Tractor saddle lifting control hydraulic system

Abstract

The invention discloses a tractor saddle lifting control hydraulic system which comprises an oil tank, a power pump, a lifting oil cylinder and a three-position four-way reversing valve, a rod cavity and a rodless cavity are formed in the lifting oil cylinder, the three-position four-way reversing valve is provided with an oil supply port P, an oil return port T, a working port A and a working port B, the working port A is connected with the rodless cavity through a first oil way, and the working port B is connected with the rodless cavity through a second oil way. The first oil way is connected with a first balance valve, the working port B is connected with the rod cavity through a second oil way, the second oil way is connected with a one-way overflow valve and a hydraulic control valve, the set pressure value of the one-way overflow valve is larger than the pilot oil pressure of the first balance valve, and a third oil way is arranged between the hydraulic control valve and the oil tank. The third oil way is provided with a two-position two-way electromagnetic reversing valve, the two-position two-way electromagnetic reversing valve is provided with a first station and a second station, the three-position four-way reversing valve is provided with a third station, a fourth station, a fifth station and a fifth station, the two-position two-way electromagnetic reversing valve is synchronously located at the second station, a valve port of the two-position two-way electromagnetic reversing valve is opened for unloading, and the pressure of hydraulic oil entering the rod cavity is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of tractors, and in particular to a saddle lifting control hydraulic system for tractors. Background Art

[0002] The saddle lifting tractors on the market are generally designed with a hydraulic system to realize the lifting and lowering functions of the saddle. Its main functions are as follows: 1) Realization of the switching function. According to the control method of lifting and lowering the saddle, it can be divided into two types: pneumatic control and electro-hydraulic control. The pneumatic control is to first change the direction of the pneumatic handle valve, and then drive the pneumatic hydraulic reversing valve to switch the flow direction of the hydraulic oil in the main oil circuit to realize the lifting and lowering of the saddle. The electro-hydraulic control is to switch the flow direction of the hydraulic oil in the main oil circuit by the electro-hydraulic reversing valve to realize the lifting and lowering of the saddle; 2) Realization of the pressure maintaining function. There are two common hydraulic system pressure maintaining functions: one is to design a single-chamber pressure maintaining oil circuit with a balancing valve at the oil inlet of the rodless chamber of the lifting cylinder, and the other is to design a double-chamber pressure maintaining oil circuit with a balancing valve at both the oil inlet of the rodless chamber and the oil inlet of the rod chamber of the lifting cylinder. The pressure-maintaining oil circuit of the single balancing valve is only designed with a balancing valve at the oil inlet of the rodless chamber of the lifting cylinder, which can only ensure that the rodless chamber of the lifting cylinder will not release pressure during operation (ensuring that the saddle of the tractor will not passively drop when working with load), but cannot maintain pressure for the rod chamber of the lifting cylinder. During normal driving of the tractor, the saddle load changes due to bumpy roads, resulting in the passive extension of the piston rod of the lifting cylinder, which not only causes abnormal lifting of the saddle, but also may damage the hydraulic components and shorten the service life of the system; the pressure-maintaining oil circuit of the double balancing valve is designed at both the oil inlet of the rodless chamber and the oil inlet of the rod chamber of the lifting cylinder. Although the balancing valve can solve the problem of abnormal lifting of the saddle in the pressure-maintaining oil circuit of the single balancing valve mentioned above, it will cause new problems: when the system is in operation, the rod chamber of the lifting cylinder will always maintain a certain oil pressure. When the driver wants to uncouple the tractor and the trailer, he needs to control the saddle system to descend. When the trailer's legs land first, the saddle has not yet fallen into place. If the saddle continues to be controlled to descend at this time, the lifting cylinder will react to lift the rear axle of the tractor, which will not only cause the tractor to fail to work normally, but also may damage related parts of the vehicle. Therefore, it is necessary to improve it. Summary of the invention

[0003] The purpose of the present invention is to provide a tractor saddle lifting control hydraulic system in view of the defects and shortcomings of the prior art, which has a simple and reasonable structure and is easy to operate. It can not only control the tractor saddle to achieve the lowering function, but also solve the problem of the prior art that the lifting cylinder will react to lift the rear axle of the tractor.

[0004] To achieve the above object, the present invention adopts the following technical solutions: A saddle lifting control hydraulic system for a tractor according to the present invention comprises an oil tank, a power pump and a lifting oil cylinder. The oil suction port of the power pump is connected to the oil outlet of the oil tank. A piston rod assembly is movably arranged in the lifting oil cylinder. The piston rod assembly divides the inner cavity of the lifting oil cylinder into a rod cavity and a rodless cavity. The system also comprises a three-position four-way reversing valve. The three-position four-way reversing valve is respectively provided with an oil supply P port, an oil return T port, a working A port and a working B port. The oil outlet of the power pump is connected to the oil supply P port, the oil return T port is connected to the oil return port of the oil tank, the working A port is connected to the rodless cavity through a first oil circuit, a first balancing valve is connected to the first oil circuit, the working B port is connected to the rod cavity through a second oil circuit, a one-way relief valve and a hydraulic control valve are connected to the second oil circuit, the hydraulic control valve is used to maintain the pressure of the rod cavity, the one-way relief valve is connected to the hydraulic control valve, the working B port is also connected to the first balancing valve through a first pilot oil circuit, the working A port It is also connected to the hydraulic control valve through a second pilot oil circuit, the set pressure value of the one-way relief valve is greater than the pilot oil pressure of the first balancing valve, a third oil circuit is also provided between the hydraulic control valve and the oil return port of the oil tank, a two-position two-way electromagnetic reversing valve is connected to the third oil circuit, the two-position two-way electromagnetic reversing valve has a first position and a second position, and its oil circuit valve port is closed when it is in the first position, the three-position four-way reversing valve has a third position, a fourth position and a fifth position, when it is in the third position, the oil supply P port is connected to the working A port, and the working B port is connected to the oil return T port, when it is in the fourth position, the working A port, the working B port, the oil supply P port and the oil return T port are all connected, and the system has no oil pressure, when it is in the fifth position, the two-position two-way electromagnetic reversing valve is synchronously located in the second position, the oil supply P port is connected to the working B port, the working A port is connected to the oil return T port, and the oil circuit valve port of the two-position two-way electromagnetic reversing valve is opened to unload, thereby reducing the hydraulic oil pressure entering the rod chamber.

[0005] Furthermore, the hydraulic control valve is a hydraulically controlled one-way valve, and the hydraulically controlled one-way valve is respectively provided with an oil port B1, an oil port B2 and a pilot oil port B3. The oil port B1 is connected to the one-way relief valve, and the pilot oil port B3 is connected to the working port A through the second pilot oil circuit. Under normal circumstances, the oil port B1 is not connected to the oil port B2. When the oil pressure of the oil port B1 or the pilot oil port B3 reaches the set pressure value of the hydraulically controlled one-way valve, the oil port B1 is connected to the oil port B2.

[0006] Further, the hydraulic control valve is a second balancing valve, and the second balancing valve is respectively provided with an oil port D1, an oil port D2 and a pilot oil port D3. The oil port D1 is connected to the one-way relief valve, and the pilot oil port D3 is connected to the working port A through the second pilot oil circuit. Under normal circumstances, the oil port D1 is not connected to the oil port D2. When the oil pressure of the oil port D1 or the pilot oil port D3 reaches the set pressure value of the hydraulically controlled one-way valve, the oil port D1 is connected to the oil port D2.

[0007] Furthermore, the three-position four-way reversing valve is a three-position four-way electromagnetic reversing valve.

[0008] Furthermore, the three-position four-way reversing valve is a three-position four-way electro-hydraulic reversing valve.

[0009] Furthermore, it also includes an air filter, which is connected to the oil tank.

[0010] Furthermore, it also includes an oil suction filter, which is arranged between the oil outlet of the oil tank and the oil inlet of the power pump.

[0011] Furthermore, it also includes a stop valve, which is arranged between the oil outlet of the oil tank and the oil inlet of the power pump.

[0012] Furthermore, it also includes an oil return filter, which is arranged to connect the two-position two-way electromagnetic reversing valve and the oil return port of the oil tank.

[0013] Furthermore, it also includes a throttle valve, which is arranged to connect the two-position two-way electromagnetic reversing valve and the oil return port of the oil tank.

[0014] The beneficial effects of the present invention are as follows: in the tractor saddle lifting control hydraulic system described in the present invention, when the hydraulic control valve is a hydraulically controlled one-way valve and the three-position four-way reversing valve is a three-position four-way solenoid reversing valve, the working principle of the hydraulic system to realize the saddle lowering function is as follows: the power pump suction port sucks low-pressure hydraulic oil from the oil tank through the stop valve and the oil suction filter, and then converts it into high-pressure oil and pumps it into the three-position four-way solenoid reversing valve. At this time, the driver operates the three-position four-way solenoid reversing valve to shift to the fifth position, and the two-position two-way solenoid reversing valve is synchronously shifted to the second position (the three-position four-way solenoid reversing valve and the two-position two-way solenoid reversing valve are both operated by the driver to shift to the fifth position, and the two-position two-way solenoid reversing valve is synchronously shifted to the second position). The reversing valve is energized at the same time). At this time, the hydraulic oil is divided into two paths after passing through the three-position four-way solenoid reversing valve. One path of hydraulic oil is connected with the pilot oil port A3 of the first balancing valve through the first pilot oil path, and the other path of hydraulic oil is connected to the oil port C1 of the one-way relief valve through the second oil path. When the oil pressure value rises to the set pressure of the one-way relief valve, the channel of the one-way relief valve opens, and the hydraulic oil enters the hydraulic control one-way valve oil port B1 from its oil port C1 through the oil port C2. At this time, the hydraulic oil can freely pass from the hydraulic control one-way valve oil port B1 through its oil port B2. After that, the hydraulic oil is divided into two paths, one of which leads to the rod chamber of the lifting cylinder. , and the other returns to the oil tank through the third oil circuit. At this time, the valve port of the two-position two-way solenoid reversing valve is opened, and the hydraulic oil returns to the oil tank after being filtered by the return oil filter. It should be noted that most of the hydraulic oil returns to the oil tank through the third oil circuit, and a small amount of hydraulic oil enters the rod chamber. The hydraulic oil pressure entering the rod chamber is very small but can push the piston rod assembly to retract it. In addition, since the set pressure value of the one-way relief valve is greater than the pilot oil pressure of the first balancing valve, that is, only when the oil pressure out of the working B port reaches the set pressure value of the one-way relief valve, the hydraulic oil can pass through the second oil circuit and the third oil circuit. At this time, the hydraulic oil pressure leading to the first pilot oil circuit can ensure that the main oil circuit of the first balancing valve is opened, which ultimately controls the saddle of the tractor to realize the lowering function, and solves the problem in the prior art that the lifting cylinder will react to lift the rear axle of the tractor. If a one-way relief valve is not set, most of the hydraulic oil coming out of the working B port will directly return to the oil tank through the third oil circuit. At this time, the hydraulic oil pressure coming out of the working B port is very low, and the hydraulic oil pressure leading to the first pilot oil circuit may not be sufficient to open the main oil circuit of the first balancing valve, and the hydraulic oil in the rodless cavity cannot return to the oil tank normally, affecting its use.

[0015] In other embodiments, the above-mentioned three-position four-way electromagnetic reversing valve can also be replaced by a three-position four-way electro-hydraulic reversing valve, and the above-mentioned hydraulically controlled one-way valve can also be replaced by a second balancing valve, which can achieve the same function. The second user can flexibly choose to make replacements according to their actual needs and usage scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the hydraulic system principle of the present invention; Figure 2It is a schematic diagram of the working principle of the tractor when controlling the saddle to lift; Figure 3 It is a schematic diagram of the working principle of the tractor when controlling the saddle to descend; Figure 4 It is a schematic diagram of the working principle of the tractor during driving; Figure 5 It is a schematic diagram of the principle of a hydraulic system in which the hydraulically controlled one-way valve of the present invention is replaced by a second balancing valve; Figure 6 It is a schematic diagram of the principle of a hydraulic system in which a three-position four-way electromagnetic directional control valve of the present invention is replaced by a three-position four-way electro-hydraulic directional control valve.

[0017] Figure 1-Figure 6 In: 1. Oil tank; 2. Power pump; 3. First balancing valve; 4. Lifting cylinder; 41. Rod chamber; 42. Rodless chamber; 5. Two-position two-way solenoid directional valve; 6. Hydraulic-controlled one-way valve; 7. One-way relief valve; 8. Second balancing valve; 9. Three-position four-way solenoid directional valve; 10. Three-position four-way electro-hydraulic directional valve; 11. Oil suction filter; 12. Stop valve; 13. Oil return filter; 14. Pressure measuring joint; 15. Explosion-proof valve; 16. Relief valve; 17. Air filter; 18. Throttle valve; 19. First oil circuit; 20. Second oil circuit; 21. Third oil circuit; 22. First pilot oil circuit; 23. Second pilot oil circuit; 24. Oil supply P port; 25. Oil return T port; 26. Working A port; 27. Working B port. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with the accompanying drawings.

[0019] like Figure 1-Figure 6The hydraulic system for controlling the lifting of a saddle on a tractor shown in the figure comprises an oil tank 1, a power pump 2 and a lifting cylinder 4. The oil suction port of the power pump 2 is connected to the oil outlet of the oil tank 1. Specifically, the oil tank 1 stores, provides and recovers hydraulic oil for the hydraulic system. The function of the power pump 2 is to absorb low-pressure hydraulic oil from the oil tank 1 and convert it into high-pressure hydraulic oil to provide to the system. It is the power source of the entire hydraulic system. The lifting cylinder 4 is the actuator of the system, and its cylinder barrel is fixed on the frame. Preferably, in this embodiment, two lifting cylinders 4 are provided, and a piston rod assembly is movably provided in the lifting cylinder 4. The piston rod assembly divides the inner cavity of the lifting cylinder 4 into a rod cavity 41 and a rodless cavity 42. The piston rod assembly comprises a piston and a piston rod. The piston and the piston rod The rod is fixedly connected, and the piston rod of the lifting cylinder 4 is connected to the saddle of the whole vehicle. Its function is to realize the relative movement of the piston rod and the cylinder according to the hydraulic oil pressure, flow and direction parameters provided by the system, so as to achieve the control of the lifting or lowering function of the saddle. It also includes a three-position four-way reversing valve, and the three-position four-way reversing valve is respectively provided with an oil supply P port 24, an oil return T port 25, a working A port 26 and a working B port 27. The oil outlet of the power pump 2 is connected to the oil supply P port 24, the oil return T port 25 is connected to the oil return port of the oil tank 1, the working A port 26 is connected to the rodless chamber 42 through the first oil circuit 19, the first oil circuit 19 is connected to the first balancing valve 3, the working B port 27 is connected to the rod chamber 41 through the second oil circuit 20, and the second The oil circuit 20 is connected with a one-way overflow valve 7 and a hydraulic control valve, the hydraulic control valve is used to maintain the pressure of the rod chamber 41, the one-way overflow valve 7 is connected to the hydraulic control valve, the working B port 27 is also connected to the first balance valve 3 through the first pilot oil circuit 22, the working A port 26 is also connected to the hydraulic control valve through the second pilot oil circuit 23, the set pressure value of the one-way overflow valve 7 is greater than the pilot oil pressure of the first balance valve 3, and a third oil circuit 21 is also provided between the hydraulic control valve and the oil return port of the oil tank 1, and the third oil circuit 21 is connected with a two-position two-way electromagnetic reversing valve 5, the two-position two-way electromagnetic reversing valve 5 has a first position and a second position, and its oil circuit valve port is closed when it is in the first position, and the three-position four-way electromagnetic reversing valve 9 The function is to switch the flow direction of the hydraulic oil inside the system, so as to control the hydraulic system to achieve the purpose of the predetermined function. The three-position four-way reversing valve has a third position, a fourth position and a fifth position. When it is located at the third position, the oil supply P port 24 is connected with the working A port 26, and the working B port 27 is connected with the oil return T port 25. When it is located at the fourth position, the working A port 26, the working B port 27, the oil supply P port 24 and the oil return T port 25 are all connected, and the system has no oil pressure. When it is located at the fifth position, the two-position two-way solenoid reversing valve 5 is synchronously located at the second position, the oil supply P port 24 is connected with the working B port 27, the working A port 26 is connected with the oil return T port 25, and the oil circuit valve port of the two-position two-way solenoid reversing valve 5 is opened to unload, thereby reducing the hydraulic oil pressure entering the rod chamber 41.

[0020] The function of the one-way relief valve 7 is to adjust system parameters such as pressure, flow, direction, etc. The cooperation between the first balancing valve 3, the hydraulic control valve, the two-position two-way electromagnetic reversing valve 5 and the one-way relief valve 7 realizes the main functions of the hydraulic system.

[0021] Preferably, a relief valve 16 is arranged between the power pump 2 and the three-position four-way reversing valve. The function of the relief valve 16 is to limit the pressure value of the hydraulic oil entering the system. When the oil pressure is lower than the set value, the relief valve 16 does not work. When the oil pressure value is higher than the set value, the internal valve core of the relief valve 16 opens, and part of the hydraulic oil is passed into the oil tank 1 to ensure that the pressure value does not exceed the set value, thereby protecting the system.

[0022] Preferably, in the present embodiment, an explosion-proof valve 15 is also provided at the oil outlet of the rodless chamber 42 of the lifting cylinder 4. When the system is working under load and the pipeline is suddenly damaged causing a huge change in flow, the oil outlet of the rodless chamber 42 of the lifting cylinder 4 is immediately closed to stop the lifting cylinder 4 from sliding down and avoid the risk of the saddle load falling.

[0023] Preferably, in this embodiment, the hydraulic control valve is a hydraulically controlled one-way valve 6, and the hydraulically controlled one-way valve 6 is respectively provided with an oil port B1, an oil port B2 and a pilot oil port B3, the oil port B1 is connected to the one-way relief valve 7, and the pilot oil port B3 is connected to the working A port 26 through the second pilot oil circuit 23. Under normal circumstances, the oil port B1 is not connected to the oil port B2. When the oil pressure of the oil port B1 or the pilot oil port B3 reaches the set pressure value of the hydraulically controlled one-way valve 6, the oil port B1 is connected to the oil port B2.

[0024] Preferably, in this embodiment, the hydraulic control valve is a second balancing valve 8, and the second balancing valve 8 is respectively provided with an oil port D1, an oil port D2 and a pilot oil port D3, the oil port D1 is connected to the one-way relief valve 7, and the pilot oil port D3 is connected to the working A port 26 through the second pilot oil circuit 23. Under normal circumstances, the oil port D1 is not connected to the oil port D2. When the oil pressure of the oil port D1 or the pilot oil port D3 reaches the set pressure value of the hydraulically controlled one-way valve 6, the oil port D1 is connected to the oil port D2.

[0025] Preferably, in this embodiment, the three-position four-way reversing valve is a three-position four-way solenoid reversing valve 9. This solenoid reversing valve controls the movement of the valve core by turning on and off the electromagnets on both sides, thereby realizing the reversal of the fluid. When the electromagnet is powered off, the valve core returns to the initial position under the action of the spring force or other reset mechanism, changing the flow direction of the fluid again.

[0026] Preferably, in other embodiments, the three-position four-way reversing valve may also be a three-position four-way electro-hydraulic reversing valve 10. Specifically, the three-position four-way electro-hydraulic reversing valve 10 includes a small valve and a main valve, the hydraulic oil enters the small valve after passing through the power pump 2, the main valve has the third position, the fourth position and the fifth position, the small valve has the sixth position, the seventh position and the eighth position, the small valve controls the switching of the main valve oil circuit, when the small valve is located at the sixth position, the hydraulic oil enters the main valve through the small valve, and controls the oil circuit of the main valve to switch to the third position; when the small valve is located at the seventh position, the hydraulic oil cannot enter the main valve, and the main valve switches the oil circuit to the fourth position under the action of the main valve spring; when the small valve is located at the eighth position, the hydraulic oil enters the main valve through the small valve, and controls the oil circuit of the main valve to switch to the fifth position.

[0027] Preferably, in this embodiment, an air filter 17 is further included, and the air filter 17 is connected to the fuel tank 1. The air filter 17 is used to connect the interior of the fuel tank 1 with the external atmosphere and filter air impurities to ensure that the air entering the fuel tank 1 is clean, thereby avoiding dust and other particulate matter that may cause damage to the system. Such a design not only improves the stability and reliability of the system, but also extends the service life of the equipment and ensures the efficient operation of the entire system.

[0028] Preferably, in this embodiment, an oil suction filter 11 is further included, and the oil suction filter 11 is arranged between the oil outlet of the oil tank 1 and the oil inlet of the power pump 2. The function of the oil suction filter 11 is to filter the hydraulic oil impurities in the oil tank 1 to ensure that the hydraulic oil entering the system is clean.

[0029] Preferably, in this embodiment, a shut-off valve 12 is further included, and the shut-off valve 12 is arranged between the oil outlet of the oil tank 1 and the oil inlet of the power pump 2. The shut-off valve 12 can selectively cut off the oil circuit between the oil tank 1 and the power pump 2 or maintain the connectivity between the inside of the oil tank 1 and the entire hydraulic system. Such a design greatly improves the convenience of inspection and maintenance of the system. When maintenance or inspection is required, the operator can easily cut off the oil circuit through the shut-off valve 12, thereby ensuring that related work can be carried out safely and conveniently.

[0030] Preferably, in this embodiment, a return oil filter 13 is also included. The return oil filter 13 is arranged at the connection between the two-position two-way electromagnetic reversing valve 5 and the return oil port of the oil tank 1. Its main function is to filter impurities in the hydraulic oil in the system to ensure that the hydraulic oil returned to the inside of the oil tank 1 is clean.

[0031] Preferably, in this embodiment, a throttle valve 18 is further included. The throttle valve 18 is arranged to connect the two-position two-way electromagnetic reversing valve 5 with the oil return port of the oil tank 1, and can adjust the flow rate of the hydraulic oil.

[0032] Preferably, in this embodiment, the oil outlet of the power pump 2, the oil inlet and the oil outlet of the lifting cylinder 4 are all provided with pressure measuring joints 14, which are oil pressure measuring joints reserved by the system, allowing operators to use corresponding pressure measuring tools to detect the oil pressure value at a specific position. Such a design greatly facilitates the early detection and debugging of the system, and also provides great convenience for later maintenance inspections. Of course, in other embodiments, other numbers of pressure measuring joints 14 can also be provided as needed to meet the detection requirements in different situations.

[0033] Preferably, the first balancing valve 3 is respectively provided with an oil port A1, an oil port A2 and a pilot oil port A3, and the pilot oil port A3 is connected to the working B port 27 through the first pilot oil circuit 22. Under normal circumstances, the oil port A1 is not connected with the oil port A2. When the oil pressure of the oil port A1 or the pilot oil port A3 reaches the set pressure value of the first balancing valve 3, the oil port A1 is connected with the oil port A2.

[0034] The one-way relief valve 7 is a special relief valve 16, which allows the hydraulic oil to flow freely in one direction, but needs to overcome a certain pressure difference to open in the other direction. Specifically, the one-way relief valve 7 is respectively provided with oil port C1 and oil port C2. The one-way relief valve 7 allows the hydraulic oil to flow smoothly from the oil port C2 to the oil port C1, but when the hydraulic oil flows in the opposite direction, that is, from the oil port C1 to the oil port C2, the one-way relief valve 7 will remain closed until the oil pressure value of the oil port C1 increases to the preset pressure threshold of the one-way relief valve 7, and the channel of the one-way relief valve 7 will be opened. At this time, the hydraulic oil is allowed to flow from the oil port C1 to the oil port C2.

[0035] In the first embodiment, the hydraulic control valve is a hydraulically controlled one-way valve 6, and the three-position four-way reversing valve is a three-position four-way electromagnetic reversing valve 9. At this time, the working principle of the hydraulic system to realize the saddle lifting function, the working principle of the hydraulic system to realize the saddle lowering function, and the working principle of the hydraulic system to realize the pressure maintaining function are as follows: See also Figure 2The working principle of the hydraulic system to realize the saddle lifting function is as follows: the power pump 2 suction port sucks low-pressure hydraulic oil from the oil tank 1 through the stop valve 12 and the oil suction filter 11, and then converts it into high-pressure oil and pumps it into the three-position four-way solenoid reversing valve 9. At this time, the driver operates the three-position four-way solenoid reversing valve 9 to shift to the third position. At this time, the hydraulic oil is divided into two paths after passing through the three-position four-way solenoid reversing valve 9. One path of hydraulic oil is connected with the pilot oil port B3 of the hydraulic control one-way valve 6 through the second pilot oil circuit 23, so that the oil circuit valve port of the hydraulic control one-way valve 6 is opened, and the other path of hydraulic oil enters from the oil port A2 of the first balancing valve 3 through the first oil circuit 19, and comes out from the oil port A1 through the one-way valve on the left side of the first balancing valve 3, and then enters the rodless chamber 42 of the lifting cylinder 4 through the explosion-proof valve 15 to promote the lifting. The piston rod of the oil cylinder 4 extends out, and at the same time, the hydraulic oil in the rod chamber 41 of the lifting oil cylinder 4 will be discharged into two ways, through the second oil circuit 20 and the third oil circuit 21 respectively. However, at this time, the two-position two-way solenoid reversing valve 5 on the third oil circuit 21 is located in the first position and its oil circuit valve port is closed, and the hydraulic oil returns to the oil tank 1 only through the second oil circuit 20. Since the oil circuit valve port of the hydraulically controlled one-way valve 6 is open, the hydraulic oil can smoothly pass through the oil port B1 from the oil port B2 of the hydraulically controlled one-way valve 6, and then the hydraulic oil enters the oil port C2 of the one-way relief valve 7 and comes out from the oil port C1 of the one-way relief valve 7 (the hydraulic oil can freely pass through the oil port C1 from the oil port C2, but not vice versa), passes through the channel of the three-position four-way solenoid reversing valve 9, and then returns to the oil tank 1 after being filtered by the return oil filter 13, controlling the saddle of the tractor to realize the lifting function.

[0036] See also Figure 3The working principle of the hydraulic system to realize the saddle lowering function is as follows: the power pump 2 suction port sucks low-pressure hydraulic oil from the oil tank 1 through the stop valve 12 and the oil suction filter 11, and then converts it into high-pressure oil and pumps it into the three-position four-way solenoid reversing valve 9. At this time, the driver operates the three-position four-way solenoid reversing valve 9 to shift to the fifth position, and the two-position two-way solenoid reversing valve 5 is synchronously shifted to the second position (the three-position four-way solenoid reversing valve 9 and the two-position two-way solenoid reversing valve 5 are energized at the same time). At this time, the hydraulic oil passes through the three-position four-way solenoid After the reversing valve 9, the hydraulic oil is divided into two paths. One path of the hydraulic oil is connected to the pilot oil port A3 of the first balancing valve 3 through the first pilot oil path 22, and the other path of the hydraulic oil is connected to the oil port C1 of the one-way relief valve 7 through the second oil path 20. When the oil pressure value rises to the set pressure of the one-way relief valve 7, the channel of the one-way relief valve 7 opens, and the hydraulic oil enters the oil port B1 of the hydraulic control one-way valve 6 from its oil port C1 through the oil port C2. At this time, the hydraulic oil can freely pass from the oil port B1 of the hydraulic control one-way valve 6 through its oil port B2. The hydraulic oil is divided into two paths, one path leads to the rod chamber 41 of the lifting cylinder 4, and the other path returns to the oil tank 1 through the third oil path 21. At this time, the valve port of the two-position two-way electromagnetic reversing valve 5 is opened, and the hydraulic oil returns to the oil tank 1 after being filtered by the return oil filter 13. It should be noted that most of the hydraulic oil returns to the oil tank 1 through the third oil path 21, and a small amount of hydraulic oil enters the rod chamber 41. The hydraulic oil pressure entering the rod chamber 41 is very small but can push the piston rod assembly to retract it. In addition, since the set pressure value of the one-way relief valve 7 is greater than the pilot oil pressure of the first balancing valve 3, that is, only when the oil pressure out of the working B port 27 reaches the set pressure value of the one-way relief valve 7, the hydraulic oil can pass through the second oil path 20 and the third oil path 21. At this time, the hydraulic oil pressure leading to the first pilot oil path 22 can ensure that the main oil path of the first balancing valve 3 is opened, which ultimately controls the saddle of the tractor to realize the lowering function, and at the same time solves the problem that the lifting cylinder 4 in the prior art will react to lift the rear axle of the tractor. If the one-way relief valve 7 is not set, most of the hydraulic oil coming out of the working B port 27 will directly return to the oil tank 1 through the third oil circuit 21. At this time, the hydraulic oil pressure coming out of the working B port 27 is very low, and the hydraulic oil pressure leading to the first pilot oil circuit 22 may not be sufficient to open the main oil circuit of the first balancing valve 3. The hydraulic oil in the rodless chamber 42 cannot return to the oil tank 1 normally, affecting its use.

[0037] See also Figure 4The working principle of the hydraulic system to realize the pressure maintaining function is as follows: when the tractor is running normally, the power pump 2 is not working, the three-position four-way electromagnetic reversing valve 9 is in the fourth position, the working A port 26, the working B port 27, the oil supply P port 24 and the oil return T port 25 are all connected, the system has no oil pressure, the first balancing valve 3 is in the normal position state, the oil port A2 and the pilot oil port A3 have no oil pressure, the first balancing valve 3 is closed, the hydraulic oil cannot flow from the oil port A2 to the oil port A1, so the rodless chamber 42 of the lifting cylinder 4 is in a closed state; the hydraulic control one-way valve 6 is in the normal position state, the oil port B1 and the pilot oil port B3 have no oil pressure, the hydraulic control one-way valve 6 is closed, the hydraulic oil cannot flow from the oil port B2 to the oil port B1, and the two-position two-way electromagnetic reversing valve 5 is in the normal position closed state (i.e., the first position), so the rod chamber 41 of the lifting cylinder 4 is also in a closed state, thereby realizing the double-chamber pressure maintaining function of the lifting cylinder 4, ensuring the stability of the saddle height position, and achieving the purpose of protecting vehicle components.

[0038] In other embodiments, the above-mentioned three-position four-way electromagnetic reversing valve 9 can also be replaced by a three-position four-way electro-hydraulic reversing valve 10, and the above-mentioned hydraulically controlled one-way valve 6 can also be replaced by a second balancing valve 8, which can achieve the same function. The second user can flexibly choose to make replacements according to their actual needs and usage scenarios.

[0039] See for example Figure 5 In the second embodiment, the hydraulic control valve is a second balancing valve 8, and the three-position four-way reversing valve is a three-position four-way electromagnetic reversing valve 9. At this time, the working principle of the hydraulic system to realize the saddle lifting function, the working principle of the hydraulic system to realize the saddle lowering function, and the working principle of the hydraulic system to realize the pressure maintaining function are as follows: The working principle of the hydraulic system to realize the saddle lifting function is as follows: the power pump 2 suction port sucks low-pressure hydraulic oil from the oil tank 1 through the stop valve 12 and the oil suction filter 11, and then converts it into high-pressure oil and pumps it into the three-position four-way solenoid reversing valve 9. At this time, the driver operates the three-position four-way solenoid reversing valve 9 to shift to the third position. At this time, the hydraulic oil is divided into two paths after passing through the three-position four-way solenoid reversing valve 9. One path of hydraulic oil is connected with the pilot oil port D3 of the second balancing valve 8 through the second pilot oil circuit 23, so that the oil circuit valve port of the second balancing valve 8 is opened, and the other path of hydraulic oil enters from the oil port A2 of the first balancing valve 3 through the first oil circuit 19, and comes out from the oil port A1 through the one-way valve on the left side of the first balancing valve 3, and then enters the rodless chamber 42 of the lifting cylinder 4 through the explosion-proof valve 15 to promote the lifting. The piston rod of the oil cylinder 4 extends out, and at the same time, the hydraulic oil in the rod chamber 41 of the lifting oil cylinder 4 will be discharged into two ways, through the second oil circuit 20 and the third oil circuit 21 respectively. However, at this time, the two-position two-way electromagnetic reversing valve 5 on the third oil circuit 21 is located in the first position and its oil circuit valve port is closed. The hydraulic oil returns to the oil tank 1 only through the second oil circuit 20. Since the oil circuit valve port of the second balancing valve 8 is open, the hydraulic oil can smoothly pass through the oil port D1 from the oil port D2 of the second balancing valve 8, and then the hydraulic oil enters the oil port C2 of the one-way relief valve 7 and comes out from the oil port C1 of the one-way relief valve 7 (the hydraulic oil can freely pass through the oil port C1 from the oil port C2, but not vice versa), passes through the channel of the three-position four-way electromagnetic reversing valve 9, and then returns to the oil tank 1 after being filtered by the return oil filter 13, so as to control the saddle of the tractor to realize the lifting function.

[0040] The working principle of the hydraulic system to realize the saddle lowering function is as follows: the power pump 2 suction port sucks low-pressure hydraulic oil from the oil tank 1 through the stop valve 12 and the oil suction filter 11, and then converts it into high-pressure oil and pumps it into the three-position four-way solenoid reversing valve 9. At this time, the driver operates the three-position four-way solenoid reversing valve 9 to shift to the fifth position, and the two-position two-way solenoid reversing valve 5 is synchronously shifted to the second position (the three-position four-way solenoid reversing valve 9 and the two-position two-way solenoid reversing valve 5 are energized at the same time). At this time, the hydraulic oil passes through the three-position four-way solenoid After the reversing valve 9, the hydraulic oil is divided into two paths. One path of the hydraulic oil is connected to the pilot oil port A3 of the first balancing valve 3 through the first pilot oil path 22, and the other path of the hydraulic oil is connected to the oil port C1 of the one-way relief valve 7 through the second oil path 20. When the oil pressure value rises to the set pressure of the one-way relief valve 7, the channel of the one-way relief valve 7 opens, and the hydraulic oil enters the oil port D1 of the second balancing valve 8 from its oil port C1 through the oil port C2. At this time, the hydraulic oil can freely pass from the oil port D1 of the second balancing valve 8 through its oil port D2. The hydraulic oil is divided into two paths, one path leads to the rod chamber 41 of the lifting cylinder 4, and the other path returns to the oil tank 1 through the third oil path 21. At this time, the valve port of the two-position two-way electromagnetic reversing valve 5 is opened, and the hydraulic oil returns to the oil tank 1 after being filtered by the return oil filter 13. It should be noted that most of the hydraulic oil returns to the oil tank 1 through the third oil path 21, and a small amount of hydraulic oil enters the rod chamber 41. The hydraulic oil pressure entering the rod chamber 41 is very small but can push the piston rod assembly to retract it. In addition, since the set pressure value of the one-way relief valve 7 is greater than the pilot oil pressure of the first balancing valve 3, that is, only when the oil pressure out of the working D port 27 reaches the set pressure value of the one-way relief valve 7, the hydraulic oil can pass through the second oil path 20 and the third oil path 21. At this time, the hydraulic oil pressure leading to the first pilot oil path 22 can ensure that the main oil path of the first balancing valve 3 is opened, which ultimately controls the saddle of the tractor to realize the lowering function, and at the same time solves the problem that the lifting cylinder 4 in the prior art will react to lift the rear axle of the tractor.

[0041] The working principle of the hydraulic system to achieve the pressure maintaining function is as follows: when the tractor is running normally, the power pump 2 is not working, the three-position four-way electromagnetic reversing valve 9 is in the fourth position, the working A port 26, the working B port 27, the oil supply P port 24 and the oil return T port 25 are all connected, the system has no oil pressure, the first balancing valve 3 is in the normal position, the oil port A2 and the pilot oil port A3 have no oil pressure, the first balancing valve 3 is closed, the hydraulic oil cannot flow from the oil port A2 to the oil port A1, so the rodless chamber 42 of the lifting cylinder 4 is in a closed state; the second balancing valve 8 is in the normal position, the oil port D1 and the pilot oil port D3 have no oil pressure, the second balancing valve 8 is closed, the hydraulic oil cannot flow from the oil port D2 to the oil port D1, and the two-position two-way electromagnetic reversing valve 5 is in the normal position closed state (i.e., the first position), so the rod chamber 41 of the lifting cylinder 4 is also in a closed state, thereby realizing the double-chamber pressure maintaining function of the lifting cylinder 4, ensuring the stability of the saddle height position, and achieving the purpose of protecting vehicle components.

[0042] See for example Figure 6 In the third embodiment, the hydraulic control valve is a hydraulically controlled one-way valve 6, and the three-position four-way reversing valve is a three-position four-way electro-hydraulic reversing valve 10. At this time, the working principle of the hydraulic system to realize the saddle lifting function, the working principle of the hydraulic system to realize the saddle lowering function, and the working principle of the hydraulic system to realize the pressure maintaining function are as follows: The working principle of the hydraulic system to realize the saddle lifting function is as follows: the power pump 2 suction port sucks low-pressure hydraulic oil from the oil tank 1 through the stop valve 12 and the oil suction filter 11, and then converts it into high-pressure oil and pumps it into the small valve of the three-position four-way electro-hydraulic reversing valve 10. At this time, when the driver operates the small valve to shift to the sixth position, the hydraulic oil enters the main valve through the small valve, and controls the oil circuit of the main valve to switch to the third position. At this time, the hydraulic oil is divided into two paths after passing through the three-position four-way electro-hydraulic reversing valve 10. One path of hydraulic oil is connected with the pilot oil port B3 of the hydraulic control check valve 6 through the second pilot oil circuit 23, so that the oil circuit valve port of the hydraulic control check valve 6 is opened, and the other path of hydraulic oil enters from the oil port A2 of the first balancing valve 3 through the first oil circuit 19, and comes out from the oil port A1 through the one-way valve on the left side of the first balancing valve 3, and then enters the lifting cylinder through the explosion-proof valve 15. 4, pushes the piston rod of the lifting cylinder 4 to extend, and at the same time, the hydraulic oil in the rod chamber 41 of the lifting cylinder 4 will be discharged into two ways, through the second oil circuit 20 and the third oil circuit 21 respectively. However, at this time, the two-position two-way electromagnetic reversing valve 5 on the third oil circuit 21 is located in the first position and its oil circuit valve port is closed, and the hydraulic oil returns to the oil tank 1 only through the second oil circuit 20. Since the oil circuit valve port of the hydraulically controlled one-way valve 6 is opened, the hydraulic oil can smoothly pass through the oil port B1 from the oil port B2 of the hydraulically controlled one-way valve 6, and then the hydraulic oil enters the oil port C2 of the one-way relief valve 7, and comes out from the oil port C1 of the one-way relief valve 7 (the hydraulic oil can freely pass through the oil port C1 from the oil port C2, but not vice versa), passes through the channel of the three-position four-way electro-hydraulic reversing valve 10, and then returns to the oil tank 1 after being filtered by the return oil filter 13, so as to control the saddle of the tractor to realize the lifting function.

[0043] The working principle of the hydraulic system to realize the saddle lowering function is as follows: the power pump 2 suction port sucks low-pressure hydraulic oil from the oil tank 1 through the stop valve 12 and the oil suction filter 11, and then converts it into high-pressure oil and pumps it into the small valve of the three-position four-way electro-hydraulic reversing valve 10. At this time, when the driver operates the small valve to the eighth position, the hydraulic oil enters the main valve through the small valve, controls the oil circuit of the main valve to switch to the fifth position, and the two-position two-way solenoid reversing valve 5 is synchronously switched to the second position (the three-position four-way electro-hydraulic reversing valve 10 and the two-position two-way solenoid reversing valve 5 are simultaneously ), at this time, the hydraulic oil is divided into two paths after passing through the three-position four-way electro-hydraulic reversing valve 10. One path of hydraulic oil is connected to the pilot oil port A3 of the first balancing valve 3 through the first pilot oil path 22, and the other path of hydraulic oil is connected to the oil port C1 of the one-way relief valve 7 through the second oil path 20. When the oil pressure value rises to the set pressure of the one-way relief valve 7, the channel of the one-way relief valve 7 opens, and the hydraulic oil enters the oil port B1 of the hydraulic control one-way valve 6 from its oil port C1 through the oil port C2. At this time, the hydraulic oil can freely flow from the oil port B1 of the hydraulic control one-way valve 6 1 through its oil port B2, and then the hydraulic oil is divided into two paths, one leading to the rod chamber 41 of the lifting cylinder 4, and the other returning to the oil tank 1 through the third oil path 21. At this time, the valve port of the two-position two-way electromagnetic reversing valve 5 is opened, and the hydraulic oil returns to the oil tank 1 after being filtered by the return oil filter 13. It should be noted that most of the hydraulic oil returns to the oil tank 1 through the third oil path 21, and a small amount of hydraulic oil enters the rod chamber 41. The hydraulic oil pressure entering the rod chamber 41 is very small but can push the piston rod assembly to retract it. In addition, by When the set pressure value of the one-way relief valve 7 is greater than the pilot oil pressure of the first balancing valve 3, that is, only when the oil pressure out of the working B port 27 reaches the set pressure value of the one-way relief valve 7, the hydraulic oil can pass through the second oil circuit 20 and the third oil circuit 21. At this time, the hydraulic oil pressure leading to the first pilot oil circuit 22 can ensure that the main oil circuit of the first balancing valve 3 is opened, and finally the saddle of the tractor is controlled to realize the descending function, and at the same time, the problem that the lifting cylinder 4 in the prior art will react to lift the rear axle of the tractor is solved.

[0044] The working principle of the hydraulic system to achieve the pressure maintaining function is as follows: when the tractor is driving normally, the power pump 2 is not working, the small valve of the three-position four-way electro-hydraulic reversing valve 10 is in the seventh position, the hydraulic oil cannot enter the main valve, and the main valve is switched to the fourth position under the action of the main valve spring. The working A port 26, the working B port 27, the oil supply P port 24 and the oil return T port 25 are all connected, the system has no oil pressure, the first balancing valve 3 is in the normal position, the oil port A2 and the pilot oil port A3 have no oil pressure, the first balancing valve 3 is closed, and the hydraulic oil cannot enter the oil port A2 flows to the oil port A1, so the rodless chamber 42 of the lifting cylinder 4 is in a closed state; the hydraulically controlled one-way valve 6 is in a normal position state, there is no oil pressure between the oil port B1 and the pilot oil port B3, the hydraulically controlled one-way valve 6 is closed, and the hydraulic oil cannot flow from the oil port B2 to the oil port B1. At the same time, the two-position two-way electromagnetic reversing valve 5 is in a normal position closed state (i.e., the first working position), so the rod chamber 41 of the lifting cylinder 4 is also in a closed state, thereby realizing the double-chamber pressure maintenance function of the lifting cylinder 4, ensuring the stability of the saddle height position, and achieving the purpose of protecting vehicle components.

[0045] The above description is only a preferred embodiment of the present invention, so all equivalent changes or modifications made according to the structure, characteristics and principles described in the scope of the patent application of the present invention are included in the scope of the patent application of the present invention.

Claims

1. A tractor saddle lifting control hydraulic system, comprising an oil tank (1), a power pump (2) and a lifting cylinder (4), wherein the oil suction port of the power pump (2) is connected to the oil outlet of the oil tank (1), and a piston rod assembly is movably provided in the lifting cylinder (4), and the piston rod assembly divides the inner cavity of the lifting cylinder (4) into a rod cavity (41) and a rodless cavity (42), characterized in that: The invention also comprises a three-position four-way reversing valve, wherein the three-position four-way reversing valve is respectively provided with an oil supply P port (24), an oil return T port (25), a working A port (26) and a working B port (27); the oil outlet of the power pump (2) is connected to the oil supply P port (24), the oil return T port (25) is connected to the oil return port of the oil tank (1), the working A port (26) is connected to the rodless chamber (42) via a first oil circuit (19), the first oil circuit (19) is connected to a first balancing valve (3), and the working B port (27) is connected to the rodless chamber (42) via a second oil circuit (19). (20) is connected to the rod chamber (41), the second oil circuit (20) is connected to a one-way relief valve (7) and a hydraulic control valve, the hydraulic control valve is used to maintain the pressure of the rod chamber (41), the one-way relief valve (7) is connected to the hydraulic control valve, the working B port (27) is also connected to the first balancing valve (3) through the first pilot oil circuit (22), the working A port (26) is also connected to the hydraulic control valve through the second pilot oil circuit (23), the set pressure value of the one-way relief valve (7) is greater than the first The pilot oil pressure of the balancing valve (3) is provided between the hydraulic control valve and the oil return port of the oil tank (1). A second oil circuit (21) is connected to the second oil circuit (21). The second oil circuit (21) has a first position and a second position. When the second oil circuit (5) is in the first position, its oil circuit valve port is closed. The third oil circuit (21) has a third position, a fourth position and a fifth position. When the second oil circuit (21) is in the third position, the oil supply port (24) is connected to the working port (26), and the working port (27) is open. The two-position two-way solenoid reversing valve (5) is connected to the oil return T port (25). When the two-position two-way solenoid reversing valve (5) is located in the fourth position, the working A port (26), the working B port (27), the oil supply P port (24) and the oil return T port (25) are all connected, and the system has no oil pressure. When the two-position two-way solenoid reversing valve (5) is located in the fifth position, the oil supply P port (24) is connected to the working B port (27), the working A port (26) is connected to the oil return T port (25), and the oil circuit valve port of the two-position two-way solenoid reversing valve (5) is opened to unload, thereby reducing the pressure of the hydraulic oil entering the rod chamber (41).

2. A tractor saddle lifting control hydraulic system according to claim 1, characterized in that: The hydraulic control valve is a hydraulically controlled non-return valve (6). The hydraulically controlled non-return valve (6) is provided with an oil port B1, an oil port B2 and a pilot oil port B3 respectively. The oil port B1 is connected to the non-return relief valve (7). The pilot oil port B3 is connected to the working port A (26) via the second pilot oil circuit (23). Under normal conditions, the oil port B1 is not connected to the oil port B2. When the oil pressure of the oil port B1 or the pilot oil port B3 reaches the set pressure value of the hydraulically controlled non-return valve (6), the oil port B1 is connected to the oil port B2.

3. A tractor saddle lifting control hydraulic system according to claim 1, characterized in that: The hydraulic control valve is a second balancing valve (8). The second balancing valve (8) is respectively provided with an oil port D1, an oil port D2 and a pilot oil port D3. The oil port D1 is connected to the one-way relief valve (7). The pilot oil port D3 is connected to the working port A (26) via the second pilot oil circuit (23). Under normal conditions, the oil port D1 is not connected to the oil port D2. When the oil pressure of the oil port D1 or the pilot oil port D3 reaches the set pressure value of the hydraulically controlled one-way valve (6), the oil port D1 is connected to the oil port D2.

4. A tractor saddle lifting control hydraulic system according to claim 1, characterized in that: The three-position four-way directional control valve is a three-position four-way electromagnetic directional control valve (9).

5. The tractor saddle lifting control hydraulic system according to claim 1, characterized in that: The three-position four-way directional control valve is a three-position four-way electro-hydraulic directional control valve (10).

6. A tractor saddle lifting control hydraulic system according to claim 1, characterized in that: It also includes an air filter (17), wherein the air filter (17) is connected to the oil tank (1).

7. A tractor saddle lifting control hydraulic system according to claim 1, characterized in that: It also includes an oil suction filter (11), which is arranged between the oil outlet of the oil tank (1) and the oil inlet of the power pump (2).

8. The tractor saddle lifting control hydraulic system according to claim 1, characterized in that: It also comprises a stop valve (12), wherein the stop valve (12) is arranged between the oil outlet of the oil tank (1) and the oil inlet of the power pump (2).

9. A tractor saddle lifting control hydraulic system according to claim 1, characterized in that: It also includes an oil return filter (13), wherein the oil return filter (13) is arranged to connect the two-position two-way electromagnetic reversing valve (5) with the oil return port of the oil tank (1).

10. A tractor saddle lifting control hydraulic system according to claim 1, characterized in that: It also includes a throttle valve (18), which is arranged to connect the two-position two-way electromagnetic reversing valve (5) with the oil return port of the oil tank (1).

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