Hydraulic suspension systems and engineering vehicles

Abstract

This invention provides a hydropneumatic suspension hydraulic system and an engineering vehicle. The hydropneumatic suspension hydraulic system includes a left suspension cylinder group, a right suspension cylinder group, a first connecting oil circuit, a second connecting oil circuit, a rigidity / flexibility switching valve, and a combined suspension main valve. The first connecting oil circuit connects the rod-side chamber of the left suspension cylinder group and the rodless chamber of the right suspension cylinder group. The second connecting oil circuit connects the rodless chamber of the left suspension cylinder group and the rod-side chamber of the right suspension cylinder group. Both the first and second connecting oil circuits are equipped with rigidity / flexibility switching valves. The combined suspension main valve is connected to both the first and second connecting oil circuits. The combined suspension main valve and the rigidity / flexibility switching valve cooperate to control the movement or locking of the left and right suspension cylinder groups. This invention reduces the number of main valves required by integrating the left and right suspension main valves into a single combined suspension main valve, saving installation space, simplifying hydraulic lines and pipelines, and making manufacturing easier.

Description

Technical Field

[0001] This invention belongs to the field of engineering vehicle technology, and particularly relates to an oil-pneumatic suspension hydraulic system and an engineering vehicle. Background Technology

[0002] Currently, hydropneumatic suspension systems are widely used in engineering vehicles. These systems mainly consist of flexible accumulators, suspension cylinders, suspension control valves, and stiffness-flexibility switching valves. With its unique controllability of vehicle posture, as well as superior damping characteristics, anti-roll performance, and axle load balance, hydropneumatic suspension can maximally meet the complex application requirements of engineering vehicles.

[0003] To achieve precise adjustment of vehicle body posture, the main valve integrates hydraulic valve components such as the vehicle height control valve, height speed control valve, and vehicle posture holding valve. Secondly, to meet different driving needs, hydropneumatic suspension systems generally have two operating modes: rigid and flexible. The rigid / flexible switching valve, which switches between modes, is usually integrated with the suspension main valve. Finally, to protect components such as accumulators and for maintenance safety, some suspension main valves also integrate overflow valve components and emergency unloading ball valves. In summary, a single suspension main valve integrates numerous components, and the internal oil passages of the main valve body are intricate. Furthermore, each suspension cylinder on one side of the vehicle body is controlled by an independent suspension main valve, making the piping connections of existing suspension systems quite complex. Summary of the Invention

[0004] The main objective of this invention is to propose an oil-gas suspension hydraulic system and engineering vehicle, aiming to solve the technical problems of numerous integrated plugs and complex system pipeline connections in existing crane oil-gas suspension systems.

[0005] To achieve the above objectives, the present invention provides a hydropneumatic suspension hydraulic system, the hydropneumatic suspension hydraulic system comprising:

[0006] Left suspension cylinder assembly and right suspension cylinder assembly;

[0007] The first connecting oil circuit connects the rod chamber of the left suspension cylinder group and the rodless chamber of the right suspension cylinder group;

[0008] The second connecting oil circuit connects the rodless chamber of the left suspension cylinder group and the rod chamber of the right suspension cylinder group;

[0009] The rigid-flexible switching valve is provided on both the first and second connecting oil lines; and

[0010] The combined suspension main valve is connected to both the first connecting oil circuit and the second connecting oil circuit. The combined suspension main valve and the rigidity-flexibility switching valve cooperate to control the movement or locking of the left suspension cylinder group and the right suspension cylinder group.

[0011] In an embodiment of the present invention, the hydropneumatic suspension hydraulic system further includes a first oil inlet circuit and a second oil inlet circuit, and the combined suspension main valve includes a first working port and a second working port. The first oil inlet circuit is connected to the first working port and the first connecting circuit, and the second oil inlet circuit is connected to the second working port and the second connecting circuit.

[0012] In an embodiment of the present invention, the combined suspension main valve includes a composite control valve and a main valve block that is plate-connected to the composite control valve. The main valve block is an integrated valve assembly structure, and the first working port and the second working port are located on the upper end face of the main valve block.

[0013] In an embodiment of the present invention, an oil inlet and an oil return port are provided on one side of the main valve block, and there are two composite control valves, namely a left control valve and a right control valve, wherein the left control valve and the right control valve have the same structure; wherein.

[0014] The left control valve includes:

[0015] The first internal working port is located on the first side of the left control valve and is connected to the first working port;

[0016] The first internal oil inlet and the first internal oil return are both located on the second side of the left control valve. The first internal oil inlet is connected to the oil inlet through the first internal oil inlet passage, and the first internal oil return is connected to the oil return through the first internal oil return passage.

[0017] The right control valve includes:

[0018] The second internal working oil port is on the same side as the first internal working oil port and located on the first side of the right control valve. The second internal working oil port and the second working oil port are connected.

[0019] The second internal oil inlet and the second internal oil return port are both located on the second side of the right control valve. The second internal oil inlet and the oil inlet are connected through the second internal oil inlet passage, and the second internal oil return port and the oil return port are connected through the second internal oil return passage.

[0020] In an embodiment of the present invention, the main valve block includes an upward flow valve and a downward flow valve. The first internal oil inlet passage and the second internal oil inlet passage are both provided with the upward flow valve, and the first internal oil return passage and the second internal oil return passage are both provided with the downward flow valve.

[0021] In an embodiment of the present invention, the main valve block further includes a return oil lock-up valve. The lower end face of the main valve block is provided with a third working oil port and a fourth working oil port that are connected to the return oil port through an internal main return oil passage. The return oil lock-up valve is located on the internal main return oil passage. The third working oil port is connected to the rodless chamber of the right suspension cylinder group through a first return oil passage. The fourth working oil port is connected to the rodless chamber of the left suspension cylinder group through a second return oil passage.

[0022] In an embodiment of the present invention, the combined suspension main valve has a first internal connecting oil passage, which connects the first oil inlet circuit and the second oil inlet circuit. The first internal connecting oil passage is equipped with a check valve, and both the first return oil circuit and the second return oil circuit are equipped with return oil check valves.

[0023] In an embodiment of the present invention, the hydropneumatic suspension hydraulic system further includes a second internal connecting oil passage, which connects the first internal connecting oil passage and the return port, and the main valve block further includes a safety relief valve disposed on the second internal connecting oil passage.

[0024] In an embodiment of the present invention, the composite control valve includes a valve body and a valve core inserted into the valve body, wherein the end of the valve core has a tapered structure.

[0025] In an embodiment of the present invention, the rigid-flexible switching valve includes a pneumatic shut-off valve and a pneumatic solenoid valve. The pneumatic shut-off valve includes a connected position in which the valve body is in a flow state and a shut-off position in which the valve body is in a throttling state. The pneumatic solenoid valve is used to control the pneumatic shut-off valve to switch between the connected position and the shut-off position.

[0026] In an embodiment of the present invention, an engineering vehicle is also proposed, the engineering vehicle including the hydropneumatic suspension hydraulic system as described above.

[0027] Through the above technical solutions, the hydropneumatic suspension hydraulic system provided by the embodiments of the present invention has the following beneficial effects:

[0028] This application employs a first connecting oil circuit to connect the rod-side chamber of the left suspension cylinder group and the rodless chamber of the right suspension cylinder group, and a second connecting oil circuit to connect the rodless chamber of the left suspension cylinder group and the rod-side chamber of the right suspension cylinder group. A rigid-flexibility switching valve is installed on both the first and second connecting oil circuits to control the rigidity / flexibility switching between the left and right suspension cylinder groups. Compared to the prior art where multiple main valves control the actions of multiple suspension cylinder groups, this invention combines the left and right suspension main valves in the existing hydropneumatic suspension hydraulic system into a single combined suspension main valve. This combined suspension main valve is connected to both the first and second connecting oil circuits. The combined suspension main valve and the rigid-flexibility switching valve cooperate to control the actions or locking of the left and right suspension cylinder groups. This improvement reduces the number of main valves by at least half. Compared to the prior art, the total number of inserts such as lift valves is reduced by half, and the total number of internal oil passages in the existing main valve is also reduced by half, saving installation space, simplifying the complexity of hydraulic pipeline connections, and making assembly more convenient.

[0029] Other features and advantages of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0030] The accompanying drawings are provided to illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0031] Figure 1 This is a schematic diagram of the hydraulic principle of an existing hydropneumatic suspension hydraulic system;

[0032] Figure 2 This is a schematic diagram of the hydraulic principle of an oil-pneumatic suspension hydraulic system according to an embodiment of the present invention;

[0033] Figure 3 This is a schematic diagram of the hydraulic principle of the combined suspension main valve in the hydropneumatic suspension system according to the present invention;

[0034] Figure 4 This is a schematic diagram of the left composite control valve in the combined suspension main valve according to the present invention.

[0035] Explanation of reference numerals in the attached figures

[0036] Detailed Implementation

[0037] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0038] In existing technologies, to control the hydraulic system of a pneumatic suspension, the movement of each cylinder is typically controlled independently, requiring a separate suspension main valve 50 for each side. The entire vehicle requires at least four suspension main valves 50, leading to numerous connecting pipes, complex structure, and difficulty in troubleshooting potential faults in the crane's hydraulic system. Furthermore, currently, each suspension main valve 50 has numerous integrated components and a complex internal oil passage system, resulting in many potential fault points and significant manufacturing challenges for the valve body. Therefore, from both the hydraulic system perspective and the main valve composition, existing pneumatic suspension hydraulic systems are expensive to manufacture and structurally complex.

[0039] In view of this, such as Figure 2 As shown, in an embodiment of the present invention, a hydropneumatic suspension hydraulic system is provided, which includes a left suspension cylinder group 10, a right suspension cylinder group 20, a first connecting oil circuit L1, a second connecting oil circuit L2, a rigidity / flexibility switching valve, and a combined suspension main valve 30. The first connecting oil circuit L1 connects the rod chamber of the left suspension cylinder group 10 and the rodless chamber of the right suspension cylinder group 20. The second connecting oil circuit L2 connects the rodless chamber of the left suspension cylinder group 10 and the rod chamber of the right suspension cylinder group 20. There are two rigidity / flexibility switching valves, which are respectively located on the first connecting oil circuit L1 and the second connecting oil circuit L2 and control the rigidity / flexibility switching between the left suspension cylinder group 10 and the right suspension cylinder group 20. The combined suspension main valve 30 is connected to both the first connecting oil circuit L1 and the second connecting oil circuit L2. The combined suspension main valve 30 and the rigidity / flexibility switching valve cooperate to control the operation or locking of the left suspension cylinder group 10 and the right suspension cylinder group 20.

[0040] In this configuration, the left suspension cylinder represents the left-side suspension cylinder group within the same suspension group, and the right suspension cylinder represents the right-side suspension cylinder group within the same suspension group. The rodless or rod-type chambers of the suspension cylinder groups on the same side are connected in series.

[0041] This invention combines the left and right suspension main valves in the existing oil-pneumatic suspension hydraulic system into a combined suspension main valve 30, reducing the number of main valves by at least half. Compared with the prior art, the total number of plug-in components such as lift valves is reduced by half, and the total number of internal oil passages of the existing main valve is also reduced by half, saving installation space for the main valve, simplifying the complexity of hydraulic pipeline connections, and making assembly more convenient.

[0042] In an embodiment of the present invention, the hydropneumatic suspension hydraulic system further includes a first oil inlet circuit L3 and a second oil inlet circuit L4. The combined suspension main valve 30 includes a first working port A1 and a second working port A2. The first oil inlet circuit L3 connects the first working port A1 and the first connecting circuit L1, and the second oil inlet circuit L4 connects the second working port A2 and the second connecting circuit L2. Hydraulic oil entering from the first working port A1 or the second working port A2 enters the connecting circuit through the first oil inlet circuit L3 or the second oil inlet circuit L4, respectively, to achieve oil circuit connectivity. Furthermore, the hydraulic circuits of the left and right suspension cylinder assemblies can be controlled independently without affecting each other.

[0043] In an embodiment of the present invention, the combined suspension main valve 30 includes a composite control valve 31 and a main valve block inserted into the composite control valve 31. The main valve block is an integrated valve assembly structure, wherein a first working port A1 and a second working port A2 are opened on the upper end face of the main valve block, and the first working port A1 and the second working port A2 are respectively connected to the rod chambers of the left suspension cylinder assembly 10 and the right suspension cylinder assembly 20; an oil inlet P and an oil return port T are opened on the side of the main valve block, and the oil inlet P and the oil return port T are respectively connected to the pressure oil passage and the return oil passage of the hydraulic system. Specifically, the main valve block integrates necessary valve components such as an upward flow valve 32, a downward flow valve 33, a return oil lock valve 34, a safety relief valve 36, and a one-way valve 35. Since the lifting and other control valve components are no longer integrated with the valve body 311 of the composite control valve 31, the processing difficulty of the internal oil passage of the valve body 311 of the composite control valve 31 is reduced, and the main valve is more convenient to manufacture.

[0044] like Figure 3 As shown, the composite control valve 31 is a three-position, three-way composite control valve, meaning it includes three working positions: left, middle, and right. In this hydropneumatic suspension system, there are two composite control valves 31, designated as a left control valve and a right control valve. The left and right control valves have identical structures and include three ports.

[0045] The left control valve includes:

[0046] The first internal working port C1 is located on the first side of the left control valve and is connected to the first working port A1;

[0047] The first internal oil inlet P1 and the first internal oil return port T1 are both located on the second side of the left control valve. The first internal oil inlet P1 is connected to the oil inlet P through the first internal oil inlet passage M1, and the first internal oil return port T1 is connected to the oil return port T through the first internal oil return passage M3.

[0048] The right control valve includes:

[0049] The second internal working port C2 is on the same side as the first internal working port C1 and located on the first side of the right control valve. The second internal working port C2 is connected to the second working port A2.

[0050] The second internal oil inlet P2 and the second internal oil return port T2 are both located on the second side of the right control valve. The second internal oil inlet P2 and the oil inlet P are connected through the second internal oil inlet passage M2, and the second internal oil return port T2 and the oil return port T are connected through the second internal oil return passage M4.

[0051] Specifically, when the pneumatic shut-off valve is in the connected position, in the left working position, the working ports (first working port A1 and second working port A2) are connected to the inlet port P, enabling the extension function of the suspension cylinder piston rod, while simultaneously isolating the working ports (first working port A1 and second working port A2) from the return port T. In the right working position, the working ports (first working port A1 and second working port A2) are connected to the return port T, enabling the retraction function of the suspension cylinder piston rod, while simultaneously isolating the working ports (first working port A1 and second working port A2) from the inlet port P. In the middle working position, the working ports (first working port A1 and second working port A2), the inlet port P, and the return port T are mutually isolated, enabling the position locking of the suspension cylinder piston rod. Furthermore, for ease of testing, a corresponding pressure test port can be individually installed at each port.

[0052] Furthermore, both the first internal oil inlet passage M1 and the second internal oil inlet passage M2 are equipped with an upward flow valve 32, and both the first internal oil return passage M3 and the second internal oil return passage M4 are equipped with a downward flow valve 33. The upward flow valve 32 has a pressure compensation function and is used to adjust the flow rate in the internal oil inlet passage; one upward flow valve 32 controls the upward speed of one side of the suspension cylinder assembly. The downward flow valve 33 also has a pressure compensation function and is used to adjust the flow rate in the internal oil return passage; one downward flow valve 33 controls the downward speed of one side of the suspension cylinder assembly.

[0053] Furthermore, the lower end face of the main valve block is also provided with a third working port B1 and a fourth working port B2, which are connected to the return oil port T through the internal main return oil passage M7. The return oil lock valve 34 is located on the internal main return oil passage M7. The third working port B1 is connected to the rodless chamber of the right suspension cylinder group 20 through the first return oil passage L5, and the fourth working port B2 is connected to the rodless chamber of the left suspension cylinder group 10 through the second return oil passage L6. Both the first return oil passage L5 and the second return oil passage L6 are provided with return oil check valves 37. The return oil check valves 37 are isolation check valves between the third working port B1 and the fourth working port B2, which not only realizes that the third working port B1 and the fourth working port B2 are respectively unidirectionally guided to the oil inlet end of the return oil lock valve 34, but also prevents the hydraulic oil in the rodless chambers of the left and right suspension cylinder groups from flowing together.

[0054] In an embodiment of the present invention, the hydropneumatic suspension hydraulic system further includes a second internal connecting oil passage M6, which connects to the first internal connecting oil passage M5 and the return port T. A safety relief valve 36 is provided on the second internal connecting oil passage M6. The safety relief valve 36 is used to limit the system high pressure and prevent hydraulic components such as accumulators from being damaged by high pressure impact.

[0055] In an embodiment of the present invention, the combined suspension main valve 30 has a first internal connecting oil passage M5, which connects the first oil inlet line L3 and the second oil inlet line L4. The first internal connecting oil passage M5 is provided with a one-way valve 35, which is a one-way valve for isolating the first working oil port A1 and the second working oil port A2. This not only enables the first working oil port A1 and the second working oil port A2 to be unidirectionally guided to the oil inlet end of the safety relief valve 36, but also prevents the hydraulic oil in the rod chambers of the left and right suspension cylinder assemblies from being cross-connected.

[0056] like Figure 4 The diagram shows the structure of a single composite control valve 31. This valve 31 includes a valve body 311 and a valve core 312 inserted into the valve body 311. The end of the valve core 312 is a tapered structure 313. The valve core 312 of this composite control valve 31 switches its operating position using a mechanism similar to a spool valve. Therefore, the actuation method of the valve core 312 can include two types: electromagnetic actuation and mechanical handle actuation. That is, each composite control valve 31 can be equipped with an emergency switching handle to manually switch the operating position of the composite control valve 31 after electrical control failure, ensuring that the hydropneumatic suspension system still functions. On the other hand, when the main valve core 312 is stuck by a foreign object, if the electromagnetic actuation cannot drive the main valve core 312 to move and clear the stuck object, the valve core 312 can be manually moved using a mechanical handle, thereby successfully eliminating the problem of the valve core 312 being stuck. Figure 3 The diagram shows the structure of the left control valve. The main oil passages (and C1→P1 and C1→T1) employ a cone valve structure, ensuring reliable isolation between oil ports C1, P1, and T1 when the oil passages need to be cut off. Furthermore, the end of the valve core 312 is designed as a cone structure 313, which improves the sealing performance of the contact area between the valve core 312 and the valve body 311. Therefore, compared with the prior art, the composite control valve 31 of this invention offers diverse control methods and effectively eliminates the problem of movement jamming of the valve core 312, ensuring stable operation of the hydropneumatic suspension system.

[0057] In an embodiment of the present invention, the rigid-flexible switching valve includes a pneumatic shut-off valve 42 and a pneumatic solenoid valve 41. The pneumatic shut-off valve 42 includes a connected position where the valve body 311 is in a flow-through state and a shut-off position where the valve body 311 is in a throttling state. The pneumatic solenoid valve 41 is located on the connecting oil line between the pressure air source and the pneumatic shut-off valve 42 and is used to control the switching of the pneumatic shut-off valve 42 between the connected and shut-off positions. The rod chamber and rodless chamber of the suspension cylinder groups on the left and right sides are controlled to be connected to each other by two corresponding pneumatic shut-off valves 42. The rod chamber of all cylinder groups is directly connected to the accumulator group. By controlling the connection and disconnection of the control ports at the upper and lower ends of the pneumatic shut-off valve 42 through the pneumatic solenoid valve 41, the working position of the pneumatic shut-off valve 42 is switched, so as to finally complete the conversion between the rigid and flexible working modes of the hydropneumatic suspension.

[0058] In summary, compared with the existing structure of rigid-flexible switching valve and main valve integration, the rigid-flexible switching valve of the present invention is no longer integrated with the main valve. The structure is changed from a cartridge-type pneumatic cone valve to an independently installed pneumatic shut-off valve 42. The valve port adopts a spherical sealing structure. The spherical sealing structure has a better sealing effect than the line sealing structure, reducing the probability of internal leakage of the system.

[0059] Furthermore, the hydropneumatic suspension hydraulic system involved in this invention has the following main functions: individual lifting, synchronous lifting, lifting of all axles, and vehicle body posture locking, which will be described one by one below. For ease of description, it is assumed that the vehicle consists of two suspension groups, front and rear. The left and right sides of the front suspension group are referred to as the left front point and right front point, respectively, and the left and right sides of the rear suspension group are referred to as the left rear point and right rear point, respectively.

[0060] (1) Individual lifting control mode: This refers to lifting control on one side of the vehicle body. Taking the suspension cylinder group at the left front point as an example, the suspension lifting and lowering control will be introduced separately. Figure 1 As shown, when the electromagnet at the left end of the pneumatic solenoid valve 41 is energized, the pneumatic solenoid valve 41 is in the left position. The lower end of the pneumatic shut-off valve 42 is connected to the pressurized air source, and the pneumatic shut-off valve 42 switches to the connected position, connecting the rodless chamber and the rod chamber of the suspension cylinder assembly on both sides. This mode is the flexible mode of the hydropneumatic suspension.

[0061] In this mode, when the left electromagnet of the right-side composite control valve 31 is energized, the composite control valve 31 switches to the left working position. The pressure oil source connects the rod chamber of the right suspension cylinder group 20 and the rodless chamber of the left suspension cylinder group 10 in sequence through the second working oil port A2 and the pneumatic shut-off valve 42. Since pressure oil is supplied between both the rod chamber and the rodless chamber, and the effective working area of ​​the rodless chamber is larger than that of the rod chamber, the hydraulic oil force in the rodless chamber is greater than that in the rod chamber. Therefore, the piston rod of the left suspension cylinder group 10 extends under the pressure of the pressure oil in the rodless chamber, realizing the independent rise of the left front point of the vehicle body.

[0062] When the right electromagnet of the right-side composite control valve 31 is energized, the composite control valve 31 switches to the right working position. The return oil line is connected to the rod chamber of the right suspension cylinder group 20 and the rodless chamber of the left suspension cylinder group 10 in sequence through the second working oil port A2 and the pneumatic shut-off valve 42. Under the action of the vehicle body weight, the piston rod of the left suspension cylinder group 10 retracts, realizing the independent descent of the left front point of the vehicle body.

[0063] Similarly, the lifting control of the suspension cylinder assembly at the right front point is the same as described above, and will not be repeated here.

[0064] (2) Synchronous lifting control mode: refers to the synchronous lifting control of the entire vehicle body. This synchronous lifting control needs to be performed in flexible mode.

[0065] In flexible mode, such as Figure 2 As shown, the electromagnets at the left end of the composite control valves 31 on both sides are energized, and all composite control valves 31 are switched to the left working position. The pressure oil source connects the rod chamber of the left suspension cylinder group 10 and the rodless chamber of the right suspension cylinder group 20 in sequence through the first working oil port A1 and the pneumatic shut-off valve 42. At the same time, the pressure oil source connects the rodless chamber of the left suspension cylinder group 10 and the rod chamber of the right suspension cylinder group 20 in sequence through the second working oil port A2 and the pneumatic shut-off valve 42. The left and right suspension cylinder groups are kept in differential connection. Under the pressure difference between the rod chamber and the rodless chamber, the piston rod of all suspension cylinder groups extends. Due to the pressure compensation effect of the rising flow in the oil inlet, the entire vehicle body rises synchronously.

[0066] In flexible mode, such as Figure 2 As shown, the electromagnets at the right end of the composite control valves 31 on both the left and right sides are energized, and all composite control valves 31 are switched to the right working position. The return oil line connects the rod chamber of the left suspension cylinder group 10 and the rodless chamber of the right suspension cylinder group 20 in sequence through the first working oil port A1 and the pneumatic shut-off valve 42. At the same time, the return oil line connects the rod chamber of the left suspension cylinder group 10 and the rodless chamber of the right suspension cylinder group 20 in sequence through the second working oil port A2 and the pneumatic shut-off valve 42. The left and right suspension cylinder groups are kept in differential connection. Under the pressure difference between the rod chamber and the rodless chamber, the piston rod of all suspension cylinder groups retracts. Due to the pressure compensation effect of the flow reduction valve 33 on the return oil line, the entire vehicle body is lowered synchronously.

[0067] (3) All Axles Lifting Mode: This refers to the crane lifting all axles to their highest position above the ground when the outriggers are extended. This function can only be implemented in rigid mode, such as... Figure 1As shown, when the electromagnet at the left end of the pneumatic solenoid valve 41 is de-energized, the pneumatic solenoid valve 41 operates in the right position. The upper end of the pneumatic shut-off valve 42 is connected to the pressurized air source, and the pneumatic shut-off valve 42 switches to the shut-off position, isolating the rodless chamber and the rod chamber of the suspension cylinder assembly on both sides. This mode is the rigid mode of the hydropneumatic suspension.

[0068] In this rigid mode, on the one hand, the electromagnets at the left ends of the composite control valves 31 on both sides are energized, and all composite control valves 31 switch to the left working position. The pressure oil source is connected to the rod chambers of the left and right suspension cylinder assemblies through the first working oil port A1 and the second working oil port A2, respectively. At the same time, on the other hand, the electromagnet at the right end of the return oil lock valve 34 is energized, and the return oil lock valve 34 switches to the connected position. The return oil line is connected to the rodless chambers of the left and right suspension cylinder assemblies through the third working oil port B1 and the fourth working oil port B2, respectively. Since the piston rod is fixed at the connection with the frame and the cylinder barrel is movable at the connection with the axle, it is equivalent to the piston rod being fixed. This results in the piston rod retracting relative to the cylinder barrel under the pressure of the rod chamber pressure oil, and all axles are raised to their highest position above the ground.

[0069] (4) Vehicle body posture locking mode, which means that the vehicle body position is stably maintained, that is, the position of the hydropneumatic suspension cylinder is locked. When all the solenoid valves in the hydropneumatic suspension system are de-energized, the composite control valve 31 is switched to the neutral position and the return oil lock valve 34 is also switched to the lock position. Due to the cone valve line sealing structure built into the above two components and the safety relief valve 36, the cavities of all suspension cylinder groups are in a closed state. At this time, the position of the hydropneumatic suspension cylinder is locked, and the vehicle body position is stably maintained.

[0070] In an embodiment of the present invention, an engineering vehicle is also proposed, which includes the above-described hydropneumatic suspension hydraulic system. This engineering vehicle employs all embodiments of the above-described hydropneumatic suspension hydraulic system and therefore possesses all the beneficial effects of such a system, which will not be elaborated upon further here.

[0071] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0072] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0073] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0074] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A hydropneumatic suspension hydraulic system, characterized in that, The hydropneumatic suspension hydraulic system includes: Left suspension cylinder assembly (10) and right suspension cylinder assembly (20); The first connecting oil circuit (L1) connects the rod chamber of the left suspension cylinder group (10) and the rodless chamber of the right suspension cylinder group (20); The second connecting oil circuit (L2) connects the rodless chamber of the left suspension cylinder group (10) and the rod chamber of the right suspension cylinder group (20); A rigid-flexible switching valve is provided on both the first connecting oil passage (L1) and the second connecting oil passage (L2); and A combined suspension main valve (30) is connected to both the first connecting oil circuit (L1) and the second connecting oil circuit (L2). The combined suspension main valve (30) cooperates with the rigidity-flexibility switching valve to control the movement or locking of the left suspension cylinder group (10) and the right suspension cylinder group (20). The combined suspension main valve (30) includes a first working port (A1), a second working port (A2), a composite control valve (31), and a main valve block that is plate-connected to the composite control valve (31). The main valve block is an integrated valve group structure. An oil inlet (P) and an oil return port (T) are provided on one side of the main valve block. There are two composite control valves (31), which are a left control valve and a right control valve, respectively. The left control valve and the right control valve have the same structure. The left control valve includes: The first internal working port (C1) is located on the first side of the left control valve and is connected to the first working port (A1); The first internal oil inlet (P1) and the first internal oil return (T1) are both located on the second side of the left control valve. The first internal oil inlet (P1) is connected to the oil inlet through the first internal oil inlet passage (M1), and the first internal oil return (T1) is connected to the oil return through the first internal oil return passage (M3). The right control valve includes: The second internal working port (C2) is on the same side as the first internal working port (C1) and located on the first side of the right control valve. The second internal working port (C2) and the second working port (A2) are connected. The second internal oil inlet (P2) and the second internal oil return (T2) are both located on the second side of the right control valve. The second internal oil inlet (P2) and the oil inlet are connected through the second internal oil inlet passage (M2). The second internal oil return (T2) and the oil return (T4) are connected through the second internal oil return passage (M4).

2. The hydropneumatic suspension hydraulic system according to claim 1, characterized in that, The hydropneumatic suspension hydraulic system further includes a first oil inlet circuit (L3) and a second oil inlet circuit (L4). The first oil inlet circuit (L3) is connected to the first working oil port (A1) and the first connecting oil circuit (L1), and the second oil inlet circuit (L4) is connected to the second working oil port (A2) and the second connecting oil circuit (L2).

3. The hydropneumatic suspension hydraulic system according to claim 2, characterized in that, The first working oil port (A1) and the second working oil port (A2) are located on the upper end face of the main valve block.

4. The hydropneumatic suspension hydraulic system according to claim 1, characterized in that, The main valve block includes an upward flow valve (32) and a downward flow valve (33). The first internal oil inlet passage (M1) and the second internal oil inlet passage (M2) are both equipped with the upward flow valve (32), and the first internal oil return passage (M3) and the second internal oil return passage (M4) are both equipped with the downward flow valve (33).

5. The hydropneumatic suspension hydraulic system according to claim 2, characterized in that, The main valve block also includes a return oil lock valve (34). The lower end face of the main valve block is provided with a third working oil port (B1) and a fourth working oil port (B2) that are connected to the return oil port through the internal main return oil passage (M7). The return oil lock valve (34) is located on the internal main return oil passage (M7). The third working oil port (B1) is connected to the rodless chamber of the right suspension cylinder group (20) through the first return oil passage (L5). The fourth working oil port (B2) is connected to the rodless chamber of the left suspension cylinder group (10) through the second return oil passage (L6).

6. The hydropneumatic suspension hydraulic system according to claim 5, characterized in that, The combined suspension main valve (30) has a first internal connecting oil passage (M5), which connects the first oil inlet passage (L3) and the second oil inlet passage (L4). The first internal connecting oil passage (M5) is equipped with a check valve (35), and both the first return oil passage (L5) and the second return oil passage (L6) are equipped with return oil check valves (37).

7. The hydropneumatic suspension hydraulic system according to claim 6, characterized in that, The hydropneumatic suspension hydraulic system also includes a second internal connecting oil passage (M6), which connects the first internal connecting oil passage (M5) and the return port (T). The main valve block also includes a safety relief valve (36) located on the second internal connecting oil passage (M6).

8. The hydropneumatic suspension hydraulic system according to any one of claims 1 to 7, characterized in that, The composite control valve (31) includes a valve body (311) and a valve core (312) inserted into the valve body (311), the end of which is a tapered structure (313).

9. The hydropneumatic suspension hydraulic system according to any one of claims 1 to 7, characterized in that, The rigid-flexible switching valve includes a pneumatic shut-off valve (42) and a pneumatic solenoid valve (41). The pneumatic shut-off valve (42) includes a connected position where the valve body is in a flow state and a shut-off position where the valve body is in a throttling state. The pneumatic solenoid valve (41) is used to control the pneumatic shut-off valve (42) to switch between the connected position and the shut-off position.

10. An engineering vehicle, characterized in that, The engineering vehicle includes the hydropneumatic suspension hydraulic system according to any one of claims 1 to 9.

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