Double cylinder synchronous control hydraulic system and fire truck

Abstract

The invention discloses a dual-cylinder synchronous control hydraulic system and a fire truck, which relates to the field of hydraulic control, and includes: a main reversing valve assembly, a first oil port is connected to the oil outlet of the main pump assembly, a second oil port is connected to the control oil ports of the first and third balancing valves, the hydraulic oil ports of the second and fourth balancing valves, and the third oil port is connected to the hydraulic oil port of the third balancing valve and the control oil port of the fourth balancing valve; the first balancing valve is connected to the rodless cavity of the first oil cylinder; the second balancing valve is connected to the rod cavity of the first oil cylinder, the hydraulic oil port is connected to the control oil port of the first balancing valve, the control oil port of the second balancing valve, the hydraulic oil port of the first balancing valve and the rodless cavity of the second oil cylinder are connected; the third balancing valve is connected to the rodless cavity of the second oil cylinder; the fourth balancing valve is connected to the rod cavity of the second oil cylinder, the hydraulic oil port is connected to the control oil port of the third balancing valve, and the control oil port is connected to the hydraulic oil port of the third balancing valve. The invention can ensure the synchronization of the dual-cylinder movement and simplify the pipeline.

Description

Technical Field

[0001] The invention belongs to the technical field of hydraulic control, and in particular relates to a double-cylinder synchronous control hydraulic system and a fire truck. Background Art

[0002] As fire trucks develop towards larger sizes, the load force borne by the cylinders is gradually increasing. Limited by the structure of the entire vehicle and the size of the cylinders, a dual hydraulic cylinder structure is currently usually used to meet the load requirements. Due to the special structural layout of the fire truck, it is easy to cause the two cylinders to be subjected to unbalanced forces, and the influence of the eccentric load will inevitably cause deviations when the cylinders move and the balance valves are opened, resulting in cylinder jitter or creeping. At present, the following three methods are usually used to solve the above defects: the first method is to use three balance valves for control, and each of the two cylinder rodless chambers is provided with a balance valve to control the movement of the cylinders. A total balance valve is set in the total return oil circuit to control the cylinder speed to ensure synchronization; the second method is to use an electric proportional control balance valve or servo control to ensure cylinder synchronization by adjusting the control strategy; the third method is to set a one-way throttle valve in the total return oil circuit.

[0003] However, when the first two methods are adopted, the corresponding hydraulic control system is relatively complex, the hydraulic control cost is high, and it is difficult to control the speed of the oil cylinder and the flow matching control. When the third method is adopted, it is difficult to match the throttle valve, and the throttle valve is used to achieve dual-cylinder synchronous control, which cannot fully guarantee that the oil cylinder can run at the designed speed, and will also cause a large amount of hydraulic energy loss. Summary of the invention

[0004] In order to solve some or all of the technical problems existing in the above-mentioned prior art, the present invention provides a dual-cylinder synchronous control hydraulic system and a fire truck.

[0005] The technical solution of the present invention is as follows:

[0006] In a first aspect, a dual-cylinder synchronous control hydraulic system is provided, comprising:

[0007] A main pump assembly connected to the oil tank for providing hydraulic oil;

[0008] A main reversing valve assembly, having at least three oil ports and an oil return port, wherein the first oil port of the main reversing valve assembly is communicated with the oil outlet of the main pump assembly, the second oil port of the main reversing valve assembly is communicated with the control oil port of the first balancing valve, the hydraulic oil port of the second balancing valve, the control oil port of the third balancing valve and the hydraulic oil port of the fourth balancing valve respectively, the third oil port of the main reversing valve assembly is communicated with the hydraulic oil port of the third balancing valve and the control oil port of the fourth balancing valve respectively, the oil return port of the main reversing valve assembly is communicated with the oil tank, and the oil return port of the main reversing valve assembly can be communicated with the second oil port or the third oil port, and the main reversing valve assembly is used to control the flow direction of the hydraulic oil;

[0009] The first balancing valve is arranged in the hydraulic oil circuit of the rodless chamber of the first oil cylinder, the hydraulic oil circuit of the first balancing valve is communicated with the rodless chamber of the first oil cylinder, and the oil return port of the first balancing valve is communicated with the oil tank;

[0010] The second balancing valve is arranged on the hydraulic oil circuit of the rod chamber of the first oil cylinder, the hydraulic oil circuit of the second balancing valve is communicated with the rod chamber of the first oil cylinder, the hydraulic oil port of the second balancing valve is communicated with the control oil port of the first balancing valve, the control oil port of the second balancing valve is communicated with the hydraulic oil port of the first balancing valve, and the control oil port of the second balancing valve and the hydraulic oil port of the first balancing valve are also communicated with the rodless chamber of the second oil cylinder;

[0011] The third balancing valve is arranged on the hydraulic oil circuit of the rodless chamber of the second oil cylinder, the hydraulic oil circuit of the third balancing valve is connected with the rodless chamber of the second oil cylinder, the oil return port of the third balancing valve is connected with the oil tank, the first balancing valve and the third balancing valve are both pilot balancing valves, and the minimum opening pressure of the third balancing valve is greater than the maximum opening pressure of the first balancing valve;

[0012] The fourth balancing valve is arranged on the hydraulic oil circuit of the rod chamber of the second cylinder. The hydraulic oil circuit of the fourth balancing valve is connected with the rod chamber of the second cylinder. The hydraulic oil port of the fourth balancing valve is connected with the control oil port of the third balancing valve. The control oil port of the fourth balancing valve is connected with the hydraulic oil port of the third balancing valve.

[0013] In some optional implementations, an explosion-proof valve is provided on the hydraulic oil circuit between the hydraulic oil port of the first balancing valve and the rodless chamber of the second oil cylinder;

[0014] The explosion-proof valve is a hydraulically controlled two-position two-way valve, the control oil port of the explosion-proof valve is connected to the hydraulic oil circuit of the rodless chamber close to the second oil cylinder, when the explosion-proof valve is in a normal position, the two channel ports of the explosion-proof valve are connected through a throttle valve, and when the explosion-proof valve is in another state position, the two channel ports of the explosion-proof valve are cut off.

[0015] In some optional implementations, the first balancing valve includes:

[0016] a first hydraulically controlled two-position two-way valve, wherein a first channel port of the first hydraulically controlled two-position two-way valve is communicated with a hydraulic oil port of the first balancing valve, a second channel port of the first hydraulically controlled two-position two-way valve is communicated with a rodless chamber of the first oil cylinder, a control oil port of the first hydraulically controlled two-position two-way valve is communicated with a control oil port and an oil return port of the first balancing valve respectively through a damping hole, when the first hydraulically controlled two-position two-way valve is in a normal position, the first channel port of the first hydraulically controlled two-position two-way valve is communicated with a second channel port through a one-way valve, and when the first hydraulically controlled two-position two-way valve is in another state position, the second channel port of the first hydraulically controlled two-position two-way valve is communicated with the first channel port through a throttle valve;

[0017] A first overflow valve, wherein the oil inlet of the first overflow valve is communicated with the rodless chamber of the first oil cylinder, and the oil outlet of the first overflow valve is communicated with the control oil port of the first hydraulically controlled two-position two-way valve.

[0018] In some optional implementations, the second balancing valve includes:

[0019] a second relief valve, wherein a control oil port of the second relief valve is communicated with a control oil port of the second balancing valve through a damping hole, an oil inlet of the second relief valve is communicated with a rod chamber of the first oil cylinder, and an oil outlet of the second relief valve is communicated with a hydraulic oil port of the second balancing valve;

[0020] A first one-way valve, wherein the oil inlet of the first one-way valve is communicated with the hydraulic oil port of the second balancing valve, and the oil outlet of the first one-way valve is communicated with the rod chamber of the first oil cylinder.

[0021] In some optional implementations, the third balancing valve includes:

[0022] a second hydraulically controlled two-position two-way valve, wherein the first channel port of the second hydraulically controlled two-position two-way valve is communicated with the hydraulic oil port of the third balancing valve, the second channel port of the second hydraulically controlled two-position two-way valve is communicated with the rodless chamber of the second oil cylinder, the control oil port of the second hydraulically controlled two-position two-way valve is communicated with the control oil port and the oil return port of the third balancing valve respectively through a damping hole, when the second hydraulically controlled two-position two-way valve is in a normal position, the first channel port of the second hydraulically controlled two-position two-way valve is communicated with the second channel port through a one-way valve, and when the second hydraulically controlled two-position two-way valve is in another state position, the second channel port of the second hydraulically controlled two-position two-way valve is communicated with the first channel port through a throttle valve;

[0023] A third relief valve, wherein the oil inlet of the third relief valve is communicated with the rodless chamber of the second oil cylinder, and the oil outlet of the third relief valve is communicated with the control oil port of the second hydraulically controlled two-position two-way valve.

[0024] In some optional implementations, the fourth balancing valve includes:

[0025] a fourth relief valve, wherein the control oil port of the fourth relief valve is communicated with the control oil port of the fourth balancing valve through a damping hole, the oil inlet of the fourth relief valve is communicated with the rod chamber of the second oil cylinder, and the oil outlet of the fourth relief valve is communicated with the hydraulic oil port of the fourth balancing valve;

[0026] A second one-way valve, wherein the oil inlet of the second one-way valve is communicated with the hydraulic oil port of the fourth balancing valve, and the oil outlet of the second one-way valve is communicated with the rod chamber of the second oil cylinder.

[0027] In some optional implementations, the main pump assembly includes:

[0028] A hydraulic pump, wherein an oil inlet of the hydraulic pump is connected to the oil tank, and an oil outlet of the hydraulic pump is connected to an oil outlet of the main pump assembly;

[0029] A plunger cylinder, wherein the rod chamber of the plunger cylinder is communicated with the oil outlet of the hydraulic pump, and the rodless chamber of the plunger cylinder is communicated with the first channel port of the hydraulically controlled two-position three-way valve located at the lower side;

[0030] The hydraulically controlled two-position three-way valve, the control oil port of the hydraulically controlled two-position three-way valve is connected to the oil outlet of the hydraulic pump, the second channel port of the hydraulically controlled two-position three-way valve located on the upper side is connected to the oil outlet of the hydraulic pump, and the third channel port of the hydraulically controlled two-position three-way valve located on the upper side is connected to the oil tank.

[0031] In some optional implementations, the main reversing valve assembly includes:

[0032] A flow valve, the oil inlet of which is connected to the first oil port of the main reversing valve assembly;

[0033] A three-position eight-way reversing valve has three channel ports located on the upper side and five channel ports located on the lower side, the first channel port and the third channel port located on the upper side are respectively connected to the return oil port of the main reversing valve assembly, the second channel port located on the upper side is connected to the oil outlet port of the flow valve, the fourth channel port located on the lower side is connected to the control oil port and the set load port of the flow valve, the fifth channel port located on the lower side is connected to the oil inlet of the fifth overflow valve, the sixth channel port located on the lower side is connected to the second oil port of the main reversing valve assembly, the seventh channel port located on the lower side is connected to the third oil port of the main reversing valve assembly, the eighth channel port located on the lower side is connected to the The oil inlet is connected, when the three-position eight-way reversing valve is in the middle position, the first channel port, the fourth channel port, the fifth channel port, the sixth channel port and the eighth channel port are connected, the second channel port is cut off, and the third channel port and the seventh channel port are connected; when the three-position eight-way reversing valve is in the left position, the first channel port and the sixth channel port are connected, the second channel port, the fourth channel port, the seventh channel port and the eighth channel port are connected, the third channel port is cut off, and the fifth channel port is cut off; when the three-position eight-way reversing valve is in the right position, the first channel port is cut off, the second channel port, the fourth channel port, the fifth channel port and the sixth channel port are connected, the third channel port and the seventh channel port are connected, and the eighth channel port is cut off;

[0034] The oil outlet of the fifth relief valve is connected to the oil return port of the main reversing valve assembly;

[0035] The sixth relief valve, the oil outlet of which is connected to the oil return port of the main reversing valve assembly;

[0036] A first pilot valve is connected to the control oil port on the left side of the three-position eight-way reversing valve, and is used to control the three-position eight-way reversing valve to move to the right;

[0037] The second pilot valve is connected to the control oil port on the right side of the three-position eight-way reversing valve, and is used to control the three-position eight-way reversing valve to move to the left side.

[0038] In some optional implementations, the first pilot valve and the second pilot valve are both electrically controlled two-position three-way valves;

[0039] The first channel port of the first pilot valve located on the upper side is communicated with an oil outlet port of a pressure reducing valve, the oil inlet port of the pressure reducing valve is communicated with a first oil port of the main reversing valve assembly, the second channel port of the first pilot valve located on the upper side is communicated with an oil return port and an oil drain port of the main reversing valve assembly respectively, the oil drain port of the main reversing valve assembly is communicated with the oil tank, the third channel port of the first pilot valve located on the lower side is communicated with a control oil port on the left side of the three-position eight-way reversing valve, when the first pilot valve is in the left position, the first channel port of the first pilot valve is communicated with the third channel port, and the second channel port is cut off, when the first pilot valve is in the right position, the first channel port of the first pilot valve is cut off, and the second channel port is communicated with the third channel port;

[0040] The first channel port of the second pilot valve located on the upper side is respectively connected to the oil return port and the oil drain port of the main reversing valve assembly, the second channel port of the second pilot valve located on the upper side is connected to the oil outlet port of the pressure reducing valve, and the third channel port of the second pilot valve located on the lower side is connected to the control oil port on the right side of the three-position eight-way reversing valve. When the second pilot valve is in the left position, the first channel port of the second pilot valve is connected to the third channel port, and the second channel port is cut off. When the second pilot valve is in the right position, the first channel port of the second pilot valve is cut off, and the second channel port is connected to the third channel port.

[0041] In a second aspect, a fire truck is also provided, comprising the above-mentioned dual-cylinder synchronous control hydraulic system.

[0042] The main advantages of the technical solution of the present invention are as follows:

[0043] The dual-cylinder synchronous control hydraulic system and fire truck of the present invention are provided with two pilot balancing valves with different opening pressures. When performing dual-cylinder synchronous control, one pilot balancing valve is opened first, and the other pilot balancing valve is used as the main balancing valve to control the running speed of the dual cylinders, thereby ensuring the synchronization, stability and safety of the dual-cylinder movement and simplifying the control pipeline layout; and an explosion-proof valve is provided between the two pilot balancing valves, so that when the balancing valve pipeline bursts, the explosion-proof valve can be used to lock the oil cylinder, thereby further ensuring the safety and reliability of the long-term operation of the oil cylinder. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] The drawings described herein are used to provide a further understanding of the embodiments of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0045] Figure 1 A hydraulic principle diagram of a dual-cylinder synchronous control hydraulic system provided by an embodiment of the present invention;

[0046] Figure 2for Figure 1 Hydraulic principle diagram of explosion-proof valve in;

[0047] Figure 3 for Figure 1 The hydraulic principle diagram of the first balancing valve in FIG.

[0048] Figure 4 for Figure 1 The hydraulic principle diagram of the second balancing valve in FIG.

[0049] Figure 5 for Figure 1 The hydraulic principle diagram of the third balancing valve in FIG.

[0050] Figure 6 for Figure 1 The hydraulic principle diagram of the fourth balancing valve in FIG.

[0051] Figure 7 for Figure 1 The hydraulic schematic diagram of the main pump assembly in;

[0052] Figure 8 for Figure 1 Hydraulic schematic diagram of the main reversing valve assembly in.

[0053] Description of reference numerals:

[0054] 1-main pump assembly, 101-hydraulic pump, 102-plunger cylinder, 103-hydraulic controlled two-position three-way valve;

[0055] 2-main reversing valve assembly, 201-flow valve, 202-three-position eight-way reversing valve, 203-fifth relief valve, 204-sixth relief valve, 205-first pilot valve, 206-second pilot valve, 207-pressure reducing valve, 208-seventh relief valve, 209-safety valve;

[0056] 3-first balancing valve, 301-first hydraulically controlled two-position two-way valve, 302-first overflow valve;

[0057] 4-second balancing valve, 401-second overflow valve, 402-first one-way valve;

[0058] 5-third balancing valve, 501-second hydraulically controlled two-position two-way valve, 502-third overflow valve;

[0059] 6-fourth balancing valve, 601-fourth overflow valve, 602-second one-way valve;

[0060] 7-Fuel tank;

[0061] 8-First oil cylinder;

[0062] 9- Second oil cylinder;

[0063] 10- Explosion-proof valve. DETAILED DESCRIPTION

[0064] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention and the corresponding drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0065] The technical solution provided by the embodiments of the present invention is described in detail below with reference to the accompanying drawings.

[0066] refer to Figure 1 An embodiment of the present invention provides a dual-cylinder synchronous control hydraulic system, the system comprising:

[0067] A main pump assembly 1, connected to the oil tank 7, for providing hydraulic oil;

[0068] The main reversing valve assembly 2 has at least three oil ports and an oil return port T. The first oil port P of the main reversing valve assembly 2 is connected to the oil outlet C of the main pump assembly 1. The second oil port A of the main reversing valve assembly 2 is respectively connected to the control oil port K1 of the first balancing valve 3, the hydraulic oil port V2 of the second balancing valve 4, the control oil port K3 of the third balancing valve 5 and the hydraulic oil port V4 of the fourth balancing valve 6. The third oil port B of the main reversing valve assembly 2 is respectively connected to the hydraulic oil port V3 of the third balancing valve 5 and the control oil port K4 of the fourth balancing valve 6. The oil return port T of the main reversing valve assembly 2 is connected to the oil tank 7, and the oil return port T of the main reversing valve assembly 2 can be connected to the second oil port A or the third oil port B. The main reversing valve assembly 2 is used to control the flow direction of the hydraulic oil;

[0069] The first balancing valve 3 is arranged in the hydraulic oil circuit of the rodless chamber of the first oil cylinder 8, the hydraulic oil circuit of the first balancing valve 3 is connected with the rodless chamber of the first oil cylinder 8, and the oil return port T1 of the first balancing valve 3 is connected with the oil tank 7;

[0070] The second balancing valve 4 is arranged on the hydraulic oil circuit of the rod chamber of the first oil cylinder 8, the hydraulic oil circuit of the second balancing valve 4 is connected with the rod chamber of the first oil cylinder 8, the hydraulic oil port V2 of the second balancing valve 4 is connected with the control oil port K1 of the first balancing valve 3, the control oil port K2 of the second balancing valve 4 is connected with the hydraulic oil port V1 of the first balancing valve 3, and the control oil port K2 of the second balancing valve 4 and the hydraulic oil port V1 of the first balancing valve 3 are also connected with the rodless chamber of the second oil cylinder 9;

[0071] The third balancing valve 5 is arranged on the hydraulic oil circuit of the rodless chamber of the second oil cylinder 9. The hydraulic oil circuit of the third balancing valve 5 is connected with the rodless chamber of the second oil cylinder 9. The oil return port T3 of the third balancing valve 5 is connected with the oil tank 7. The first balancing valve 3 and the third balancing valve 5 are both pilot balancing valves. The minimum opening pressure of the third balancing valve 5 is greater than the maximum opening pressure of the first balancing valve 3.

[0072] The fourth balancing valve 6 is arranged on the hydraulic oil circuit of the rod chamber of the second cylinder 9. The hydraulic oil circuit of the fourth balancing valve 6 is connected with the rod chamber of the second cylinder 9. The hydraulic oil port V4 of the fourth balancing valve 6 is connected with the control oil port K3 of the third balancing valve 5. The control oil port K4 of the fourth balancing valve 6 is connected with the hydraulic oil port V3 of the third balancing valve 5.

[0073] Specifically, when the dual-cylinder synchronous control hydraulic system provided by an embodiment of the present invention is in use, the main pump assembly 1 draws hydraulic oil from the oil tank 7 and delivers it to the first oil port P of the main reversing valve assembly 2. The main reversing valve assembly 2 outputs the hydraulic oil from the second oil port A or the third oil port B according to the actual control situation.

[0074] When the hydraulic oil is output from the second oil port A of the main reversing valve assembly 2, the hydraulic oil reaches the control oil circuit of the first balancing valve 3, the hydraulic oil circuit of the second balancing valve 4, the control oil circuit of the third balancing valve 5 and the hydraulic oil circuit of the fourth balancing valve 6 through the pipeline. Since the control oil port K1 of the first balancing valve 3 is connected with the hydraulic oil port V2 of the second balancing valve 4, the hydraulic oil port V2 of the second balancing valve 4 is connected with the rod chamber of the first oil cylinder 8, the control oil port K3 of the third balancing valve 5 is connected with the hydraulic oil port V4 of the fourth balancing valve 6, and the hydraulic oil port V4 of the fourth balancing valve 6 is connected with the rod chamber of the second oil cylinder 9, the maximum opening pressure of the first balancing valve 3 is less than the minimum opening pressure of the third balancing valve 5. When the oil inlet pressure of the hydraulic oil port V2 of the second balancing valve 4 (that is, the oil inlet pressure of the rod chamber of the first oil cylinder 8) reaches the opening pressure value of the first balancing valve 3, the first balancing valve 3 opens first, and as the pressure of the control oil port K1 increases, the pressure of the control oil port K1 increases. As the force value increases, the opening of the first balancing valve 3 gradually increases until it reaches the maximum; when the hydraulic oil pressure continues to increase until the oil inlet pressure of the control oil port K3 of the third balancing valve 5 reaches the opening pressure value of the third balancing valve 5, the third balancing valve 5 opens. When the third balancing valve 5 is opened, since the control oil port K2 of the second balancing valve 4 and the hydraulic oil port V1 of the first balancing valve 3 are also connected to the rodless chamber of the second cylinder 9, the hydraulic oil of the rodless chamber of the first cylinder 8 enters the rodless chamber side of the second cylinder 9 through the hydraulic oil circuit of the first balancing valve 3, and returns to the oil tank 7 together with the hydraulic oil of the rodless chamber of the second cylinder 9 through the hydraulic oil circuit of the third balancing valve 5 and the third oil port B of the main reversing valve assembly 2. The control oil of the first balancing valve 3 and the control oil of the second balancing valve 4 return to the oil tank 7 through the return oil ports T1 and T3 connected to themselves, thereby causing the first cylinder 8 and the second cylinder 9 to retract synchronously, thereby realizing the synchronous retraction of the two cylinders.

[0075] When the hydraulic oil is output from the third oil port B of the main reversing valve assembly 2, the hydraulic oil reaches the hydraulic oil circuit of the third balancing valve 5 and the control oil circuit of the fourth balancing valve 6 through the pipeline, and the hydraulic oil reaches the rodless chamber of the second cylinder 9 through the hydraulic oil circuit of the third balancing valve 5. Since the hydraulic oil port V1 of the first balancing valve 3 and the control oil port K2 of the second balancing valve 4 are connected to the rodless chamber of the second cylinder 9, the hydraulic oil coming out of the third balancing valve 5 also reaches the hydraulic oil circuit of the first balancing valve 3 and the control oil circuit of the second balancing valve 4 through the pipeline, and the hydraulic oil reaches the rodless chamber of the first cylinder 8 through the hydraulic oil circuit of the first balancing valve 3. The opening pressure of the second balancing valve 4 and the fourth balancing valve 6 is relatively small. Under the action of hydraulic oil, the second balancing valve 4 and the fourth balancing valve 6 are fully opened, and the rodless chamber of the first cylinder 8 and the rodless chamber of the second cylinder 9 are pushed outward under the action of hydraulic oil. At the same time, the hydraulic oil discharged from the rod chamber of the first cylinder 8 returns to the oil tank 7 through the hydraulic oil circuit of the second balancing valve 4 and the second oil port A of the main reversing valve assembly 2, and the hydraulic oil discharged from the rod chamber of the second cylinder 9 returns to the oil tank 7 through the hydraulic oil circuit of the fourth balancing valve 6 and the second oil port A of the main reversing valve assembly 2, so that the first cylinder 8 and the second cylinder 9 are extended synchronously, realizing the synchronous extension of the two cylinders.

[0076] refer to Figure 1 and Figure 2 Furthermore, in one embodiment of the present invention, an explosion-proof valve 10 is provided on the hydraulic oil circuit between the hydraulic oil port V1 of the first balancing valve 3 and the rodless chamber of the second oil cylinder 9; the explosion-proof valve 10 is a hydraulically controlled two-position two-way valve, and the control oil port of the explosion-proof valve 10 is connected to the hydraulic oil circuit near the rodless chamber of the second oil cylinder 9. When the explosion-proof valve 10 is in a normal position, the two channel ports of the explosion-proof valve 10 are connected through a throttle valve, and when the explosion-proof valve 10 is in another state position, the two channel ports of the explosion-proof valve 10 are cut off.

[0077] By setting the explosion-proof valve 10 of the above-mentioned structural form, when the pressure difference of the pipelines on both sides of the explosion-proof valve 10 exceeds the preset spring setting value of the explosion-proof valve 10, the explosion-proof valve 10 will automatically switch from the normal position to another state position, so that the hydraulic oil circuit of the first balancing valve 3 and the control oil circuit of the second balancing valve 4 are disconnected from the hydraulic oil circuit between the rodless chamber of the second oil cylinder 9, which can avoid rollover when the pipeline bursts and the oil cylinder is depressurized, thereby ensuring the safety and reliability of the oil cylinder during long-term operation.

[0078] refer to Figure 1-6 In order to realize the synchronous operation of the two cylinders, ensure the stability, safety and reliability of the synchronous motion control of the two cylinders, and simplify the layout of the hydraulic pipeline; in one embodiment of the present invention, the first balancing valve 3 includes:

[0079] A first hydraulically controlled two-position two-way valve 301, wherein the first channel port of the first hydraulically controlled two-position two-way valve 301 is connected to the hydraulic oil port V1 of the first balancing valve 3, the second channel port of the first hydraulically controlled two-position two-way valve 301 is connected to the rodless chamber of the first oil cylinder 8, the control oil port of the first hydraulically controlled two-position two-way valve 301 is connected to the control oil port K1 and the oil return port T1 of the first balancing valve 3 through the damping hole respectively, when the first hydraulically controlled two-position two-way valve 301 is in the normal position, the first channel port of the first hydraulically controlled two-position two-way valve 301 is connected to the second channel port through the one-way valve, and when the first hydraulically controlled two-position two-way valve 301 is in another state position, the second channel port of the first hydraulically controlled two-position two-way valve 301 is connected to the first channel port through the throttle valve;

[0080] The first overflow valve 302 , the oil inlet of the first overflow valve 302 is communicated with the rodless chamber of the first oil cylinder 8 , and the oil outlet of the first overflow valve 302 is communicated with the control oil port of the first hydraulically controlled two-position two-way valve 301 .

[0081] Further, the second balancing valve 4 comprises:

[0082] A second relief valve 401, the control oil port of the second relief valve 401 is connected to the control oil port K2 of the second balancing valve 4 through a damping hole, the oil inlet of the second relief valve 401 is connected to the rod chamber of the first oil cylinder 8, and the oil outlet of the second relief valve 401 is connected to the hydraulic oil port V2 of the second balancing valve 4;

[0083] The first one-way valve 402 , the oil inlet of the first one-way valve 402 is connected to the hydraulic oil port V2 of the second balance valve 4 , and the oil outlet of the first one-way valve 402 is connected to the rod chamber of the first oil cylinder 8 .

[0084] Further, the third balancing valve 5 comprises:

[0085] A second hydraulically controlled two-position two-way valve 501, wherein the first channel port of the second hydraulically controlled two-position two-way valve 501 is connected to the hydraulic oil port V3 of the third balancing valve 5, the second channel port of the second hydraulically controlled two-position two-way valve 501 is connected to the rodless chamber of the second oil cylinder 9, the control oil port of the second hydraulically controlled two-position two-way valve 501 is respectively connected to the control oil port K3 and the return oil port T3 of the third balancing valve 5 through the damping hole, when the second hydraulically controlled two-position two-way valve 501 is in the normal position, the first channel port of the second hydraulically controlled two-position two-way valve 501 is connected to the second channel port through the one-way valve, and when the second hydraulically controlled two-position two-way valve 501 is in another state position, the second channel port of the second hydraulically controlled two-position two-way valve 501 is connected to the first channel port through the throttle valve;

[0086] The third relief valve 502 , the oil inlet of the third relief valve 502 is connected to the rodless chamber of the second oil cylinder 9 , and the oil outlet of the third relief valve 502 is connected to the control oil port of the second hydraulically controlled two-position two-way valve 501 .

[0087] Further, the fourth balancing valve 6 comprises:

[0088] The fourth relief valve 601, the control oil port of the fourth relief valve 601 is connected with the control oil port K4 of the fourth balancing valve 6 through the damping hole, the oil inlet of the fourth relief valve 601 is connected with the rod chamber of the second oil cylinder 9, and the oil outlet of the fourth relief valve 601 is connected with the hydraulic oil port V4 of the fourth balancing valve 6;

[0089] The second one-way valve 602 , the oil inlet of the second one-way valve 602 is connected to the hydraulic oil port V4 of the fourth balancing valve 6 , and the oil outlet of the second one-way valve 602 is connected to the rod chamber of the second oil cylinder 9 .

[0090] In one embodiment of the present invention, when the oil inlet pressure of the control oil port of the first hydraulically controlled two-position two-way valve 301 reaches the opening pressure, the first hydraulically controlled two-position two-way valve 301 switches to another state position, has a throttling function, and as the oil inlet pressure increases, the opening of the throttle valve inside the channel gradually increases until it reaches the maximum opening. When the oil inlet pressure of the control oil port of the second hydraulically controlled two-position two-way valve 501 reaches the opening pressure, the second hydraulically controlled two-position two-way valve 501 switches to another state position, has a throttling function, and as the oil inlet pressure increases, the opening of the throttle valve inside the channel gradually increases until it reaches the maximum opening.

[0091] refer to Figure 3 In order to prevent impurities in the hydraulic oil from damaging the control elements in the first hydraulically controlled two-position two-way valve 301, a filter is provided in front of the oil inlet of the damping hole on the control oil circuit of the first hydraulically controlled two-position two-way valve 301, and a filter is provided in front of the oil inlet of the first overflow valve 302.

[0092] refer to Figure 5 In order to prevent impurities in the hydraulic oil from damaging the control elements in the second hydraulically controlled two-position two-way valve 501, a filter is provided in front of the oil inlet of the damping hole on the control oil circuit of the second hydraulically controlled two-position two-way valve 501, and a filter is provided in front of the oil inlet of the third overflow valve 502.

[0093] Further, refer to Figure 1 and Figure 7 In one embodiment of the present invention, the main pump assembly 1 comprises:

[0094] A hydraulic pump 102, wherein the oil inlet of the hydraulic pump 102 is connected to the oil tank 7, and the oil outlet of the hydraulic pump 102 is connected to the oil outlet C of the main pump assembly 1;

[0095] The plunger cylinder 102, the rod chamber of the plunger cylinder 102 is connected to the oil outlet of the hydraulic pump 102, and the rodless chamber of the plunger cylinder 102 is connected to the first channel port of the hydraulically controlled two-position three-way valve 103 located at the lower side;

[0096] A hydraulically controlled two-position three-way valve 103, the control oil port of the hydraulically controlled two-position three-way valve 103 is connected to the oil outlet of the hydraulic pump 102, the second channel port of the hydraulically controlled two-position three-way valve 103 located on the upper side is connected to the oil outlet of the hydraulic pump 102, and the third channel port of the hydraulically controlled two-position three-way valve 103 located on the upper side is connected to the oil tank 7.

[0097] Based on the main pump assembly 1 of the above-mentioned structural type, the main pump assembly 1 has a pressure cut-off function. Among them, the hydraulically controlled two-position three-way valve 103 is used to control the displacement of the main pump assembly 1. The hydraulically controlled two-position three-way valve 103 is used as a pressure cut-off valve. When the system pressure reaches the set spring setting value of the hydraulically controlled two-position three-way valve 103, the hydraulically controlled two-position three-way valve 103 changes direction and controls the plunger cylinder 102 to move to the left, so that the main pump assembly 1 reaches the minimum displacement, which can be used to meet the internal leakage.

[0098] Further, refer to Figure 1 and Figure 8 In one embodiment of the present invention, the main reversing valve assembly 2 includes:

[0099] The oil inlet of the flow valve 201 is connected with the first oil port P of the main reversing valve assembly 2;

[0100] The three-position eight-way reversing valve 202 has three channel ports located on the upper side and five channel ports located on the lower side. The first channel port and the third channel port located on the upper side are respectively connected to the return oil port T of the main reversing valve assembly 2, the second channel port located on the upper side is connected to the oil outlet of the flow valve 201, the fourth channel port located on the lower side is connected to the control oil port of the flow valve 201 and the set load port Ls, the fifth channel port located on the lower side is connected to the oil inlet of the fifth relief valve 203, the sixth channel port located on the lower side is connected to the second oil port A of the main reversing valve assembly 2, the seventh channel port located on the lower side is connected to the third oil port B of the main reversing valve assembly 2, and the eighth channel port located on the lower side is connected to the sixth overflow valve 203. The oil inlet of the valve 204 is connected. When the three-position eight-way reversing valve 202 is in the middle position, the first channel port, the fourth channel port, the fifth channel port, the sixth channel port and the eighth channel port are connected, the second channel port is blocked, and the third channel port and the seventh channel port are connected. When the three-position eight-way reversing valve 202 is in the left position, the first channel port and the sixth channel port are connected, the second channel port, the fourth channel port, the seventh channel port and the eighth channel port are connected, the third channel port is blocked, and the fifth channel port is blocked. When the three-position eight-way reversing valve 202 is in the right position, the first channel port is blocked, the second channel port, the fourth channel port, the fifth channel port and the sixth channel port are connected, the third channel port and the seventh channel port are connected, and the eighth channel port is blocked;

[0101] The fifth relief valve 203, the oil outlet is connected to the oil return port T of the main reversing valve assembly 2;

[0102] The sixth relief valve 204, the oil outlet is connected to the oil return port T of the main reversing valve assembly 2;

[0103] The first pilot valve 205 is connected to the control oil port on the left side of the three-position eight-way reversing valve 202, and is used to control the three-position eight-way reversing valve 202 to move to the right;

[0104] The second pilot valve 206 is connected to the control oil port on the right side of the three-position eight-way reversing valve 202, and is used to control the three-position eight-way reversing valve 202 to move to the left side.

[0105] In one embodiment of the present invention, in the above-mentioned main reversing valve assembly 2, the working position of the three-position eight-way reversing valve 202 is switched by controlling the first pilot valve 205 and the second pilot valve 206, so as to realize the flow direction control of the hydraulic oil, and then control the movement direction of the oil cylinder. Specifically, when the three-position eight-way reversing valve 202 is controlled to move to the right to the right position by the first pilot valve 205, the hydraulic oil is discharged from the second oil port A of the main reversing valve assembly 2, and the oil cylinder retracts; when the three-position eight-way reversing valve 202 is controlled to move to the left to the left position by the second pilot valve 206, the hydraulic oil is discharged from the third oil port B of the main reversing valve assembly 2, and the oil cylinder extends.

[0106] refer to Figure 8 In order to improve the control stability and reliability of the three-position eight-way reversing valve 202 and simplify the pipeline layout, in one embodiment of the present invention, the first pilot valve 205 and the second pilot valve 206 are both electrically controlled two-position three-way valves;

[0107] The first channel port of the first pilot valve 205 located on the upper side is communicated with the oil outlet port of a pressure reducing valve 207, the oil inlet port of the pressure reducing valve 207 is communicated with the first oil port P of the main reversing valve assembly 2, the second channel port of the first pilot valve 205 located on the upper side is respectively communicated with the return oil port T and the oil drain port Y of the main reversing valve assembly 2, the oil drain port Y of the main reversing valve assembly 2 is communicated with the oil tank 7, the third channel port of the first pilot valve 205 located on the lower side is communicated with the control oil port on the left side of the three-position eight-way reversing valve 202, when the first pilot valve 205 is in the left position, the first channel port of the first pilot valve 205 is communicated with the third channel port, and the second channel port is cut off, when the first pilot valve 205 is in the right position, the first channel port of the first pilot valve 205 is cut off, and the second channel port is communicated with the third channel port;

[0108] The first channel port of the second pilot valve 206 located on the upper side is respectively connected to the return oil port T and the drain oil port Y of the main reversing valve assembly 2, the second channel port of the second pilot valve 206 located on the upper side is connected to the oil outlet port of the pressure reducing valve 207, and the third channel port of the second pilot valve 206 located on the lower side is connected to the control oil port on the right side of the three-position eight-way reversing valve 202. When the second pilot valve 206 is in the left position, the first channel port of the second pilot valve 206 is connected to the third channel port, and the second channel port is cut off. When the second pilot valve 206 is in the right position, the first channel port of the second pilot valve 206 is cut off, and the second channel port is connected to the third channel port.

[0109] Specifically, based on the main reversing valve assembly 2 of the above structure, when it is necessary to control the hydraulic oil to be discharged from the second oil port A of the main reversing valve assembly 2 to control the retraction movement of the cylinder, the first pilot valve 205 is controlled to be energized. At this time, the first pilot valve 205 is switched to the left position, and the hydraulic oil flowing in from the first oil port P of the main reversing valve assembly 2 flows to the first channel port of the first pilot valve 205 through the pressure reducing valve 207, and flows to the control oil port on the left side of the three-position eight-way reversing valve 202 through the third channel port connected to the first channel port. When the oil inlet pressure of the control oil port reaches the opening pressure of the three-position eight-way reversing valve 202, the three-position eight-way reversing valve 202 moves to the right and then switches to the right position. At this time, the three-position eight-way reversing valve 202 The second channel port is connected with the fourth channel port, the fifth channel port and the sixth channel port. The hydraulic oil entering from the second channel port reaches the control oil port of the flow valve 201 and the set load port Ls through the fourth channel port to realize the flow adjustment of the flow valve 201, flows to the fifth overflow valve 203 through the fifth channel port, and flows to the second oil port A of the main reversing valve assembly 2 through the sixth channel port. The hydraulic oil flows out from the second oil port A and reaches the rod chambers of the two oil cylinders through the balance valve; at the same time, the hydraulic oil discharged from the rodless chambers of the two oil cylinders flows to the third oil port B of the main reversing valve assembly 2 through the balance valve, and the hydraulic oil flowing out of the third oil port B returns to the oil tank 7 through the seventh channel port and the third channel port of the three-position eight-way reversing valve 202. Since the second pilot valve 206 is not energized, the second channel port of the second pilot valve 206 connected to the pressure reducing valve 207 is in a cut-off state.

[0110] When it is necessary to control the hydraulic oil to be discharged from the third oil port B of the main reversing valve assembly 2 to control the extension movement of the oil cylinder, the second pilot valve 206 is controlled to be energized. At this time, the second pilot valve 206 switches to the right position, and the hydraulic oil flowing in from the first oil port P of the main reversing valve assembly 2 flows to the second channel port of the second pilot valve 206 through the pressure reducing valve 207, and flows to the control oil port on the right side of the three-position eight-way reversing valve 202 through the third channel port connected to the second channel port. When the oil inlet pressure of the control oil port reaches the opening pressure of the three-position eight-way reversing valve 202, the three-position eight-way reversing valve 202 moves to the left and then switches to the left position. At this time, the second channel port and the fourth channel port of the three-position eight-way reversing valve 202 are opened. The hydraulic oil entering from the second channel port reaches the control oil port of the flow valve 201 and the set load port Ls through the fourth channel port to achieve the flow adjustment of the flow valve 201, flows to the sixth relief valve 204 through the eighth channel port, and flows to the third oil port B of the main reversing valve assembly 2 through the seventh channel port. The hydraulic oil flows out from the third oil port B and reaches the rodless chambers of the two oil cylinders through the balance valve; at the same time, the hydraulic oil discharged from the rod chambers of the two oil cylinders flows to the second oil port A of the main reversing valve assembly 2 through the balance valve, and the hydraulic oil flowing out of the second oil port A returns to the oil tank 7 through the sixth channel port and the first channel port of the three-position eight-way reversing valve 202. Since the first pilot valve 205 is not energized, the first channel port of the first pilot valve 205 connected to the pressure reducing valve 207 is in a cut-off state.

[0111] The fifth relief valve 203 is used to protect the piston chamber of the oil cylinder, and the sixth relief valve 204 is used to protect the rodless chamber of the oil cylinder, so as to avoid damage to hydraulic components such as the oil cylinder due to excessive pressure.

[0112] Furthermore, in one embodiment of the present invention, in order to prevent impurities in the hydraulic oil from damaging the control elements of the three-position eight-way reversing valve 202, a filter is provided in front of the first channel port of the first pilot valve 205, and a filter is provided in front of the second channel port of the second pilot valve 206.

[0113] refer to Figure 8 In one embodiment of the present invention, a seventh relief valve 208 is also installed between the oil outlet of the pressure reducing valve 207 and the oil drain port Y of the main reversing valve assembly 2. The seventh relief valve 208 is used to control the hydraulic oil pressure flowing to the pilot valve to ensure that the hydraulic oil pressure does not exceed the set pressure value.

[0114] Specifically, the set pressure of the seventh relief valve 208 is set to a set pressure value. When the hydraulic oil pressure exceeds the set pressure, the seventh relief valve 208 opens to overflow, thereby achieving a constant pressure overflow effect.

[0115] refer to Figure 8In one embodiment of the present invention, a safety valve 209 is installed between the first oil port P and the oil return port T of the main reversing valve assembly 2, and the safety valve 209 is used for safety protection.

[0116] Specifically, the safety valve 209 includes an eighth relief valve, the set pressure of the eighth relief valve is higher than the maximum working pressure of the hydraulic system. Therefore, when the pressure of the hydraulic system exceeds the set maximum working pressure, the eighth relief valve opens to overflow and discharge excess flow pressure, thereby achieving safety protection.

[0117] Furthermore, in one embodiment of the present invention, in addition to the damping holes provided in the balancing valve as described above, damping holes may also be provided before and after different channel openings and oil ports according to actual needs.

[0118] Specifically, refer to Figure 1-8 In one embodiment of the present invention, a damping hole is provided in front of the oil inlet of the pressure reducing valve 207; a damping hole is provided in front of the oil inlet of the safety valve 209; a damping hole is provided between the third channel port of the first pilot valve 205 and the control oil port on the left side of the three-position eight-way reversing valve 202; a damping hole is provided between the third channel port of the second pilot valve 206 and the control oil port on the right side of the three-position eight-way reversing valve 202; when the three-position eight-way reversing valve 202 is in the middle position, damping holes are provided on the inner side of the fifth channel port and the inner side of the seventh channel port; when the three-position eight-way reversing valve 202 is in the left position, a damping hole is provided on the inner side of the second channel port, and a damping hole is provided in front of the connecting point between the second channel port and the fourth channel port and the eighth channel port; when the three-position eight-way reversing valve 202 is in the right position, a damping hole is provided on the inner side of the second channel port, and a damping hole is provided in front of the connecting point between the second channel port and the fourth channel port and the fifth channel port.

[0119] The damping hole is used to play the role of throttling, pressure regulation, buffering and vibration prevention, so as to improve the safety and stability of the dual-cylinder synchronous control hydraulic system.

[0120] In a second aspect, an embodiment of the present invention further provides a fire truck, which includes the above-mentioned dual-cylinder synchronous control hydraulic system.

[0121] A dual-cylinder synchronous control hydraulic system and a fire truck provided in an embodiment of the present invention are provided with two pilot balancing valves with different opening pressures. When performing dual-cylinder synchronous control, one pilot balancing valve is opened first, and the other pilot balancing valve is used as the main balancing valve to control the operating speed of the dual cylinders, thereby ensuring the synchronization, stability and safety of the dual-cylinder movement and simplifying the control pipeline layout; and an explosion-proof valve is provided between the two pilot balancing valves, so that when the balancing valve pipeline bursts, the explosion-proof valve can be used to lock the cylinder, thereby further ensuring the safety and reliability of the long-term operation of the cylinder.

[0122] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In addition, "front", "back", "left", "right", "upper" and "lower" in this article are all referenced to the placement state shown in the accompanying drawings.

[0123] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A dual-cylinder synchronous control hydraulic system, characterized in that: include: A main pump assembly connected to the oil tank for providing hydraulic oil; A main reversing valve assembly, having at least three oil ports and an oil return port, wherein the first oil port of the main reversing valve assembly is communicated with the oil outlet of the main pump assembly, the second oil port of the main reversing valve assembly is communicated with the control oil port of the first balancing valve, the hydraulic oil port of the second balancing valve, the control oil port of the third balancing valve and the hydraulic oil port of the fourth balancing valve respectively, the third oil port of the main reversing valve assembly is communicated with the hydraulic oil port of the third balancing valve and the control oil port of the fourth balancing valve respectively, the oil return port of the main reversing valve assembly is communicated with the oil tank, and the oil return port of the main reversing valve assembly can be communicated with the second oil port or the third oil port, and the main reversing valve assembly is used to control the flow direction of the hydraulic oil; The first balancing valve is arranged in the hydraulic oil circuit of the rodless chamber of the first oil cylinder, the hydraulic oil circuit of the first balancing valve is communicated with the rodless chamber of the first oil cylinder, and the oil return port of the first balancing valve is communicated with the oil tank; The second balancing valve is arranged on the hydraulic oil circuit of the rod chamber of the first oil cylinder, the hydraulic oil circuit of the second balancing valve is communicated with the rod chamber of the first oil cylinder, the hydraulic oil port of the second balancing valve is communicated with the control oil port of the first balancing valve, the control oil port of the second balancing valve is communicated with the hydraulic oil port of the first balancing valve, and the control oil port of the second balancing valve and the hydraulic oil port of the first balancing valve are also communicated with the rodless chamber of the second oil cylinder; The third balancing valve is arranged on the hydraulic oil circuit of the rodless chamber of the second oil cylinder, the hydraulic oil circuit of the third balancing valve is connected with the rodless chamber of the second oil cylinder, the oil return port of the third balancing valve is connected with the oil tank, the first balancing valve and the third balancing valve are both pilot balancing valves, and the minimum opening pressure of the third balancing valve is greater than the maximum opening pressure of the first balancing valve; The fourth balancing valve is arranged on the hydraulic oil circuit of the rod chamber of the second cylinder. The hydraulic oil circuit of the fourth balancing valve is connected with the rod chamber of the second cylinder. The hydraulic oil port of the fourth balancing valve is connected with the control oil port of the third balancing valve. The control oil port of the fourth balancing valve is connected with the hydraulic oil port of the third balancing valve.

2. The dual-cylinder synchronous control hydraulic system according to claim 1, characterized in that: An explosion-proof valve is provided on the hydraulic oil circuit between the hydraulic oil port of the first balancing valve and the rodless chamber of the second oil cylinder; The explosion-proof valve is a hydraulically controlled two-position two-way valve, the control oil port of the explosion-proof valve is connected to the hydraulic oil circuit of the rodless chamber close to the second oil cylinder, when the explosion-proof valve is in a normal position, the two channel ports of the explosion-proof valve are connected through a throttle valve, and when the explosion-proof valve is in another state position, the two channel ports of the explosion-proof valve are cut off.

3. The dual-cylinder synchronous control hydraulic system according to claim 1, characterized in that: The first balancing valve comprises: a first hydraulically controlled two-position two-way valve, wherein a first channel port of the first hydraulically controlled two-position two-way valve is communicated with a hydraulic oil port of the first balancing valve, a second channel port of the first hydraulically controlled two-position two-way valve is communicated with a rodless chamber of the first oil cylinder, a control oil port of the first hydraulically controlled two-position two-way valve is communicated with a control oil port and an oil return port of the first balancing valve respectively through a damping hole, when the first hydraulically controlled two-position two-way valve is in a normal position, the first channel port of the first hydraulically controlled two-position two-way valve is communicated with a second channel port through a one-way valve, and when the first hydraulically controlled two-position two-way valve is in another state position, the second channel port of the first hydraulically controlled two-position two-way valve is communicated with the first channel port through a throttle valve; A first overflow valve, wherein the oil inlet of the first overflow valve is communicated with the rodless chamber of the first oil cylinder, and the oil outlet of the first overflow valve is communicated with the control oil port of the first hydraulically controlled two-position two-way valve.

4. The dual-cylinder synchronous control hydraulic system according to claim 3, characterized in that: The second balancing valve comprises: a second relief valve, wherein a control oil port of the second relief valve is communicated with a control oil port of the second balancing valve through a damping hole, an oil inlet of the second relief valve is communicated with a rod chamber of the first oil cylinder, and an oil outlet of the second relief valve is communicated with a hydraulic oil port of the second balancing valve; A first one-way valve, wherein the oil inlet of the first one-way valve is communicated with the hydraulic oil port of the second balancing valve, and the oil outlet of the first one-way valve is communicated with the rod chamber of the first oil cylinder.

5. The dual-cylinder synchronous control hydraulic system according to claim 4, characterized in that: The third balancing valve comprises: a second hydraulically controlled two-position two-way valve, wherein the first channel port of the second hydraulically controlled two-position two-way valve is communicated with the hydraulic oil port of the third balancing valve, the second channel port of the second hydraulically controlled two-position two-way valve is communicated with the rodless chamber of the second oil cylinder, the control oil port of the second hydraulically controlled two-position two-way valve is communicated with the control oil port and the oil return port of the third balancing valve respectively through a damping hole, when the second hydraulically controlled two-position two-way valve is in a normal position, the first channel port of the second hydraulically controlled two-position two-way valve is communicated with the second channel port through a one-way valve, and when the second hydraulically controlled two-position two-way valve is in another state position, the second channel port of the second hydraulically controlled two-position two-way valve is communicated with the first channel port through a throttle valve; A third relief valve, wherein the oil inlet of the third relief valve is communicated with the rodless chamber of the second oil cylinder, and the oil outlet of the third relief valve is communicated with the control oil port of the second hydraulically controlled two-position two-way valve.

6. The dual-cylinder synchronous control hydraulic system according to claim 5, characterized in that: The fourth balancing valve comprises: a fourth relief valve, wherein the control oil port of the fourth relief valve is communicated with the control oil port of the fourth balancing valve through a damping hole, the oil inlet of the fourth relief valve is communicated with the rod chamber of the second oil cylinder, and the oil outlet of the fourth relief valve is communicated with the hydraulic oil port of the fourth balancing valve; A second one-way valve, wherein the oil inlet of the second one-way valve is communicated with the hydraulic oil port of the fourth balancing valve, and the oil outlet of the second one-way valve is communicated with the rod chamber of the second oil cylinder.

7. The dual-cylinder synchronous control hydraulic system according to claim 1, characterized in that: The main pump assembly comprises: A hydraulic pump, wherein an oil inlet of the hydraulic pump is connected to the oil tank, and an oil outlet of the hydraulic pump is connected to an oil outlet of the main pump assembly; A plunger cylinder, wherein the rod chamber of the plunger cylinder is communicated with the oil outlet of the hydraulic pump, and the rodless chamber of the plunger cylinder is communicated with the first channel port of the hydraulically controlled two-position three-way valve located at the lower side; The hydraulically controlled two-position three-way valve, the control oil port of the hydraulically controlled two-position three-way valve is connected to the oil outlet of the hydraulic pump, the second channel port of the hydraulically controlled two-position three-way valve located on the upper side is connected to the oil outlet of the hydraulic pump, and the third channel port of the hydraulically controlled two-position three-way valve located on the upper side is connected to the oil tank.

8. The dual-cylinder synchronous control hydraulic system according to claim 1, characterized in that: The main reversing valve assembly comprises: A flow valve, the oil inlet of which is connected to the first oil port of the main reversing valve assembly; A three-position eight-way reversing valve has three channel ports located on the upper side and five channel ports located on the lower side, the first channel port and the third channel port located on the upper side are respectively connected to the return oil port of the main reversing valve assembly, the second channel port located on the upper side is connected to the oil outlet port of the flow valve, the fourth channel port located on the lower side is connected to the control oil port and the set load port of the flow valve, the fifth channel port located on the lower side is connected to the oil inlet of the fifth overflow valve, the sixth channel port located on the lower side is connected to the second oil port of the main reversing valve assembly, the seventh channel port located on the lower side is connected to the third oil port of the main reversing valve assembly, the eighth channel port located on the lower side is connected to the The oil inlet is connected, when the three-position eight-way reversing valve is in the middle position, the first channel port, the fourth channel port, the fifth channel port, the sixth channel port and the eighth channel port are connected, the second channel port is cut off, and the third channel port and the seventh channel port are connected; when the three-position eight-way reversing valve is in the left position, the first channel port and the sixth channel port are connected, the second channel port, the fourth channel port, the seventh channel port and the eighth channel port are connected, the third channel port is cut off, and the fifth channel port is cut off; when the three-position eight-way reversing valve is in the right position, the first channel port is cut off, the second channel port, the fourth channel port, the fifth channel port and the sixth channel port are connected, the third channel port and the seventh channel port are connected, and the eighth channel port is cut off; The oil outlet of the fifth relief valve is connected to the oil return port of the main reversing valve assembly; The oil outlet of the sixth relief valve is connected to the oil return port of the main reversing valve assembly; A first pilot valve is connected to the control oil port on the left side of the three-position eight-way reversing valve, and is used to control the three-position eight-way reversing valve to move to the right; The second pilot valve is connected to the control oil port on the right side of the three-position eight-way reversing valve, and is used to control the three-position eight-way reversing valve to move to the left side.

9. The dual-cylinder synchronous control hydraulic system according to claim 8, characterized in that: The first pilot valve and the second pilot valve are both electrically controlled two-position three-way valves; The first channel port of the first pilot valve located on the upper side is communicated with an oil outlet port of a pressure reducing valve, the oil inlet port of the pressure reducing valve is communicated with a first oil port of the main reversing valve assembly, the second channel port of the first pilot valve located on the upper side is communicated with an oil return port and an oil drain port of the main reversing valve assembly respectively, the oil drain port of the main reversing valve assembly is communicated with the oil tank, the third channel port of the first pilot valve located on the lower side is communicated with a control oil port on the left side of the three-position eight-way reversing valve, when the first pilot valve is in the left position, the first channel port of the first pilot valve is communicated with the third channel port, and the second channel port is cut off, when the first pilot valve is in the right position, the first channel port of the first pilot valve is cut off, and the second channel port is communicated with the third channel port; The first channel port of the second pilot valve located on the upper side is respectively connected to the oil return port and the oil drain port of the main reversing valve assembly, the second channel port of the second pilot valve located on the upper side is connected to the oil outlet port of the pressure reducing valve, and the third channel port of the second pilot valve located on the lower side is connected to the control oil port on the right side of the three-position eight-way reversing valve. When the second pilot valve is in the left position, the first channel port of the second pilot valve is connected to the third channel port, and the second channel port is cut off. When the second pilot valve is in the right position, the first channel port of the second pilot valve is cut off, and the second channel port is connected to the third channel port.

10. A fire truck, characterized in that: A dual-cylinder synchronous control hydraulic system comprising any one of claims 1-9.

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