Multifunctional hydraulic system

Abstract

According to the multifunctional hydraulic system, an oil tank, an oil inlet of a load-sensitive pump, an oil outlet of the load-sensitive pump and an external mechanism are connected end to end to form a loop; an oil outlet of the load-sensitive pump is communicated with an oil inlet of the first reversing valve and an oil inlet of the second reversing valve, an oil outlet of the first reversing valve is communicated with a load-sensitive opening of the load-sensitive pump, an oil outlet of the second reversing valve is communicated with an oil inlet of the first overflow valve, and an oil outlet of the first overflow valve is communicated with an oil tank. The set pressure of the pressure valve in the load-sensitive pump is greater than that of the first overflow valve; the oil inlet of the first reversing valve can be communicated with the oil outlet at the conduction station, and the oil inlet of the second reversing valve can be cut off at the cut-off station and communicated with the oil outlet of the second reversing valve at the conduction station. Through switching of different stations of the first reversing valve and the second reversing valve, the hydraulic system can output pressure of different gears to be matched with external mechanisms with different pressure requirements, and meanwhile low noise, energy conservation and effective cooling can be taken into consideration.

Description

Technical Field

[0001] The invention relates to the field of hydraulics, and in particular to a multifunctional hydraulic system. Background Art

[0002] At present, in the marine engineering field, the oil pumps that are more commonly used in open pump hydraulic systems are load sensitive pumps, constant pressure pumps, etc.

[0003] When the mechanism is not moving, the load-sensitive pump only outputs a very low load-sensitive pressure and almost no flow output. At this time, the noise is very low. When the mechanism is moving, the pressure output by the oil pump depends on the size of the load, which is more energy-efficient. However, this pump is only suitable for occasions where the actuator and the oil pump are relatively close. It is not suitable for occasions where the oil pump and the actuator are far apart. When the distance is far, the response is slower, and the set pressure of the pump's load-sensitive pressure valve needs to be increased. If it is adjusted too high, it will no longer be energy-efficient.

[0004] Constant pressure pumps are suitable for situations where the distance between the actuator and the pump is very far. When the mechanism is not moving, the oil pump maintains a high-pressure constant-pressure standby state with almost no flow output. At this time, the noise is still very loud. When the mechanism moves, it can respond quickly to output pressure and flow, but it is not energy-efficient.

[0005] In addition, when the mechanism is not moving, the load-sensitive pump is on standby with load-sensitive pressure, or the constant pressure pump is on standby with constant pressure, there is no return oil entering the cooler. If the system reaches high temperature at this time, the oil pump needs to be unloaded to allow low-pressure and high-flow hydraulic oil to enter the return oil cooler for cooling.

[0006] Often an open pump needs to supply oil to multiple actuators with large load differences. When a constant pressure pump is used to supply oil, if there is only one constant pressure, it cannot provide good pressure protection for the low-load mechanism, and the energy loss is relatively serious. Due to the continuous high pressure, the life of the components will be shortened and it will be more prone to leakage.

[0007] In summary, the hydraulic system in the related art has the following problems:

[0008] First, the power pump in the hydraulic system cannot provide low noise and energy saving as well as long-distance power for the mechanism;

[0009] Second, the system cannot be cooled effectively;

[0010] Third, the pressure cannot be switched according to the needs of the organization, resulting in energy loss, reduced service life, leakage risks and other abnormalities. Summary of the invention

[0011] The present invention is made to solve the above-mentioned technical problems, and its purpose is to provide a multifunctional hydraulic system which can provide a multi-level adaptive pressure for the mechanism.

[0012] The invention discloses a multifunctional hydraulic system, comprising: a load-sensitive pump and an oil tank, wherein the oil tank, the oil inlet of the load-sensitive pump, the oil outlet of the load-sensitive pump and an external mechanism are connected end to end to form a loop; a first reversing valve, a second reversing valve and a first relief valve, wherein the oil outlet of the load-sensitive pump is connected to the oil inlet of the first reversing valve and the oil inlet of the second reversing valve respectively, the oil outlet of the first reversing valve is connected to the load-sensitive port of the load-sensitive pump, the oil outlet of the second reversing valve is connected to the oil inlet of the first relief valve, and the oil outlet of the first relief valve is connected to the oil tank; the set pressure of the pressure valve in the load-sensitive pump is greater than the set pressure of the first relief valve; when the first reversing valve is in its own conduction position, the oil inlet of the first reversing valve is connected to the oil outlet of the first reversing valve, when the second reversing valve is in its own cut-off position, the oil inlet of the second reversing valve is cut off, and when the second reversing valve is in its own conduction position, the oil inlet of the second reversing valve is connected to the oil outlet of the second reversing valve.

[0013] Optionally, a second overflow valve is further included, the oil outlet of the load-sensitive pump is connected to the oil inlet of the second overflow valve, the oil outlet of the second overflow valve is connected to the oil tank, when the first reversing valve is in its own cut-off position, the oil inlet of the first reversing valve is cut off, the set pressure of the second overflow valve>the set pressure of the pressure valve in the load-sensitive pump>the set pressure of the first overflow valve>the set pressure of the load-sensitive valve.

[0014] Optionally, the second overflow valve has a control port, and the hydraulic system also includes a third reversing valve and a cooling device, the oil inlet of the third reversing valve is connected to the control port of the second overflow valve, and the oil outlet of the third reversing valve is connected to the oil tank via the cooling device; when the third reversing valve is in its own cut-off position, the oil inlet of the third reversing valve is cut off, and when the third reversing valve is in its own conduction position, the oil inlet of the third reversing valve is connected to the oil outlet of the third reversing valve.

[0015] Optionally, when the hydraulic system is in a shutdown state, the first reversing valve is in its own cut-off position, the second reversing valve is in its own cut-off position, and the third reversing valve is in its own conduction position.

[0016] Optionally, it also includes a controller and a temperature sensor. The first reversing valve, the second reversing valve and the third reversing valve are all solenoid valves. The controller is respectively connected to the first reversing valve, the second reversing valve, the third reversing valve and the cooling device. When the oil temperature of the hydraulic system is ≥ the temperature threshold, the temperature sensor generates a temperature signal. The controller responds to the temperature signal to drive the first reversing valve to its own conduction position, the second reversing valve to its own shut-off position, the third reversing valve to its own conduction position, and controls the cooling device to start.

[0017] Optionally, a one-way valve is further included, and the oil outlet of the load-sensing pump is connected to the oil inlet of the second overflow valve via the one-way valve.

[0018] Optionally, a damper is further included, and the oil outlet of the load-sensitive pump is connected to the oil inlet of the first reversing valve and the oil inlet of the second reversing valve respectively through the damper.

[0019] Optionally, the first relief valve is a proportional relief valve.

[0020] The beneficial effects of the present invention are as follows:

[0021] The present application discloses a multifunctional hydraulic system, comprising: a load-sensitive pump and an oil tank, wherein the oil tank, the oil inlet of the load-sensitive pump, the oil outlet of the load-sensitive pump and an external mechanism are connected end to end to form a loop; a first reversing valve, a second reversing valve and a first relief valve, wherein the oil outlet of the load-sensitive pump is connected to the oil inlet of the first reversing valve and the oil inlet of the second reversing valve respectively, the oil outlet of the first reversing valve is connected to the load-sensitive port of the load-sensitive pump, the oil outlet of the second reversing valve is connected to the oil inlet of the first relief valve, and the oil outlet of the first relief valve is connected to the oil tank; the set pressure of the pressure valve in the load-sensitive pump is greater than the set pressure of the first relief valve; when the first reversing valve is in its own conduction position, the oil inlet of the first reversing valve is connected to the oil outlet of the first reversing valve, when the second reversing valve is in its own cut-off position, the oil inlet of the second reversing valve is cut off, and when the second reversing valve is in its own conduction position, the oil inlet of the second reversing valve is connected to the oil outlet of the second reversing valve.

[0022] In summary, it can be seen that by switching the different positions of the first reversing valve and the second reversing valve, the output pressure of the hydraulic system can correspond to the pressure set by the first overflow valve and the pressure set by the pressure valve in the load sensitive pump, respectively, and then output pressures of different gears to match external mechanisms with different pressure requirements. In this way, the hydraulic system can supply oil to multiple external mechanisms with large load differences, so as to provide pressure protection for low-load mechanisms, reduce energy loss, increase component life, and avoid safety hazards such as leakage.

[0023] At the same time, it can take into account low noise and energy saving and provide power for the organization over long distances; and it can effectively cool the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above features and advantages of the present invention can be better understood after reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings. In the drawings, the components are not necessarily drawn to scale, and components with similar related properties or features may have the same or similar reference numerals.

[0025] Figure 1 It is a schematic diagram of the present invention when it is shut down;

[0026] Figure 2 is a schematic diagram of the present invention when it is on standby;

[0027] Figure 3 is a schematic diagram of a standby cooling cycle of the present invention;

[0028] Figure 4 It is a schematic diagram of the present invention at the first gear working pressure;

[0029] Figure 5 is a schematic diagram of the present invention at the second gear working pressure;

[0030] Figure 6 It is a schematic diagram of the first-level working pressure of the proportional relief valve adopted in the present invention.

[0031] Description of reference numerals:

[0032] 10-Load sensing pump,

[0033] S10- oil inlet of load-sensing pump, P10- oil outlet of load-sensing pump, Ls10- load-sensing port of load-sensing pump,

[0034] 11-Fuel tank,

[0035] 12-External mechanism,

[0036] 21-First reversing valve,

[0037] P21-the oil inlet of the first reversing valve, B21-the oil outlet of the first reversing valve, A21-the other oil outlet of the first reversing valve, T21-the oil return port of the first reversing valve,

[0038] 22- Second reversing valve,

[0039] P22-the oil inlet of the second reversing valve, B22-the oil outlet of the second reversing valve, A22-the other oil outlet of the second reversing valve, T22-the oil return port of the second reversing valve,

[0040] 23- The third reversing valve,

[0041] P23-the oil inlet of the third reversing valve, A23-the oil outlet of the third reversing valve, B23-the other oil outlet of the third reversing valve, T23-the oil return port of the third reversing valve,

[0042] 31- first relief valve,

[0043] P31-the oil inlet of the first relief valve, A31-the oil outlet of the first relief valve,

[0044] 32-Second relief valve,

[0045] P32-the oil inlet of the second relief valve, A32-the oil outlet of the second relief valve, K32-the control port of the second relief valve,

[0046] 40-Cooling device,

[0047] 50- one-way valve,

[0048] 60- Damping. DETAILED DESCRIPTION

[0049] The present invention is further described below in conjunction with specific embodiments and drawings. More details are elaborated in the following description to facilitate a full understanding of the present invention. However, the present invention can obviously be implemented in a variety of other ways different from the description herein. Those skilled in the art can make similar generalizations and deductions based on actual application situations without violating the connotation of the present invention. Therefore, the protection scope of the present invention should not be limited by the content of this specific embodiment.

[0050] It should be noted that these and other subsequent drawings are only examples and are not drawn to scale, and should not be used to limit the actual scope of protection required by the present invention.

[0051] The hydraulic system in the related technology has the following problems: First, the power pump in the hydraulic system cannot take into account both low noise and energy saving and long-distance power supply for the mechanism; second, it cannot effectively cool the system; third, it cannot switch the pressure according to the needs of the mechanism, resulting in energy loss, reduced service life, leakage risks and other abnormalities. Therefore, in order to solve such problems, the technical solution of this application is produced, which is combined with the following Figure 1 to Figure 6 To elaborate.

[0052] like Figure 4 and Figure 5 As shown, the present application discloses a multifunctional hydraulic system, including: a load-sensing pump 10 , an oil tank 11 , a first reversing valve 21 , a second reversing valve 22 and a first overflow valve 31 .

[0053] Among them, the oil tank 11, the oil inlet S10 of the load-sensitive pump 10, the oil outlet P10 of the load-sensitive pump 10 and the external mechanism 12 are connected end to end to form a loop; the external mechanism 12 can be a mechanism that requires hydraulic drive, such as an oil cylinder, and the external mechanism 12 is respectively connected to the oil outlet P10 of the load-sensitive pump 10 and the oil return port T1 of the system. A pressure valve and a load-sensitive valve are arranged in the load-sensitive pump 10, wherein the pressure valve can be a pressure cut-off valve, a constant pressure valve, etc. When working, the power provided by the load-sensitive pump 10 can drive the external mechanism 12 to perform corresponding actions.

[0054] The oil outlet P10 of the load sensing pump is respectively connected to the oil inlet P21 of the first reversing valve 21 and the oil inlet P22 of the second reversing valve 22, the oil outlet B21 of the first reversing valve 21 is connected to the load sensing port Ls10 of the load sensing pump 10, the other oil outlet A21 of the first reversing valve 21 is disconnected, and the oil return port T21 of the first reversing valve is connected to the oil tank 11.

[0055] The oil outlet B22 of the second reversing valve 22 is connected to the oil inlet P31 of the first relief valve 31, the other oil outlet A22 of the second reversing valve is disconnected, the oil return port T22 of the second reversing valve is connected to the oil tank 11, and the oil outlet A31 of the first relief valve is connected to the oil tank 11. The first relief valve 31 can be a pilot-operated or direct-acting relief valve. The set pressure of the pressure valve in the load sensing pump 10 is greater than the set pressure of the first relief valve 31.

[0056] When the external mechanism 12 needs to be controlled to perform an action, Figure 4 As shown, the first reversing valve 21 is controlled to be in the self-conduction position, and the second reversing valve 22 is controlled to be in the self-conduction position. At this time, the oil inlet P21 of the first reversing valve is connected to the oil outlet B21 of the first reversing valve, and the oil inlet P22 of the second reversing valve is connected to the oil outlet B22 of the second reversing valve. At the same time, the load-sensing pump 10 is running, and the oil output from the oil outlet P10 of the load-sensing pump flows back to the load-sensing port Ls1 of the load-sensing pump through the oil inlet P21 of the first reversing valve and the oil outlet B21 of the first reversing valve in the first path. 0, so as to feedback pressure to the load sensing pump 10; the second path flows to the oil inlet P31 of the first relief valve through the oil inlet P22 of the second reversing valve and the oil outlet B22 of the second reversing valve, and after overcoming the pressure set by the first relief valve 31, it is connected to the oil outlet A31 of the first relief valve, and then flows back to the oil tank 11 from the oil outlet A31 of the first relief valve; the third path supplies the external mechanism 12, at which time the output pressure of the hydraulic system corresponds to the pressure set by the first relief valve 31, so as to match the external mechanism 12 that needs this pressure.

[0057] When it is necessary to control the external mechanism 12 to perform an action, it can also be done as follows Figure 5 As shown, the first reversing valve 21 is controlled to be in its own conduction position, and the second reversing valve 22 is controlled to be in its own cut-off position. At this time, the oil inlet P22 of the second reversing valve is cut off because it is connected to another oil outlet A22 of the second reversing valve. At this time, the load-sensing pump 10 is running, and the oil output from the oil outlet P10 of the load-sensing pump, in the first way, flows back to the load-sensing port Ls10 of the load-sensing pump through the oil inlet P21 of the first reversing valve and the oil outlet B21 of the first reversing valve in sequence, so as to feedback pressure to the load-sensing pump 10; the second way supplies the external mechanism 12. At this time, the output pressure of the hydraulic system corresponds to the pressure set by the pressure valve in the load-sensing pump 10, so as to match the external mechanism 12 that requires this pressure.

[0058] From the above, it can be seen that by switching the different working positions of the first reversing valve 21 and the second reversing valve 22, the output pressure of the hydraulic system can correspond to the pressure set by the first overflow valve 31 and the pressure set by the pressure valve in the load sensitive pump 10, respectively, and then output pressures of different gears to match the external mechanisms 12 with different pressure requirements. In this way, the hydraulic system can supply oil to multiple external mechanisms 12 with large load differences, so as to provide pressure protection for low-load mechanisms, reduce energy loss, increase component life, and avoid safety hazards such as leakage.

[0059] Optionally, multiple external mechanisms 12 can be connected in parallel, and each external mechanism 12 is configured with a control valve in a one-to-one correspondence, and a controller is configured to connect each control valve, and a pressure sensor is configured to connect the controller. When the first reversing valve 21 is in its own conduction position, and the second reversing valve 22 is in its own conduction position, the output pressure of the hydraulic system corresponds to the pressure set by the first overflow valve 31, the pressure sensor generates a first pressure signal in response to the set pressure of the first overflow valve 31, and the controller responds to the first pressure signal to control the corresponding control valve of the external mechanism 12 matching the set pressure of the first overflow valve 31 to open, so that the external mechanism 12 corresponding to the opened control valve can be actuated; when the first reversing valve 21 is in its own conduction position, and the second reversing valve 22 is in its own cut-off position, the output pressure of the hydraulic system corresponds to the set pressure of the pressure valve in the load-sensitive pump 10, the pressure sensor generates a second pressure signal in response to the set pressure of the pressure valve in the load-sensitive pump 10, and the controller responds to the second pressure signal to control the corresponding control valve of the external mechanism 12 matching the set pressure of the pressure valve in the load-sensitive pump 10 to open, so that the external mechanism 12 corresponding to the opened control valve can be actuated.

[0060] Optionally, Figure 6 is a schematic diagram of the first gear working pressure in another embodiment, and Figure 4 The difference is: Figure 6 The first relief valve 31 in the system adopts a proportional relief valve. As mentioned above, when the first reversing valve 21 is in its own conduction position and the second reversing valve 22 is in its own conduction position, the output pressure of the hydraulic system corresponds to the pressure set by the first relief valve 31, that is, the set pressure of the proportional relief valve. Through the pressure adjustment of the proportional relief valve, stepless pressure regulation of multiple pressure levels can be achieved, so that the duration of the system's maximum design pressure will be shorter, the component life can be longer, and it will be less likely to leak.

[0061] Alternatively, if Figure 2As shown, the hydraulic system of the present application further includes a second overflow valve 32, the oil outlet P10 of the load-sensing pump is connected to the oil inlet P32 of the second overflow valve 32, and the oil outlet A32 of the second overflow valve is connected to the oil tank 11. When the first reversing valve 21 is in its own cut-off position, the oil inlet P21 of the first reversing valve is cut off, and the set pressure of the second overflow valve 32>the set pressure of the pressure valve in the load-sensing pump 10>the set pressure of the first overflow valve 31>the set pressure of the load-sensing valve.

[0062] When the system is in standby state, the external mechanism 12 is not driven. At this time, the first reversing valve 21 and the second reversing valve 22 are both in their own cut-off positions, and the output pressure of the load-sensitive pump 10 is the set pressure of the load-sensitive valve, which is usually about 20 bar. In this way, in the first aspect, the hydraulic system is on standby at low pressure, the noise is extremely low, and the experience is very good; in the second aspect, the pressure of the load feedback of the external mechanism 12 can be changed from a position far away from the load-sensitive pump 10 to a related valve group very close to the outlet of the load-sensitive pump 10, so as to take into account low noise and energy saving and provide power for the mechanism over a long distance; in the third aspect, the set pressure of the second relief valve 32 is relatively high, which can provide overload protection for the hydraulic system of this application. When the hydraulic system is on standby normally, the second relief valve 32 is disconnected. When the hydraulic system is overloaded abnormally, resulting in the internal load pressure of the system ≥ the set pressure of the second relief valve 32, the second relief valve 32 is turned on and unloaded to prevent the hydraulic system from being overloaded and damaged.

[0063] Optionally, the set pressure of the second relief valve 32>the set pressure of the pressure valve>the set pressure of the first relief valve 31>the set pressure of the load sensing valve. The pressure of the first relief valve 31, the pressure of the pressure valve, and the pressure of the second relief valve 32 are all set within the pressure range of 40 to 420 bar, and the pressure of the load sensing valve is set within the pressure range of 14 to 25 bar.

[0064] The second relief valve 32 provides overload protection, so its set pressure is the largest in the hydraulic system. The pressure valve of the load-sensing pump 10 and the first relief valve 31 mainly provide different gear pressure outputs for the hydraulic system, so the pressures of the two are different. The load-sensing valve is mainly for the feedback pressure of the load-sensing pump 10, and provides the pressure of the load-sensing pump 10 when in standby mode, so its set pressure is the smallest in the hydraulic system, generally 20 bar.

[0065] Optionally, the second relief valve 32 has a control port K32. The second relief valve 32 may be a pilot-operated relief valve, a relief valve with an external remote control port, or may be replaced by a logic valve combination.

[0066] The hydraulic system further includes a third reversing valve 23 and a cooling device 40, wherein the oil inlet P23 of the third reversing valve is connected to the control port K32 of the second relief valve, the oil outlet A23 of the third reversing valve is connected to the oil tank 11 via the cooling device 40, the other oil outlet B23 of the third reversing valve is disconnected, and the oil return port T23 of the third reversing valve is connected to the oil tank 11. The cooling device 40 may be an air-cooled cooler, a water-cooled cooler, or other types of coolers instead.

[0067] like Figure 2 As shown, when the third reversing valve 23 is in its own cut-off position, the oil inlet P23 of the third reversing valve is cut off because it is connected to another oil outlet B23 of the third reversing valve; Figure 3 As shown, when the third reversing valve 23 is in its own conduction position, the oil inlet P23 of the third reversing valve is connected to the oil outlet A23 of the third reversing valve.

[0068] The third reversing valve 23 and the cooling device 40 are provided to realize the unloading of the second relief valve 32, as follows:

[0069] like Figure 3 As shown, when the hydraulic system is on standby, if the oil temperature inside the system is too high, it needs to be unloaded. At this time, the third reversing valve 23 is in its own conduction position, the first reversing valve 21 is in its own conduction position, and the second reversing valve 22 is in its own cut-off position. The control port K32 of the second relief valve is directly connected to the oil tank 11 via the oil inlet P23 of the third reversing valve and the oil outlet A23 of the third reversing valve, so that the pressure difference between the oil inlet P32 of the second relief valve and the oil outlet A32 of the second relief valve 32 is basically zero, thereby enabling the second relief valve 32 to be unloaded.

[0070] In this way, under the unloading action of the second relief valve 32, the output pressure in the hydraulic system is low, and the load sensing pump 10 can output flow at the maximum displacement. Specifically, the oil output from the oil outlet P10 of the load sensing pump flows back to the load sensing port Ls10 of the load sensing pump through the first reversing valve 21 in one way, so as to feedback pressure to the load sensing pump 10, and flows back to the oil tank 11 after cooling through the second relief valve 32 in the other way, thereby realizing circulating cooling of the hydraulic system.

[0071] In summary, the second relief valve 32 and the third reversing valve 23 can cooperate with each other in the standby state of the hydraulic system to achieve overload protection or unloading through the second relief valve 32, thereby realizing the reuse of the second relief valve 32.

[0072] Alternatively, if Figure 1As shown, when the hydraulic system is in a shutdown state, the load-sensitive pump 10 stops working, the first reversing valve 21 is in its own cut-off position, the second reversing valve 22 is in its own cut-off position, and the third reversing valve 23 is in its own conduction position, then the control port K32 of the second overflow valve is opened, and the second overflow valve 32 maintains an overflow unloading state, which is beneficial to protecting the system.

[0073] Optionally, the hydraulic system further includes a controller and a temperature sensor, the first reversing valve 21, the second reversing valve 22 and the third reversing valve 23 are all solenoid valves, and the controller is respectively connected to the first reversing valve 21, the second reversing valve 22, the third reversing valve 23 and the cooling device 40, so that the intelligent control of the present application can be improved, as follows:

[0074] like Figure 1 As shown, when the hydraulic system is shut down, the first reversing valve 21, the second reversing valve 22 and the third reversing valve 23 shall not be energized, and the first reversing valve 21 is in the cut-off position, the second reversing valve 22 is in the cut-off position, and the third reversing valve 23 is in the on position, then the control port K32 of the second overflow valve is opened, and the second overflow valve 32 performs a load-unloading function, and after the load-sensitive pump 10 stops, it is beneficial to protect the hydraulic system.

[0075] like Figure 2 As shown, when overload protection is required during standby, the first reversing valve 21 shall not be powered, the second reversing valve 22 shall not be powered, the third reversing valve 23 shall be powered, the first reversing valve 21 is in the cut-off position, the second reversing valve 22 is in the cut-off position, the third reversing valve 23 is in the cut-off position, the control port K32 of the second overflow valve is disconnected, and the set pressure of the second overflow valve 32 is used as the overload protection pressure of the hydraulic system. The output pressure of the hydraulic system is the set pressure of the load-sensitive valve in the load-sensitive pump 10, which is generally around 20 bar. At this time, low-pressure standby is used, the noise is extremely low, and the experience is very good.

[0076] like Figure 3 As shown, during the standby process of the hydraulic system, if the oil temperature of the hydraulic system is ≥ the temperature threshold, the temperature sensor generates a temperature signal, and the controller responds to the temperature signal to energize the first reversing valve 21, de-energize the second reversing valve 22, and de-energize the third reversing valve 23, so as to drive the first reversing valve 21 to its own conduction position, the second reversing valve 22 to its own cut-off position, and the third reversing valve 23 to its own conduction position, and control the cooling device 40 to open. At this time, the control port K32 of the second overflow valve is connected to the oil tank 11, and the pressure difference between the oil inlet P32 of the second overflow valve and the oil outlet A32 of the second overflow valve is substantially 0. The second overflow valve 32 is directly turned on to realize unloading, and the oil flows back to the oil tank 11 through the second overflow valve 32 and the cooling device 40 in turn, and then circulates and cools.

[0077] When the oil temperature of the hydraulic system is cooled to less than the temperature threshold, the controller controls the first reversing valve 21 to be de-energized, the second reversing valve 22 to be de-energized, and the third reversing valve 23 to be energized. The first reversing valve 21 is in the cut-off position, the second reversing valve 22 is in the cut-off position, and the third reversing valve 23 is in the cut-off position. The hydraulic system is reset to Figure 2 The standby overload protection state shown can of course also be switched to other working states, which will not be described in detail here.

[0078] like Figure 4 and Figure 5 As shown, when the external mechanism 12 needs to be actuated, the pressure can be switched to different gears according to the pressure requirements of different external mechanisms 12. Specifically, Figure 4 As shown, the controller controls the first reversing valve 21 to be energized, the second reversing valve 22 to be energized, and the third reversing valve 23 to be energized, so as to drive the first reversing valve 21 to be in its own conduction position, the second reversing valve 22 to be in its own conduction position, and the third reversing valve 23 to be in its own cut-off position. At this time, the load-sensing pump 10 is running, and the oil output from the oil outlet P10 of the load-sensing pump flows back to the load-sensing port Ls10 of the load-sensing pump through the oil inlet P21 of the first reversing valve and the oil outlet B21 of the first reversing valve in the first path in turn, so as to provide the load-sensing pump with a high pressure. 10 feedback pressure; the second path flows to the oil inlet P31 of the first relief valve through the oil inlet P22 of the second reversing valve and the oil outlet B22 of the second reversing valve, and after overcoming the pressure set by the first relief valve 31, it is connected to the oil outlet A31 of the first relief valve, and then flows back to the oil tank 11 from the oil outlet A31 of the first relief valve; the third path supplies the external mechanism 12, at this time, the output pressure of the hydraulic system corresponds to the pressure set by the first relief valve 31 to match the external mechanism 12 that needs this pressure, and the second relief valve 32 is used for overload protection.

[0079] You can also Figure 5 As shown, the controller controls the first reversing valve 21 to be energized, the second reversing valve 22 to be de-energized, and the third reversing valve 23 to be energized, so as to drive the first reversing valve 21 to be in its own conduction position, the second reversing valve 22 to be in its own cut-off position, and the third reversing valve 23 to be in its own cut-off position. At this time, the load-sensing pump 10 is running, and the oil output from the oil outlet P10 of the load-sensing pump, in the first way, flows back to the load-sensing port Ls10 of the load-sensing pump through the oil inlet P21 of the first reversing valve and the oil outlet B21 of the first reversing valve in sequence, so as to feedback pressure to the load-sensing pump 10; the second way supplies the external mechanism 12. At this time, the output pressure of the hydraulic system corresponds to the pressure set by the pressure valve in the load-sensing pump 10, so as to match the external mechanism 12 that needs this pressure, and the second relief valve 32 is used for overload protection.

[0080] Optionally, the hydraulic system further includes a one-way valve 50, and the oil outlet P10 of the load sensing pump is connected to the oil inlet P32 of the second overflow valve via the one-way valve 50. The one-way valve 50 can prevent oil backflow and improve the safety of the hydraulic system.

[0081] Optionally, a damper 60 is further included, and the oil outlet P10 of the load-sensitive pump is connected to the oil inlet P21 of the first reversing valve and the oil inlet P22 of the second reversing valve respectively through the damper 60. After the oil source output from the load-sensitive pump 10 passes through the damper 60, it can be used as feedback to the load-sensitive port Ls10 of the load-sensitive pump to control the oil source, thereby achieving a constant pressure or a constant pressure cut-off pressure of the load-sensitive pump 10.

[0082] Although the present invention is disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope defined by the claims of the present invention.

Claims

1. A multifunctional hydraulic system, characterized in that: include: A load-sensitive pump (10) and an oil tank (11), wherein the oil tank (11), an oil inlet (S10) of the load-sensitive pump, an oil outlet (P10) of the load-sensitive pump and an external mechanism (12) are connected end to end to form a loop; a first reversing valve (21), a second reversing valve (22) and a first overflow valve (31); the oil outlet (P10) of the load-sensing pump is connected to the oil inlet (P21) of the first reversing valve and the oil inlet (P22) of the second reversing valve respectively; the oil outlet (B21) of the first reversing valve is connected to the load-sensing port (Ls10) of the load-sensing pump; the oil outlet (B22) of the second reversing valve is connected to the oil inlet (P31) of the first overflow valve; and the oil outlet (A31) of the first overflow valve is connected to the oil tank (11); The set pressure of the pressure valve in the load-sensing pump (10) is greater than the set pressure of the first relief valve (31); When the first reversing valve (21) is in its on position, the oil inlet (P21) of the first reversing valve is connected to the oil outlet (B21) of the first reversing valve; when the second reversing valve (22) is in its off position, the oil inlet (P22) of the second reversing valve is off; and when the second reversing valve (22) is in its on position, the oil inlet (P22) of the second reversing valve is connected to the oil outlet (B22) of the second reversing valve.

2. The hydraulic system according to claim 1, characterized in that: It also includes a second overflow valve (32), the oil outlet (P10) of the load sensing pump is connected to the oil inlet (P32) of the second overflow valve, and the oil outlet (A32) of the second overflow valve is connected to the oil tank (11). When the first reversing valve (21) is in its own cut-off position, the oil inlet (P21) of the first reversing valve is cut off. The set pressure of the second relief valve (32)>the set pressure of the pressure valve in the load sensing pump (10)>the set pressure of the first relief valve (31)>the set pressure of the load sensing valve.

3. The hydraulic system according to claim 2, characterized in that: The second overflow valve (32) has a control port (K32), The hydraulic system further comprises a third reversing valve (23) and a cooling device (40), wherein an oil inlet (P23) of the third reversing valve is connected to a control port (K32) of the second overflow valve, and an oil outlet (A23) of the third reversing valve is connected to the oil tank (11) via the cooling device (40); When the third reversing valve (23) is in its own cut-off position, the oil inlet (P23) of the third reversing valve is cut off; when the third reversing valve (23) is in its own conduction position, the oil inlet (P23) of the third reversing valve is connected to the oil outlet (A23) of the third reversing valve.

4. The hydraulic system according to claim 3, characterized in that: When the hydraulic system is in a shutdown state, the first reversing valve (21) is in its own cut-off position, the second reversing valve (22) is in its own cut-off position, and the third reversing valve (23) is in its own conduction position.

5. The hydraulic system according to claim 3, characterized in that: The device also includes a controller and a temperature sensor, wherein the first reversing valve (21), the second reversing valve (22) and the third reversing valve (23) are all solenoid valves, and the controller is respectively connected to the first reversing valve (21), the second reversing valve (22), the third reversing valve (23) and the cooling device (40). When the oil temperature of the hydraulic system is greater than or equal to a temperature threshold, the temperature sensor generates a temperature signal, and the controller responds to the temperature signal to drive the first reversing valve (21) to be in its own conduction position, the second reversing valve (22) to be in its own shutoff position, the third reversing valve (23) to be in its own conduction position, and controls the cooling device (40) to be turned on.

6. The hydraulic system according to claim 3, characterized in that: It also includes a one-way valve (50), and the oil outlet (P10) of the load-sensing pump is connected to the oil inlet (P32) of the second overflow valve via the one-way valve (50).

7. The hydraulic system according to claim 1, characterized in that: It also includes a damper (60), and the oil outlet (P10) of the load-sensitive pump is connected to the oil inlet (P21) of the first reversing valve and the oil inlet (P22) of the second reversing valve through the damper (60).

8. The hydraulic system according to claim 1, characterized in that: The first relief valve (31) is a proportional relief valve.

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