Active hydraulic suspension system, control method and vehicle

Abstract

The application discloses an active hydraulic suspension system, a control method and a vehicle. The active hydraulic suspension system comprises a hydraulic actuator, a piston in a cylinder of the hydraulic actuator separates a recovery cavity and a compression cavity; a first accumulator is communicated with the recovery cavity through a recovery oil path; a second accumulator is communicated with the compression cavity through a compression oil path; a fluid on-off valve is arranged between the two oil paths and is configured to communicate the two cavities when being turned on, or cut off the communication to form a first independent loop of the recovery cavity and the first accumulator and a second independent loop of the compression cavity and the second accumulator when being turned off. The application realizes adaptive adjustment of suspension stiffness by switching a hydraulic loop, and takes into account driving comfort and dynamic posture control.

Description

Technical Field

[0001] This invention relates to the field of vehicle technology, and more particularly to an active hydraulic suspension system, control method, and vehicle. Background Technology

[0002] Currently, hydraulic suspension systems are widely used in the field of active and semi-active vehicle suspension technology due to their high power density and fast response characteristics. Existing hydraulic suspension systems typically employ an architecture with two fixed interconnected chambers of hydraulic cylinders or throttling control via complex valve systems. However, this traditional architecture has limitations in addressing vehicle ride comfort and dynamic attitude control. When the two chambers are fixedly interconnected, the system's equivalent stiffness is low. While this is beneficial for comfort, it cannot provide sufficient anti-roll or anti-pitch capabilities under conditions requiring high stiffness support, such as braking, acceleration, or cornering. If damping is increased through valve throttling to suppress vehicle movement, it leads to increased impact sensation and reduced ride comfort. Summary of the Invention

[0003] The purpose of this invention is to provide an active hydraulic suspension system, control method, and vehicle for providing a hydraulic suspension system that can balance driving comfort and dynamic attitude control.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] An active hydraulic suspension system, comprising:

[0006] A hydraulic actuator, comprising a cylinder and a piston disposed within the cylinder, the piston dividing the cylinder into a recovery chamber and a compression chamber;

[0007] An accumulator, comprising a first accumulator and a second accumulator, wherein the first accumulator and the second accumulator are respectively disposed in a recovery oil circuit and a compression oil circuit, the first accumulator being connected to the recovery chamber through the recovery oil circuit, and the second accumulator being connected to the compression chamber through the compression oil circuit;

[0008] A fluid on / off valve is disposed between the compressed oil circuit and the restored oil circuit;

[0009] The fluid on / off valve connects the recovery chamber and the compression chamber in a conducting state, or disconnects the fluid connection between the recovery chamber and the compression chamber in a disconnected state, so that the recovery chamber and the first accumulator form a first independent circuit, and the compression chamber and the second accumulator form a second independent circuit.

[0010] Preferably, it further includes a first damping valve and a second damping valve, wherein the recovery chamber is connected to the first accumulator via the first damping valve, and the compressed oil circuit is connected to the second accumulator via the second damping valve;

[0011] One end of the fluid on / off valve is connected to the oil circuit between the first damping valve and the first accumulator, and the other end of the fluid on / off valve is connected to the oil circuit between the second damping valve and the second accumulator.

[0012] Preferably, the fluid on / off valve is a normally open solenoid valve or a normally open proportional solenoid valve;

[0013] And / or, the first damping valve and the second damping valve are continuously adjustable damping valves or passive valve systems;

[0014] And / or, a first temperature and pressure sensor is provided between the first accumulator and the fluid on / off valve, and a second temperature and pressure sensor is provided between the second accumulator and the fluid on / off valve.

[0015] Preferably, it further includes an oil source unit and a reversing valve assembly, wherein the oil source unit is selectively fluidly connected to the recovery oil circuit and / or the compression oil circuit through the reversing valve assembly to fill or drain oil into the hydraulic actuator.

[0016] Preferably, the reversing valve assembly includes a plurality of solenoid valves;

[0017] The multiple solenoid valves are configured to achieve independent oil filling and emptying of a single wheel or synchronous oil filling and emptying of wheels on the same axle through different on / off combinations;

[0018] And / or, the reversing valve assembly includes a two-position four-way solenoid valve or a three-position four-way solenoid valve connected in parallel to the fluid on / off valve, and / or a throttle valve is provided between the two-position four-way solenoid valve or the three-position four-way solenoid valve and the oil source unit.

[0019] And / or, the oil source unit includes multiple unidirectional or bidirectional pumps for controlling the pumping direction of the oil.

[0020] Preferably, it further includes a temperature balancing device, which includes a temperature accumulator and a temperature control valve;

[0021] The temperature control valve is located between the main oil circuit of the system and the temperature accumulator, and the temperature control valve controls the fluid connection between the temperature accumulator and the main oil circuit of the system to compensate for the volume change caused by the change in oil temperature.

[0022] Preferably, the hydraulic actuator is a shock absorber or a hydraulic cylinder;

[0023] At least a portion of the first accumulator, the second accumulator, the fluid on / off valve, and the first damping valve and the second damping valve are integrated inside the shock absorber or hydraulic cylinder; or...

[0024] The first accumulator, the second accumulator, the fluid on / off valve, the first damping valve, and the second damping valve are integrated on a separate valve island, which is connected to the shock absorber or hydraulic cylinder via pipelines.

[0025] Furthermore, the present invention also provides a control method for an active hydraulic suspension system, applied to the hydraulic suspension system as described above, characterized in that it includes:

[0026] Under comfortable operating conditions, the fluid on / off valve is controlled to open, so that the recovery chamber and the compression chamber are fluidly connected to provide the first system stiffness;

[0027] Under attitude control conditions, the fluid on / off valve is controlled to disconnect, cutting off the fluid connection between the recovery chamber and the compression chamber, so that the recovery chamber and the first accumulator form a first independent circuit, and the compression chamber and the second accumulator form a second independent circuit, so as to provide a second system stiffness greater than the first system stiffness.

[0028] Preferably, the triggering conditions for the attitude control condition include: detecting that the vehicle is in a braking, acceleration, turning, lane changing or large displacement state;

[0029] The control method further includes:

[0030] During height adjustment, the fluid on / off valve and directional valve group are controlled, and the oil source unit is controlled to fill or drain oil into the hydraulic actuator to adjust the vehicle height.

[0031] Under active power conditions, the active power control of a single wheel can be achieved by controlling the combination of the on and off states of multiple solenoid valves in the directional valve group, or by controlling the synchronous active power control of the wheels on the same axle.

[0032] Furthermore, the present invention also provides a vehicle, characterized in that it includes a vehicle body and an active hydraulic suspension system as described above, the active hydraulic suspension system being connected between the vehicle body and the wheels.

[0033] Compared with the prior art, the beneficial effects of the present invention include at least the following:

[0034] By installing a fluid on / off valve between the recovery and compression oil circuits and configuring independent accumulators for each chamber, multiple dynamic modes can be switched. In comfort mode, the fluid on / off valve is open, connecting the recovery and compression chambers. At this point, the pressure in both chambers tends to balance, and the system's equivalent stiffness is mainly determined by the accumulator volume and piston area, exhibiting low stiffness characteristics. This effectively isolates high-frequency road vibrations, ensuring ride comfort. In attitude control mode, the fluid on / off valve is closed, cutting off the fluid connection between the two chambers. This creates two independent hydraulic spring circuits: one between the recovery chamber and the first accumulator, and another between the compression chamber and the second accumulator. The total system stiffness then becomes the parallel superposition of the stiffnesses of the two independent circuits, with the stiffness value proportional to the square of the annular area of ​​the recovery chamber and the piston area of ​​the compression chamber, thus increasing stiffness. This stiffness adjustment mode, without relying on complex mechanical linkages or expensive actuators for continuous output, can suppress braking dive, acceleration pitch, and cornering roll while maintaining smoothness during normal driving. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the oil circuit of the active hydraulic suspension system according to an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of a hydraulic circuit in which multiple solenoid valves in an embodiment of the present invention are replaced with two-position four-way solenoid valves and three-position four-way solenoid valves.

[0037] Figure 3 This is a schematic diagram of the hydraulic circuit for the conduction of a two-position four-way solenoid valve and a three-position four-way solenoid valve according to an embodiment of the present invention.

[0038] In the diagram: 1. Hydraulic actuator; 11. Compression chamber; 12. Piston; 13. Recovery chamber; 21. First accumulator; 22. Second accumulator; 31. Recovery oil circuit; 32. Compression oil circuit; 4. Fluid on / off valve; 51. First damping valve; 52. Second damping valve; 61. First temperature and pressure sensor; 62. Second temperature and pressure sensor; 71. Temperature accumulator; 72. Temperature control valve; 8. Oil source unit; 9. Directional valve assembly; 91. First directional valve; 92. Second directional valve; 93. Third directional valve; 94. Fourth directional valve; 95. Fifth directional valve; 96. Sixth directional valve; 10. Throttle valve; 101. Two-position four-way solenoid valve; 102. Three-position four-way solenoid valve. Detailed Implementation

[0039] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, they are provided to make the invention more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and therefore repeated descriptions of them will be omitted.

[0040] The terms used to express position and direction in this invention are illustrated with the accompanying drawings, but changes can be made as needed, and all such changes are included within the scope of protection of this invention.

[0041] like Figures 1 to 3 As shown, this embodiment provides an active hydraulic suspension system, which includes a hydraulic actuator 1, a first accumulator 21, a second accumulator 22, and a fluid on / off valve 4. The hydraulic actuator 1 includes a cylinder and a piston 12 disposed within the cylinder, which divides the cylinder into a restoring chamber 13 and a compression chamber 11. As a moving component of the suspension system, the hydraulic actuator 1 physically isolates the restoring chamber 13 from the compression chamber 11 via the piston 12, but controls fluid connection or disconnection through an external hydraulic circuit. The first accumulator 21 is fluidly connected to the restoring chamber 13 via a restoring oil passage 31, and the second accumulator 22 is fluidly connected to the compression chamber 11 via a compression oil passage 32. In this embodiment, the first accumulator 21 and the second accumulator 22 are preferably gas-filled accumulators, utilizing the compressibility of gas to provide hydraulic spring stiffness.

[0042] Furthermore, a fluid on / off valve 4 is disposed between the recovery oil circuit 31 and the compression oil circuit 32. The fluid on / off valve 4 is configured to, in the open state, allow fluid communication between the recovery chamber 13 and the compression chamber 11, or in the closed state, cut off the fluid communication between the recovery chamber 13 and the compression chamber 11, so that the recovery chamber 13 and the first accumulator 21 form a first independent circuit, and the compression chamber 11 and the second accumulator 22 form a second independent circuit. When the fluid on / off valve 4 is open, the pressures in the recovery chamber 13 and the compression chamber 11 tend to be balanced, and the system's equivalent stiffness is mainly determined by the accumulator volume and the cross-sectional area of ​​the piston 12, exhibiting low stiffness characteristics. When the fluid on / off valve 4 is disconnected, the two chambers are decoupled. The restoration chamber 13 and the first accumulator 21, and the compression chamber 11 and the second accumulator 22, respectively form independent hydraulic spring units. At this time, the total system stiffness becomes the parallel superposition of the stiffness of the two independent circuits. Since the stiffness of the hydraulic spring is proportional to the square of the effective working area, the system stiffness in the disconnected state will be higher than that in the conducting state, thus meeting the high support stiffness requirement of vehicle attitude control. In the above-mentioned comfort and attitude control conditions, the following reversing valve group 9 is normally closed.

[0043] Furthermore, this embodiment also includes a first damping valve 51 and a second damping valve 52. The recovery oil circuit 31 is connected to the first accumulator 21 via the first damping valve 51, and the compression oil circuit 32 is connected to the second accumulator 22 via the second damping valve 52. It should be emphasized that one end of the fluid on / off valve 4 is connected to the oil circuit between the first damping valve 51 and the first accumulator 21, and the other end of the fluid on / off valve 4 is connected to the oil circuit between the second damping valve 52 and the second accumulator 22. This connection method ensures that when the fluid on / off valve 4 is disconnected, the first damping valve 51 is still connected in series between the recovery chamber 13 and the first accumulator 21, and the second damping valve 52 is still connected in series between the compression chamber 11 and the second accumulator 22, so that each of the two independent circuits retains its complete damping function. If the fluid on / off valve 4 is located on the side of the damping valve closer to the hydraulic actuator 1, it may cause one side of the circuit to lose damping control or form a dead zone when disconnected, thus failing to achieve the expected independent suspension performance. Therefore, the relative positional relationship between the fluid on / off valve 4 and the damping valve is the key to realizing dual independent circuits.

[0044] Furthermore, the fluid on / off valve 4 is a normally open solenoid valve or a normally open proportional solenoid valve. When the fluid on / off valve 4 is de-energized, it remains in the conducting state. Specifically, when the vehicle experiences an electrical system failure, controller power failure, or wiring harness breakage, the fluid on / off valve 4 automatically resets to the conducting state due to power loss, forcing the suspension system into a low-stiffness comfort mode. This avoids the risk of excessive suspension stiffness, causing severe vehicle bouncing or loss of control, due to the valve accidentally locking in the off state. Furthermore, the low-stiffness mode ensures that the vehicle maintains basic ride comfort and tire contact even after losing active control. In contrast, if a normally closed valve is used, a power failure would cause the suspension to enter a high-stiffness attitude control mode, which could pose serious safety hazards in high-speed driving or emergency obstacle avoidance scenarios. Additionally, the first damping valve 51 and the second damping valve 52 can be continuously adjustable damping valves or passive valve systems. When a continuously adjustable damping valve is used, the system can further achieve stepless adjustment of the damping force, providing more precise chassis dynamic control. When a passive valve system is used, system cost and control complexity can be reduced, making it suitable for vehicle configurations with high cost-effectiveness requirements. Regardless of the type of damping valve used, the function of stiffness switching by the fluid on / off valve 4 is not affected.

[0045] Furthermore, the active hydraulic suspension system also includes an oil supply unit 8 and a reversing valve assembly 9. The oil supply unit 8 is selectively fluidly connected to the recovery oil circuit 31 and / or the compression oil circuit 32 via the reversing valve assembly 9 to supply or discharge oil to the hydraulic actuator 1. In other words, the oil supply unit 8 and the reversing valve assembly 9 are superimposed on the suspension system as an independent functional module. This means that regardless of whether the oil supply unit 8 is working or what state the reversing valve assembly 9 is in, the function of the fluid on / off valve 4 in switching the connection between the recovery chamber 13 and the compression chamber 11 remains effective and undisturbed. This ensures that when the system loses its active oil supply capability, it can still degenerate into a semi-active suspension with stiffness self-adaptation capability, guaranteeing the minimum safe driving performance of the entire vehicle.

[0046] In this embodiment, the oil source unit 8 includes a bidirectional pump, which is configured to control the pumping direction of the oil by reversing its rotation. Specifically, the bidirectional pump is typically driven by a reversible motor. When the motor rotates forward, the bidirectional pump draws oil from the reservoir and pumps it to the high-pressure port of the directional valve assembly 9, providing filling pressure to the hydraulic actuator 1. When the motor rotates in reverse, the inlet and outlet functions of the bidirectional pump are interchanged, drawing the oil in the hydraulic actuator 1 back to the reservoir, thus achieving oil discharge and pressure reduction. Compared to the traditional scheme that uses a unidirectional pump in conjunction with a complex directional valve assembly 9 to change the flow direction, the use of a bidirectional pump significantly reduces the number of hydraulic components and the volume of the valve island, lowers the system's internal resistance and control complexity, and improves transmission efficiency.

[0047] In some embodiments, the oil source unit 8 further includes multiple unidirectional pumps (not shown in the figure). By setting multiple unidirectional pumps to control the pumping direction of the oil, the setting can be made according to the actual installation space. The principle is the same as described above and will not be repeated here.

[0048] Furthermore, the directional valve assembly 9 includes multiple solenoid valves, which are configured to achieve independent oil filling and emptying of a single wheel or synchronous oil filling and emptying of wheels on the same axle through different on / off combinations. To avoid limiting the protection scope to specific valve body numbers or specific oil circuit connection forms, the control logic of the directional valve assembly 9 is summarized here. The directional valve assembly 9 is essentially a hydraulic flow distribution matrix, which contains several solenoid valves that act as switches (hereinafter collectively referred to as the first directional valve 91, the second directional valve 92, etc.). One end of these solenoid valves converges to the main oil circuit of the oil source unit 8, and the other end is independently connected to the recovery oil circuit 31 or compression oil circuit 32 of each wheel hydraulic actuator 1.

[0049] For example, when a single-wheel independent adjustment mode is required, the control system only activates the first and second directional valves 91 and 92 corresponding to the target wheel, while keeping the directional valves corresponding to other wheels closed. At this time, the oil output from the oil source unit 8 is precisely guided to the hydraulic actuator 1 of the target wheel, while the oil circuits of other wheels are physically isolated and do not affect each other. This mode is suitable for vehicle maintenance lifting, single-wheel extrication, or fine-tuning for changes in load on a single wheel. When a synchronous adjustment mode for wheels on the same axle is required, the control system simultaneously activates the first and second directional valves 91 and 92, as well as the third and sixth directional valves 93 and 96, corresponding to the wheels on both sides of the same axle (such as the front or rear axle). At this time, the oil output from the oil source unit 8 flows in parallel into the two hydraulic actuators 1. Because the oil pressure in both circuits is balanced at the source, synchronous raising and lowering of the left and right wheel heights can be achieved. This mode is often used for switching the overall vehicle height mode or for overall height reduction and drag reduction during high-speed driving. In practical engineering, an independent two-position two-way valve combination can be used depending on the integration level of the valve island, or an integrated multi-position multi-way valve can be used to achieve an equivalent on / off combination. In another embodiment, the directional valve group 9 can also be a two-position four-way solenoid valve 101 or a three-position four-way solenoid valve 102 connected in parallel to the fluid on / off valve 4. In addition, the two-position four-way solenoid valve 101 can be replaced by the first directional valve 91 and the second directional valve 92, and the three-position four-way solenoid valve 102 can be replaced by the third directional valve 93, the fourth directional valve 94, the fifth directional valve 95, and the sixth directional valve 96. The principle is the same, and it will not be described in detail here. However, such replacements can be selectively designed according to the size of the installation space, which greatly improves the adaptability of the hydraulic circuit. However, a throttle valve 10 is also provided between the two-position four-way solenoid valve 101 or the three-position four-way solenoid valve 102 and the oil source unit 8. The throttle valve 10 can regulate the flow rate of the oil in the oil circuit to maintain a corresponding balance. For example, if multiple solenoid valves are proportional solenoid valves, then the flow rate can be adjusted without setting up a throttle valve 10, relying solely on the function of the solenoid valve itself.

[0050] Furthermore, during intense attitude control, such as emergency braking to prevent nose-diving, in addition to disconnecting the fluid on / off valve 4 to increase passive stiffness, the oil source unit 8 can be simultaneously controlled to quickly replenish oil to the compression chamber 11, actively offsetting the compression stroke caused by load transfer. This achieves a faster and stronger attitude suppression effect than simple passive stiffness variation, enabling the active hydraulic suspension system of this embodiment to cover all working conditions from ultimate comfort to extreme handling.

[0051] Furthermore, the active hydraulic suspension system also includes a temperature balancing device, which comprises a temperature accumulator 71 and a temperature control valve 72. The temperature control valve 72 is located between the system's main oil circuit and the temperature accumulator 71, and is configured to control the fluid communication between the temperature accumulator 71 and the system's main oil circuit to compensate for volume changes caused by oil temperature variations. In this embodiment, a temperature balancing device is used as a volume compensation mechanism. When the temperature of the left hydraulic actuator 1 rises, the oil volume expands. The system monitors the system pressure change through a height sensor (not shown in the figure) or a temperature and pressure sensor. After a period of time, during non-active power operation, the temperature control valve 72 is activated, and the oil source unit 8 rotates clockwise to pump the oil from the left hydraulic actuator 1 into the temperature accumulator 71, achieving oil balancing in the shock absorber. Conversely, when the temperature decreases, the oil source unit 8 rotates counterclockwise to pump the oil from the temperature accumulator 71 into the hydraulic actuator 1, achieving oil balancing, similar to the working principle of other shock absorbers. Through this dynamic volume change action, the temperature balancing device can effectively maintain the stability of the pressure reference of the system under different thermal states, ensuring the long-term consistency of the suspension stiffness characteristics.

[0052] Furthermore, the temperature balancing device is an optional auxiliary component in this invention. Even without the temperature balancing device, the fluid on / off valve 4 can still independently perform on / off actions, switching between comfort mode and attitude control mode. Therefore, the temperature balancing device mainly aims to further improve the system's performance under extreme temperature environments or long-term high-intensity operating conditions, enhancing product stability.

[0053] In addition, the aforementioned temperature control valve 72 can be a normally closed solenoid valve, which is briefly energized and opened only when temperature compensation is required, or it can be a proportional solenoid valve, which continuously adjusts the opening degree according to the magnitude of temperature or pressure deviation to achieve more precise volume compensation control. Furthermore, the trigger control of the temperature balancing device can also be implemented in various ways. For example, the oil temperature signal can be directly collected in real time by a temperature sensor installed in the oil circuit, and the temperature control valve 72 is triggered when the oil temperature change exceeds a preset threshold; alternatively, the static pressure change of the main oil circuit can be monitored by a temperature and pressure sensor, and the compensation program is initiated when a pressure deviation that does not match the vehicle height change for a certain period of time, or a volume change caused by temperature, is detected. The temperature and pressure sensors include a first temperature and pressure sensor 61 and a second temperature and pressure sensor 62. The first temperature and pressure sensor 61 is located between the first accumulator 21 and the fluid on / off valve 4, and the second temperature and pressure sensor 62 is located between the second accumulator 22 and the fluid on / off valve 4.

[0054] Furthermore, the hydraulic actuator 1 is a shock absorber or a hydraulic cylinder. Regarding the installation positions of functional components such as the first accumulator 21, the second accumulator 22, the fluid on / off valve 4, and the first damping valve 51 and the second damping valve 52, this invention provides two implementation schemes to adapt to the chassis space layout and maintenance needs of different vehicle models.

[0055] Preferably, at least a portion of the first accumulator 21, the second accumulator 22, the fluid on / off valve 4, and the first damping valve 51 and the second damping valve 52 are integrated inside the shock absorber. This distributed integration scheme makes full use of the external contour space or internal redundant volume of the shock absorber cylinder. For example, the first accumulator 21 and the second accumulator 22 can be fixed to the outer wall of the cylinder body in a coaxial or lateral parallel manner, while the fluid on / off valve 4 and the damping valve are embedded in the cylinder body end cover or a specially designed valve block, which directly connects to the cylinder body oil port. This highly integrated structural design significantly reduces the number and length of external hydraulic lines, not only reducing the risk of leakage due to loose pipe joints, but also effectively saving layout space in the chassis wheel arch area. In addition, since the functional components move with the shock absorber as a whole, the number of fixing points on the vehicle body side is reduced, which is conducive to achieving a lightweight and compact chassis.

[0056] Preferably, the first accumulator 21, the second accumulator 22, the fluid on / off valve 4, and the first damping valve 51 and the second damping valve 52 are integrated on a separate valve island (not shown in the figure), which is connected to the shock absorber via pipelines. In this centralized arrangement, the valve island, as an independent hydraulic control module, is installed in a sprung position such as under the body longitudinal beam, subframe, or floor, and is connected to the shock absorber's recovery chamber 13 and compression chamber 11 via two high-pressure hoses, respectively. This arrangement transfers the complex valve system and accumulator assembly from the violently vibrating unsprung region to the relatively stable sprung region. On the one hand, it improves the working environment of the hydraulic components and extends their service life; on the other hand, it greatly facilitates production assembly and after-sales maintenance. When it is necessary to inspect or replace valves or accumulators, it is not necessary to disassemble the entire shock absorber assembly; the operation can be performed only at the valve island. At the same time, moving the large-mass accumulator and valve assembly to the sprung region also helps to reduce the unsprung mass, further improving the dynamic response of the suspension system.

[0057] In practical applications, technicians can choose between the two solutions based on the specific vehicle's chassis architecture, cost targets, and maintenance strategies. They can even combine these two arrangements on different axles of the same vehicle. Regardless of the integration method, any structure that includes the hydraulic actuator 1, dual accumulators, and bridging fluid on / off valve 4 falls within the protection scope of this invention.

[0058] This embodiment provides a control method for a hydraulic suspension system. This control method is applied to any of the active hydraulic suspension systems described in the foregoing embodiments. The control method includes the following steps:

[0059] In step S100, under comfortable operating conditions, all directional valve assemblies 9 (i.e., multiple solenoid valves) are closed, and the control fluid on / off valve 4 is opened, allowing fluid communication between the recovery chamber 13 and the compression chamber 11 to provide the first system stiffness. Specifically, comfortable operating conditions typically correspond to the vehicle's operation on smooth roads, low-speed driving, or slightly bumpy roads. The control system monitors vehicle status parameters in real time through onboard sensors. When it determines that there is no current attitude control requirement and no height adjustment command has been received, it is considered to be in comfortable operating conditions. In this state, the control system sends a power-off or power-on signal to the fluid on / off valve 4 (depending on whether the valve body is normally open or normally closed) to keep it open. At this time, the oil passage barrier between the recovery chamber 13 and the compression chamber 11 is removed, and the pressure in the two chambers quickly tends to balance. The effective pressure-bearing area inside the hydraulic actuator 1 degenerates into the cross-sectional area of ​​the piston 12. Since the cross-sectional area of ​​the piston 12 is much smaller than the effective area of ​​the piston 12, the equivalent stiffness of the system is significantly reduced, forming a soft, low-stiffness mode. This low stiffness characteristic can efficiently absorb high-frequency micro-vibrations from the road surface, preventing vibration energy from being transferred to the vehicle body, thus ensuring excellent ride comfort.

[0060] In step S200, under attitude control conditions, all directional valve groups 9 (i.e., multiple solenoid valves) are closed, and the control fluid on / off valve 4 is disconnected, cutting off the fluid connection between the recovery chamber 13 and the compression chamber 11. This allows the recovery chamber 13 to form a first independent circuit with the first accumulator 21, and the compression chamber 11 to form a second independent circuit with the second accumulator 22, providing a second system stiffness greater than the first system stiffness. Specifically, attitude control conditions refer to scenarios where the vehicle undergoes drastic changes and the suspension needs to provide additional support to suppress abnormal vehicle posture. When the control system detects that the preset attitude control trigger conditions are met, it immediately performs a switch. In the disconnected state, the fluid exchange channel between the recovery chamber 13 and the compression chamber 11 is physically closed, and the two are decoupled into two completely independent hydraulic spring units. At this time, the stiffness on the recovery chamber 13 side is determined by the annular area of ​​the first accumulator 21 and the recovery chamber 13, and the stiffness on the compression chamber 11 side is determined by the area of ​​the second accumulator 22 and the piston 12 of the compression chamber 11. The total system stiffness becomes the sum of the two. Since the stiffness of a hydraulic spring is proportional to the square of its effective area, and the stiffnesses of the two independent circuits are superimposed in parallel, the stiffness of the second system is greater than that of the first system. This high-stiffness mode can effectively resist vehicle pitch or roll caused by load transfer, improve the stability of tire contact load, and thus ensure driving safety under extreme conditions.

[0061] Preferably, the triggering conditions for attitude control include detecting that the vehicle is in a braking, acceleration, turning, lane changing, or large displacement state. In specific implementation, the control system comprehensively judges the situation by collecting multi-dimensional signals such as longitudinal acceleration, lateral acceleration, steering wheel angle, wheel speed difference, and suspension displacement sensors. For example, when the longitudinal deceleration exceeds a preset threshold, such as 0.3g, it is determined to be an emergency braking condition, triggering attitude control to prevent nose-diving. When the lateral acceleration exceeds the threshold or the steering wheel angle rate is too fast, it is determined to be a sharp turning condition, triggering attitude control to suppress body roll; when the suspension compression travel is close to the limit block or the wheel suspension travel is too large, it is determined to be a large displacement state, triggering attitude control to provide progressive buffer protection. In addition, the triggering conditions can also be extended to scenarios such as emergency obstacle avoidance and hill start. This triggering mechanism based on multi-source signal fusion ensures the timeliness and accuracy of switching, avoiding the loss of comfort caused by false triggering or the safety risks caused by missed triggering.

[0062] Furthermore, the control method also includes control during height adjustment. During height adjustment, the fluid on / off valve 4 and the directional valve group 9 are controlled, and the oil supply unit 8 is controlled to supply or discharge oil to the hydraulic actuator 1 to adjust the vehicle height (i.e., lifting and wheel-lifting actions). Specifically, as follows... Figure 1 As shown, the left front / rear wheels are located on the left, and the right front / rear wheels are located on the right. When the left wheel is lifted and the right wheel is raised, the motor of the oil source unit 8 rotates counterclockwise. The oil in the left recovery chamber 13 passes through the first damping valve 51 and merges with the oil in the first accumulator 21. It then flows through the first reversing valve 91, the oil source unit 8, the second reversing valve 92, and the second damping valve 52 to the left compression chamber 11. At this time, the pressure in the chamber increases, achieving the lifting of the left side of the vehicle body. Simultaneously, the oil in the right compression chamber 11 passes through the second damping valve 52 and merges with the oil in the second accumulator 22. It then flows through the fifth reversing valve 95, the oil source unit 8, the fourth reversing valve 94, and the first damping valve 51 to the right recovery chamber 13. Another oil path leads to the second accumulator 22. At this time, the pressure in the chamber increases, achieving the lifting of the right wheel. The solid black dots on the oil paths in the diagram indicate where the oil can flow between them.

[0063] When the left wheel and right wheel are lifted, the motor of the oil source unit 8 rotates counterclockwise. The oil path in the left recovery chamber 13 is the same as described above, and will not be repeated here. At the same time, the oil in the right recovery chamber 13 passes through the first damping valve 51 and merges with the oil in the first accumulator 21. Then, it passes through the third reversing valve 93, the oil source unit 8, and the sixth reversing valve 96. At this time, one oil path leads to the second accumulator 22, and the other oil path goes through the second damping valve 52 to the right compression chamber 11. The pressure in the chamber increases, realizing the lifting action of the right wheel.

[0064] Similarly, it can also realize the lifting of the left wheel and the right wheel, the lifting of the left wheel and the right wheel, and the independent lifting and lifting of the left wheel and the right wheel. In this way, the function of independent control of the four wheels of the fully active suspension can be realized through a single oil source unit 8, which saves costs and installation space. The wheel movements will not be described in detail here.

[0065] Therefore, under active power conditions, by controlling the on / off combinations of multiple solenoid valves in the directional valve assembly 9, independent single-wheel or synchronous active power control of wheels on the same axle can be achieved. For example, when the vehicle needs to be raised as a whole to pass through an obstacle, the control system simultaneously activates the directional valves corresponding to the four wheels, driving the oil source unit 8 to pump oil in the forward direction, achieving synchronous lifting of all four wheels. When the vehicle needs to perform single-wheel traction or maintenance lifting, only the directional valve corresponding to the target wheel is activated, while the directional valves of the other wheels are closed, achieving precise local height adjustment.

[0066] The coordinated control of this fluid on / off valve 4 and the directional valve group 9 enables the same hydraulic system to be compatible with both passive variable stiffness and active height adjustment functions, greatly improving the system's integration and functional reuse rate.

[0067] This embodiment provides a vehicle using the aforementioned active hydraulic suspension system. The vehicle includes a body and four wheel assemblies. Hydraulic actuators are connected between the body and each wheel. Furthermore, the accumulators, cross-connection valves, and damping valves corresponding to each actuator are integrated into a valve island assembly. The oil supply unit and directional valve group are centrally located. Under different operating conditions, by controlling the opening or closing of each cross-connection valve, the system can switch between a low-stiffness comfort mode and a high-stiffness attitude control mode, and can achieve independent leveling of a single wheel or synchronous height adjustment of all four wheels.

[0068] 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 invention without departing from the principles and spirit of the invention, and all such changes should fall within the protection scope of the claims of the present invention.

Claims

1. An active hydraulic suspension system, characterized in that, include: A hydraulic actuator, comprising a cylinder and a piston disposed within the cylinder, the piston dividing the cylinder into a recovery chamber and a compression chamber; An accumulator, comprising a first accumulator and a second accumulator, wherein the first accumulator and the second accumulator are respectively disposed in a recovery oil circuit and a compression oil circuit, the first accumulator being connected to the recovery chamber through the recovery oil circuit, and the second accumulator being connected to the compression chamber through the compression oil circuit; A fluid on / off valve is disposed between the compressed oil circuit and the restored oil circuit; The fluid on / off valve connects the recovery chamber and the compression chamber in a conducting state, or disconnects the fluid connection between the recovery chamber and the compression chamber in a disconnected state, so that the recovery chamber and the first accumulator form a first independent circuit, and the compression chamber and the second accumulator form a second independent circuit.

2. The active hydraulic suspension system according to claim 1, characterized in that, It also includes a first damping valve and a second damping valve, the recovery chamber is connected to the first accumulator via the first damping valve, and the compressed oil circuit is connected to the second accumulator via the second damping valve; One end of the fluid on / off valve is connected to the oil circuit between the first damping valve and the first accumulator, and the other end of the fluid on / off valve is connected to the oil circuit between the second damping valve and the second accumulator.

3. The active hydraulic suspension system according to claim 2, characterized in that, The fluid on / off valve is a normally open switch solenoid valve or a normally open proportional solenoid valve. And / or, the first damping valve and the second damping valve are continuously adjustable damping valves or passive valve systems; And / or, a first temperature and pressure sensor is provided between the first accumulator and the fluid on / off valve, and a second temperature and pressure sensor is provided between the second accumulator and the fluid on / off valve.

4. The active hydraulic suspension system according to claim 1, characterized in that, It also includes an oil source unit and a reversing valve assembly, wherein the oil source unit is selectively fluidly connected to the recovery oil circuit and / or the compression oil circuit through the reversing valve assembly to fill or drain oil into the hydraulic actuator.

5. The active hydraulic suspension system according to claim 4, characterized in that, The reversing valve group includes multiple solenoid valves; The multiple solenoid valves are configured to achieve independent oil filling and emptying of a single wheel or synchronous oil filling and emptying of wheels on the same axle through different on / off combinations; And / or, the reversing valve group includes a two-position four-way solenoid valve or a three-position four-way solenoid valve connected in parallel to the fluid on / off valve, and / or a throttle valve is provided between the two-position four-way solenoid valve or the three-position four-way solenoid valve and the oil source unit. And / or, the oil source unit includes multiple unidirectional or bidirectional pumps for controlling the pumping direction of the oil.

6. The active hydraulic suspension system according to claim 1, characterized in that, It also includes a temperature balancing device, which includes a temperature accumulator and a temperature control valve; The temperature control valve is located between the main oil circuit of the system and the temperature accumulator, and the temperature control valve controls the fluid connection between the temperature accumulator and the main oil circuit of the system to compensate for the volume change caused by the change in oil temperature.

7. The active hydraulic suspension system according to claim 2, characterized in that, The hydraulic actuator is a shock absorber or a hydraulic cylinder; At least a portion of the first accumulator, the second accumulator, the fluid on / off valve, and the first damping valve and the second damping valve are integrated inside the shock absorber or hydraulic cylinder; or... The first accumulator, the second accumulator, the fluid on / off valve, the first damping valve, and the second damping valve are integrated on a separate valve island, which is connected to the shock absorber or hydraulic cylinder via pipelines.

8. A control method for an active hydraulic suspension system, applied to the active hydraulic suspension system as described in any one of claims 1 to 7, characterized in that, include: Under comfortable operating conditions, the fluid on / off valve is controlled to open, so that the recovery chamber and the compression chamber are fluidly connected to provide the first system stiffness; Under attitude control conditions, the fluid on / off valve is controlled to disconnect, cutting off the fluid connection between the recovery chamber and the compression chamber, so that the recovery chamber and the first accumulator form a first independent circuit, and the compression chamber and the second accumulator form a second independent circuit, so as to provide a second system stiffness greater than the first system stiffness.

9. The control method according to claim 8, characterized in that, The triggering conditions for the attitude control operation include: detecting that the vehicle is in a braking, acceleration, turning, lane changing or large displacement state; The control method further includes: During height adjustment, the fluid on / off valve and directional valve group are controlled, and the oil source unit is controlled to fill or drain oil into the hydraulic actuator to adjust the vehicle height. Under active power conditions, the active power control of a single wheel can be achieved by controlling the combination of the on and off states of multiple solenoid valves in the directional valve group, or by controlling the synchronous active power control of the wheels on the same axle.

10. A vehicle, characterized in that, The vehicle includes a vehicle body and an active hydraulic suspension system as described in any one of claims 1 to 7, the active hydraulic suspension system being connected between the vehicle body and the wheels.

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