Lift hydraulic system and loader

Abstract

This invention relates to a load-holding valve. To address the incompatibility between load-holding protection functions and hydraulic damping modules in existing lifting hydraulic systems, this invention constructs a lifting hydraulic system and a loader. The lifting hydraulic system includes a hydraulic damping module, a controller, a pressure sensor, and a load-holding valve connected to the large and small chamber interfaces of the lifting cylinder control valve. The load-holding valve comprises a cone valve, a load-holding control solenoid valve electrically connected to the controller, and a damping orifice. The inlet and outlet ends of the cone valve are respectively connected to the large chamber interface of the lifting cylinder control valve and the large chamber of the lifting cylinder. The hydraulic control end of the cone valve is connected to the load port via the damping orifice and to the T-port via the load-holding control solenoid valve. The controller controls the load-holding control solenoid valve to be in a closed or open state according to whether the pressure at the large chamber interface of the lifting cylinder control valve is less than a predetermined value. This invention enables the simultaneous implementation of boom damping and load-holding functions on the loader.

Description

Technical Field

[0001] This invention relates to a load holding valve, and more specifically, to a lifting hydraulic system and a loader. Background Technology

[0002] Load holding valves are typically mounted on the lifting cylinders of a lifting device, such as the boom cylinder in a loader boom lifting hydraulic system. Figure 1 As shown, in the hydraulic system for lifting the boom of the loader, the hydraulic pump 2 draws oil from the hydraulic oil tank 1 and supplies oil to the distribution valve 3. The A1 port of the boom coupling of the distribution valve 3 is connected to the large chamber of the boom cylinder 4 through the hydraulically controlled load holding valve 5, and the B1 port is connected to the small chamber of the boom cylinder. When the hydraulic hose assembly between the A1 port of the boom coupling and the load holding valve 5 bursts, the load holding valve 5 activates, locking the hydraulic oil in the large chamber 4 of the boom cylinder, protecting the material and the entire machine from damage.

[0003] In existing technology, some loaders are equipped with hydraulic shock absorption modules, such as Figure 1 As shown, ports A1 and B1 of the boom coupling of the distribution valve 3 are simultaneously connected to the damping control valve 7 in the hydraulic damping module. When the boom damping function is activated, the working device shakes up and down during operation. The hydraulic oil in the large chamber of the boom cylinder 4 can enter the accumulator 6 through the damping control valve 7. The hydraulic oil fluctuations caused by the up-and-down shaking can be absorbed by the accumulator 6, thus reducing the vibration of the working device and achieving the boom damping function.

[0004] In the existing technology, when the boom shock absorber function is used alone, there is leakage in the valve stem during the shock absorption process. After a period of time, the hydraulic oil in the accumulator decreases, the shock absorption effect decreases until it fails. At this time, the pump cannot automatically fill the accumulator with liquid to store energy.

[0005] The existing load holding valve 4 is incompatible with the hydraulic damping module. When the loader is in transport mode, the working device bounces up and down. When the boom damping function is automatically activated, the pressure oil of the accumulator 6 enters the load holding valve 5 through the damping control valve 7 and then enters the large chamber of the boom cylinder 4. However, the hydraulic oil in the large chamber of the boom cylinder 4 cannot enter the damping control valve 7 through the load holding valve 5. Therefore, the pressure fluctuations caused by the up and down of the working device cannot be filtered out, and the boom damping effect cannot be achieved. This results in the boom damping function and the load holding valve function being unable to coexist. Summary of the Invention

[0006] The technical problem to be solved by the present invention is the incompatibility between the load holding protection function and the hydraulic shock absorption module in the existing lifting hydraulic system. The present invention provides a lifting hydraulic system and a loader so that boom shock absorption and boom descent locking can be achieved simultaneously on the loader.

[0007] The technical solution of this invention to achieve its objective is as follows: A lifting hydraulic system is constructed, comprising a hydraulic oil tank, a hydraulic pump with its suction port connected to the hydraulic oil tank, a lifting cylinder control valve with its inlet port connected to the hydraulic pump port, a lifting cylinder, and a hydraulic damping module. The large and small chamber interfaces of the lifting cylinder control valve are connected to the hydraulic damping module; the small chamber interface of the lifting cylinder control valve is connected to the small chamber of the lifting cylinder. The system is characterized by further including a controller, a pressure sensor connected to the controller and used to detect the pressure at the large chamber interface of the lifting cylinder control valve, and a load holding valve.

[0008] The load holding valve has a P port communicating with the large cavity interface of the lifting cylinder control valve, a T port communicating with the hydraulic oil tank, and a load port communicating with the large cavity of the lifting cylinder. It also includes a cone valve, a load holding control solenoid valve whose control end is electrically connected to the controller, and a damping orifice. The inlet and outlet ends of the cone valve are respectively connected to the P port and the load port. The hydraulic control end of the cone valve is connected to the load port through the damping orifice and to the T port through the load holding control solenoid valve.

[0009] When the pressure at the large chamber interface of the lifting cylinder control valve is less than a predetermined value, the controller controls the load holding control solenoid valve to be in the off state; when the pressure at the large chamber interface of the lifting cylinder control valve is greater than a predetermined value, the controller controls the load holding control solenoid valve to be in the on state.

[0010] In the lifting hydraulic system of the present invention, the load holding valve further includes an overload valve, the inlet and outlet of which are respectively connected to the load port and the T port.

[0011] In the lifting hydraulic system of the present invention, the hydraulic damping module includes an accumulator and a damping control valve. The damping control valve has an X2 port connected to the accumulator, a T3 port connected to the hydraulic oil tank, a HEAD port connected to the large cavity interface of the lifting cylinder control valve, and a ROD port connected to the small cavity interface of the lifting cylinder control valve. It also includes a damping valve and a damping control solenoid valve whose electrical control terminal is electrically connected to the controller.

[0012] The shock-absorbing valve has a port b connected to port X2, a port c connected to port HEAD, a port e connected to port ROD, and a port d connected to port T3; when the shock-absorbing valve is in the normal position, ports b, c, d, and e are mutually cut off; when the shock-absorbing valve is in the shock-absorbing position, ports c and b are connected, and ports d and e are connected.

[0013] The shock-absorbing control solenoid valve is a two-position three-way valve, which has an f port connected to the hydraulic control end of the shock-absorbing valve, a g port connected to the T3 port, and an h port connected to the X2 port. When the f port is connected to either the g port or the h port and the f port is connected to the g port, the shock-absorbing valve is in the normal position. When the f port is connected to the h port, the shock-absorbing valve is in the shock-absorbing position.

[0014] In the lifting hydraulic system of the present invention, the system further includes a shock absorption enabling device; the shock absorption enabling device is connected to the controller and is used to send shock absorption on and shock absorption off signals to the controller; when the controller receives the shock absorption on signal, the controller controls the shock absorption control solenoid valve to make its f port and h port conduct; when the controller receives the shock absorption off signal, the controller controls the shock absorption control solenoid valve to make its f port and g port conduct.

[0015] In the lifting hydraulic system of the present invention, the shock-absorbing control valve further includes a P3 port connected to the pump port of the hydraulic pump and also includes a filling valve and a check valve. The shock-absorbing valve further includes an a port connected to the oil outlet of the check valve. The oil inlet of the check valve is connected to the oil outlet of the filling valve, and the oil inlet of the filling valve is connected to the P3 port. When the shock-absorbing valve is in the normal position, the a port and the b port are connected. When the shock-absorbing valve is in the shock-absorbing position, the a port is closed.

[0016] In the lifting hydraulic system of the present invention, the system also includes an accumulator pressure sensor connected to the controller for detecting the accumulator pressure. When the accumulator pressure is less than a preset pressure value, the controller controls the shock absorption control solenoid valve to make its f port and g port open.

[0017] In the lifting hydraulic system of the present invention, the system also includes a load feedback electromagnetic switch valve that is electrically connected to the controller at the control terminal. The hydraulic pump is a variable pump, and the two oil ports of the load feedback electromagnetic switch valve are respectively connected to the LS port and P3 port of the hydraulic pump.

[0018] In the lifting hydraulic system of the present invention, the shock absorption control valve further includes a filling overflow valve, a throttle valve, and a second damping orifice. The oil inlet of the check valve is connected to the oil outlet of the filling valve through the throttle valve. The oil inlet of the check valve is connected to both the oil inlet of the filling overflow valve and the spring cavity of the filling valve through the second damping orifice. The oil outlet of the filling overflow valve is connected to port T3. The hydraulic control cavity at the right end of the valve stem of the filling valve is connected to the oil inlet. When the filling valve is in the left position, the oil inlet and oil outlet are cut off. When it is in the middle position, the oil inlet and oil outlet are connected. When it is in the right position, the oil inlet and oil outlet are connected through the third damping orifice on the valve stem.

[0019] In the lifting hydraulic system of the present invention, the shock absorption control valve further includes a safety valve, the oil inlet of which is connected to port X2 and the oil outlet of which is connected to port T3.

[0020] The technical solution of the present invention to achieve its purpose is as follows: a loader is constructed, characterized in that it includes the aforementioned lifting hydraulic system, wherein the lifting cylinder is a boom cylinder.

[0021] Compared with the prior art, the present invention can simultaneously install a load holding valve and a hydraulic shock absorption module on a loader. After the shock absorption function is activated, the accumulator and the large chamber of the boom cylinder are bidirectionally connected, so that the loader can reduce the shock of the working device during the material transportation process. In addition, the boom cylinder is locked to prevent retraction when the boom cylinder connecting pipe bursts, so that the boom shock absorption function and the load holding function coexist. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the existing hydraulic lifting system for loader booms.

[0023] Figure 2 This is a schematic diagram of the hydraulic system for lifting and lowering the boom of the present invention.

[0024] Figure 3 This is a schematic diagram of the load holding valve in this invention.

[0025] Figure 4 This is a schematic diagram of the shock absorption control valve in this invention.

[0026] Component names and serial numbers in the diagram:

[0027] 1. Hydraulic oil tank; 2. Hydraulic pump; 3. Distribution valve; 4. Boom cylinder; 5. Load holding valve; 6. Accumulator; 7. Shock absorption control valve; 8. Controller; 9. Pressure sensor; 10. Load feedback solenoid switch valve; 11. Accumulator pressure sensor; 12. Shock absorption enabling operating device.

[0028] 51. Cone valve, 52. Damping orifice, 53. Load holding control solenoid valve, 54. Overload valve.

[0029] 71. Filling valve, 72. Check valve, 73. Shock damping valve, 74. Shock damping control solenoid valve, 75. Safety valve, 76. Filling overflow valve, 77. Throttling valve, 78. Second damping orifice. Detailed Implementation

[0030] The specific implementation plan is described below with reference to the attached diagram.

[0031] Figure 2 The hydraulic system for lifting a boom in an embodiment of the present invention is shown. The boom lifting hydraulic system mainly includes a hydraulic oil tank 1, a hydraulic pump 2, a distribution valve 3, a boom cylinder (i.e., a lifting cylinder) 4, a load holding valve 5, a controller 8, a pressure sensor 9, a load feedback solenoid switch valve 10, an accumulator pressure sensor 11, a shock absorption enabling device 12, etc.

[0032] The suction port of hydraulic pump 2 is connected to hydraulic oil tank 1, drawing hydraulic oil from it. The inlet of distribution valve 3 is connected to the pump port of hydraulic pump 2, obtaining high-pressure hydraulic oil from the hydraulic system via hydraulic pump 2. Hydraulic pump 2 is a variable displacement piston pump, and its displacement is controlled and regulated by the pressure at its load feedback port (LS port).

[0033] In this embodiment, the distribution valve 3 is an electrically controlled distribution valve. On the loader, the distribution valve 3 is used to control the boom cylinder 4 and the bucket cylinder (not shown in the figure). The distribution valve 3 has a boom linkage main valve and a bucket linkage main valve. The boom linkage main valve serves as the lifting cylinder control valve for controlling the lifting of the boom cylinder 4. The T port of the distribution valve 3 is connected to the hydraulic oil tank 1 to realize the return of hydraulic oil.

[0034] The large cavity interface, namely port A1, of the lifting cylinder control valve in the distribution valve 3 is connected to the large cavity of the boom cylinder 4 via the load holding valve 5. The small cavity interface, namely port B1, of the lifting cylinder control valve in the distribution valve 3 is connected to the small cavity of the boom cylinder 4.

[0035] like Figure 3 As shown, the load holding valve 5 has a P port, a T port, and a load port (A port), and includes a cone valve 51, a load holding control solenoid valve 53, a damping orifice 52, and an overload valve 54. The oil inlet of the cone valve 51 is connected to the P port, the oil outlet of the cone valve 51 is connected to the load port (A port), and the hydraulic control end of the cone valve 51 is connected to the load port via the damping orifice 52, and is also connected to the T port via the load holding control solenoid valve 53. The P port is connected to the large cavity interface (A1 port) of the lifting cylinder control valve in the distribution valve 3, the T port is connected to the hydraulic oil tank 1, and the load port (A) is connected to the large cavity of the boom cylinder 4.

[0036] The load holding control solenoid valve 53 is normally closed (i.e., when its solenoid coil is de-energized) with both ports shut off and not conducting. When the solenoid coil is energized, the two ports of the load holding control solenoid valve 53 are open. The solenoid coil of the load holding control solenoid valve 53 is connected to the controller 8, which controls its on / off state. The controller 8 can be the overall controller of the loader.

[0037] The inlet of the overload valve 54 is connected to the load port, and the outlet is connected to the T port. The overload valve 54 is used to limit the pressure in the large chamber of the boom cylinder. When the boom cylinder is overloaded, the overload valve 54 opens to overflow, guiding the oil in the large chamber of the boom cylinder to the hydraulic oil tank.

[0038] The hydraulic damping module includes an accumulator 6 and a damping control valve 7.

[0039] like Figure 4As shown, the shock absorption control valve 7 has oil ports such as P3 port, X2 port, T3 port, HEAD port, and ROD port, and includes a filling valve 71, a one-way valve 72, a shock absorption valve 73, a shock absorption control solenoid valve 74, a safety valve 75, and a filling overflow valve 76.

[0040] Port P3 is connected to the pump port of hydraulic pump 2 and is used to introduce high-pressure oil from the hydraulic pump. The accumulator 6 is then charged and stored through the charging valve 71.

[0041] The X2 port is connected to the accumulator 6, the T3 port is connected to the hydraulic oil tank 1, the HEAD port is connected to the large cavity interface of the lifting cylinder control valve in the distribution valve 3, and the ROD port is connected to the small cavity interface of the lifting cylinder control valve in the distribution valve 3.

[0042] The oil inlet of the filling valve 71 is connected to port P3, and the oil outlet is connected to port a of the shock absorber valve 73 via check valve 72.

[0043] The shock absorber valve 73 has a port b connected to the X2 port, a port c connected to the HEAD port, a port e connected to the ROD port, a port d connected to the T3 port, and a port a connected to the oil outlet of the check valve 72. When the shock absorber valve 73 is in the normal position, ports c, d, and e are mutually cut off, while ports a and b are connected. When the shock absorber valve 73 is in the damping position, ports c and b are connected, ports d and e are connected, and ports a are cut off from the other oil ports of the shock absorber valve 73.

[0044] The shock-absorbing control solenoid valve 74 is a two-position three-way valve, which has an f port connected to the hydraulic control end of the shock-absorbing valve 73, a g port connected to the T3 port, and an h port connected to the X2 port. The f port can be selectively connected to either the g port or the h port. That is, when the solenoid coil of the shock-absorbing control solenoid valve 74 is energized, the f port is connected to the h port, and when the solenoid coil is de-energized, the f port is connected to the g port. When the f port and the g port are connected, the shock-absorbing valve 73 is in the normal position, and when the f port and the h port are connected, the shock-absorbing valve is in the shock-absorbing position.

[0045] The inlet of the one-way valve 72 is connected to the outlet of the filling valve 71 via the throttle valve 77, and the inlet of the filling valve 71 is connected to port P3. Port P3 is connected to port LS of the hydraulic pump 2 via the load feedback solenoid valve 10, and the control terminal of the load feedback solenoid valve 10 is electrically connected to the controller 8. The load feedback solenoid valve 10 is a two-position two-way solenoid valve.

[0046] The accumulator pressure sensor 11 is used to detect the pressure of the accumulator and is connected to the controller.

[0047] The inlet of the one-way valve 72 is connected to the outlet of the filling valve 71 via the throttle valve 77. The inlet of the one-way valve 72 is also connected to both the inlet of the filling overflow valve 76 and the spring chamber of the filling valve 71 via the second damping orifice 78. The outlet of the filling overflow valve 76 is connected to port T3. The hydraulic control chamber at the right end of the valve stem of the filling valve 71 is connected to the inlet via the valve stem oil passage. When the filling valve 71 is in the left position, the inlet and outlet are cut off; in the middle position, the inlet and outlet are connected; and in the right position, the inlet is connected to the outlet via the third damping orifice 79 on the valve stem. The filling overflow valve 76 is used to limit the maximum filling pressure of the accumulator 6.

[0048] When the pressure at port P3 is zero, the valve stem of the filling valve 71 is in the left position under the action of the spring in the left end spring chamber, and no filling is performed.

[0049] When the pressure at port P3 rises to a level greater than that of accumulator 6 but less than the overflow set pressure of the filling overflow valve 76, the filling valve 71 moves to the neutral position, and the hydraulic pump 2 fills the accumulator 6 with liquid. At this time, under the action of the throttle valve 77 and the second damping orifice 78, the forces acting on the left and right ends of the valve stem of the filling valve 71 will remain in a dynamic equilibrium state until the filling is completed.

[0050] When the pressure of the accumulator 6 rises to a level greater than the set pressure of the filling overflow valve 76, the filling overflow valve 76 opens. The pressure in the spring chamber at the left end of the valve stem of the filling valve 71 drops instantaneously, causing the dynamic balance of forces at both ends of the valve stem of the filling valve 71 to be broken and move to the right position. At this time, a small amount of oil will flow through the third damping orifice 79, the throttle valve 77, and the second damping orifice 78 of the right-position oil circuit of the filling valve 71, and return to the oil tank from the filling overflow valve 76. Under the action of these three dampings, the force at the left end of the valve stem of the filling valve 71 is less than the force at the right end. Although the pressure at port P3 continues to rise, the filling valve 71 always remains in the right position, and the filling overflow valve 76 also remains in the overflow state.

[0051] When the pressure of accumulator 6 remains constant, and the pressure at port P3 continues to drop to a level lower than the set pressure of the filling overflow valve 76, the filling overflow valve 76 closes, and the force on the left end of the valve stem of filling valve 71 is greater than the force on the right end, causing it to move to the left position, thus completing the entire filling cycle.

[0052] The inlet of safety valve 75 is connected to port X2, and the outlet is connected to port T3. Port X2 is connected to accumulator 6. When the pressure in accumulator 6 is higher than the set pressure of safety valve 75, safety valve 75 opens to release pressure.

[0053] like Figure 2As shown, pressure sensor 9 is configured to detect the pressure at the large chamber port (A1 port) of the lifting cylinder control valve in distribution valve 3. Pressure sensor 9 is connected to the whole machine controller 7. When the pressure detected by pressure sensor 9 is less than a predetermined value, for example, when the connecting hose between the large chamber port of the lifting cylinder control valve in distribution valve 3 and the P port of load holding valve 5 bursts, controller 8 de-energizes load holding control solenoid valve 53, thereby putting cone valve 51 in the closed state.

[0054] The lifting hydraulic system includes a shock-damping enabling operating device 12, which can be a switch or a touch button on a machine instrument. Figure 2 As shown, the damping enable operating device 12 is connected to the controller 8 and is used to send damping open and damping close signals to the controller 8. When the controller 8 receives the damping open signal and the pressure at the large chamber interface of the lifting cylinder control valve is greater than a predetermined value, the controller 8 controls the load holding control solenoid valve 53 to be in the conducting state and controls the damping control solenoid valve 74 to make its f port and h port conduct. When the controller 8 receives the damping close signal, the controller controls the damping control solenoid valve 74 to make its f port and g port conduct.

[0055] In this implementation, when the connecting hose between the large chamber interface of the lifting cylinder control valve in the distribution valve 3 and the P port of the load holding valve 5 bursts, or other malfunctions cause the pressure at the large chamber interface of the lifting cylinder control valve to be less than the predetermined value, the controller 8 de-energizes the load holding control solenoid valve 53 and puts it in the closed state. The pressure at the hydraulic control end of the cone valve 51 is equal to the pressure at the load port and is in the closed state. The cone valve 51 is closed, and the load holding valve 5 functions to maintain the bucket height and prevent the bucket from falling or crashing to the ground.

[0056] In this embodiment of the loader, during normal operation, the pressure at the large chamber interface (A1 port) of the lifting cylinder control valve exceeds a predetermined value. The controller 8 energizes the load holding control solenoid valve 53 to reverse direction. The hydraulic control end of the cone valve 51 is connected to the T port via the load holding control solenoid valve 53, allowing the cone valve 51 to be opened by hydraulic oil pressure at either the inlet or outlet. When the lifting cylinder control valve is in the boom lifting function position, hydraulic oil from the hydraulic pump 2 enters the load holding valve through the large chamber interface of the lifting cylinder control valve in the distribution valve 3 and the P port of the load holding valve 5, opening the cone valve 51 and entering the large chamber 4 of the boom cylinder to achieve boom lifting. Alternatively, when the lifting cylinder control valve is in the boom lowering function position, the oil in the large chamber of the boom cylinder is pushed open by the piston, flowing into the distribution valve 3 through the large chamber interface of the lifting cylinder control valve, and then back to the hydraulic oil tank 1 through the return oil path of the distribution valve 3, achieving boom lowering.

[0057] When the machine is operating normally, when the boom damping function of the hydraulic damping module is activated by the damping enable operating device 12, the controller 8 energizes the damping control solenoid valve 74, and its f port and h port are connected. The pressure oil in the accumulator 6 acts on the hydraulic control end of the damping valve 73 through the damping control solenoid valve 74, causing the valve stem of the damping valve 73 to switch and work in the damping position. At this time, the large chamber of the boom cylinder is bidirectionally connected to the accumulator 6 through the cone valve 51, the c port and the b port of the damping valve 73, so that the vibration can be absorbed by the accumulator 6 and the boom damping function can be realized.

[0058] When the boom damping function of the hydraulic damping module is not activated, the high-pressure oil supplied by the hydraulic pump 2 is supplied to the accumulator 6 through the normal position oil circuit (conducting port a and port b) of the filling valve 71, throttle valve 77, check valve 72, and damping valve 73 to fill and store energy until the pressure of the accumulator 6 rises to the predetermined value, causing the filling valve 71 to close.

[0059] When the boom damping function of the hydraulic damping module is activated, the controller 8 detects the pressure of the accumulator 6 through the accumulator pressure sensor 11. When the pressure of the accumulator 6 is detected to be lower than the preset pressure value, the controller 8 de-energizes the damping control solenoid valve 74, and the f port and g port of the damping control solenoid valve 74 are connected. The damping valve 73 returns to the normal position, and the controller 8 controls the load feedback solenoid valve 10 to be turned on, transmitting the liquid filling load feedback signal to the LS port of the hydraulic pump 2. The hydraulic pump 2 outputs pressure oil through the damping valve 73 to fill the accumulator 6 with liquid and store energy, thus realizing the automatic liquid filling function.

[0060] This invention enables the simultaneous installation of a load holding valve and a hydraulic shock absorption module on a loader. After the shock absorption function is activated, the accumulator and the large chamber of the boom cylinder are bidirectionally connected, thereby reducing the vibration of the working device during loader operation. Furthermore, it locks the boom cylinder's retraction when the boom cylinder connecting pipe bursts, thus achieving the coexistence of boom shock absorption and load holding functions.

Claims

1. A lifting hydraulic system, comprising a hydraulic oil tank, a hydraulic pump with its suction port connected to the hydraulic oil tank, a lifting cylinder control valve with its inlet port connected to the pump port of the hydraulic pump, a lifting cylinder, and a hydraulic damping module; wherein the large cavity interface and the small cavity interface of the lifting cylinder control valve are connected to the hydraulic damping module; and the small cavity interface of the lifting cylinder control valve is connected to the small cavity of the lifting cylinder; characterized in that... It also includes a controller, a pressure sensor connected to the controller and used to detect the pressure at the large chamber interface of the lifting cylinder control valve, and a load holding valve; The load holding valve has a P port communicating with the large cavity interface of the lifting cylinder control valve, a T port communicating with the hydraulic oil tank, and a load port communicating with the large cavity of the lifting cylinder. It also includes a cone valve, a load holding control solenoid valve whose control end is electrically connected to the controller, and a damping orifice. The inlet and outlet ends of the cone valve are respectively connected to the P port and the load port. The hydraulic control end of the cone valve is connected to the load port through the damping orifice and to the T port through the load holding control solenoid valve. When the pressure at the large chamber interface of the lifting cylinder control valve is less than a predetermined value, the controller controls the load holding control solenoid valve to be in the off state; when the pressure at the large chamber interface of the lifting cylinder control valve is greater than a predetermined value, the controller controls the load holding control solenoid valve to be in the on state. The hydraulic damping module includes an accumulator and a damping control valve. The damping control valve has an X2 port connected to the accumulator, a T3 port connected to the hydraulic oil tank, a HEAD port connected to the large cavity interface of the lifting cylinder control valve, and a ROD port connected to the small cavity interface of the lifting cylinder control valve. It also includes a damping valve and a damping control solenoid valve electrically connected to the controller. The shock-absorbing valve has a port b connected to port X2, a port c connected to port HEAD, a port e connected to port ROD, and a port d connected to port T3; when the shock-absorbing valve is in the normal position, ports b, c, d, and e are mutually cut off; when the shock-absorbing valve is in the shock-absorbing position, ports c and b are connected, and ports d and e are connected. The shock-absorbing control solenoid valve is a two-position three-way valve, which has an f port connected to the hydraulic control end of the shock-absorbing valve, a g port connected to the T3 port, and an h port connected to the X2 port. When the f port is connected to either the g port or the h port and the f port is connected to the g port, the shock-absorbing valve is in the normal position. When the f port is connected to the h port, the shock-absorbing valve is in the shock-absorbing position.

2. The lifting hydraulic system according to claim 1, characterized in that... The load holding valve also includes an overload valve, the inlet and outlet of which are connected to the load port and the T port, respectively.

3. The lifting hydraulic system according to claim 1, characterized in that... The system also includes a vibration damping enable operating device; The vibration damping enabling device is connected to the controller and is used to send vibration damping on and vibration damping off signals to the controller. When the controller receives the vibration damping on signal, the controller controls the vibration damping control solenoid valve to make its f port and h port conduct. When the controller receives the vibration damping off signal, the controller controls the vibration damping control solenoid valve to make its f port and g port conduct.

4. The lifting hydraulic system according to claim 3, characterized in that... The shock-absorbing control valve also has a P3 port connected to the hydraulic pump port and includes a filling valve and a check valve. The shock-absorbing valve also has an a port connected to the oil outlet of the check valve. The oil inlet of the check valve is connected to the oil outlet of the filling valve, and the oil inlet of the filling valve is connected to the P3 port. When the shock-absorbing valve is in the normal position, the a port and the b port are connected. When the shock-absorbing valve is in the shock-absorbing position, the a port is closed.

5. The lifting hydraulic system according to claim 4, characterized in that... The system also includes an accumulator pressure sensor connected to the controller for detecting accumulator pressure. When the accumulator pressure is less than a preset pressure value, the controller controls the shock absorption control solenoid valve to connect its f port and g port.

6. The lifting hydraulic system according to claim 5, characterized in that... The system also includes a load feedback solenoid valve that is electrically connected to the controller. The hydraulic pump is a variable pump. The two ports of the load feedback solenoid valve are connected to the LS port and P3 port of the hydraulic pump, respectively.

7. The lifting hydraulic system according to claim 4, characterized in that... The shock absorption control valve also includes a filling overflow valve, a throttle valve, and a second damping orifice. The oil inlet of the one-way valve is connected to the oil outlet of the filling valve through the throttle valve. The oil inlet of the one-way valve is connected to both the oil inlet of the filling overflow valve and the spring cavity at the left end of the valve stem of the filling valve through the second damping orifice. The oil outlet of the filling overflow valve is connected to port T3. The hydraulic control cavity at the right end of the valve stem of the filling valve is connected to the oil inlet. When the filling valve is in the left position, the oil inlet and oil outlet are cut off. When it is in the middle position, the oil inlet and oil outlet are connected. When it is in the right position, the oil inlet is connected to the oil outlet through the third damping orifice on the valve stem.

8. The lifting hydraulic system according to claim 4, characterized in that... The shock absorption control valve also includes a safety valve, the oil inlet of which is connected to port X2, and the oil outlet of which is connected to port T3.

9. A loader, characterized in that... It includes the lifting hydraulic system according to any one of claims 1 to 8, wherein the lifting cylinder is a boom cylinder.

Images