; 211-First directional control valve; 22-Second passive actuator; 221-Second directional control valve; 23-Third passive actuator; 231-Third directional control valve; 3-First switching valve; 4-First check valve; 5-Controller; 6-Second switching valve; 7-Replenishment circuit; 71-Back pressure valve; 72-Oil tank; 73-Second check valve; 8-One-way switching valve; 9-Third switching valve; 10-First oil source; 11-Pressure sensor; 12-Second oil source; 13-Operating handle;

[0056] 100-Boom cylinder; 200-Bucket cylinder; 300-Stick cylinder; 400-Slewing motor; 500-Boom mechanism; 600-Bucket mechanism; 700-Stick mechanism; 800-Slewing platform. Detailed Implementation

[0057] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] The core of this invention is to provide a series-drive hydraulic system for actuators, which recovers hydraulic system energy while reducing equipment investment costs and maintenance complexity. Another core aspect of this invention is to provide an excavator including the aforementioned series-drive hydraulic system for actuators, which also recovers hydraulic system energy while reducing equipment investment costs and maintenance complexity.

[0059] Please refer to Figure 1This invention provides a series-drive hydraulic system for actuators, including an active actuator 1, a passive actuator 2, a first switching valve 3, a first check valve 4, and a controller 5. The active actuator 1 includes a cylinder and a piston rod. The cylinder includes a rod chamber and a rodless chamber, and the piston rod is used for bearing loads. The inlet of the first switching valve 3 is connected to the rodless chamber of the active actuator 1. The inlet of the first check valve 4 is connected to the outlet of the first switching valve 3, and the outlet of the first check valve 4 is connected to the inlet of the passive actuator 2. The controller 5 is connected to the first switching valve 3. When the controller 5 receives an action request signal from the passive actuator 2 during the piston rod retraction condition, it controls the first switching valve 3 to open, so that the hydraulic oil in the rodless chamber of the active actuator 1 flows to the passive actuator 2 via the first switching valve 3 and the first check valve 4.

[0060] It should be noted that in this embodiment of the invention, the active actuator 1 is a hydraulic cylinder. An external force G1 acts on the piston rod of the active actuator 1. G1 acts as an external load driven by the active actuator 1 and exerts a force on the piston rod of the active actuator 1, which is mainly gravity. The direction of the force G1 is opposite to the extension direction of the piston rod of the active actuator 1. That is, under the action of G1, the oil in the rodless chamber of the active actuator 1 is pressurized.

[0061] The passive actuator 2 is a relative concept to the active actuator 1. The passive actuator 2 refers to the actuator connected to the active actuator 1 via the first switching valve 3 and the first check valve 4. The passive actuator 2 can be driven by hydraulic oil output from the rodless chamber of the active actuator 1. The passive actuator 2 can be a hydraulic motor or a hydraulic cylinder, etc., and the number of passive actuators 2 can be one or at least two. Each passive actuator 2 is used to drive the corresponding mechanism in the equipment belonging to the series-connected hydraulic system. It can be understood that each passive actuator 2 is connected to a corresponding directional valve, and the passive actuator 2 and its corresponding directional valve form a passive actuation device. By switching the directional valve of the passive actuation device, the working state of the corresponding passive actuator 2 is switched.

[0062] The first switching valve 3 and the first check valve 4 are connected between the active actuator 1 and the passive actuator 2, forming a series oil circuit between them. The first switching valve 3 controls the opening and closing of the series oil circuit. When the first switching valve 3 is a first throttle valve, the flow rate through it can be controlled by adjusting its opening. The first check valve 4 allows oil to flow into the inlet of the passive actuator 2 through its outlet, but prohibits reverse flow. When the piston rod of the active actuator 1 is retracted, when the controller 5 receives the action request signal from the passive actuator 2, it controls the first switching valve 3 to open, allowing the return oil from the rodless chamber of the active actuator 1 to flow into the inlet of the passive actuator 2 through the first switching valve 3 and the first check valve 4, thereby driving the passive actuator 2 to move and enabling the active actuator 1 and the passive actuator 2 to be driven in series.

[0063] When there are multiple passive actuators 2, there are correspondingly multiple directional control valves. The passive actuators 2 and the corresponding directional control valves form multiple passive actuator devices. For example, there are three passive actuator devices, namely a first passive actuator device, a second passive actuator device, and a third passive actuator device. The first passive actuator device includes a first passive actuator 21 and a first directional control valve 211. The second passive actuator device includes a second passive actuator 22 and a second directional control valve 221. The third passive actuator device includes a third passive actuator 23 and a third directional control valve 231. Further, for example, the first passive actuator 21 acts on a load G2, which pressurizes the oil inlet of the first passive actuator 21. The second passive actuator 22 acts on a load G3, which pressurizes the oil inlet of the second passive actuator 22. The third passive actuator 23 acts on a load G4, which pressurizes the oil inlet of the third passive actuator 23. When the return oil pressure of the rodless chamber of the active actuator 1 is greater than the inlet oil pressure of the first passive actuator 21, and the piston rod of the active actuator 1 is retracted, when the controller 5 receives the action request signal of the first passive actuator 21, the controller 5 controls the first switching valve 3 and the corresponding first directional valve 211 to open. The piston rod of the active actuator 1 retracts under the action of G1. The return oil output from the rodless chamber of the active actuator 1 reaches the inlet oil passage of the first passive actuator 21 through the series oil passage, thereby driving the first passive actuator 21 to move. That is, at this time, the rodless chamber of the active actuator 1 and the inlet chamber of the first passive actuator 21 are connected in series. The return oil of the active actuator 1 is used to directly drive the movement of the first passive actuator 21. This driving state is called series drive. Similarly, when the return oil pressure of the rodless chamber of the active actuator 1 is greater than the inlet oil pressure of the second passive actuator 22, and the piston rod of the active actuator 1 is retracted, when the controller 5 receives the action request signal of the second passive actuator 22, the controller 5 controls the first switching valve 3 and the corresponding second directional valve 221 to open, so that the active actuator 1 and the second passive actuator 22 are driven in series. Similarly, when the return oil pressure of the rodless chamber of the active actuator 1 is greater than the inlet oil pressure of the third passive actuator 23, and the piston rod of the active actuator 1 is retracted, when the controller 5 receives the action request signal of the third passive actuator 23, the controller 5 controls the first switching valve 3 and the corresponding third directional valve 231 to open, so that the active actuator 1 and the third passive actuator 23 are driven in series. That is, when the piston rod of the active actuator 1 is retracted, when the controller 5 receives an action request signal from one or more of the first passive actuator 21, the second passive actuator 22 and the third passive actuator 23, the controller 5 controls the first switching valve 3 and the directional valve corresponding to each action request signal to open, so that the active actuator 1 and one or more passive actuators 2 can be driven in series.

[0064] In other words, the actuator-tandem drive hydraulic system provided in this embodiment of the invention utilizes the return oil from the active actuator 1 to drive the passive actuator 2 simultaneously, achieving series drive between the active actuator 1 and the passive actuator 2. During series drive, the work done by the load G1 on the active actuator 1 is converted into hydraulic energy of the system, and this hydraulic energy is used to drive the passive actuator 2, thereby reusing the energy generated by the external load G1, achieving energy saving or speed increase, making the energy-saving system simpler and more reliable, and reducing the system's heat generation. That is, compared with related technologies, there is no need to add energy storage devices such as accumulators for energy recovery and reuse. Therefore, while recovering the energy of the hydraulic system, it reduces equipment investment costs and maintenance complexity. In addition, during series drive, other oil sources can be reduced or eliminated to provide flow, thus significantly reducing the passive actuator 2's demand on the main pump's flow and power.

[0065] Furthermore, such as Figure 1 As shown, in some embodiments, the actuator series drive hydraulic system further includes a one-way switching valve 8 and a third switching valve 9. The oil inlet of the one-way switching valve 8 is connected to the rodless chamber of the active actuator 1, and the oil outlet of the one-way switching valve 8 is connected to the rod chamber of the active actuator 1. The oil inlet of the third switching valve 9 is connected to the first oil source 10, and the oil outlet of the third switching valve 9 is connected to the rod chamber of the active actuator 1. The controller 5 is connected to the one-way switching valve 8 and the third switching valve 9 respectively, and the controller 5 is used to control the one-way switching valve 8 and the third switching valve 9 to open or close.

[0066] Understandably, when the third switching valve 9 is open and the one-way switching valve 8 is closed, oil is supplied to the rod chamber of the active actuator 1 through the first oil source 10. When the third switching valve 9 is a third throttle valve, the flow rate through the third throttle valve is controlled by controlling the valve opening. When the third switching valve 9 is closed and the one-way switching valve 8 is open, the rodless chamber and the rod chamber of the active actuator 1 are connected through the one-way switching valve 8. Oil from the rodless chamber of the active actuator 1 flows into the rod chamber of the active actuator 1 through the one-way switching valve 8. The reverse flow of this oil is stopped by the one-way switching valve 8 to prevent the active actuator 1 from sucking in air.

[0067] In some embodiments, the actuator series drive hydraulic system further includes a second switching valve 6 and a replenishing oil circuit 7. The inlet of the second switching valve 6 is connected to the rodless chamber of the active actuator 1. The replenishing oil circuit 7 includes a back pressure valve 71 and an oil tank 72. The inlet of the back pressure valve 71 is connected to the outlet of the second switching valve 6, and the outlet of the back pressure valve 71 is connected to the oil tank 72. The inlet of the back pressure valve 71 is also connected to the rod chamber of the active actuator 1 and the outlet of the passive actuator 2, respectively. A second check valve 73 is provided between the back pressure valve 71 and the rod chamber of the active actuator 1, and the inlet of the second check valve 73 is connected to the inlet of the back pressure valve 71.

[0068] In this embodiment, when the active actuator 1 operates alone or when the flow rate through the first switching valve 3 is insufficient to reach the return oil flow rate output by the active actuator 1, the controller 5 can open the valve port of the second switching valve 6 to output part of the return oil from the active actuator 1 to the replenishment circuit 7. When the second switching valve 6 is a second throttle valve, the flow rate through the second throttle valve is controlled by controlling the valve port opening, thereby allowing the active actuator 1 to control its speed according to the requirements of the operating handle 13. In addition, the inlet of the back pressure valve 71 of the replenishment circuit 7 is also connected to the outlet of the second switching valve 6 and the outlet of the passive actuator 2. The back pressure valve 71 is used to establish replenishment pressure. The second check valve 73 allows oil to flow from the replenishment circuit 7 to the rod chamber of the active actuator 1, but prohibits reverse flow. When the pressure in the rod chamber of the active actuator 1 is lower than the replenishment pressure, the oil output from the outlet of the passive actuator 2 and the outlet of the second switching valve 6 can replenish the rod chamber of the active actuator 1 through the second check valve 73, thereby preventing the active actuator 1 from sucking in cavitation. When the oil pressure output from the outlets of the passive actuator 2 and the second switching valve 6 is higher than the pressure value set by the back pressure valve 71 in the replenishment circuit 7, the output oil, in addition to meeting the replenishment requirements of the rod chamber of the active actuator 1, will be discharged into the oil tank 72 through the back pressure valve 71, so that the replenishment pressure in the circuit is only slightly higher than the pressure in the oil tank 72. That is, the return oil output from the second throttle valve and the passive actuator 2 can replenish the rod chamber of the active actuator 1 through the replenishment circuit 7.

[0069] Furthermore, during series drive, the inlet pressure of the passive actuator 2 will vary with the load acting on it; sometimes the inlet pressure of the passive actuator 2 is low, and sometimes it is high. Especially when there are multiple passive actuators 2, due to differences in load and actuator parameters, the inlet pressure of each actuator 2 may vary significantly. Series drive can only be achieved when the return pressure of the rodless chamber of the driving actuator 1 is greater than the inlet pressure of the passive actuator 2. Additionally, if the return pressure of the rodless chamber of the driving actuator 1 is significantly higher than the inlet pressure of the passive actuator 2, a large pressure loss will occur in the series hydraulic circuit.

[0070] To achieve series drive under different passive actuators 2 and different load variations, and to reduce the pressure difference in the series oil circuit, it is necessary to control the return oil pressure of the rodless chamber of the active actuator 1. To facilitate the control of the return oil pressure of the rodless chamber of the active actuator 1, in some embodiments, when both the one-way valve 8 and the third valve 9 are closed, the pressure of the rodless chamber of the active actuator 1 is in a non-pressurized mode; when the one-way valve 8 is open and the third valve 9 is closed, the pressure of the rodless chamber of the active actuator 1 is in a self-pressurized mode; when the third valve 9 is open and the one-way valve 8 is closed, the pressure of the rodless chamber of the active actuator 1 is in an externally pressurized mode. The pressure value of the rodless chamber of the active actuator 1 in the externally pressurized mode is greater than the pressure value of the rodless chamber of the active actuator 1 in the non-pressurized mode, and less than the pressure value of the rodless chamber of the active actuator 1 in the self-pressurized mode.

[0071] In other words, in this embodiment, the rodless chamber of the active actuator 1 has three pressure modes: non-pressurized mode, self-pressurized mode, and externally pressurized mode.

[0072] Define the pressure of the rodless chamber of the active actuator 1 as Ph, the pressure of the rod chamber of the active actuator 1 as Pr, the oil inlet pressure of the passive actuator 2 as Pb, the oil pressure application area of ​​the rodless chamber of the active actuator 1 as Ah, and the oil pressure application area of ​​the rod chamber of the active actuator 1 as Ar. It can be understood that Ah > Ar.

[0073] When the pressure in the rodless chamber of the active actuator 1 is in the non-pressurized mode, both the one-way valve 8 and the third valve 9 are closed. At this time, the second valve 6 can be opened, connecting the rod chamber of the active actuator 1 to the oil replenishment circuit 7. That is, when the active actuator 1 moves, only the oil replenishment circuit 7 is needed to replenish the oil, and no other hydraulic pump is required to supply oil. Since the oil replenishment pressure is set relatively low, the pressure Pr in the rod chamber of the active actuator 1 can be approximately zero at this time, that is, Pr=0. At this time, under the action of load G1, the return oil pressure of the rodless chamber of the active actuator 1 is: Ph= G1 / Ah. When the pressure in the rodless chamber of the actuator 1 is in self-pressurization mode, the one-way valve 8 opens and the third valve 9 closes. At this time, the rodless chamber and the rod chamber of the actuator 1 are connected by the one-way valve 8, allowing the oil in the rodless chamber of the actuator 1 to flow into the rod chamber. The pressure in the rodless chamber of the actuator 1 is Ph, and the pressure in the rod chamber is Pr. The pressure difference through the one-way valve 8 is ΔP1, i.e.: Pr = Ph - ΔP1. When the one-way switch valve 8 is a one-way throttle valve, the larger the opening of the one-way switch valve 8, the smaller the pressure difference ΔP1. In most cases where the pressure in the rodless chamber of the active actuator 1 is in the self-pressurization mode, the controller 5 controls the opening of the one-way throttle valve to be sufficiently large, so that ΔP1 can be neglected as zero, that is, Pr=Ph. At this time, the pressure in the rodless chamber of the active actuator 1 is Ph=G1 / (Ah-Ar). When the pressure in the rodless chamber of the active actuator 1 is in the external pressurization mode, the third switch valve 9 is opened, the one-way switch valve 8 is closed, the first oil source 10 supplies oil to the rod chamber of the active actuator 1, the oil pressure in the rod chamber of the active actuator 1 is Pr, and the oil pressure in the rodless chamber of the active actuator 1 is When the value of G1 remains constant, the larger Pr is, the larger Ph is.

[0074] Define the value of the pressure Ph in the rodless chamber of the active actuator 1 in the non-pressurization mode as Ph1, the value in the external pressurization mode as Ph2, and the value in the self-pressurization mode as Ph3. When G1 is the same and the pressure difference generated by the one-way switch valve 8 is not considered, Ph1=G1 / Ah, Ph3=G1 / (Ah-Ar). Since Ah is usually much larger than Ah-Ar, Ph3 is much larger than Ph1. When the active actuator 1 and the passive actuator 2 are in the series driving state, under the non-pressurization mode and the self-pressurization mode, the pressures Ph1 and Ph3 in the rodless chamber of the active actuator 1 can be prevented from changing with the oil inlet pressure Pb of the passive actuator 2. However, when the rodless chamber of the active actuator 1 is in the external pressurization mode, Ph2 changes with the oil inlet pressure Pb of the passive actuator 2. In the external pressurization mode, define the power of the first oil source 10 supplying oil to the active actuator 1 as N, and the oil inlet flow rate into the rod chamber of the active actuator 1 as Qr, then N=Pr×Qr. Qr depends on the speed demand of the active actuator 1. When the speed demand of the active actuator 1 is determined, the larger the pressure in the rodless chamber of the active actuator 1 is, the larger the pressure Pr in the rod chamber of the active actuator 1 is, and the larger the input power N of the first oil source 10 is. However, the supply power of the first oil source 10 needs to be limited, so the maximum value of Ph2 also needs to be limited. In this embodiment, the magnitude of Ph2 is limited between Ph1 and Ph3, that is: Ph1<Ph2<Ph3. This solution is beneficial to reducing the pressure loss generated on the series oil circuit during series driving.

[0075] As can be seen from the above, when the pressure in the rodless chamber of the active actuator 1 is in the non-pressurized mode and the self-pressurized mode, only the negative load G1 acting on the active actuator 1 is needed to drive the active actuator 1 to move and generate the required flow for driving the passive actuator 2. There is no need for the first oil source 10 to provide flow and power. However, in the external pressurized mode, the first oil source 10 is required to provide part of the flow and power. Therefore, in the series drive state, the pressure in the rodless chamber of the active actuator 1 in the non-pressurized mode and the self-pressurized mode can reduce the oil source requirement of the active actuator 1 compared with the external pressurized mode. Moreover, in the external pressurized mode, the pressure of Ph2 can be controlled between Ph1 and Ph3.

[0076] Furthermore, such as Figure 1 As shown, in some embodiments, the oil outlet of the first switching valve 3 is provided with a pressure sensor 11, which is connected to the controller 5. The controller 5 is used to control the one-way switching valve 8 and the third switching valve 9 to open or close according to the pressure detected by the pressure sensor 11.

[0077] It is understandable that the pressure Ph in the rodless chamber of the active actuator 1 is also the inlet pressure of the first switching valve 3; the inlet pressure Pb of the passive actuator 2 is also the outlet pressure of the first switching valve 3. In this embodiment, a pressure sensor 11 is installed at the outlet of the first switching valve 3 to detect the outlet pressure Pb of the first switching valve 3 in real time. At the same time, the pressure sensor 11 transmits the pressure Pb to the controller 5 so that the controller 5 controls the one-way switching valve 8 and the third switching valve 9 to open or close according to the inlet pressure Pb of the passive actuator 2, so that the pressure mode of the rodless chamber of the active actuator 1 matches the inlet pressure Pb of the passive actuator 2, thereby reducing the pressure difference in the series oil circuit.

[0078] It should be noted that this embodiment does not limit the specific control method of the controller 5 to control the one-way switching valve 8 and the third switching valve 9 to open or close according to the oil inlet pressure Pb of the passive actuator 2, as long as the pressure mode of the rodless chamber of the active actuator 1 can be matched with the oil inlet pressure Pb of the passive actuator 2.

[0079] In some embodiments, the pressure detected by pressure sensor 11 is defined as Pb, and controller 5 is configured to: when Pb < P1, control both check valve 8 and third switch valve 9 to close; when P2 < Pb < P3, control the third switch valve 9 to open and the check valve 8 to close; when Pb > P4, control the check valve 8 to open and the third switch valve 9 to close; when P1 ≤ Pb ≤ P2, when the pressure in the rodless chamber was in the non-pressurized mode, control both check valve 8 and third switch valve 9 to close. All valves 9 are closed. When the pressure in the rodless chamber was in external pressure mode last time, the third switch valve 9 is opened and the one-way switch valve 8 is closed. When P3≤Pb≤P4, when the pressure in the rodless chamber was in external pressure mode last time, the third switch valve 9 is opened and the one-way switch valve 8 is closed. When the pressure in the rodless chamber was in self-pressurization mode last time, the one-way switch valve 8 is opened and the third switch valve 9 is closed. Among them, P1, P2, P3 and P4 are preset pressure values, 0<P1<P2<P3<P4.

[0080] In other words, this embodiment divides five pressure ranges by pre-setting four pressure values: P1, P2, P3, and P4, namely: less than P1, [P1, P2], [P2, P3], [P3, P4], and greater than P4. After the pressure sensor 11 sends the detected pressure Pb to the controller 5, the controller 5 automatically switches the mode of the return oil pressure Ph of the active actuator 1 according to the pressure range in which the pressure Pb is located, so as to adapt to the change of the inlet oil pressure Pb of the passive actuator 2. It should be noted that, among these, less than P1 is the low-pressure range, [P2, P3] is the medium-pressure range, and greater than P4 is the high-pressure range; [P1, P2] and [P3, P4] are two dead zone ranges, which are much smaller than the ranges of the other ranges. The reason for setting these two ranges [P1, P2] and [P3, P4] is to avoid the problem of system jitter caused by the frequent switching of the rodless chamber pressure Ph of the active actuator 1 between different pressure modes when the oil inlet pressure Pb of the passive actuator 2 fluctuates frequently. That is, when the oil inlet pressure Pb of the passive actuator 2 detected by the pressure sensor 11 falls into the range [P1, P2], the controller 5 controls the rodless chamber pressure Ph of the active actuator 1 to be in the pressure mode of the rodless chamber previously. That is, when the pressure of the rodless chamber was in the non-pressurized mode previously, the controller controls both the one-way valve 8 and the third valve 9 to be closed, so that the pressure of the rodless chamber is in the non-pressurized mode under the current pressure judgment; when the pressure of the rodless chamber was in the externally pressurized mode previously, the controller controls the third valve 9 to be opened and the one-way valve 8 to be closed, so that the pressure of the rodless chamber is in the externally pressurized mode under the current pressure judgment; that is, when the oil inlet pressure Pb of the passive actuator 2 falls into the range [P1, P2], the pressure of the rodless chamber of the active actuator 1 can be in the non-pressurized mode or in the externally pressurized mode, depending on the pressure mode of the rodless chamber of the active actuator 1 previously. Similarly, when the oil inlet pressure Pb of the passive actuator 2 detected by the pressure sensor 11 falls into the range [P3, P4], the controller 5 controls the rodless chamber pressure Ph of the active actuator 1 to be in the pressure mode previously experienced by the rodless chamber. That is, when the pressure of the rodless chamber was in the external pressure mode previously, the controller controls the third switch valve 9 to open and the one-way switch valve 8 to close, so that the pressure of the rodless chamber is in the external pressure mode under the current pressure judgment. When the pressure of the rodless chamber was in the self-pressurization mode previously, the controller controls the one-way switch valve 8 to open and the third switch valve 9 to close, so that the pressure of the rodless chamber is in the self-pressurization mode under the current pressure judgment. In other words, when the oil inlet pressure Pb of the passive actuator 2 falls into the range [P3, P4], the pressure of the rodless chamber of the active actuator 1 can be in the external pressure mode or the self-pressurization mode, depending on the pressure mode previously experienced by the rodless chamber of the active actuator 1.When the inlet pressure Pb of the passive actuator 2 detected by pressure sensor 11 falls into the range less than P1, both the one-way valve 8 and the third valve 9 are closed, so that the pressure of the rodless chamber is in the non-pressurized mode under the current pressure judgment. When the inlet pressure Pb of the passive actuator 2 detected by pressure sensor 11 falls into the range of [P2, P3], the third valve 9 is opened and the one-way valve 8 is closed, so that the pressure of the rodless chamber is in the external pressurized mode under the current pressure judgment. When the inlet pressure Pb of the passive actuator 2 detected by pressure sensor 11 falls into the range greater than P4, the one-way valve 8 is opened and the third valve 9 is closed, so that the pressure of the rodless chamber is in the self-pressurized mode under the current pressure judgment.

[0081] like Figure 2As shown, when implementing the above control process, variables M1, F1 and F2 can be defined in the control program of the controller 5. M1 is used to record the current pressure mode of the rodless chamber of the active actuator 1. Exemplarily, M1 may have three assignments, which are A, B and C respectively, where A represents the non-pressurization mode, B represents the external pressurization mode, and C represents the self-pressurization mode. F1 and F2 are used to record the last pressure mode of the rodless chamber of the active actuator 1 at the end of each program cycle, so as to determine the pressure mode of the rodless chamber of the active actuator 1 when Pb falls into [P1, P2] or [P3, P4] in the next cycle. F1 is used to determine whether the pressure mode of the rodless chamber of the active actuator 1 is the non-pressurization mode or the external pressurization mode when Pb falls into [P1, P2], and F2 is used to determine whether the pressure mode of the rodless chamber of the active actuator 1 is the external pressurization mode or the self-pressurization mode when Pb falls into [P3, P4]. Exemplarily, during program initialization, the value of F1 is set as F1=B, and the value of F2 is set as F2=C. After the program initialization phase is completed, the cycle phase is entered. In the cycle phase, the controller 5 determines whether series control is required. For example, when the piston rod of the active actuator 1 is in the retraction working condition, if the controller 5 receives an action request signal of the passive actuator 2, it indicates that the series control instruction is true, and series control is required at this time; when the series control instruction is false, the program returns to the start of the program cycle. When series control is required, the controller 5 reads the Pb pressure value detected by the pressure sensor 11 and performs comparison: when Pb<P1, the variable M1 is assigned as A, at this time, the Ph pressure control of the rodless chamber of the active actuator 1 is set to the non-pressurization mode; and F1=A is assigned, which represents that the pressure mode of the rodless chamber of the active actuator 1 in this cycle is the non-pressurization mode; when P1≤Pb≤P2, the variable M1 is assigned as F1, that is, M1=F1, at this time, the program sets the pressure control mode of the rodless chamber of the active actuator 1 according to the recorded value or initial value of F1 in the previous cycle; when P2<Pb<P3, the variables M1=B, F1=B, F2=B, at this time, the pressure control mode of the rodless chamber of the active actuator 1 is set to the external pressurization mode; when P3≤Pb≤P4, the variable M1=F2, at this time, the program sets the pressure control mode of the rodless chamber of the active actuator 1 according to the recorded value or initial value of F2 in the previous cycle; when Pb>P4, the variables M1=C, F2=C, at this time, the pressure control mode of the rodless chamber of the active actuator 1 is set to the self-pressurization mode. In the program cycle phase, according to the assignment of M1, the controller 5 controls the on-off of the one-way switch valve 8 and the third switch valve 9, so that the rodless chamber of the active actuator 1 is in the required pressure mode, and the cycle proceeds in this way until the program cycle ends.

[0082] As can be seen, in this embodiment, under the series drive state, when the oil inlet pressure Pb of the passive actuator 2 changes in different ranges, the return oil pressure Ph of the active actuator 1 can also be adjusted accordingly. This not only ensures that the return oil pressure of the active actuator 1 is greater than the oil inlet pressure of the passive actuator 2, but also avoids that the pressure difference in the series oil circuit is too high. Thus, even when the load of the passive actuator 2 changes significantly, the system can still perform series drive control of the active actuator 1 and the passive actuator 2, and ensure that the pressure loss in the series oil circuit does not become too large.

[0083] In addition to the control methods mentioned above, the following control method can also be used: a pressure mode that controls and adjusts the return oil pressure of the active actuator 1.

[0084] In some embodiments, the passive actuator 2 includes a first passive actuator 21, a second passive actuator 22, and a third passive actuator 23. The oil inlet pressure of the first passive actuator 21 meets a first preset threshold, the oil inlet pressure of the second passive actuator 22 meets a second preset threshold, and the oil inlet pressure of the third passive actuator 23 meets a third preset threshold. The highest value of the first preset threshold is less than the minimum value of the second preset threshold, and the highest value of the second preset threshold is less than the minimum value of the third preset threshold. The controller 5 is configured to: when the piston rod of the active actuator 1 is retracted, upon receiving an action request signal from the first passive actuator 21, control both the one-way switching valve 8 and the third switching valve 9 to close; when the piston rod of the active actuator 1 is retracted, upon receiving an action request signal from the second passive actuator 21, control both the one-way switching valve 8 and the third switching valve 9 to close; when the piston rod of the active actuator 1 is retracted, upon receiving a second passive actuator 22, control both the one-way switching valve 8 and the third switching valve 9 to close. When the actuator 22 receives an action request signal, or when the first passive actuator 21 and the second passive actuator 22 are simultaneously received, the third switching valve 9 is controlled to open and the one-way switching valve 8 is controlled to close. When the piston rod of the actuator 1 is retracted, when the third passive actuator 23 receives an action request signal, or when the first passive actuator 21 and the third passive actuator 23 are simultaneously received, or when the second passive actuator 22 and the third passive actuator 23 are simultaneously received, or when the first passive actuator 21, the second passive actuator 22 and the third passive actuator 23 are simultaneously received, the one-way switching valve 8 is controlled to open and the third switching valve 9 is controlled to close.

[0085] In other words, this embodiment pre-maps the pressure mode of the rodless chamber of the active actuator 1 to the action request signals of each passive actuator 2 in the program of the controller 5 based on the load differences of different passive actuators 2. The pressure mode of the rodless chamber of the active actuator 1 is controlled according to the mapping relationship between the pressure mode of the rodless chamber of the active actuator 1 and the action request signals of each passive actuator 2. For example, if the inlet pressure of the first passive actuator 21 meets a first preset threshold, it indicates that the inlet pressure of the first passive actuator 21 is relatively low, and the first passive actuator 21 is defined as a low-pressure actuator; if the inlet pressure of the second passive actuator 22 meets a second preset threshold, it indicates that the inlet pressure of the second passive actuator 22 is moderate, and the second passive actuator 22 is defined as a medium-pressure actuator; if the inlet pressure of the third passive actuator 23 meets a third preset threshold, it indicates that the inlet pressure of the third passive actuator 23 is high, and the third passive actuator 23 is defined as a high-pressure actuator. When a single passive actuator 2 is driven in series with the active actuator 1, during the piston rod retraction of the active actuator 1, when the controller 5 receives the action request signal from the first passive actuator 21, it controls the pressure of the rodless chamber of the active actuator 1 to be in a non-pressurized mode; during the piston rod retraction of the active actuator 1, when the controller 5 receives the action request signal from the second passive actuator 22, it controls the pressure of the rodless chamber of the active actuator 1 to be in an externally pressurized mode; during the piston rod retraction of the active actuator 1, when the controller 5 receives the action request signal from the third passive actuator 23, it controls the pressure of the rodless chamber of the active actuator 1 to be in a self-pressurized mode. When the controller 5 simultaneously receives action request signals from multiple (more than two) passive actuators 2, it controls the pressure mode of the rodless chamber of the active actuator 1 to be the pressure mode of the rodless chamber of the active actuator 1 corresponding to the passive actuator 2 with the highest inlet pressure.

[0086] like Figure 3As shown, in implementing the above control process, a variable M2 can be defined in the control program of controller 5. M2 is used to record the current pressure mode of the rodless chamber of the active actuator 1. For example, M2 can have four values: A, B, C, and D. Here, A represents the non-pressurized mode, B represents the externally pressurized mode, C represents the self-pressurized mode, and D represents the modeless state. In addition, preset numerical constants a0, a1, a2, and a3 are set in the control system of controller 5. a0 is the threshold for determining whether the piston rod of the active actuator 1 retracts, a1 is the threshold for determining whether the first passive actuator 21 operates, a2 is the threshold for determining whether the second passive actuator 22 operates, and a3 is the threshold for determining whether the third passive actuator 23 operates. When S0>a0, S1>a1, S2≤a2, and S3≤a3 are simultaneously satisfied, the active actuator 1 and the first passive actuator 21 operate simultaneously, realizing the series drive of the active actuator 1 on the first passive actuator 21, while the second passive actuator 22 and the third passive actuator 23 do not operate. At this time, the pressure mode of the rodless chamber of the active actuator 1 is set to the non-pressurized mode, that is, M2=A. When S0>a0, S2>a2, and S3≤a3 are simultaneously satisfied, the active actuator 1 and the second passive actuator 22 operate simultaneously, while the third passive actuator 23 does not operate. At this time, whether the first passive actuator 21 operates or not is not considered. Regardless of whether the first passive actuator 21 operates or not, the pressure mode of the rodless chamber of the active actuator 1 is set to the externally pressurized mode, that is, M2=B. When S0>a0 and S3>a3 are simultaneously satisfied, the active actuator 1 and the third passive actuator 23 operate simultaneously, regardless of whether the first passive actuator 21 and the second passive actuator 22 operate. That is, the first passive actuator 21 may or may not operate, and the second passive actuator 22 may or may not operate. Regardless of whether the first passive actuator 21 and the second passive actuator 22 operate, the pressure mode of the rodless chamber of the active actuator 1 is set to the self-pressurizing mode, that is, M2=C. When S0, S1, S2, and S3 are in other states, the pressure mode of the rodless chamber of the active actuator 1 is set to the no-mode, and M2=D.

[0087] In other words, in this embodiment, when performing series drive control, when there are multiple passive actuators 2 in the system and the oil inlet pressure load of each passive actuator 2 is significantly different, the control method of this embodiment can be adopted. That is, the controller 5 can identify the passive actuators 2 in different load states according to the action request signals of each passive actuator 2 and thereby retrieve the pressure mode of the rodless chamber of the corresponding active actuator 1 to match it. In this way, not only can series drive control be performed on passive actuators 2 with different loads, but also excessive pressure difference loss between the active actuator 1 and the passive actuator 2 in the series oil circuit can be avoided.

[0088] As can be seen, the above text presents two methods for controlling the pressure mode of the rodless chamber of the active actuator 1. Specifically, the pressure mode of the rodless chamber of the active actuator 1 is adjusted according to the magnitude of the pressure Pb exerted by the passive actuator 2; or, based on the mapping relationship between the pressure modes of each passive actuator 2 and the rodless chamber of the active actuator 1, the pressure mode of the rodless chamber of the active actuator 1 is controlled according to the action request commands of each passive actuator 2. In use, those skilled in the art can choose one pair to control the pressure mode of the rodless chamber of the active actuator 1, or they can switch between the two control methods according to different operating conditions to control the pressure mode of the rodless chamber of the active actuator 1.

[0089] In addition, in some embodiments, the controller 5 is configured to close the first switching valve 3, the one-way switching valve 8 and the third switching valve 9 and open the second switching valve 6 when only an action request signal from the active actuator 1 is received.

[0090] Understandably, when the controller 5 receives only the action request signal of the active actuator 1, it indicates that the active actuator 1 is acting alone and is in a non-series drive state. At this time, the controller 5 controls the second switching valve 6 to open and the first switching valve 3, the one-way switching valve 8 and the third switching valve 9 to close, so that the active actuator 1 can act under the load G1. The return oil from the rodless chamber of the active actuator 1 is output to the oil replenishment circuit 7 through the second switching valve 6, and the oil replenishment circuit 7 replenishes the rod chamber of the active actuator 1, without the need for other oil sources to supply oil to the active actuator 1.

[0091] Furthermore, such as Figure 1 As shown, in some embodiments, the oil inlet of the passive actuator 2 is also connected to the second oil source 12; the controller 5 is configured to control the second oil source 12 to supply oil to the passive actuator 2 when only the action request signal of the passive actuator 2 is received.

[0092] In other words, when the controller 5 only receives the action request signal of the actuator, it indicates that the active actuator 1 does not move and only the passive actuator 2 moves. At this time, it is a non-series drive state. In this embodiment, the second oil source 12 supplies oil to the corresponding passive actuator 2 to drive the corresponding passive actuator 2 to move.

[0093] In addition, to facilitate sending action request signals for the active actuator 1 and the passive actuator 2 to the controller 5, such as Figure 1 As shown, in some embodiments, the controller 5 is connected to an operating handle 13, which is used to send action request signals of the active actuator 1 and the passive actuator 2 to the controller 5.

[0094] In other words, by setting up the operating handle 13, the operating handle 13 can issue different action request signals according to different operations of the operator and transmit them to the controller 5. Then, the controller 5 controls the first switching valve 3, the second switching valve 6, the one-way switching valve 8, the third switching valve 9 and various directional valves according to the action request signals it receives, thereby controlling the actions of the active actuator 1 and the passive actuator 2.

[0095] like Figure 4 As shown, in addition to the aforementioned actuator-tandem drive hydraulic system, this embodiment of the invention also provides an excavator including the actuator-tandem drive hydraulic system disclosed in the above embodiments. This excavator further includes a boom cylinder 100, a bucket cylinder 200, a stick cylinder 300, and a swing motor 400. The active actuator 1 of the actuator-tandem drive hydraulic system is the boom cylinder 100, and the number of passive actuators 2 in the actuator-tandem drive hydraulic system is three: the bucket cylinder 200, the stick cylinder 300, and the swing motor 400. The structure of other parts of this excavator can be found in related technologies and will not be described further here.

[0096] The key point of this embodiment is that the excavator includes the actuator series drive hydraulic system disclosed in the above embodiments, and at least has the beneficial effects of the actuator series drive hydraulic system, which will not be repeated here.

[0097] In other words, the actuator tandem drive hydraulic system disclosed in the above embodiments is applied to an excavator. The active actuator 1 is the boom cylinder 100 of the excavator, which is used to drive the boom mechanism 500 of the excavator to rise and fall. There are three passive actuators 2, namely the bucket cylinder 200, the stick cylinder 300, and the swing motor 400 of the excavator. The bucket cylinder 200 is used to drive the bucket mechanism 600 of the excavator to retract and swing outward. The stick cylinder 300 is used to drive the stick mechanism 700 of the excavator to retract and swing outward. The swing motor 400 is used to drive the swing platform 800 mechanism of the excavator to move. The boom mechanism 500, bucket mechanism 600, and stick mechanism 700 constitute the working device of the excavator. The lowering action of the boom mechanism 500 corresponds to the retraction action of the piston rod of the boom cylinder 100. The boom cylinder 100 is subjected to a gravitational load G1 from the working device. When the retraction action of the piston rod of the boom cylinder 100 needs to be combined with one or more passive actuators 2 of the bucket cylinder 200, stick cylinder 300, and swing motor 400, a series drive control can be performed. That is, when the boom mechanism 500 is lowered, the return oil from the rodless chamber of the boom cylinder 100 drives one or more passive actuators 2 of the bucket cylinder 200, stick cylinder 300, and swing motor 400 to move, thereby realizing the reuse of the potential energy of the working device and reducing the flow and power requirements of the pump source for the boom cylinder 100, bucket cylinder 200, stick cylinder, and swing motor 400.

[0098] The loads acting on the bucket cylinder 200, stick cylinder 300, and swing motor 400 differ significantly. During operation, in many cases, the swing motor 400 requires the highest inlet pressure, followed by the stick cylinder 300, while the bucket cylinder 200 requires the lowest. When the boom cylinder 100 is driven in series with the bucket cylinder 200, stick cylinder 300, and swing motor 400, different pressure modes can be adopted for the return oil pressure of the rodless chamber of the boom cylinder 100 based on the load state of the bucket cylinder 200, stick cylinder 300, and swing motor 400 in the actuator series drive hydraulic system, according to the mapping relationship between the inlet pressure of each passive actuator 2 or the pressure mode of the rodless chamber of each passive actuator 2 and the active actuator 1. This allows the boom cylinder 100 to drive more passive actuators 2 while reducing circuit pressure loss. For example, when the boom cylinder 100 and the swing motor 400 are driven in series, the rodless chamber of the boom cylinder 100 adopts a self-pressurized mode; when the boom cylinder 100 and the stick cylinder 300 are driven in series, the rodless chamber of the boom cylinder 100 adopts an externally pressurized mode or a non-pressurized mode; when the boom cylinder 100 and the bucket cylinder 200 are driven in series, a non-pressurized mode is adopted.

[0099] When controlling the pressure mode of the rodless chamber of the boom cylinder 100, the pressure mode of the rodless chamber of the boom cylinder 100 can be pre-mapped with the action request signals of each passive actuator 2 in the program of the controller 5 according to the load differences of the bucket cylinder 200, the stick cylinder 300 and the swing motor 400. The controller 5 switches the pressure mode of the rodless chamber of the boom cylinder 100 according to the action request signals of each passive actuator 2 output by the operating handle 13, so that the return oil pressure of the active actuator 1 can be automatically adapted to the passive actuator 2 under different load conditions, which can reduce the pressure loss of the series circuit caused by the passive actuator 2 under different load conditions.

[0100] Under certain working conditions, the inlet oil pressure of the passive actuator 2 varies greatly with the load. In this case, the pressure mode of the rodless chamber of the boom cylinder 100 can be automatically switched according to the magnitude of the inlet oil pressure Pb of the passive actuator 2, such as the bucket cylinder 200, the boom cylinder 300, and the swing motor 400, so that the return oil pressure of the boom cylinder 100 can automatically adapt to the change in the inlet oil pressure of the passive actuator 2.

[0101] It should also be noted that, in this specification, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0102] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0103] The actuator-tandem drive hydraulic system and excavator provided by this invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of this invention.

Claims

1. A series-drive hydraulic system for actuators, characterized in that, include: An active actuator (1) includes a cylinder body and a piston rod, the cylinder body including a rod chamber and a rodless chamber, and the piston rod being used for bearing; Passive actuator (2); The first switching valve (3) has its oil inlet connected to the rodless chamber; The first check valve (4) has its inlet connected to the outlet of the first switching valve (3), and the outlet of the first check valve (4) is connected to the inlet of the passive actuator (2). The controller (5), connected to the first switching valve (3), is used to control the first switching valve (3) to open when it receives the action request signal of the passive actuator (2) under the piston rod retraction condition, so that the hydraulic oil in the rodless chamber flows to the passive actuator (2) through the first switching valve (3) and the first check valve (4).

2. The actuator-connected series drive hydraulic system according to claim 1, characterized in that, Also includes: One-way switching valve (8), the oil inlet of which is connected to the rodless chamber, and the oil outlet of the one-way switching valve (8) is connected to the rod chamber; The third switching valve (9) has its inlet connected to the first oil source (10), and its outlet is connected to the rod chamber. The controller (5) is connected to the one-way switching valve (8) and the third switching valve (9) respectively. The controller (5) is used to control the one-way switching valve (8) and the third switching valve (9) to open or close.

3. The actuator-connected series drive hydraulic system according to claim 2, characterized in that, When both the one-way switching valve (8) and the third switching valve (9) are closed, the pressure in the rodless chamber is in a non-pressurized mode; When the one-way switching valve (8) is open and the third switching valve (9) is closed, the pressure in the rodless chamber is in a self-pressurizing mode; When the third switching valve (9) is open and the one-way switching valve (8) is closed, the pressure in the rodless chamber is in the external pressure mode; The pressure in the rodless chamber during the externally pressurized mode is greater than the pressure in the non-pressurized mode, but less than the pressure in the rodless chamber during the self-pressurized mode.

4. The actuator-connected series drive hydraulic system according to claim 3, characterized in that, The oil outlet of the first switching valve (3) is equipped with a pressure sensor (11), which is connected to the controller (5). The controller (5) is used to control the one-way switching valve (8) and the third switching valve (9) to open or close according to the pressure detected by the pressure sensor (11).

5. The actuator-tandem drive hydraulic system according to claim 4, characterized in that, The pressure detected by the pressure sensor (11) is defined as Pb, and the controller (5) is configured as follows: When Pb < P1, both the one-way switching valve (8) and the third switching valve (9) are closed. When P2 < Pb < P3, the third switching valve (9) is opened and the one-way switching valve (8) is closed. When Pb > P4, the one-way switching valve (8) is opened and the third switching valve (9) is closed. When P1≤Pb≤P2, when the pressure of the rodless chamber was in the non-pressurized mode, the one-way switch valve (8) and the third switch valve (9) are both closed; when the pressure of the rodless chamber was in the external pressurized mode, the third switch valve (9) is opened and the one-way switch valve (8) is closed. When P3≤Pb≤P4, when the pressure of the rodless chamber was in the external pressure mode, the third switch valve (9) is opened and the one-way switch valve (8) is closed; when the pressure of the rodless chamber was in the self-pressure mode, the one-way switch valve (8) is opened and the third switch valve (9) is closed. Among them, P1, P2, P3 and P4 are preset pressure values, where 0 < P1 < P2 < P3 < P4.

6. The actuator-connected series drive hydraulic system according to claim 3, characterized in that, The passive actuator (2) includes a first passive actuator (21), a second passive actuator (22) and a third passive actuator (23). The oil inlet pressure of the first passive actuator (21) meets a first preset threshold, the oil inlet pressure of the second passive actuator (22) meets a second preset threshold, and the oil inlet pressure of the third passive actuator (23) meets a third preset threshold. The highest value of the first preset threshold is less than the lowest value of the second preset threshold, and the highest value of the second preset threshold is less than the lowest value of the third preset threshold. The controller (5) is configured as follows: When the piston rod is retracted, upon receiving the action request signal from the first passive actuator (21), both the one-way switching valve (8) and the third switching valve (9) are closed. When the piston rod is retracted, when the action request signal of the second passive actuator (22) is received, or when the action request signals of the first passive actuator (21) and the second passive actuator (22) are received simultaneously, the third switching valve (9) is controlled to open and the one-way switching valve (8) is controlled to close. When the piston rod retracts, upon receiving an action request signal from the third passive actuator (23), or simultaneously receiving action request signals from the first passive actuator (21) and the third passive actuator (23), or simultaneously receiving action request signals from the second passive actuator (22) and the third passive actuator (23), or simultaneously receiving action request signals from the first passive actuator (21), the second passive actuator (22) and the third passive actuator (23), control the one-way switching valve (8) to open and the third switching valve (9) to close.

7. The actuator-tandem drive hydraulic system according to any one of claims 2-6, characterized in that, Also includes: The second switching valve (6) has its oil inlet connected to the rodless chamber; The oil replenishment circuit (7) includes a back pressure valve (71) and an oil tank (72). The oil inlet of the back pressure valve (71) is connected to the oil outlet of the second switching valve (6), and the oil outlet of the back pressure valve (71) is connected to the oil tank (72). The oil inlet of the back pressure valve (71) is also connected to the oil outlet of the rod chamber and the passive actuator (2), respectively. A second check valve (73) is provided between the back pressure valve (71) and the rod chamber. The oil inlet of the second check valve (73) is connected to the oil inlet of the back pressure valve (71).

8. The actuator-tandem drive hydraulic system according to claim 7, characterized in that, The controller (5) is configured as follows: When only the action request signal of the active actuator (1) is received, the first switching valve (3), the one-way switching valve (8) and the third switching valve (9) are all closed, and the second switching valve (6) is opened.

9. The actuator-connected drive hydraulic system according to any one of claims 1-6, characterized in that, The oil inlet of the passive actuator (2) is also connected to a second oil source (12); the controller (5) is configured to control the second oil source (12) to supply oil to the passive actuator (2) when only an action request signal of the passive actuator (2) is received; And / or, the controller (5) is connected to an operating handle (13), which is used to send action request signals of the active actuator (1) and the passive actuator (2) to the controller (5).

10. An excavator, characterized in that, The system includes a boom cylinder (100), a bucket cylinder (200), a stick cylinder (300), a swing motor (400), and a series-drive hydraulic system for actuators as described in any one of claims 1-9. The active actuator (1) of the series-drive hydraulic system for actuators is the boom cylinder (100), and the number of passive actuators (2) of the series-drive hydraulic system for actuators is three, namely the bucket cylinder (200), the stick cylinder (300), and the swing motor (400).

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