Hydraulic system and working machine

Abstract

The application provides a hydraulic system and an engineering machine. The hydraulic system comprises a load-sensitive pump and a tool oil supply valve group. The tool oil supply valve group comprises a first valve. The first valve can connect an oil outlet of the load-sensitive pump and a load pressure feedback signal output port. The first valve can feed the pressure of the oil outlet of the load-sensitive pump to the load pressure feedback signal output port of the load-sensitive pump. The pressure on both sides of a load-sensitive valve core of the load-sensitive pump is equal, so that the load-sensitive pump is in a constant pressure control mode. Thus, the tool can work through constant pressure control. This setting can avoid load feedback signal lag, improve system responsiveness, and reduce the action delay when the tool works. The controllability of the equipment is improved, and the production efficiency is improved.

Description

Technical Field

[0001] This application relates to the field of engineering machinery technology, specifically to a hydraulic system and engineering machinery. Background Technology

[0002] Currently, hydraulic systems for construction machinery attachments use gear pump systems and multi-way valves. The gear pump system still outputs a fixed amount of power during the attachment's micro-movement process, resulting in high system heat generation and energy consumption. If traditional load-sensitive piston pumps and multi-way valves are used, the hydraulic system of the attachment is much farther from the main unit (for example, the pipeline can reach 30m for a container front-end crane), the pipeline is long, the oil viscosity is high at low temperatures in winter, and the load feedback signal is delayed, resulting in poor system responsiveness and long action delay. Summary of the Invention

[0003] In view of this, this application provides a hydraulic system that solves the problem of poor system responsiveness and long action delay caused by load feedback signal lag. This application also provides an engineering machine including the above-mentioned hydraulic system.

[0004] To achieve the above objectives, this application provides the following technical solution:

[0005] A hydraulic system, comprising:

[0006] Load-sensitive pump;

[0007] The attachment includes an oil supply valve assembly, including a first valve, which connects the oil outlet of the load-sensitive pump to the load pressure feedback signal output port.

[0008] The first valve can feed back the pressure at the outlet of the load-sensitive pump to the load pressure feedback signal output port of the load-sensitive pump, and the pressure on both sides of the load-sensitive valve core of the load-sensitive pump is equal, so that the load-sensitive pump is in constant pressure control mode.

[0009] Preferably, the accessory oil supply valve assembly is located close to the load-sensitive pump.

[0010] Preferably, the first valve is a two-position three-way valve. When the first valve is in the left position, the load pressure feedback signal output port is connected to the drain port of the hydraulic system; when the first valve is in the right position, the outlet port of the load-sensitive pump is connected to the load pressure feedback signal output port.

[0011] Preferably, the attachment oil supply valve assembly further includes an electro-proportional pressure reducing valve, which is a two-position three-way valve. When the electro-proportional pressure reducing valve is in the left position, the oil outlet of the load-sensitive pump is connected to the pressure shut-off valve of the load-sensitive pump; when the electro-proportional pressure reducing valve is in the right position, the pressure shut-off valve is connected to the load-sensitive pre-compensation multi-way valve of the hydraulic system.

[0012] Preferred, including:

[0013] A rotary motor is connected to the load-sensitive pre-compensated multi-way valve of the hydraulic system.

[0014] A rotary motor control valve assembly, wherein the two oil ports of the rotary motor control valve assembly are respectively connected to the rotary motor and the load-sensitive pre-compensation multi-way valve of the hydraulic system;

[0015] The rotary motor control valve group includes a second valve, which is a two-position three-way valve. When the second valve is in the left position, the brake of the rotary motor is connected to the load-sensitive pre-compensation multi-way valve; when the second valve is in the right position, the brake is connected to the oil outlet of the load-sensitive pump.

[0016] Preferably, the second valve is connected to the oil outlet of the load-sensitive pump, and the rotary motor control valve group further includes a pressure reducing valve disposed between the second valve and the oil outlet of the load-sensitive pump.

[0017] Preferred,

[0018] The rotary motor control valve group also includes a third valve, which is a two-position, two-way valve. When the third valve is in the left position, the outlet of the pressure reducing valve is connected to port A and port B of the rotary motor control valve group through two check valves, respectively, and the two check valves allow hydraulic oil to flow from the pressure reducing valve to port A and port B of the rotary motor control valve group. When the third valve is in the right position, the third valve is a check valve that allows hydraulic oil to flow from port A and port B of the rotary motor control valve group to the pressure reducing valve.

[0019] The first and second ports connecting the load-sensitive pre-compensation multi-way valve to ports A and B of the rotary motor control valve group are disconnected.

[0020] Preferably, the system includes a side-shifting cylinder, a telescopic cylinder, and a rotary locking cylinder connected to a load-sensitive pre-compensation multi-way valve, wherein a hydraulic lock is provided between the load-sensitive pre-compensation multi-way valve and one or more of the side-shifting cylinder, the telescopic cylinder, the rotary locking cylinder, and the rotary motor.

[0021] Preferably, the load-sensitive pre-compensation multi-way valve includes a first section connected to the rotary motor, a second section connected to the lateral displacement cylinder, a third section connected to the telescopic cylinder, and a fourth section connected to the rotary lock cylinder, wherein at least one of the first section, the second section, the third section, and the fourth section includes a valve core differential position.

[0022] An engineering machine, comprising the hydraulic system described in any one of the above claims.

[0023] The hydraulic system provided in this application includes a first valve in the attachment oil supply valve group. This first valve connects the outlet of the load-sensitive pump to the load pressure feedback signal output port. By feeding back the pressure from the outlet of the load-sensitive pump to the load pressure feedback signal output port of the load-sensitive pump through the first valve, the pressure on both sides of the load-sensitive valve core of the load-sensitive pump is equalized, thus putting the load-sensitive pump in a constant pressure control mode. This allows for constant pressure control of the attachment. This configuration avoids load feedback signal lag, improves system responsiveness, and reduces the action time of the attachment during operation. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the hydraulic system provided in this embodiment.

[0026] Figure 2 for Figure 1 The first enlarged view of the middle section.

[0027] Figure 3 for Figure 1 The second enlarged view in the middle.

[0028] Figure 4 for Figure 1 The third enlarged view.

[0029] exist Figures 1-4 middle:

[0030] 1-Load-sensitive pump, 2-Attachment oil supply valve assembly, 3-Load-sensitive pre-compensation multi-way valve, 4-Rotary motor, 5-Rotary motor control valve assembly, 6-Side shift cylinder, 7-Telescopic cylinder, 8-Twist lock cylinder, 9-Hydraulic lock, 10-Hydraulic cylinder.

[0031] 101-Load-sensitive valve core, 102-Pressure shut-off valve, 201-First valve, 202-Electro-proportional pressure reducing valve, 301-First unit, 302-Second unit, 303-Third unit, 304-Fourth unit, 501-Second valve, 502-Pressure reducing valve, 503-Third valve;

[0032] 3031 - Valve core differential position. Detailed Implementation

[0033] This application provides a hydraulic system. This application also provides an engineering machine including the above-described hydraulic system.

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] like Figures 1 to 4 As shown in the figure, this application embodiment provides a hydraulic system that can be installed in construction machinery. The hydraulic system mainly includes a load-sensitive pump 1 and an attachment oil supply valve group 2. The attachment oil supply valve group 2 includes a first valve 201, which connects the oil outlet of the load-sensitive pump 1 to the load pressure feedback signal output port. Specifically, the first valve 201 can feed back the pressure of the oil outlet pipeline of the load-sensitive pump 1 to the load pressure feedback signal output port of the load-sensitive pump 1. The pressures on both sides of the load-sensitive valve core 101 of the load-sensitive pump 1 are equal, so that the load-sensitive pump 1 is in a constant pressure control mode. It should be noted that the oil outlet pipeline of the load-sensitive pump 1 refers to the pipeline connected to the P port (oil outlet) of the load-sensitive pump 1, and the load pressure feedback signal output port of the load-sensitive pump 1 refers to the LS port (feedback port) of the load-sensitive pump 1. Conventionally, the LS port of the load-sensitive pump 1 feeds back the pressure of the hydraulic oil at the attachment position, and then adjusts the pressure at the oil outlet of the load-sensitive pump 1. The pressure adjustment path is relatively long, and the response time is relatively long. Here, the first valve 201 is set to feed back the pressure of the oil outlet line of the load-sensitive pump 1 to the LS port of the load-sensitive pump 1. This enables the load-sensitive pump 1 to be controlled under constant pressure, thereby improving the working efficiency of the load-sensitive pump 1 and reducing the response time.

[0036] In this embodiment, an optional implementation method is provided. The first valve 201 is a solenoid valve. The first valve 201 controls the connection and closure of the oil outlet line of the load-sensitive pump 1 and the load pressure feedback signal output port. When the solenoid valve is not energized, the load-sensitive pump 1 of the hydraulic system can adjust according to the load of the attachment. When the solenoid valve is energized, the load-sensitive pump 1 of the hydraulic system changes to a constant pressure control mode, and the pressure at the oil outlet of the load-sensitive pump 1 no longer changes according to the pressure of the attachment, thereby improving the corresponding efficiency of the hydraulic system.

[0037] In this embodiment, another optional implementation is also provided. The first valve 201 is provided with two valves that control opening and closing. One valve controls the connection and closing of the oil outlet line of the load-sensitive pump 1 and the load pressure feedback signal output port, and the other valve controls the connection and closing of the oil line of the attachment position and the load pressure feedback signal output port. This can also realize the switching between load-sensitive mode and constant pressure control mode.

[0038] The hydraulic system described above, by setting a first valve 201 in the attachment oil supply valve group 2, and connecting the two oil ports of the first valve 201 to the oil outlet line of the load-sensitive pump 1 and the load pressure feedback signal output port respectively, feeds back the pressure of the oil outlet line of the load-sensitive pump 1 to the load pressure feedback signal output port of the load-sensitive pump 1 through the first valve 201. In this way, the pressure on both sides of the load-sensitive valve core 101 of the load-sensitive pump 1 is equal, so that the load-sensitive pump 1 is in a constant pressure control mode. In this way, the attachment can be controlled by constant pressure. This setting can avoid the load feedback signal lag, improve the system responsiveness, and reduce the action time of the attachment during operation.

[0039] In some embodiments, the attachment oil supply valve assembly 2 is located close to the load-sensitive pump 1. Specifically, the attachment oil supply valve assembly 2 is located between the oil outlet line of the load-sensitive pump 1 and the load pressure feedback signal output port of the load-sensitive pump 1, and the attachment common valve assembly is located close to the load-sensitive pump 1. This arrangement places the control part of the load-sensitive pump 1 (i.e., the attachment oil supply valve assembly 2) near the load-sensitive pump 1, thereby improving the pump's responsiveness.

[0040] In addition, the attachment oil supply valve group 2 can also be set near the load-sensitive pre-compensation multi-way valve 3 of the hydraulic system, and ensure that the two oil ports of the first valve 201 in the attachment oil supply valve group 2 are respectively connected to the oil outlet pipeline of the load-sensitive pump 1 and the load pressure feedback signal output port, so that constant pressure control can also be achieved.

[0041] In the following embodiments, the rotation action of the rotary motor 4 is taken as an example. The working methods of the lateral displacement cylinder 6, the telescopic cylinder 7 and the rotary locking cylinder 8 are similar to those of the rotary motor 4, and will not be described in detail here.

[0042] In some embodiments, the first valve 201 is a two-position three-way valve. When the first valve 201 is in the left position, the load pressure feedback signal output port is connected to the drain port of the hydraulic system; when the first valve 201 is in the right position, the oil outlet of the load-sensitive pump 1 is connected to the load pressure feedback signal output port. For example, assuming that the rotary motor 4 (described below) needs to be rotated, after the controller receives the action request, it assigns a certain current value to DT1 (the valve in the load-sensitive pre-compensation multi-way valve 3 that controls the rotary motor 4). At the same time, the first valve 201 is energized, feeding back the oil outlet of the load-sensitive pump 1 to the load pressure feedback signal output port of the load-sensitive pump 1. Since the pressure at the left P port and the right LS port of the load-sensitive valve core 101 are equal, under the action of the spring force, the load-sensitive valve core 101 is always pushed to the leftmost position. At this time, the load-sensitive valve core 101 does not have the function of adjusting the displacement, and the pump enters the constant pressure control mode. In other words, the first valve 201 can switch the load-sensitive pump 1 in constant pressure mode. By setting the first valve 201 as a two-position three-way solenoid valve, the regulation efficiency of the first valve 201 can be improved, the response is fast, and the degree of automation is high.

[0043] Here, the type and model of the first valve 201 are not limited, as long as it is ensured that the load pressure feedback signal output port of the first valve 201 is connected to the drain port of the hydraulic system in the first state; and that the oil outlet line of the load-sensitive pump 1 is connected to the load pressure feedback signal output port in the second state. It should be noted that the drain port refers to the port where the first valve 201 is connected to the hydraulic cylinder 10.

[0044] Furthermore, in some embodiments, the accessory oil supply valve assembly 2 also includes an electro-proportional pressure reducing valve 202. The electro-proportional pressure reducing valve 202 is a two-position three-way valve. When the electro-proportional pressure reducing valve 202 is in the left position, the oil outlet line of the load-sensitive pump 1 is connected to the pressure shut-off valve 102 of the load-sensitive pump 1; when the electro-proportional pressure reducing valve 202 is in the right position, the pressure shut-off valve 102 is connected to the load-sensitive pre-compensation multi-way valve 3 of the hydraulic system. It should be noted that the electro-proportional valve adjusts the cross-sectional area of ​​the valve core according to the magnitude of the control signal, thereby achieving the process goal and requirement of adjusting the pressure. Based on the embodiment of setting the first valve 201 in the hydraulic system, an electro-proportional pressure reducing valve 202 is set. The electro-proportional pressure reducing valve 202 can be set to a constant pressure value. When the pressure cut-off value required by the load is greater, the current of the electro-proportional pressure reducing valve 202 is greater, and the pressure cut-off setting value corresponding to the pressure cut-off valve 102 core is greater, so as to achieve a greater pressure cut-off value. At the same time, the electro-proportional valve outputs different currents according to the pressure cut-off requirements of different actions (this pressure cut-off requirement is obtained by testing under actual working conditions while ensuring speed), so as to achieve different constant pressure control pressures for different working conditions and achieve the purpose of energy saving. After opening the first valve 201 to switch the load-sensitive pump 1 to constant pressure mode, the pressure required by the attachment under different working conditions is first measured. Then, the electro-proportional pressure reducing valve 202 is adjusted according to the different working conditions of the attachment so that the pressure adjusted by the electro-proportional pressure reducing valve 202 meets the pressure required under different working conditions. The electro-proportional pressure reducing valve 202 is connected to the pressure cut-off valve 102 of the load-sensitive pump 1, which can also adjust the pressure at the oil outlet of the load-sensitive pump 1, ensuring that the oil outlet pressure of the load-sensitive pump 1 meets the pressure required by the attachment under the current working conditions. This setting saves energy and reduces emissions, avoiding pressure waste.

[0045] It should be noted that, based on the command signal, the flow rate required for the attachment's operation is calculated. If the pump's maximum displacement at idle speed still cannot meet the flow rate requirement (Q=V), then... n, where Q is the flow rate, V is the displacement of the load-sensitive pump 1, and n is the speed of the load-sensitive pump 1, then the power source accelerates to the speed n1 = Q1 / Vmax; if the maximum displacement of the pump at the standby speed meets the flow requirement, then the standby speed is maintained; because the flow rate of the attachment is relatively small, the maximum flow rate required by the attachment can generally be met in the standby state. The attachment is a general term for rotary motor 4, side-shifting cylinder 6, telescopic cylinder 7, and rotary locking cylinder 8, etc.

[0046] In addition, the electro-proportional pressure reducing valve 202 can be replaced with the first pressure reducing valve. The first pressure reducing valve can also reduce the pressure of the hydraulic oil fed back to the pressure cut-off valve 102 of the load-sensitive pump 1. Adjusting the opening of the first pressure reducing valve can also achieve the above effect. The adjustment method is basically the same as the above implementation method. The difference is that, under normal circumstances, the opening of the first pressure reducing valve needs to be manually adjusted to finally achieve the adjustment of the oil outlet pressure of the load-sensitive pump 1.

[0047] In some embodiments, the hydraulic system includes a rotary motor 4 and a rotary motor control valve assembly 5. The rotary motor 4 is connected to the load-sensitive pre-compensation multi-way valve 3 of the hydraulic system; the two ports of the rotary motor control valve assembly 5 are respectively connected to the rotary motor 4 and the load-sensitive pre-compensation multi-way valve 3 of the hydraulic system; wherein, the rotary motor control valve assembly 5 includes a second valve 501, which is a two-position three-way valve. When the second valve 501 is in the left position, the brake of the rotary motor 4 is connected to the load-sensitive pre-compensation multi-way valve 3; when the second valve 501 is in the right position, the brake is connected to the outlet line of the load-sensitive pump 1. Specifically, the motor brake control second valve 501 is simultaneously energized, at which time the second valve 501 is in the right position, the brake is connected to the outlet line of the load-sensitive pump 1, and the pressure of the outlet of the load-sensitive pump 1 is supplied to the motor brake port, opening the motor brake, thereby achieving braking of the motor. By setting the second valve 501, the connection between the oil outlet line of the load-sensitive pump 1 and the brake of the rotary motor 4 is adjusted, thereby quickly braking the rotary motor 4.

[0048] It should be noted that by setting the second valve 501 in this way, the braking of the motor is changed to an external setting. Compared with the existing technology, this second valve 501 can brake the rotary motor 4 directly through the brake, or it can control the braking of the rotary motor 4 through hydraulic means, increasing the number of control methods and increasing the selectivity during operation.

[0049] It should also be noted that the position of the P port (that is, the connection port between the second valve 501 and the hydraulic oil circuit) of the rotary motor control valve group 5 is not limited, as long as the second valve 501 has pressure when it is energized when the rotary motor 4 needs to be braked.

[0050] Furthermore, in some embodiments, the second valve 501 is connected to the oil outlet line of the load-sensitive pump 1, and the rotary motor control valve assembly 5 also includes a pressure reducing valve 502 disposed between the second valve 501 and the oil outlet line of the load-sensitive pump 1. Specifically, when it is necessary to brake the rotary motor 4, the second valve 501, which controls the motor braking, is energized, reducing the pressure in the oil outlet line of the load-sensitive pump 1 by the pressure reducing valve 502 and then supplying it to the motor brake port, thereby opening the motor brake and completing the motor braking. Since the hydraulic oil pressure required for motor braking is not large, the pressure reducing valve 502 is disposed between the second valve 501 and the oil outlet line of the load-sensitive pump 1 to adjust the hydraulic oil pressure required by the second valve 501 for braking the rotary motor 4, resulting in better performance during use.

[0051] In some embodiments, the rotary motor control valve group 5 further includes a third valve 503, which is a two-position two-way valve. When the third valve 503 is in the left position, the outlet of the pressure reducing valve 502 is connected to port A and port B of the rotary motor control valve group 5 through two check valves, and the two check valves allow hydraulic oil to flow from the pressure reducing valve 502 to port A and port B of the rotary motor control valve group 5. When the third valve 503 is in the right position, the third valve 503 is a check valve that allows hydraulic oil to flow from port A and port B of the rotary motor control valve group 5 to the pressure reducing valve 502. The first port and the second port of the load-sensitive pre-compensation multi-way valve 3 connected to port A and port B of the rotary motor control valve group 5 are disconnected. Specifically, when braking the rotary motor 4 via a built-in hydraulic circuit cutoff, a third valve 503 is installed. When the rotary motor 4 is operating normally, the third valve 503 is not energized. However, at this time, the outlet of the pressure reducing valve 502 is connected to port A and port B of the rotary motor control valve group 5 through two check valves. The two check valves allow hydraulic oil to flow from the pressure reducing valve 502 to ports A and B of the rotary motor control valve group 5. Furthermore, the first and second ports of the load-sensitive pre-compensation multi-way valve 3 connected to ports A and B of the rotary motor control valve group 5 are disconnected. This ensures that ports A and B of the motor control valve group always have a relatively small pressure waiting, thus ensuring that ports A and B of the rotary motor control valve group 5 always have standby pressure. When braking is required, it can brake quickly and respond rapidly.

[0052] In some embodiments, the hydraulic system includes a side-shifting cylinder 6, a telescopic cylinder 7, and a locking cylinder 8 connected to a load-sensitive pre-compensation multi-way valve 3. A hydraulic lock 9 is provided between the load-sensitive pre-compensation multi-way valve 3 and one or more of the side-shifting cylinder 6, telescopic cylinder 7, locking cylinder 8, and rotary motor 4. It should be noted that the hydraulic lock 9 is a safety device primarily used to protect the machine in abnormal situations. Simultaneously, the hydraulic lock 9 can also prevent the machine from losing control during material transport, protecting the safety of production personnel. The working principle of the hydraulic lock 9 is to lock large-area moving parts through a closed hydraulic system. When the hydraulic system is in normal working condition, the oil can flow smoothly. When the hydraulic system malfunctions, the locking component automatically starts working, locking the hydraulic system and thus the entire machine. For example, when the telescopic cylinder 7 is jammed by debris or blocked, the hydraulic lock 9 will immediately take effect, stopping the machine's operation and preventing further damage or injury. In this way, the machine will not lose control due to hydraulic system failure, thereby ensuring production safety.

[0053] In addition, a balance valve can be installed between the load-sensitive pre-compensation multi-way valve 3 and one or more of the side-shift cylinder 6, telescopic cylinder 7, rotary lock cylinder 8, and rotary motor 4. The balance valve can change the opening of the throttle valve and regulate the flow rate of the fluid to achieve a constant flow rate, thereby making the operation of the hydraulic system more stable and reliable.

[0054] In some embodiments, the load-sensitive pre-compensation multi-way valve 3 includes a first section 301 connected to the rotary motor 4, a second section 302 connected to the lateral displacement cylinder 6, a third section 303 connected to the telescopic cylinder 7, and a fourth section 304 connected to the rotary locking cylinder 8. At least one of the first section 301, the second section 302, the third section 303, and the fourth section 304 includes a valve core differential position 3031. It should be noted that the first section 301 refers to the part of the load-sensitive pre-compensation multi-way valve 3 that controls the operation of the rotary motor 4, the second section 302 refers to the part of the load-sensitive pre-compensation multi-way valve 3 that controls the operation of the lateral displacement cylinder 6, the third section 303 refers to the part of the load-sensitive pre-compensation multi-way valve 3 that controls the telescopic cylinder 7, and the fourth section 304 refers to the part of the load-sensitive pre-compensation multi-way valve 3 that controls the rotary locking cylinder 8. The valve core differential position 3031 refers to the differential function when the solenoid valves in the first, second, third, and fourth sections (301, 302, 303, and 304) are in one of these positions. The differential function means that when oil is supplied to both chambers of the hydraulic cylinder simultaneously (the two chambers are connected), because the effective area of ​​the rodless chamber is larger than that of the rod chamber, the hydraulic oil pressure acting on both ends is the same. The force of the hydraulic oil acting on the rodless end of the piston is greater than the force acting on the rod chamber. The piston will be pushed towards the rod chamber under the combined force of these forces. At this time, the hydraulic oil in the rod chamber is discharged and merges with the hydraulic oil supplied by the pump, flowing together towards the rodless chamber. The hydraulic oil flowing towards the rodless chamber at this time comes from both the pump and the rod chamber, thus accelerating the extension speed. The differential circuit can increase the extension speed of a single-piston rod cylinder without increasing the pump flow rate, which means significant cost savings.

[0055] An engineering machine includes the aforementioned hydraulic system. Since the engineering machine includes the aforementioned hydraulic system, the beneficial effects brought by the hydraulic system are as described above and will not be repeated here.

[0056] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0057] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0058] It should also be noted that in the apparatus, equipment, and methods of this application, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered as equivalent solutions of this application.

[0059] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0060] It should be understood that the qualifiers “first,” “second,” “third,” “fourth,” “fifth,” and “sixth” used in the description of the embodiments of this application are only used to more clearly illustrate the technical solutions and are not intended to limit the scope of protection of this application.

[0061] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A hydraulic system, characterized in that, include: Load-sensitive pump; The attachment includes an oil supply valve assembly, including a first valve, which connects the oil outlet of the load-sensitive pump to the load pressure feedback signal output port. A rotary motor is connected to the load-sensitive pre-compensated multi-way valve of the hydraulic system; A rotary motor control valve assembly, wherein the two oil ports of the rotary motor control valve assembly are respectively connected to the rotary motor and the load-sensitive pre-compensation multi-way valve of the hydraulic system; The first valve can feed back the pressure at the outlet of the load-sensitive pump to the load pressure feedback signal output port of the load-sensitive pump, and the pressure on both sides of the load-sensitive valve core of the load-sensitive pump is equal, so that the load-sensitive pump is in constant pressure control mode. The rotary motor control valve group includes a second valve, which is a two-position three-way valve. When the second valve is in the left position, the brake of the rotary motor is connected to the load-sensitive pre-compensation multi-way valve; when the second valve is in the right position, the brake is connected to the oil outlet of the load-sensitive pump. The second valve is connected to the oil outlet of the load-sensitive pump, and the rotary motor control valve group further includes a pressure reducing valve disposed between the second valve and the oil outlet of the load-sensitive pump; The rotary motor control valve group also includes a third valve, which is a two-position, two-way valve. When the third valve is in the left position, the outlet of the pressure reducing valve is connected to port A and port B of the rotary motor control valve group through two check valves, respectively, and the two check valves allow hydraulic oil to flow from the pressure reducing valve to port A and port B of the rotary motor control valve group. When the third valve is in the right position, the third valve is a check valve that allows hydraulic oil to flow from port A and port B of the rotary motor control valve group to the pressure reducing valve. The first and second ports connecting the load-sensitive pre-compensation multi-way valve to ports A and B of the rotary motor control valve group are disconnected.

2. The hydraulic system according to claim 1, characterized in that, The attachment oil supply valve assembly is located near the load-sensitive pump.

3. The hydraulic system according to claim 1, characterized in that, The first valve is a two-position three-way valve. When the first valve is in the left position, the load pressure feedback signal output port is connected to the drain port of the hydraulic system; when the first valve is in the right position, the outlet port of the load-sensitive pump is connected to the load pressure feedback signal output port.

4. The hydraulic system according to claim 1 or 3, characterized in that, The attachment oil supply valve group also includes an electro-proportional pressure reducing valve, which is a two-position three-way valve. When the electro-proportional pressure reducing valve is in the left position, the oil outlet of the load-sensitive pump is connected to the pressure shut-off valve of the load-sensitive pump; when the electro-proportional pressure reducing valve is in the right position, the pressure shut-off valve is connected to the load-sensitive pre-compensation multi-way valve of the hydraulic system.

5. The hydraulic system according to claim 1, characterized in that, It includes a side-shifting cylinder, a telescopic cylinder, and a rotary locking cylinder connected to a load-sensitive pre-compensation multi-way valve. A hydraulic lock is provided between the load-sensitive pre-compensation multi-way valve and one or more of the side-shifting cylinder, the telescopic cylinder, the rotary locking cylinder, and the rotary motor.

6. The hydraulic system according to claim 5, characterized in that, The load-sensitive pre-compensation multi-way valve includes a first section connected to the rotary motor, a second section connected to the lateral displacement cylinder, a third section connected to the telescopic cylinder, and a fourth section connected to the rotary lock cylinder. At least one of the first section, the second section, the third section, and the fourth section includes a valve core differential position.

7. An engineering machinery, characterized in that, The hydraulic system comprising any one of claims 1-6.

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