A hydraulic interconnected suspension system and its control method

Abstract

The present invention relates to a hydraulic interconnected suspension system and a control method thereof. The control method of the hydraulic interconnected suspension system includes obtaining one or more of a steering wheel angle sensor signal, an accelerator brake pedal sensor signal, an inertial navigation unit sensor signal, and a driving decision signal; determining the interconnected configuration of the hydraulic interconnected suspension and the suspension target control force F d or the target control torque T d according to one or more of the steering wheel angle sensor signal, the accelerator brake pedal sensor signal, the inertial navigation unit sensor signal, and the driving decision signal; calculating the actual output force F or the actual output torque T of the suspension according to the hydraulic sensor signal; using the error e of the suspension output force or torque as feedback, and realizing the control of the target control force F d or the target control torque T d by changing the oil pressure difference.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle suspensions, and particularly to a hydraulically interconnected suspension system and a control method thereof. Background Art

[0002] With the social development and progress and the rapid growth of the automobile ownership, people's current demands for automobiles have been upgraded from simple carrying requirements to all-round requirements such as ride comfort, comfort, and stability. During the vehicle driving process, the disturbances caused by road unevenness, the changes in driving conditions, and the driver's operation behaviors will all affect the vehicle ride comfort, comfort, and handling stability, etc.

[0003] An automobile suspension is an elastic connection component between the body (frame) and the wheels (axles), and is the general term for all force transmission connection devices, which is used to maintain the vehicle body stability and relieve the vibration and impact caused by road unevenness. It generally consists of elastic elements, guiding devices, shock absorbers, etc. As an actuator, the vehicle suspension system can generate suspension forces to act on the vehicle system, improve the vehicle dynamics performance, and is closely related to the handling stability, ride comfort, and safety of the vehicle.

[0004] The suspension system mainly includes a passive suspension system, a semi-active suspension system, and an active suspension system. Since the stiffness and damping parameters of the traditional passive suspension system cannot be adjusted, it can only sacrifice secondary performance on the basis of meeting the main performance requirements, and it has always been unable to balance the conflicting requirements of vehicle handling stability and ride comfort. In the case of variable environments or high performance requirements and complex influencing factors, the passive suspension cannot meet the performance requirements when the road excitation and working conditions change. The semi-active suspension shock absorber has adjustable damping and can generate variable control forces by using control strategies. However, its damping can usually only be adjusted within a limited range, so it cannot fully provide the ideal control forces for the vehicle under various working conditions, and the improvement results for the vehicle ride comfort and handling stability are very limited. In contrast, due to the presence of actuators, the active controllable suspension system can adjust the required control forces in real time according to the vehicle motion state and the changes in external excitations, which can significantly improve the vehicle dynamics performance and enhance the ride comfort and handling stability during the vehicle driving process, etc.

[0005] CN104228509B discloses a suspension with adjustable suspension height under passive control, having a vehicle body and road wheels, including a suspension corner connecting the road wheels to the vehicle body, and the suspension corner maintaining the contact between the road wheels and the road surface. The suspension system includes a bladder arranged at the suspension corner for pumping fluid in response to the force generated at the wheel and maintaining a certain amount of fluid; an accumulator in fluid communication with the bladder for selectively accumulating the fluid through the bladder and releasing the fluid to the bladder; a valve for selectively holding the accumulated fluid in the accumulator and releasing the fluid from the accumulator, and the height of the bladder changes in response to the amount of fluid held by the bladder to set the height of the vehicle's suspension system at the suspension corner.

[0006] For a traditional active suspension system, generally four sets of active actuation systems need to be installed on each of the front, rear, left, and right suspensions respectively to achieve active vehicle body attitude control. This solution poses relatively high requirements for system control accuracy, failure rate, and economic cost. In contrast, the intelligent hydraulically interconnected suspension has many advantages. For example, the intelligent hydraulically interconnected suspension only uses one set of independent actuators, which can effectively improve the contradictory relationship among the performances of the suspension system. And by cooperating with the corresponding control strategy to execute the interconnected configuration switching, the vertical, roll, and pitch control of the vehicle body attitude can be achieved, and the system economic cost and failure rate are effectively reduced. Secondly, the intelligent hydraulically interconnected suspension can actively adjust the state of the suspension, so as to adapt to the vehicle's requirements for comfort and handling stability according to external excitation and road conditions.

[0007] In addition, on the one hand, there are differences in the understanding of those skilled in the art; on the other hand, although the applicant studied a large number of documents and patents when making this invention, due to space limitations, all details and contents are not listed in detail. However, this does not mean that this invention does not possess the features of these prior arts. On the contrary, this invention already possesses all the features of the prior arts, and the applicant reserves the right to add relevant prior arts in the background art. Summary of the Invention

[0008] Aiming at the deficiencies of the prior art, the present invention provides a hydraulically interconnected suspension system and its control method, aiming to solve at least one or more technical problems existing in the prior art.

[0009] To achieve the above object, the present invention provides a control method for a hydraulically interconnected suspension system, including:

[0010] Obtaining one or more of a steering wheel angle sensor signal, an accelerator brake pedal sensor signal, an inertial navigation unit sensor signal, and a driving decision signal;

[0011] Determine the interconnected configuration of the hydraulic interconnected suspension and the suspension target control force F based on one or more of the steering wheel angle sensor signal, the accelerator and brake pedal sensor signal, the inertial navigation unit sensor signal, and the driving decision signal d or the target control torque T d ;

[0012] Calculate the actual output force F or the actual output torque T of the suspension according to the hydraulic sensor signal, and use the error e of the suspension output force or torque as feedback;

[0013] Control the target control force F d or the target control torque T d by changing the oil pressure difference. In particular, compared with the prior art which usually uses four independent actuators to generate output forces to control the vehicle body attitude, the present invention only uses one actuator, and realizes active attitude control by adjusting the pressure difference on the basis of a passive hydraulic system. Under the condition of achieving the same control effect, the cost and energy consumption of the system are reduced.

[0014] Preferably, the target control torque T d satisfies the relationship with the vehicle state:

[0015]

[0016] where k i (i = 1, 2,..., 6) is the state feedback coefficient, which can be obtained by calculating control strategies such as LQR control or H-infinity control, is the body roll angle, and s i (i = 1,..., 4) is the suspension linear displacement. In particular, when performing state feedback in the prior art, the vertical absolute displacement of the vehicle body or wheels is mostly used, and this state quantity is difficult to directly measure, and an observer needs to be designed, which increases the cost of design and debugging. The method proposed by the present invention uses the suspension linear displacement to replace the vertical absolute displacement of the vehicle body and wheels for state feedback. Under the condition of sacrificing a small amount of control effect, the overall controller design is simple and easy to tune.

[0017] Preferably, the error e of the suspension output force or torque satisfies the relationship:

[0018] e = T d - T HIS

[0019] where T d is the target control torque, and T HISThe actual output torque of the suspension. Taking vehicle roll control as an example, in the prior art, the actual roll angle of the vehicle is mostly used as feedback to directly control the output force of the actuator. The method proposed by the present invention adds a target roll torque tracking link between the roll angle and the actuator output force, and the tracking control algorithm takes into account the nonlinear characteristics of the hydraulic system, so that good control effects can be maintained under various roll degrees.

[0020] Preferably, the present invention provides a hydraulically interconnected suspension system, comprising:

[0021] A sensor configured to acquire one or more of a steering wheel angle sensor signal, an accelerator brake pedal sensor signal, an inertial navigation unit sensor signal, a driving decision signal, and a hydraulic sensor signal;

[0022] A controller configured to determine the interconnected configuration of the hydraulically interconnected suspension and the target control force F d or the target control torque T d according to one or more of the steering wheel angle sensor signal, the accelerator brake pedal sensor signal, the inertial navigation unit sensor signal, and the driving decision signal, and calculate the actual output force F or the actual output torque T of the suspension according to the hydraulic sensor signal, and use the error e of the suspension output force or torque as feedback to achieve the control of the target control force F d or the target control torque T d by changing the oil pressure difference.

[0023] Preferably, the present invention further relates to a hydraulically interconnected suspension, comprising:

[0024] A first oil cylinder, a second oil cylinder, a third oil cylinder, and a fourth oil cylinder and an adjustment oil cylinder connected to each other through hydraulic pipelines;

[0025] A first reversing valve, a second reversing valve, and a third reversing valve connected to each other through hydraulic pipelines, wherein the first reversing valve is arranged between the first oil cylinder and the second oil cylinder, the second reversing valve is arranged between the front side oil cylinder and the rear side oil cylinder, and the third reversing valve is arranged between the third oil cylinder and the fourth oil cylinder;

[0026] A first energy accumulator and a second energy accumulator connected to each other through hydraulic pipelines, and the first energy accumulator and the second energy accumulator are connected to the adjustment oil cylinder through hydraulic pipelines; and

[0027] An actuator, and the actuator is connected to the adjustment oil cylinder through a hydraulic pipeline.

[0028] Preferably, the actuator changes the oil pressure difference by driving the piston rod of the adjustment oil cylinder to move.

[0029] Preferably, the actuator comprises:

[0030] A servo motor;

[0031] A coupling, connected to the output shaft of the servo motor;

[0032] A lead screw, connected to the output shaft of the servo motor through the coupling and drivingly connected to the piston rod of the adjusting cylinder;

[0033] Wherein,

[0034] The rotation of the output shaft of the servo motor provides the movement of the piston rod along the axial direction of the lead screw.

[0035] Preferably, when the vehicle rolls, the hydraulic pressure difference formed by the left cylinder and the right cylinder generates an anti-roll moment T, and the anti-roll moment T and the accumulator pressure satisfy the relationship:

[0036] T = 2t b (A1 + A2)(P1 - P2)

[0037] Wherein, A1 is the piston area of the upper chamber of the cylinder on the compression side, A2 is the piston area of the lower chamber of the cylinder on the lifting side, t b is half of the distance between the left and right cylinders, and P1 and P2 are the pressures in the first accumulator and the second accumulator respectively.

[0038] Preferably, the hydraulic pressure difference is related to the output flow rate Q of the adjusting cylinder, and the output flow rate Q of the adjusting cylinder satisfies the relationship:

[0039]

[0040] Wherein, q1 = A1v1 - A2v2 + A1v3 - A2v4, q2 = A1v2 - A2v1 - A2v3 + A1v4, where γ is the adiabatic coefficient of the gas, V p is the volume of the accumulator, P p is the pre-charge pressure of the accumulator, and v1, v2, v3, and v4 are the moving speeds of the first cylinder, the second cylinder, the third cylinder, and the fourth cylinder respectively.

[0041] Preferably, in the present invention, the first cylinder and the second cylinder are interconnected through the first hydraulic branch and / or the second hydraulic connection;

[0042] Preferably, in the present invention, the third cylinder and the fourth cylinder are interconnected through the third hydraulic branch and / or the fourth hydraulic branch;

[0043] Preferably, in the present invention, the front cylinder and the rear cylinder are interconnected through the first hydraulic main path and / or the second hydraulic main path.

[0044] Preferably, the present invention further relates to a motor vehicle, including the hydraulic interconnected suspension described in the present invention.

[0045] The beneficial technical effects of the present invention at least include: The present invention provides a hydraulically interconnected suspension and its control method. By simply combining different states of three reversing valves, the hydraulically interconnected suspension can be switched between three configurations of anti-roll, anti-pitch, and anti-vertical, enabling the vehicle suspension system to have multiple active control modes, reducing the roll angle during vehicle steering, the pitch angle during starting and braking, and the vertical vibration amplitude on bumpy roads, etc., so as to meet the handling stability and ride comfort requirements of the vehicle under different working conditions. The hydraulic control system provided by the present invention uses common hydraulic and electromechanical components, which has the advantages of compact structure, low energy consumption, and low cost. Moreover, the method of generating active control force by driving the piston rod of the regulating cylinder to move by the actuator to change the pressure difference between two accumulators is simple and efficient, and realizes active force control in each configuration at a low cost.

[0046] In particular, compared with the prior art that uses four independent actuators to control the vehicle body attitude, the present invention can achieve active control of the vehicle body attitude by adding three groups of solenoid valves and one actuator on the basis of the passive hydraulically interconnected suspension system, which has the advantages of low cost, low energy consumption, and high reliability. The functions that the system can achieve include: controlling the vertical vibration of the vehicle body on bumpy roads, improving the vehicle's passing performance by adjusting the vehicle body height, controlling the roll and pitch motion postures of the vehicle body during sharp turning, rapid acceleration and deceleration of the vehicle, and improving the handling stability and ride comfort of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a schematic diagram of the anti-roll configuration of a hydraulically interconnected suspension according to a preferred embodiment provided by the present invention;

[0048] Figure 2 is a schematic diagram of the anti-vertical configuration of a hydraulically interconnected suspension according to a preferred embodiment provided by the present invention;

[0049] Figure 3 is a schematic diagram of the anti-pitch configuration of a hydraulically interconnected suspension according to a preferred embodiment provided by the present invention;

[0050] Figure 4 is an assembly schematic diagram of a regulating cylinder and an actuator according to a preferred embodiment provided by the present invention;

[0051] Figure 5 is a control schematic diagram of a hydraulically interconnected suspension system according to a preferred embodiment provided by the present invention;

[0052] Figure 6 is a relationship curve diagram between the accumulator pressure and the output anti-roll moment according to a preferred embodiment provided by the present invention;

[0053] Figure 7It is a schematic diagram of the working area for outputting anti-roll moment provided by the present invention in a preferred embodiment.

[0054] List of reference numerals

[0055] 101a: First oil cylinder; 101b: Second oil cylinder; 101c: Third oil cylinder; 101d: Fourth oil cylinder; 101e: Adjusting oil cylinder; 102a: First reversing valve; 102b: Second reversing valve; 102c: Third reversing valve; 103a: First accumulator; 103b: Second accumulator; 104: Actuator; 201: Frame; 202: Piston rod; 203: Connecting rod; 204: Nut seat; 205: Lead screw; 206a: Lead screw support; 206b: Motor support; 207: Coupling; 208: Servo motor. Detailed implementation manners

[0056] The following is a detailed description with reference to the accompanying drawings.

[0057] Embodiment 1

[0058] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood, however, that the present invention is not limited to these drawings and embodiments.

[0059] According to a preferred embodiment, Figures 1 to 3 the physical layouts and orientations of some components inside the vehicle are respectively shown when the vehicle is in different configurations. In particular, in addition to Figures 1 to 3 the vehicle suspension system shown, the vehicle generally further includes a steering system, a sensor system, etc.

[0060] Specifically, the present invention provides a hydraulically interconnected suspension system. As Figures 1 to 3 shown, the hydraulically interconnected suspension may include:

[0061] Hydraulic components, including a first oil cylinder 101a, a second oil cylinder 101b, a third oil cylinder 101c, and a fourth oil cylinder 101d corresponding to each wheel body of the vehicle, and an adjusting oil cylinder 101e.

[0062] Adjusting components, including a first reversing valve 102a, a second reversing valve 102b, and a third reversing valve 102c.

[0063] Energy storage components, including a first accumulator 103a and a second accumulator 103b.

[0064] and a drive component, including an actuator 104.

[0065] According to a preferred embodiment, the first oil cylinder 101a, the second oil cylinder 101b, the third oil cylinder 101c, and the fourth oil cylinder 101d are connected between the frame and the axle.

[0066] In particular, see Figures 1 to 3 The first oil cylinder 101a, the second oil cylinder 101b, the third oil cylinder 101c and the fourth oil cylinder 101d can be respectively arranged at the left front wheel, the right front wheel, the left rear wheel and the right rear wheel of the vehicle. Specifically, the first oil cylinder 101a, the second oil cylinder 101b, the third oil cylinder 101c and the fourth oil cylinder 101d are respectively installed at the vehicle shock absorber position to replace the original vehicle shock absorber and the lateral stabilizer bar part.

[0067] According to a preferred embodiment, Figures 1 to 3 As shown, the adjustment cylinder 101e may be disposed between a front axle (front cylinder) and a rear axle (rear cylinder) of the vehicle to be operably connected or attached to the vehicle body and wheels.

[0068] According to a preferred embodiment, the first oil cylinder 101a, the second oil cylinder 101b, the third oil cylinder 101c, the fourth oil cylinder 101d and the adjusting oil cylinder 101e may include a piston rod 202 and a cylinder barrel used in conjunction with the piston rod 202. Further, one of the piston rod and the cylinder barrel is connected to the vehicle frame, and the other is connected to the vehicle axle. In particular, the piston rod and the cylinder barrel can generate relative motion after being driven to act on the fluid in the cylinder barrel.

[0069] According to a preferred embodiment, the reversing valve may be a solenoid valve. Preferably, one or more of the first reversing valve 102a, the second reversing valve 102b or the third reversing valve 102c is a two-position four-way valve. Specifically, the reversing valve or the solenoid valve may include a cross oil circuit and a parallel oil circuit, wherein when the solenoid valve is in an off state, the cross oil circuit is connected; when the solenoid valve is in an on state, the parallel oil circuit is connected.

[0070] According to a preferred embodiment, Figures 1 to 3 As shown, the first reversing valve 102a can be arranged between the first oil cylinder 101a and the second oil cylinder 101b. The second reversing valve 102b can be arranged between the front axle and the rear axle of the vehicle. Alternatively, the second reversing valve 102b can be arranged between the front oil cylinder (101a; 101b) and the rear oil cylinder (101c; 101d). The third reversing valve 102c can be arranged between the third oil cylinder 101c and the fourth oil cylinder 101d.

[0071] According to a preferred embodiment, Figures 1 to 3 As shown, the first accumulator 103a and the second accumulator 103b are arranged between the front axle and the rear axle of the vehicle, and are connected to the regulating cylinder 101e through a hydraulic pipeline. Alternatively, the first accumulator 103a and the second accumulator 103b are arranged between the front cylinder (101a; 101b) and the rear cylinder (101c; 101d).

[0072] According to a preferred embodiment, Figures 1 to 3As shown, the first energy storage device 103a is connected to the upper chamber (or front chamber) of the regulating cylinder 101e through a hydraulic pipeline. The second energy storage device 103b is connected to the lower chamber (or rear chamber) of the regulating cylinder 101e through a hydraulic pipeline. In particular, the number of energy storage devices is not limited to the example provided in this embodiment.

[0073] According to a preferred embodiment, as Figures 1 to 3 shown, the actuator 104 is connected to the regulating cylinder 101e. Specifically, the actuator 104 is connected to the piston rod 202 of the regulating cylinder 101e to control the movement of the piston rod 202 of the regulating cylinder 101e, change the volume of the oil in the accumulator in the two oil circuits, thereby changing the oil pressure difference between the two oil circuits, and generating an active torque.

[0074] According to a preferred embodiment, as Figures 1 to 3 shown, each cylinder (101a; 101b; 101c; 101d, 101e), solenoid valve (102a; 102b; 102c), and accumulator (103a; 103b) can be connected through a hydraulic pipeline.

[0075] According to a preferred embodiment, as Figures 1 to 3 shown, a first hydraulic branch and a second hydraulic branch are connected between the first cylinder 101a and the second cylinder 101b. Specifically, the first hydraulic branch can be respectively connected to the rodless chambers of the first cylinder 101a and the second cylinder 101b. The second hydraulic branch can be respectively connected to the rod chambers of the first cylinder 101a and the second cylinder 101b. The first reversing valve 102a is arranged between the first cylinder 101a and the second cylinder 101b to switch the conduction states of the first cylinder 101a and the second cylinder 101b with each other.

[0076] According to a preferred embodiment, the first reversing valve 102a has a first conduction position and a second conduction position. Specifically, as Figure 1 shown, when the first reversing valve 102a is in the first conduction position, the first reversing valve 102a is in a disconnected state. Further, when the first reversing valve 102a is disconnected, the rodless chamber of the first cylinder 101a and the rod chamber of the second cylinder 101b communicate with each other; the rod chamber of the first cylinder 101a and the rodless chamber of the second cylinder 101b communicate with each other.

[0077] According to a preferred embodiment, as Figure 2 or Figure 3 shown, when the first reversing valve 102a is in the second conduction position, the first reversing valve 102a is in a conduction state. When the first reversing valve 102a is conducting, the rodless chambers of the first cylinder 101a and the second cylinder 101b communicate with each other; the rod chambers of the first cylinder 101a and the second cylinder 101b communicate with each other.

[0078] According to a preferred embodiment, as Figures 1 to 3 shown, a third hydraulic branch and a fourth hydraulic branch are connected between the third oil cylinder 101c and the fourth oil cylinder 101d. Specifically, the third hydraulic branch can be respectively connected to the rodless chambers of the third oil cylinder 101c and the fourth oil cylinder 101d. The fourth hydraulic branch can be respectively connected to the rod chambers of the third oil cylinder 101c and the fourth oil cylinder 101d. A third reversing valve 102c is arranged between the third oil cylinder 101c and the fourth oil cylinder 101d for switching the conduction states of the third oil cylinder 101c and the fourth oil cylinder 101d with respect to each other.

[0079] According to a preferred embodiment, the third reversing valve 102c has a third conduction position and a fourth conduction position. Specifically, as Figure 1 shown, when the third reversing valve 102c is in the third conduction position, the third reversing valve 102c is in an off state. Further, when the third solenoid valve 102a is off, the rodless chamber of the third oil cylinder 101c and the rod chamber of the fourth oil cylinder 101d communicate with each other; the rod chamber of the third oil cylinder 101c and the rodless chamber of the fourth oil cylinder 101d communicate with each other.

[0080] According to a preferred embodiment, as Figure 2 or Figure 3 shown, when the third reversing valve 102c is in the fourth conduction position, the third reversing valve 102c is in a conduction state. When the third reversing valve 102c is conducting, the rodless chambers of the third oil cylinder 101c and the fourth oil cylinder 101d communicate with each other; the rod chambers of the third oil cylinder 101c and the fourth oil cylinder 101d communicate with each other.

[0081] According to a preferred embodiment, as Figures 1 to 3 shown, a first hydraulic main path and a second hydraulic main path are connected between the front axle and the rear axle of the vehicle. Specifically, both ends of the first hydraulic main path are respectively connected to the first hydraulic branch and the third hydraulic branch. Both ends of the second hydraulic main path are respectively connected to the second hydraulic branch and the fourth hydraulic branch.

[0082] According to a preferred embodiment, as Figures 1 to 3 shown, a second reversing valve 102b is arranged between the front axle and the rear axle of the vehicle. Alternatively, the second reversing valve 102b is arranged in the first hydraulic main path and the second hydraulic main path for switching the conduction states among the first hydraulic branch, the second hydraulic branch, the third hydraulic branch, and the fourth hydraulic branch. Specifically, the second reversing valve 102b can be used to switch the conduction states between the rodless chambers and the rod chambers of the first oil cylinder 101a, the second oil cylinder 101b, the right rear oil cylinder 101c, and the fourth oil cylinder 101d.

[0083] According to a preferred embodiment, the second reversing valve 102b has a fifth conducting position and a sixth conducting position. Specifically, as Figure 1 and Figure 2 shown, when the second reversing valve 102b is in the fifth conducting position, the third reversing valve 102c is in a conducting state. Further, when the second reversing valve 102b is conducting, the first hydraulic main path connects the first hydraulic branch and the third hydraulic branch; the second hydraulic main path connects the second hydraulic branch and the fourth hydraulic branch.

[0084] According to a preferred embodiment, as Figure 3 shown, when the second reversing valve 102b is in the sixth conducting position, the second reversing valve 102b is in an off state. Further, when the second reversing valve 102b is off, the first hydraulic main path connects the first hydraulic branch and the fourth hydraulic branch; the second hydraulic main path connects the second hydraulic branch and the third hydraulic branch.

[0085] According to a preferred embodiment, the energy storage assembly may include components such as a liquid chamber, a gas chamber, a diaphragm, and a sealing rod. Specifically, a hydraulic fluid (such as hydraulic oil) is stored in the liquid chamber. A gas is stored in the gas chamber. The gas chamber can be sealed by a sealing rod. The liquid chamber and the gas chamber are separated by a diaphragm.

[0086] According to a preferred embodiment, the liquid chamber can be connected to the first hydraulic main path or the second hydraulic main path. When the hydraulic pressure in the first hydraulic main path or the second hydraulic main path increases, the hydraulic pressure in the liquid chamber increases, causing the diaphragm to move towards the gas chamber and increasing the air pressure in the gas chamber by squeezing the gas chamber until the pressures of the liquid chamber and the gas chamber are balanced with each other. In particular, before the pressures of the liquid chamber and the gas chamber are balanced, the diaphragm needs to undergo multiple reciprocating motions, and the accumulator has the function of absorbing hydraulic shocks.

[0087] According to a preferred embodiment, when the hydraulic pressure in the first hydraulic main path or the second hydraulic main path decreases, the pressure in the liquid chamber is less than the pressure in the gas chamber, causing the diaphragm to move towards the liquid chamber and increasing the air pressure in the liquid chamber by squeezing the liquid chamber until the pressures of the liquid chamber and the gas chamber are balanced with each other. During this process, the accumulator has the functions of absorbing hydraulic shocks and replenishing fluid.

[0088] According to a preferred embodiment, in the present invention, by combining different on-off states of the solenoid valves (102a; 102b; 102c), three control modes, namely an anti-roll configuration, an anti-pitch configuration, and an anti-vertical configuration, can be formed.

[0089] According to a preferred embodiment, Figures 1 to 3 schematically shows the anti-roll, anti-vertical, and anti-pitch of the vehicle in sequence.

[0090] According to a preferred embodiment, as Figure 1As shown, when the vehicle tilts to the left, it causes the cylinders on the left side (101a; 101c) to compress and the cylinders on the right side (101b; 101d) to stretch. Specifically, when the upper controller of the suspension system detects that the vehicle is in the steering roll condition, it controls the first reversing valve 102a and the third reversing valve 102c to disconnect, and the second reversing valve 102b to conduct, so that the interconnected suspension system is in the anti-roll configuration. Further, as Figure 1 shown, in the anti-roll configuration, the rodless chambers of the first cylinder 101a, the rodless chambers of the second cylinder 101b, the rodless chambers of the third cylinder 101c, the rod chambers of the fourth cylinder 101d, the first accumulator 103a and the upper chamber (or front chamber) of the regulating cylinder 101e are interconnected. At this time, the hydraulic system nodes p1, p4, p5, p7 and p10 are interconnected to form an oil circuit A; the hydraulic system nodes p2, p3, p6, p8 and p9 are interconnected to form an oil circuit B.

[0091] According to a preferred embodiment, as Figure 2 shown, when the vehicle vibrates vertically, it causes the four cylinders (101a; 101b; 101c; 101d) to compress or stretch simultaneously. Specifically, when the upper controller of the suspension system detects that the vehicle is in the vertical vibration condition, it controls the first reversing valve 102a, the second reversing valve 102b and the third reversing valve 102c to conduct, so that the interconnected suspension system is in the anti-vertical configuration. Further, as Figure 2 shown, in the anti-vertical configuration, the rodless chambers of the first cylinder 101a, the rodless chambers of the second cylinder 101b, the rodless chambers of the third cylinder 101c, the rodless chambers of the fourth cylinder 101d, the first accumulator 103a and the upper chamber (or front chamber) of the regulating cylinder 101e are interconnected. At this time, the hydraulic system nodes p1, p2, p5, p7 and p8 are interconnected to form an oil circuit C; the hydraulic system nodes p3, p4, p6, p9 and p10 are interconnected to form an oil circuit D.

[0092] According to a preferred embodiment, as Figure 3 shown, when the vehicle pitches forward, it causes the front cylinders (101a; 101b) to compress and the rear cylinders (101c; 101d) to stretch. Specifically, when the upper controller of the suspension system detects that the vehicle is in the braking pitch condition, it controls the first reversing valve 102a and the third reversing valve 102c to conduct, and the second reversing valve 102b to disconnect, so that the interconnected suspension system is in the anti-pitch configuration. Further, as Figure 3As shown, in the anti-pitch configuration, the rodless chambers of the first hydraulic cylinder 101a, the second hydraulic cylinder 101b, the rod chambers of the third hydraulic cylinder 101c and the fourth hydraulic cylinder 101d, the first accumulator 103a and the upper chamber (or front chamber) of the regulating hydraulic cylinder 101e are interconnected. At this time, the hydraulic system nodes p1, p2, p5, p9 and p10 are interconnected to form an oil circuit E; the hydraulic system nodes p3, p4, p6, p7 and p8 are interconnected to form an oil circuit F.

[0093] According to a preferred embodiment, Figure 4 The assembly schematic diagram of the regulating hydraulic cylinder 101e and the actuator 104 of the present invention is shown. Specifically, in the present invention, the regulating hydraulic cylinder 101e is fixed to the vehicle frame 201 in the middle of the vehicle chassis by fasteners (such as bolts). Further, as Figure 4 shown, the servo motor 208 and the lead screw 205 are fixed to the vehicle frame 201 by a lead screw support 206a and a motor support 206b. Among them, the servo motor 208 drives the lead screw 205 to rotate through a coupling 207. The piston rod 202 of the regulating hydraulic cylinder 101e is connected to a nut seat 204 connected to the lead screw 205 through a connecting rod 203. In particular, when the servo motor 208 drives the lead screw 205 to rotate, the nut seat 204 will drive the piston rod 202 to move linearly, thereby adjusting the hydraulic driving force generated by the regulating hydraulic cylinder 101e.

[0094] According to a preferred embodiment, in the present invention, the drive assembly, that is, the actuator 104 is connected to the piston rod 202 of the regulating hydraulic cylinder 101e. Specifically, the actuator 104 can drive the piston rod 202 to move so as to generate a stroke of approaching or departing from the liquid chamber. Further, the actuator 104 can drive the piston rod 202 to move to adjust the air chamber pressure of the accumulator, thereby changing the pressure in the first main hydraulic circuit and / or the second main hydraulic circuit.

[0095] According to a preferred embodiment, the hydraulic interconnected suspension provided in this embodiment may further include one or more regulating valves. Specifically, the regulating valve can be arranged at the inlet of one or more of the first hydraulic cylinder 101a, the second hydraulic cylinder 101b, the third hydraulic cylinder 101c or the fourth hydraulic cylinder 101d. Specifically, the regulating valve can be arranged at the inlets of the rod chambers of the first hydraulic cylinder 101a, the second hydraulic cylinder 101b, the third hydraulic cylinder 101c and the fourth hydraulic cylinder 101d. In particular, when the vehicle is in the anti-vertical vibration configuration, the damping of the hydraulic suspension system can be adjusted by controlling the regulating valve, so that the vehicle has better ride comfort.

[0096] According to a preferred embodiment, it should be understood that in order to obtain several parameters or signals for controlling the vehicle configuration, such as the body attitude angle, the suspension linear displacement, and the accumulator pressure, etc., the present invention should include several types of sensors for detecting the above signal parameters. Specifically, one or more pressure sensors can be installed at the outlet of the accumulator to measure the oil pressure in the accumulator. Or, one or more body attitude sensors can be installed at the center of mass of the vehicle body to measure the motion postures such as the body roll angle and pitch angle. Or, one or more cylinder displacement sensors can be installed in parallel at the upper and lower ends of the cylinder to measure the displacement of the cylinder piston rod relative to the cylinder block.

[0097] According to a preferred embodiment, the present invention further provides a motor vehicle, which includes the hydraulic interconnected suspension described in this embodiment. In particular, the vehicle can be a motor vehicle (such as a car, a truck, an agricultural or military equipment vehicle, etc.).

[0098] Embodiment 2

[0099] According to a preferred embodiment, based on the above embodiment, the present invention provides an intelligent hydraulic interconnected suspension system, and the present invention may further include a control method for the intelligent hydraulic interconnected suspension system.

[0100] Specifically, the control method for the intelligent hydraulic interconnected suspension system provided by the present invention may include a two-layer structure of an upper controller and a lower controller, and the specific control method includes the following steps:

[0101] Step 1: The upper controller collects one or more of the vehicle steering wheel angle sensor signal, the throttle and brake pedal sensor signal, the inertial navigation unit sensor signal, and the intelligent driving decision signal, and decides the vehicle suspension interconnected configuration and the suspension target control force F d or the target control torque T d .

[0102] Step 2: The lower controller calculates the actual output force F or the actual output torque T of the suspension according to the hydraulic sensor signal, and takes the suspension output force or torque error e as feedback to control the piston movement of the adjusting cylinder 101e.

[0103] According to a preferred embodiment, the movement of the adjusting cylinder 101e will change the oil pressure difference in the oil circuits on both sides, so that the error between the suspension output force or torque and the target value is reduced, thereby realizing the tracking of the target control force F d or the target control torque T d .

[0104] To facilitate the understanding of the structural composition and working principle of the intelligent hydraulic interconnected suspension system provided by the present invention, the following will take Figure 1Taking the anti-roll condition shown as an example, the specific implementation process of the present invention will be described in detail.

[0105] According to a preferred embodiment, the rotational speed ω of the servo motor 208 and the movement speed u of the piston rod 202 satisfy the following relationship:

[0106]

[0107] where l d is the lead of the screw thread.

[0108] According to a preferred embodiment, referring to Figure 1 , when the vehicle rolls, it causes the left hydraulic cylinders (101a; 101c) to be compressed and the right hydraulic cylinders (101b; 101d) to be stretched. Further, the hydraulic fluid in oil circuit A is pressed into the first energy storage device 103a, and the pressure of the first energy storage device 103a increases. The hydraulic fluid in oil circuit B flows out from the second energy storage device 103b, and the pressure of the second energy storage device 103b decreases. The pressure difference formed by the two side oil circuits will generate an anti-roll moment T.

[0109] According to a preferred embodiment, the anti-roll moment T and the pressure of the energy storage devices (103a; 103b) satisfy the following relationship:

[0110] T = 2t b (A1 + A2)(P1 - P2) (2)

[0111] where A1 is the piston area of the upper chamber of the left hydraulic cylinder, A2 is the piston area of the lower chamber of the right hydraulic cylinder, t b is half of the distance between the left and right hydraulic cylinders, P1 is the pressure inside the first energy storage device 103a, and P2 is the pressure inside the second energy storage device 103b.

[0112] According to a preferred embodiment, when the first hydraulic cylinder 101a, the second hydraulic cylinder 101b, the third hydraulic cylinder 101c, and the fourth hydraulic cylinder 101d move at speeds v1, v2, v3, and v4 respectively, and the output flow rate of the regulating hydraulic cylinder 101e is adjusted to u, the pressure and flow rate changes of the first energy storage device 103a and the second energy storage device 103b are as follows:

[0113]

[0114]

[0115] where V p is the volume of the energy storage device, P p is the pre-charge pressure of the energy storage device, γ is the adiabatic coefficient of the gas, and Q is the output flow rate of the regulating hydraulic cylinder 101e.

[0116] According to a preferred embodiment, the size of Q and the moving speed u of the piston rod 202 of the adjusting oil cylinder 101e satisfy the following relationship:

[0117] Q = A3u (5)

[0118] According to a preferred embodiment, the upper controller will give the target anti-roll moment T according to the vehicle state feedback d . The target anti-roll moment and the vehicle state satisfy the following relationship:

[0119]

[0120] where k i (i = 1, 2,..., 6) is the state feedback coefficient, which can be obtained by calculating control strategies such as LQR control or H-infinity control, is the body roll angle, s i (i = 1,..., 4) is the suspension linear displacement.

[0121] Taking LQR control as an example, the state space expression of the body part movement is as follows:

[0122]

[0123] where is the vehicle state vector.

[0124] Select the vehicle vertical acceleration, body roll angle, dynamic deflections of both sides of the suspension, and the magnitude of the anti-roll moment output by the active suspension as the control objectives, and design the optimization objective function as:

[0125]

[0126] Arrange Equation (8) into matrix form:

[0127]

[0128] According to a preferred embodiment, after determining the vehicle parameters and the weight coefficients of the optimization objectives, the feedback gain matrix of the optimal controller can be obtained by solving the following Riccati equation:

[0129] PA + A T P - (PB + N)R -1 (B T P + N T ) + Q = 0 (10)

[0130] The feedback gain matrix of the optimal controller is:

[0131] K = B T P + N T (11)

[0132] The target roll resistance moment is:

[0133] T d =-KX(12)

[0134] The relationship between the roll resistance moment described in Equation (2) and the accumulator pressure can be transformed into:

[0135]

[0136] According to a preferred embodiment, Figure 6 A curve graph showing the relationship between the accumulator pressure (P1; P2) and the output roll resistance moment T is shown. Specifically, a plane rectangular coordinate system is drawn with P1 and P2 as the horizontal and vertical coordinates, and the actual output roll resistance moment T in Equation (6) is replaced with the target roll resistance moment T d After that, it is a target straight line with a fixed slope in the coordinate system.

[0137] According to a preferred embodiment, as Figure 6 shown, taking the accumulator pressure at the current moment as the system state, it is a point (P1, P2) in the coordinate system. When this point moves to the target straight line, the system will output the target roll resistance moment T d . Specifically, during the operation of the system, the movement of the piston rods 202 of the left and right cylinders will cause the system state point to move within the coordinate system, and the change of the target roll resistance moment T d will cause the target straight line to move up and down along the P2 direction. Adjusting the output flow rate u of the oil cylinder 101e will cause the system state point to move in the direction of increasing P1 and decreasing P2 or increasing P2 and decreasing P1, and its trajectory is a non-linear curve. Therefore, the accurate tracking of the target moment can be achieved by controlling the flow rate of the adjusting oil cylinder 101e.

[0138] According to a preferred embodiment, taking sliding mode control as an example, the roll resistance moment tracking error e is defined as:

[0139] e=T d -T HIS (14)

[0140] The sliding mode surface s is defined as:

[0141] s=e(15)

[0142] Taking the derivative of Equation (15) gives:

[0143]

[0144] Design an exponential reaching law to make the tracking error quickly approach the sliding mode surface s:

[0145]

[0146] where ε>0 and k>0 are design parameters used to control the approaching speed of the tracking error.

[0147] According to a preferred embodiment, by combining Equation (3) and Equation (4), the system control quantity is designed, that is, the flow rate of the adjusting oil cylinder 101e is adjusted to be:

[0148]

[0149] where q1 = A1v1 - A2v2 + A1v3 - A2v4, q2 = A1v2 - A2v1 - A2v3 + A1v4.

[0150] The stability of the above sliding mode controller is proved by using the Lyapunov function. The defined positive definite Lyapunov function is:

[0151]

[0152] Taking the derivative of V gives:

[0153]

[0154] According to a preferred embodiment, is a semi-negative definite function and is not always zero. Therefore, the above closed-loop control system satisfies asymptotic stability.

[0155] According to a preferred embodiment, Figure 5 shows the control schematic diagram of the intelligent hydraulic interconnected suspension system provided by the present invention. Combining Figure 5 , the specific control process of the intelligent hydraulic interconnected suspension system of the present invention includes: the upper controller reads the body attitude angle and the suspension linear displacement signal, judges the vehicle driving state, and calculates the target torque T required to be output by the suspension system according to Equation (6) d , and at the same time collects the pressure signal of the suspension accumulator, and calculates the actual output torque magnitude T of the current suspension according to Equation (2) HIS . Thereafter, the lower controller reads the target torque T d , the actual torque T HIS magnitude, as well as the suspension linear displacement and the accumulator pressure signal, and then calculates the flow rate Q required for the adjusting oil cylinder 101e to track the target torque T according to Equation (18) through sliding mode control d , and converts it into the motor speed ω according to Equation (1).

[0156] According to a preferred embodiment, in this embodiment, according to the hydraulic system parameters, the lower controller converts the target anti-roll torque T d into the target accumulator pressure difference ΔP d, and the actual accumulator pressure difference ΔP of the current hydraulic system is obtained through the hydraulic pressure sensor. The displacement of the piston rod 202 of the control regulating cylinder 101e is driven by the actuator 104, so that the pressure difference between the two accumulators (103a; 103b) can be controlled, and the target anti-roll moment T can be achieved. d tracking.

[0157] According to a preferred embodiment, in this embodiment, the magnitude of the anti-roll moment generated by the interconnected suspension is related to the pressure difference between the oil circuits A and B. When the required anti-roll moment is constant, the more the pressure difference provided by the movement of the regulating cylinder 101e is adjusted, the smaller the pressure difference generated by the vehicle roll is required, that is, by actively controlling the regulating cylinder 101e, the anti-roll performance of the vehicle is improved.

[0158] According to a preferred embodiment, in the present invention, the output force range of the active hydraulic interconnected suspension system is determined by the maximum fluid volume difference that the regulating cylinder 101e can generate, that is, the piston area and stroke length of the regulating cylinder 101e. Specifically, for example, when the inner diameter of the regulating cylinder 101e is 40 mm and the diameter of the piston rod 202 is 25 mm, the effective stroke of the piston is 120 mm, and the static working pressure of the system is 2 MPa.

[0159] According to a preferred embodiment, Figure 7 shows a schematic diagram of the working area for outputting the anti-roll moment. Specifically, as Figure 7 (a) shows, positions 1, 2, and 3 are defined as the piston of the regulating cylinder 101e being fixed in the middle, top, and bottom of the cylinder respectively. Sinusoidal displacement excitations with opposite phases are applied to the left and right cylinders to simulate the roll movement of the suspension. Figure 7 (b) shows the variation of the anti-roll moment of the active hydraulic interconnected suspension with the roll angle when the piston of the regulating cylinder 101e is at different positions.

[0160] Furthermore, as Figure 7 (b) shows, position 1 can be regarded as the output situation of the anti-roll moment of the passive hydraulic interconnected suspension. Positions 2 and 3 correspond to the maximum anti-roll moment and the minimum anti-roll moment of the active hydraulic interconnected suspension at each roll angle respectively. The output force curves of positions 2 and 3 can approximately form a parallelogram area, which is the working area of the active hydraulic interconnected suspension system. The force or moment tracking can be achieved at any position within this area. It can be seen from the experimental simulation results that at any roll angle, the active hydraulic interconnected suspension system expands the dynamic anti-roll moment output range by about ±1000 N·m compared with the passive hydraulic interconnected suspension system.

[0161] Similarly, when the upper controller of the suspension system detects that the vehicle is in a braking pitch condition, it will control the first reversing valve 102a and the third reversing valve 102c to conduct, and the second reversing valve 102b to disconnect, so that the interconnected suspension system is in an anti-pitch configuration. See Figure 3 . In the anti-pitch configuration, the hydraulic system nodes p1, p2, p5, p9, p10 communicate with each other to form an oil circuit E; the nodes p3, p4, p6, p7, p8 communicate with each other to form an oil circuit F.

[0162] Similarly, the upper controller will give the target anti-pitch moment T according to the vehicle state feedback d . Specifically, the target anti-roll moment and the vehicle state satisfy the following relationship:

[0163]

[0164] where k i (i = 1, 2,..., 6) is the state feedback coefficient, which can be obtained by calculating control strategies such as LQR control or H-infinity control, is the body roll angle, and s i (i = 1,..., 4) is the suspension linear displacement

[0165] Similarly, the lower controller will control the displacement of the piston rod 202 of the adjusting cylinder 101e to track the target anti-pitch moment T d .

[0166] In particular, when it comes to the vehicle vertical vibration or the braking pitch condition, the specific control process is similar to the control adjustment principle for the anti-roll condition described above, so it will not be elaborated in detail. For the detailed content, please refer to the above. Those skilled in the art should be able to implement the active control adjustment for the vehicle vertical vibration or the braking pitch condition in combination with the content described above.

[0167] It should be noted that the above specific embodiments are exemplary. Those skilled in the art can come up with various solutions inspired by the disclosure of the present invention, and these solutions also belong to the disclosure scope of the present invention and fall within the protection scope of the present invention. Those skilled in the art should understand that the description and drawings of the present invention are illustrative and do not constitute a limitation to the claims. The protection scope of the present invention is defined by the claims and their equivalents. The description of the present invention contains multiple inventive concepts. Expressions such as "preferably", "according to a preferred embodiment" or "optionally" indicate that the corresponding paragraphs disclose an independent concept. The applicant reserves the right to file divisional applications according to each inventive concept.

Claims

1. A hydraulic interconnected suspension system, characterized in that, Comprising: A sensor configured to acquire one or more of a steering wheel angle sensor signal, a throttle and brake pedal sensor signal, an inertial navigation unit sensor signal, a driving decision signal, and a hydraulic sensor signal; A controller configured to determine an interconnected configuration of the hydraulic interconnected suspension and a target control force F of the suspension according to one or more of the steering wheel angle sensor signal, the throttle and brake pedal sensor signal, the inertial navigation unit sensor signal, and the driving decision signal d or a target control torque T d , calculate an actual output force F or an actual output torque T of the suspension according to the hydraulic sensor signal, and use an error e of the suspension output force or torque as feedback to control the target control force F d or the target control torque T d by changing the oil pressure difference The target control torque T d satisfies the relationship with the vehicle state: Among them, k i (i = 1, 2, …, 6) are state feedback coefficients obtained through LQR control or H-infinity control strategies, is the body roll angle, s i (i = 1, …, 4) are the suspension linear displacements, The error e of the suspension output force or torque satisfies the relationship: e = T d -T HIS ; where T d is the target control torque, and T HIS is the actual output torque of the suspension The hydraulic interconnected suspension includes: A first cylinder (101a), a second cylinder (101b), a third cylinder (101c), and a fourth cylinder (101d) and an adjustment cylinder (101e) connected to each other through hydraulic pipelines; A first reversing valve (102a), a second reversing valve (102b), and a third reversing valve (102c) connected to each other through hydraulic pipelines, wherein the first reversing valve (102a) is disposed between the first cylinder (101a) and the second cylinder (101b), the second reversing valve (102b) is disposed between the front side cylinders (101a; 101b) and the rear side cylinders (101c; 101d), and the third reversing valve (102c) is disposed between the third cylinder (101c) and the fourth cylinder (101d); A first accumulator (103a) and a second accumulator (103b) connected to each other through a hydraulic pipeline, and the first accumulator (103a) and the second accumulator (103b) are connected to the adjustment cylinder (101e) through a hydraulic pipeline; and An actuator (104), the actuator (104) being connected to the adjustment cylinder (101e) through a hydraulic pipeline, The actuator (104) changes the oil pressure difference in a manner of driving the piston rod (202) of the adjustment cylinder (101e) to move.

2. The hydraulic interconnected suspension system according to claim 1, wherein The actuator (104) includes: A servo motor (208); A coupling (207) connected to the output shaft of the servo motor (208); A lead screw (205) connected to the output shaft of the servo motor (208) through the coupling (207) and drivingly connected to the piston rod (202) of the adjustment cylinder (101e); Wherein, The rotation of the output shaft of the servo motor (208) provides the movement of the piston rod (202) along the axial direction of the lead screw (205).

3. The hydraulic interconnected suspension system according to claim 2, wherein When the vehicle rolls, the oil pressure difference formed by the left side cylinders (101a; 101c) and the right side cylinders (101b; 101d) generates an anti-roll torque T, and the anti-roll torque T and the accumulator (103a; 103b) pressure satisfy the relationship: T = 2t b (A1 + A2)(P1 - P2); Wherein, A1 is the piston area of the upper chamber of the cylinder on the compression side, a2 is the piston area of the lower chamber of the cylinder on the lifting side, and t b is half of the distance between the left and right cylinders, and P1 and P2 are the pressures in the first energy storage device (103a) and the second energy storage device (103b), respectively.

4. The hydraulic interconnected suspension system according to claim 3, characterized in that, The oil pressure difference is related to the output flow rate Q of the adjustment cylinder (101e), and the output flow rate Q of the adjustment cylinder (101e) satisfies the relationship: Among them, q1 = A1v1 - A2v2 + A1v3 - A2v4, q2 = A1v2 - A2v1 - A2v3 + A1v4, where ε > 0, k > 0 are design parameters, s is the sliding surface, the sliding surface s = e is defined, γ is the adiabatic coefficient of the gas, V p is the volume of the energy storage device, P p is the pre-charge pressure of the energy storage device, and v1, v2, v3, and v4 are the moving speeds of the first oil cylinder (101a), the second oil cylinder (101b), the third oil cylinder (101c), and the fourth oil cylinder (101d), respectively.

5. The hydraulic interconnected suspension system according to claim 4, wherein The first cylinder (101a) and the second cylinder (101b) are interconnected through a first hydraulic branch and / or a second hydraulic branch; The third cylinder (101c) and the fourth cylinder (101d) are interconnected through a third hydraulic branch and / or a fourth hydraulic branch; The front side cylinders (101a; 101b) and the rear side cylinders (101c; 101d) are interconnected through a first hydraulic main path and / or a second hydraulic main path.

6. A motor vehicle, characterized in that, Including the hydraulic interconnected suspension system according to any one of claims 1 to 5.

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