Hinged vehicle oil-gas interconnection ISD suspension vehicle body posture semi-active control method

Abstract

The invention discloses an articulated vehicle oil-gas interconnection ISD suspension vehicle body attitude semi-active control method, which comprises the following steps of: 1, designing an oil-gas interconnection ISD suspension system, and establishing an electromagnetic proportional valve and articulated vehicle kinematic model as a reference model; step 2, constructing a vehicle body attitude monitoring device to obtain road and vehicle body attitude information in real time; step 3, adding a PLC (Programmable Logic Controller), and controlling each electromagnetic reversing valve to cope with different working conditions according to different vehicle body postures; step 4, embedding a spiral tube type inerter in the oil-gas loop to improve the low-frequency vibration isolation performance of the vehicle; 5, an electromagnetic proportional valve is connected with the spiral pipe in parallel, the opening degree of the proportional valve is adjusted, the output force of the suspension is adjustable, and semi-active control over the posture of the vehicle body is achieved; and step 6, vehicle body attitude information is updated, a control effect is evaluated, and the vehicle is further controlled. Compared with a traditional suspension, the anti-rolling and anti-pitching capacity of a vehicle can be improved, semi-active control can be conducted on the suspension, and damage to hinge points is avoided.

Description

Technical Field

[0001] The present invention belongs to the field of chassis suspension of large engineering vehicles, is applicable to articulated vehicles facing unstructured roads, relates to a vehicle body posture control system, and in particular to a semi-active control method for an oil-gas interconnected ISD suspension vehicle body posture. Background Art

[0002] The research and application of vehicle posture adjustment has a long history, and vehicle posture adjustment is of great significance to improving its maneuverability. When driving in jungles and mountains, raising the position of the vehicle body can enable the vehicle to pass through various complex obstacles; when the vehicle needs to be transferred and transported in batches, lowering the position of the vehicle body can enable the vehicle to adapt to more transport carriers, and lowering the center of gravity of the vehicle can stabilize the body; lowering the body when driving on a flat road can improve the stability of the vehicle; the driver can adjust the body posture through the display and control terminal according to different road surfaces, so that the vehicle can maintain excellent driving performance on different roads. The body posture adjustment system can adjust the vehicle's high, medium, low, roll, pitch and other postures, and its core is the oil and gas spring assembly. By setting the connection method and controlling the opening and closing of the oil circuit in time, the support size of the oil and gas spring can be adjusted to achieve the purpose of adjusting the body posture.

[0003] At present, the body posture of oil-gas suspension vehicles is passively controlled and cannot be adjusted according to the vehicle's driving conditions, resulting in a large pitch angle during braking and a large roll angle during steering, which affects the vehicle's driving smoothness and driving safety. Compared with traditional suspension systems, interconnected suspension can effectively improve the vehicle's overall handling stability while ensuring ride comfort. For example, the front and rear interconnection of the suspension can effectively improve the anti-pitch performance, while the left and right interconnection can optimize the vehicle's anti-rollover performance.

[0004] Since the technical parameters of passive suspension such as stiffness and damping cannot be adjusted, it can only achieve the best performance for a certain road condition during matching design and optimization design. Under variable working conditions, there is always a contradiction between handling stability and smoothness that is difficult to coordinate, and it is impossible to make a better performance response to complex roads. Active suspension is to set an external energy source to generate and adjust an additional output force, thereby actively controlling the overall suspension output force, so that the vehicle is in the best vibration reduction state, but its complex structure and high energy consumption lead to high production difficulty and production cost, poor working stability and reliability, all of which greatly limit the research and application of active suspension. Therefore, semi-active suspension has a wide range of application prospects due to its advantages such as simple structure, low cost, low energy consumption and excellent performance. It can be used not only in commercial vehicles, but also in passenger cars and special vehicles.

[0005] At the same time, due to the unstructured roads, articulated vehicles are prone to bumps. The inertia container has a low-frequency and large-amplitude vibration reduction effect, which can suppress low-frequency vibrations and improve the smoothness and ride comfort of the vehicle, which is of great significance to the suspension research of large engineering vehicles. Summary of the invention

[0006] The purpose of this patent is to reduce the pitch angle and roll angle of articulated vehicles on unstructured roads to cope with complex working conditions such as muddy roads, complex roads in mining areas and winding mountain roads, and to avoid damage to the hinge points due to the existence of limitations. For this purpose, a semi-active control method of the vehicle body posture based on the oil-gas interconnected 1SD suspension is provided.

[0007] To achieve the above-mentioned purpose of the invention, the technical solution adopted by the present invention is a semi-active control system of the oil-gas interconnected ISD suspension body posture of an articulated vehicle, including a two-position two-way solenoid valve, a two-position four-way solenoid valve, a three-position four-way solenoid valve, a spiral tube, an electromagnetic proportional valve, a flow sensor, a PLC controller, a body posture monitoring device and six oil-gas hydraulic cylinders. The functions of the whole method are realized by the following steps:

[0008] 1. First, design an oil-gas interconnected ISD suspension system. The oil-gas hydraulic cylinder A and the oil-gas hydraulic cylinder B are installed between the cockpit body and the wheel where the cockpit is located. The rodless chambers of the two oil-gas hydraulic cylinders are connected to two different oil circuits, and the rod chambers are connected to one oil circuit. One of the oil circuits in the rodless chamber of the oil-gas hydraulic cylinder A and the oil circuit in the rod chamber are respectively connected to two ports of the three-position four-way electromagnetic reversing valve. After passing through the electromagnetic valve, the other two ports of the electromagnetic valve are connected in series with the two spiral tubes in the middle. The other end of the spiral tube is connected to one of the oil circuits in the rodless chamber of the oil-gas hydraulic cylinder B and the oil circuit in the rod chamber, so as to realize the connection of the chambers of the corresponding hydraulic cylinders under different working conditions, and connect an electromagnetic proportional valve and a flow sensor in parallel to the two spiral tubes. Oil-gas hydraulic cylinder C, oil-gas hydraulic cylinder D, oil-gas hydraulic cylinder E and oil-gas hydraulic cylinder F are installed between the cargo compartment and the wheel where the cargo compartment is located. Another oil path of the rodless chamber of oil-gas hydraulic cylinder A is connected to the rodless chamber of oil-gas hydraulic cylinder C through two-position two-way solenoid valve D, and another oil path of the rodless chamber of oil-gas hydraulic cylinder B is connected to the rodless chamber of oil-gas hydraulic cylinder D through two-position two-way solenoid valve F; at the same time, the rodless chambers of oil-gas hydraulic cylinder C and oil-gas hydraulic cylinder D are connected through two-position two-way solenoid valve E, and the rodless chambers of oil-gas hydraulic cylinder E and oil-gas hydraulic cylinder F are connected through two-position two-way solenoid valve G. Then the rodless chamber and rod chamber of oil-gas hydraulic cylinder C and oil-gas hydraulic cylinder D are connected to the two ends of two-position four-way solenoid valves B and C respectively, and the other two ends of solenoid valves B and C are connected to the rodless chamber and rod chamber of oil-gas hydraulic cylinder F and oil-gas hydraulic cylinder E respectively.

[0009] 2. Establish a kinematic model of an articulated vehicle with the hinge point located at the midpoint of the rear axle of the tractor. The kinematic model includes the tractor and the semi-trailer.f , rear axle midpoint O g , trailer axle midpoint O g and hinge point A r The vehicle kinematic model is derived from the geometric relationship in the geodetic coordinate system. Their coordinates are O f (x f ,y f ), O q (x r ,y r ), O g (x g ,y g ), A r (x a ,y a ).

[0010] Step 2-1: From the analysis, it can be seen that the tractor-trailer is a non-holonomic constraint system, that is, the number of control quantities is less than the number of state quantities, and the lateral motion and longitudinal motion of the vehicle are always coupled.

[0011]

[0012] In the formula, is the longitudinal velocity of the vehicle, is the lateral velocity of the vehicle, and θ is the heading angle of the vehicle.

[0013] Step 2-2: Ignoring lateral sliding, the axial velocity of the midpoints of all axles of the tractor-trailer is zero, and the following equation is satisfied:

[0014]

[0015] Where θ0 is the heading angle of the tractor, θ1 is the heading angle of the trailer, and δ f is the equivalent front wheel turning angle of the tractor.

[0016] Step 2-3: Take the rear axle midpoint O of the tractor q As the reference point, according to the geometric position relationship, the midpoint O of the rear axle of the tractor is established. q (x r ,y r ) and hinge point A r (x a ,y a ) is shown in the following formula (3):

[0017] x a =x f

[0018] y a =y r (3)

[0019] Step 2-4: Establish the midpoint O of the rear axle of the tractor according to the geometric position relationship q (x r ,y r ), and the midpoint O of the front axle of the tractor f (x f ,y f ) is shown in the following formula (4):

[0020] x f =x r +Lcosθ0

[0021] y f =y r +Lsinθ0 (4)

[0022] Where L is the wheelbase of the tractor and θ0 is the heading angle of the tractor.

[0023] Step 2-5: Establish the midpoint O of the rear axle of the tractor according to the geometric position relationship q (x r ,y r ) and the trailer axle midpoint O g (x g ,y g ) is shown in the following formula (5):

[0024] x g =x r -LTcosθ1

[0025] y g =y r -LTsinθ1 (5)

[0026] Where LT is the distance between the hinge point and the midpoint of the trailer axle, and θ is the heading angle of the trailer.

[0027] Assume that the rear axle midpoint of the tractor is q (x r ,y r ) The vehicle speed is V0, and the front wheel turning angle is δ f , then the midpoint of the rear axle of the tractor is O q The lateral and longitudinal vehicle speeds in the geodetic coordinate system can be expressed as shown in formula (6):

[0028]

[0029] Where V0 is the speed at the midpoint of the vehicle's rear axle, and θ0 is the heading angle of the tractor.

[0030] Step 2-6: By taking the derivative of equation (4), the velocity relationship of the midpoint Of of the front axle of the tractor can be obtained, as shown in equation (7):

[0031]

[0032] Where L is the wheelbase of the tractor and θ0 is the heading angle of the tractor.

[0033] Step 2-7: By taking the derivative of equation (5), we can get the trailer axle midpoint O g The speed relationship is shown in equation (8):

[0034]

[0035] Where LT is the distance between the hinge point and the midpoint of the trailer axle, and θ is the heading angle of the trailer.

[0036] Step 2-8: Substitute equation (7) into equation (2) and simplify to obtain the yaw rate expression of the tractor (9):

[0037]

[0038] θ0 is the heading angle of the tractor, δ f is the front wheel turning angle of the tractor.

[0039] Step 2-9: Substitute equation (8) into equation (2) and simplify to obtain:

[0040]

[0041] V0 is the speed of the midpoint of the vehicle's rear axle, θ0 is the heading angle of the tractor, θ1 is the heading angle of the semitrailer, L is the wheelbase of the tractor, and LT is the distance between the articulation point and the midpoint of the trailer axle.

[0042] Step 2-10: Based on the above derivation, integrate the equations, and the vehicle kinematic model with the articulation point located at the midpoint of the rear axle of the tractor is:

[0043]

[0044] In equation (11), V0 is the speed of the midpoint of the rear axle of the vehicle, θ0 is the heading angle of the tractor, θ1 is the heading angle of the semitrailer, L is the wheelbase of the tractor, LT is the distance between the articulation point and the midpoint of the trailer axle, δ f is the front wheel turning angle of the tractor.

[0045] Then, the mathematical model of the electromagnetic proportional valve is established. In this suspension system, the electromagnetic proportional valve plays the role of an actuator in a semi-active control system. By connecting it in parallel with the spiral tube, the opening of the electromagnetic proportional valve can be adjusted to change the flow in the electromagnetic proportional valve itself and the spiral tube, thereby changing the suspension output force through the flow diversion method. The electromagnetic proportional valve and its valve core structure used in this paper are shown in the figure.

[0046] The relationship between the flow rate through the electromagnetic proportional valve and the opening of the electromagnetic proportional valve and the pressure at both ends is described by the following formula:

[0047]

[0048] h=x0+x (14)

[0049]

[0050] In the formula, C d A is the flow coefficient of the electromagnetic proportional valve; d (h) is the flow area of ​​the electromagnetic proportional valve; A i is the cross-sectional area of ​​the spiral tube; h is the opening of the electromagnetic proportional valve; P cr is the minimum turbulence pressure; Re cr is the initial Reynolds number; v is the fluid kinematic viscosity; D H is the instantaneous hydraulic diameter of the electromagnetic proportional valve; x o is the initial opening; x is the displacement of the valve core ball relative to the initial position; A leak is the leakage area; A max is the maximum opening; r0 and d0 are the orifice radius and diameter respectively; r B ,d B are the radius and diameter of the valve core ball respectively; q1 is the flow rate through the electromagnetic proportional valve; q2 is the flow rate through the spiral tube; P1 is the pressure at the front of the electromagnetic proportional valve and the spiral tube; P2 is the pressure at the rear of the electromagnetic proportional valve and the spiral tube; μ is the viscosity coefficient of the oil; r is the inner diameter of the spiral tube; ρ is the density of the oil; D is the hydraulic diameter of the electromagnetic proportional valve; h max It is the maximum opening of the solenoid proportional valve.

[0051] Since this paper does not consider the turbulent pressure loss in the system, it is assumed that P cr The value of is zero, which can be further expressed as:

[0052]

[0053] Therefore, the damping characteristics of the electromagnetic proportional valve are considered to be consistent with the damping valve. Therefore, the pressure drop △P at both ends of the electromagnetic proportional valve e It can be expressed as:

[0054]

[0055] Since the electromagnetic proportional valve is connected in parallel with the spiral tube, according to fluid mechanics, the pressure drop across the electromagnetic proportional valve is equal to the pressure drop across the spiral tube. Therefore, the relationship between the flow rates flowing through the electromagnetic proportional valve and the spiral tube is:

[0056]

[0057] By solving equation (22), we can further obtain:

[0058]

[0059] Where, l is the length of the spiral tube after straightening; A i is the cross-sectional area of ​​the spiral tube; μ is the viscosity coefficient of the oil; A b is the flow area of ​​the spiral tube.

[0060] 3. Design a vehicle body posture monitoring device, which is composed of a gyroscope sensor, an acceleration sensor and a vehicle body height sensor, and is installed in the cab and the cargo compartment respectively. The two gyroscopes are used to measure the angular velocity of the roll or pitch of the cab and the cargo compartment in a certain period of time, and then the roll or pitch angle can be obtained by integrating them. However, the angle obtained by the integral operation itself has errors, and the errors will increase with the accumulation of time. At this time, the acceleration sensor is needed to assist in calculating the attitude angles of the cab and the cargo compartment. At this time, the calculated data is sent to the controller for analysis to obtain the angle θ1 generated by the simultaneous roll of the two compartments and the angle δ1 generated by the simultaneous pitch and the body vibration frequency f0, and compared with the pre-set roll angle θ0, pitch angle δ0 and the body low-frequency vibration threshold f1, high-frequency vibration threshold f2. If the threshold is exceeded, the solenoid valve position and the opening of the solenoid proportional valve are changed according to the pre-set strategy to control it, so as to achieve the purpose of switching the working state and suppressing vibration.

[0061] 4. Add a PLC controller, the PLC controller part includes a PLC controller 1, a lithium battery 2, and a power detection module 3. The power supply end of the PLC controller 1 and the power detection module 3 are electrically connected to the power supply end of the lithium battery 2, the PLC controller 1 and the power detection module 3 are electrically connected, and the control ends of each solenoid valve, solenoid proportional valve, flow sensor, and vehicle posture detection device are electrically connected to the I / O port of the PLC controller 1. The data measured by the flow sensors A, B and the vehicle posture detection devices A, B are used as input and connected to the input interfaces 13-16, and the solenoid proportional valves A, B and the solenoid valves A-G are connected to the output interface.

[0062] 5. The vehicle body posture monitoring device collects the longitudinal and lateral acceleration and angular velocity signals of the vehicle body and sends them to the PLC controller. The controller compares the current vehicle state parameters with the threshold values ​​set in the system to determine whether it is a muddy road condition, a complex road condition in a mining area, or a winding mountain road condition, and adjusts the corresponding working position of the solenoid valve to achieve different flow directions of oil in the oil and gas circuit under different working conditions. The oil and gas interconnection system of the present invention is divided into three working conditions, including: muddy road conditions, complex road conditions in mining areas, and winding mountain road conditions. In order to facilitate the explanation of the working principle of the interconnected oil and gas system, the rodless cavity and rod cavity of the oil and gas hydraulic cylinders A, B, C, D, E, and F are marked as a1, a2, b1, b2, c1, c2, d1, d2, e1, e2, f1, and f2 respectively, and the spiral tubes corresponding to the electromagnetic proportional valves A and B are l1 and l2.

[0063] 5-1. Muddy road conditions: When the vehicle is driving on a muddy road, the hinge point between the cockpit and the cargo compartment is prone to damage due to road settlement. At this time, the vehicle body posture monitoring device collects the longitudinal and lateral acceleration, angular velocity and height signals of the vehicle body, and sends them to the PLC controller. After calculation, the height and pitch angle of the cockpit and cargo compartment are obtained, and the hinge point angle is further calculated. If the hinge point angle exceeds the threshold set in advance, that is, δ1>δ0, the muddy road condition starts to work, and the solenoid valve A is adjusted to the lower T end by the command issued by the PLC controller. The hydraulic oil in the rodless chamber a1 of the oil-gas hydraulic cylinder A is connected to the spiral tube l1 through the three-position four-way solenoid valve A, and then connected to the rodless chamber b1 of the hydraulic cylinder B, forming the main oil circuit La. At this time, the rodless chambers a1 and b1 are interconnected, and the oil flows between them; the hydraulic oil in the oil-gas hydraulic cylinder a2 is connected to the spiral tube l2 through the solenoid valve A, and then connected to the rod chamber b2 of the hydraulic cylinder B, forming the main oil circuit Lb. At this time, the rod chambers a2 and b2 are interconnected. Solenoid valves D and F are switched to the T end, the solenoid valve is turned on, the solenoid valves E and G are placed at the O end, and the solenoid valves B and C are both at the T end. The oil in a1 and b1 flows to c1 and d1 through the solenoid valves D and F. At this time, the hydraulic cylinders A and B are respectively interconnected with the hydraulic cylinders C and D front and back, effectively reducing the angle of the hinge point and preventing damage to the hinge point.

[0064] 5-2. Complex road conditions in mining areas: When a vehicle is traveling in a mining area, due to the complex road conditions, there are many road subsidences and road protrusions, and it is also easy to produce pitch and roll. At this time, the vehicle posture monitoring device collects the longitudinal and lateral acceleration, angular velocity and height signals of the vehicle body, and sends them to the PLC controller. After calculation, the roll or pitch angle of the cockpit and cargo compartment is obtained. If the roll and pitch angles exceed the thresholds set in advance, that is, δ1>δ0 and θ1>θ0, the solenoid valves A, B, and C are adjusted to the upper P end, and the solenoid valves D, E, F, and G are all placed at the O end. The hydraulic oil in the rodless chamber a1 of the oil-gas hydraulic cylinder A flows into the spiral tube l2 through the reversing valve A, and then flows to the rod chamber of the hydraulic cylinder B to form the main oil circuit Lc. At this time, the rodless chamber a1 and the rod chamber b2 are interconnected, and the oil flows mutually; while the oil in the rod chamber a2 flows into the spiral tube l1 through the reversing valve A, and then flows to the rodless chamber of the hydraulic cylinder B to form the main oil circuit Ld. At this time, the rod chamber a2 and the rodless chamber b1 are interconnected, and the oil-gas hydraulic cylinders A and B are interconnected in the left and right reverse directions. The oil in the rodless chamber c1 of the oil-gas hydraulic cylinder C flows to the rod chamber f2 of the hydraulic cylinder F through the solenoid valve B, and the oil in c2 flows into f1 through the solenoid valve B; the oil in the rodless chamber d1 of the oil-gas hydraulic cylinder D flows into the rod chamber e2 of the hydraulic cylinder E through the solenoid valve C, and the oil in d2 flows into e1 through the solenoid valve C. At this time, the four hydraulic cylinders where the cargo compartment is located are interconnected in an X-shaped manner at the four corners, and their anti-roll and anti-pitch performance are improved at the same time.

[0065] 5-3: Winding mountain road condition: When the vehicle is driving on a winding mountain road, the longitudinal and lateral acceleration and angular velocity signals collected by the vehicle posture monitoring device are calculated and analyzed by the PLC controller. If the vehicle is in a roll state for a long time, that is, when θ1>θ0, it switches to the winding mountain road condition. At this time, the PLC controller switches the solenoid valve A to the working end P, the solenoid valves B and C to the T end, the solenoid valves D and F are placed at the O end, and the solenoid valves E and G are placed at the T end. The main oil circuits Lc and Ld of the cockpit are connected, and the hydraulic cylinders A and B are interconnected in reverse left and right. The oil in the rodless chamber c1 of the hydraulic cylinder C flows into the rodless chamber d1 of the hydraulic cylinder D through the solenoid valve E, and the oil in the rodless chamber e1 flows into the rodless chamber f1 of the hydraulic cylinder F through the solenoid valve G. At this time, the hydraulic cylinders C and D are interconnected left and right, and the hydraulic cylinders E and F are interconnected left and right, improving their anti-roll performance.

[0066] 6. A spiral tube inertia container is added to the interconnected oil circuit. The oil in the spiral tube flows in a spiral at a higher speed, thereby amplifying the rotational inertia of the oil in the spiral tube; the oil-gas spring integrates a damping valve and can be used in conjunction with the accumulator. The nitrogen in the accumulator acts as an elastic medium to store or release elastic potential energy through gas compression and expansion. The combination of the two can simultaneously play a role in buffering and vibration reduction. Based on the new electromechanical similarity theory, the organic combination of the three can play the role of the inertia container in effectively attenuating low-frequency vibrations through the medium of oil, thereby improving the vehicle's driving smoothness and road friendliness.

[0067] 7. In the oil-gas interconnected circuit, a solenoid proportional valve and a flow sensor are connected in parallel to the spiral tube. The flow sensor detects the oil volume in the parallel oil circuit. The controller can control the opening degree of the solenoid proportional valve according to the pre-set control strategy, thereby changing the oil flow through the spiral tube, comprehensively adjusting the damping force and inertia force of the suspension system, realizing the adjustability of the suspension output force, and achieving the purpose of adapting to different working conditions. When the vehicle vibrates at a low frequency, i.e., f0 < f1, the opening degree h of the solenoid proportional valve can be appropriately reduced to promote a corresponding increase in the flow through the spiral tube. This adjustment makes full use of the attenuation advantage of the inertance chamber in low-frequency vibration and effectively suppresses the influence of low-frequency vibration on vehicle stability. When the vehicle vibrates at a high frequency, i.e., f0 > f2, the opening degree h of the solenoid proportional valve can be increased to reduce or block the flow through the spiral tube, thereby avoiding the negative effect generated by the inertance chamber in high-frequency vibration.

[0068] 8. Compared with the prior art, the beneficial effects of the present invention are as follows:

[0069] (1). Compared with the passive suspension, the present invention can better cope with working conditions such as muddy roads, complex roads in mining areas, and mountain winding roads, reduce the pitch and roll angles, and prevent rollover.

[0070] (2). At the same time, semi-active control of the suspension can be realized through the solenoid proportional valve to cope with complex working conditions and improve the ride comfort and handling stability of the vehicle.

[0071] (3). According to the vehicle body attitude monitoring system, it is possible to avoid damage to the hinge point due to excessive roll or pitch angle, improving the driving safety of the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 is the control logic diagram of the whole system

[0073] Figure 2 is the oil circuit diagram of the whole system

[0074] Figure 3 is the spool structure of the solenoid proportional valve

[0075] Figure 4 In a), it is the internal oil passage diagram of the P port of the three-position four-way solenoid valve; in b), it is the internal oil passage diagram of the T port of the three-position four-way solenoid valve

[0076] Figure 5 is the oil circuit connection diagram under muddy road conditions

[0077] Figure 6 is the oil circuit connection diagram under complex road conditions in mining areas

[0078] Figure 7 is the oil circuit connection diagram under mountain winding road conditions

[0079] Figure 8 Circuit connection diagram of PLC controller

[0080] Fig. 9 Internal structure diagram of PLC controller DETAILED DESCRIPTION

[0081] The patent of the present invention is further described below in conjunction with the accompanying drawings and embodiments. The functional realization of the semi-active control system of the oil-gas interconnected ISD suspension body posture of the articulated vehicle of the present invention is shown in the figure. The muddy road condition, the complex road condition in the mining area and the winding mountain road condition are mainly for the working state of each solenoid valve; the muddy road condition mainly reduces the angle of the hinge point; the complex road condition in the mining area is mainly to effectively improve the roll stiffness and pitch stiffness at the same time; the winding mountain road condition is mainly to deal with long-term roll, prevent rollover, and improve handling stability.

[0082] The working principle of the two-position four-way solenoid valve is as follows: when the valve core is at the upper P end, port A is connected to port P, and at the same time, end B is connected to end O through the oil return port below; when the valve core is at the lower T end, the four oil ports are blocked by the valve core, independent of each other, and the oil does not communicate with each other.

[0083] The working principle of the three-position four-way solenoid valve is as follows: when the valve core is at the lower T end, the A port of the solenoid valve is connected to the O port, and the B port is connected to the P port; when the valve core is at the upper P end, the A port is connected to the P port, and the B end is connected to the O end through the lower oil return port; when the valve core is in the middle position, the four oil ports are blocked by the valve core, independent of each other, and the oil does not communicate with each other.

[0084] The specific steps are as follows:

[0085] 1. Muddy road conditions: When the vehicle is driving on a muddy road, the hinge point between the cab and the cargo compartment is easily damaged due to road settlement. At this time, the vehicle body posture monitoring device collects the longitudinal and lateral acceleration, angular velocity and vehicle height signals of the vehicle body, and sends them to the PLC controller. After calculation, the pitch angle and height of the cab and the cargo compartment are obtained, and the hinge point angle is further calculated. If the hinge point angle exceeds the threshold set in advance, that is, δ1>δ0, the pitch angle of both the cab and the cargo compartment will be too large, causing the hinge point angle to exceed the limit angle, and the vehicle handling stability, ride comfort and driving safety will be reduced. At this time, the current vehicle posture needs to be corrected, and the controller sends a command to control the solenoid valve A to adjust to the lower position, and the valve core is fixed at the T end. At this time, the external O port of the solenoid valve core is connected to the rodless chamber a1 of the oil-gas hydraulic cylinder A, the P port is connected to the rod chamber a2, the A port is connected to one end of the spiral tube oil circuit l1, and the B port is connected to one end of the spiral tube oil circuit l2. The rodless chamber a1 passes through the O port and the A port of the reversing valve to the spiral tube l1, and then to the rodless chamber b1 to form a main oil path La; the rod chamber a2 passes through the P port and the B port of the reversing valve to the spiral tube l2, and then to the rod chamber b2 to form another main oil path Lb. The solenoid valves D and F are switched to the T end, the solenoid valve is turned on, the solenoid valves E and G are placed at the O end, and the solenoid valves B and C are both at the T end. The oil in a1 and b1 flows through the solenoid valves D and F to c1 and d1. At this time, the hydraulic cylinders A and B are interconnected with the hydraulic cylinders C and D respectively. Figure 5As shown in the figure. When the vehicle pitches due to road surface settlement, the angle of the hinge point will increase, and at the same time, the vehicle body will change its attitude. Assume that the vehicle cockpit passes through a road surface settlement, the vehicle body tilts forward, the oil and gas hydraulic cylinders A and B of the cockpit move downward, and the hydraulic cylinders C and D move upward. At this time, the oil pressure in the rodless cavities a1 and b1 decreases, thereby pumping the oil in the hydraulic cylinder chambers c1 and d1 to flow through the solenoid valve and the hydraulic pipeline to the hydraulic cylinder chambers a1 and b1, causing the hydraulic cylinders C and D to move downward and suppressing the upward movement of the cargo hold, and vice versa. At this time, the oil in the rodless cavities a1 and b1 of the cockpit hydraulic cylinder is interconnected after flowing through the spiral tube and the electro-hydraulic proportional valve, and the oil in the rod chambers a2 and b2 of the cockpit hydraulic cylinder is interconnected after flowing through the spiral tube and the electro-hydraulic proportional valve. The inertia is generated by the high-speed flowing oil, greatly improving the dynamic load of the tire and its high-frequency peak value. The control of the opening degree of the electro-hydraulic proportional valve can adopt the PID control strategy. When the vehicle body attitude monitoring device sends the detected longitudinal, lateral acceleration and angular velocity signals of the vehicle body into the PLC controller, if it is analyzed that the vehicle is vibrating at a low frequency, that is, f0 < f1, the PLC controller sends a command to the electro-hydraulic proportional valve to control the electro-hydraulic proportional valve to reduce its opening degree f according to the control strategy, prompting the flow rate through the spiral tube to increase accordingly, so as to make full use of the attenuation advantage of the inertance in low-frequency vibration. In this process, the flow sensor is responsible for detecting the oil volume in the parallel oil circuit, the vehicle body attitude monitoring device collects the vehicle body state information again and feeds it back to the PLC controller for analyzing its working condition and vibration frequency, and the reversing valve changes its working position again according to the analysis result. The electro-hydraulic proportional valve adjusts the opening degree again according to the set control strategy according to the size of the vehicle body vibration frequency, so as to make the suspension output appropriate inertial force and damping force again, and so on in a cycle, thereby suppressing the suspension bounce and the vehicle body pitch, enhancing the road friendliness and improving the driving safety.

[0086] 2. Complex road conditions in mining areas: When a vehicle is traveling in a mining area, due to the complex road conditions, there are many road subsidences and road protrusions, and it is also easy to produce pitch and roll. That is, when δ1>δ0 and θ1>θ0, the vehicle posture monitoring device collects the longitudinal and lateral acceleration and angular velocity signals of the vehicle body and sends them to the PLC controller. After calculation, the roll or pitch angle and respective heights of the cockpit and cargo compartment are obtained. If the roll and pitch angles exceed the preset thresholds after comparison, the roll or pitch angles of both the cockpit and the cargo compartment will be too large, causing the angle of the hinge point to exceed the limit angle, reducing the vehicle's handling stability, ride comfort and driving safety. At this time, it is necessary to correct the current vehicle posture. The controller sends a command to control the solenoid valves A, B, and C to the upper position, and the valve core is fixed at the P end; the solenoid valves D, E, F, and G are all placed at the lower O end. At this time, the external O port of the valve core of the solenoid valve A is connected to the rodless chamber a1 of the oil-gas hydraulic cylinder A, the P port is connected to the rod chamber a2, the A port is connected to the left end of the spiral tube oil circuit l1, and the B port is connected to the left end of the spiral tube oil circuit l2. The rodless chamber a1 is connected to the spiral tube l2 through the O port and the B port of the solenoid valve A, and then to the rod chamber b2 to form a main oil circuit Lc; the rod chamber a2 is connected to the spiral tube l1 through the P port and the A port of the reversing valve A, and then to the rodless chamber b1 to form another main oil circuit Ld. The oil in the rodless chamber c1 of the oil-gas hydraulic cylinder C flows to the rod chamber f2 of the hydraulic cylinder F through the solenoid valve B, and the oil in c2 flows into f1 through the solenoid valve B; the oil in the rodless chamber d1 of the oil-gas hydraulic cylinder D flows into the rod chamber e2 of the hydraulic cylinder E through the solenoid valve C, and the oil in d2 flows into e1 through the solenoid valve C. At this time, the four hydraulic cylinders where the cargo hold is located are interconnected in an X-shape at the four corners, as shown in Figure 2. Figure 6As shown. When the vehicle encounters road subsidence or protrusions or makes turns on the complex road surface in the mining area, the body will roll or pitch. At this time, the pitch and roll stiffness must be taken into account. Assuming that the vehicle pitches, the body tilts forward, the cockpit hydraulic cylinders A and B move downward, the cargo compartment oil and gas hydraulic cylinders C and D move downward, and the hydraulic cylinders E and F move upward. The oil pressure in the rodless chambers c1 and d1 of the oil and gas hydraulic cylinders C and D increases, pushing the oil to flow to f2 and e2 through the solenoid valves B and C respectively. The oil pressure in f2 and e2 increases, giving the oil and gas hydraulic cylinders E and F a downward force, causing the oil and gas hydraulic cylinders E and F to move downward, inhibiting the upward movement of the oil and gas hydraulic cylinders E and F. At this time, the oil in the rodless chamber a1 and the rod chamber b2 of the cockpit hydraulic cylinder flows through the spiral tube and the electromagnetic proportional valve and then is interconnected. The oil in the rod chamber a2 and the rodless chamber b1 of the cockpit hydraulic cylinder flows through the spiral tube and the electromagnetic proportional valve and then is interconnected. The high-speed moving oil generates inertia, and the PID control strategy can be used to control the opening size of the electromagnetic proportional valve. When the body posture monitoring device sends the detected longitudinal, lateral acceleration and angular velocity signals of the body to the PLC controller, if it is analyzed that the vehicle is vibrating at a high frequency, that is, f0>f2, the PLC controller sends a command to the electromagnetic proportional valve, causing the electromagnetic proportional valve to increase its opening h according to the control strategy, causing the flow through the spiral tube to decrease accordingly, thereby avoiding the negative effects of the inertia container in high-frequency vibration. In this process, the flow sensor is responsible for detecting the amount of oil in the parallel oil circuit. The body posture monitoring device collects the body status information again and feeds it back to the PLC controller to analyze its working condition and vibration frequency. The reversing valve changes its working position again according to the analysis results. The electromagnetic proportional valve adjusts the opening size again according to the set control strategy according to the size of the body vibration frequency, so that the suspension outputs appropriate inertia force and damping force. This cycle is repeated to suppress suspension bounce and body roll, coordinate handling stability and smoothness, and improve driving safety.

[0087] 3. Working condition of winding mountain road: When the vehicle is driving on the winding mountain road, the vehicle is prone to long-term roll due to frequent steering. The body posture monitoring device collects the longitudinal and lateral acceleration and angular velocity signals of the body and sends them to the PLC controller. After calculation, the roll angle and height of the cockpit and cargo compartment are obtained. If the roll angle and roll time exceed the preset threshold value, that is, θ1>θ0, the vehicle is at risk of rollover, and the vehicle's handling stability and driving safety are reduced. At this time, the current vehicle posture needs to be corrected. The controller valve outputs a command to control the solenoid valve A to switch to the working end P, the solenoid valves B and C to switch to the T end, the solenoid valves D and F to the O end, and the solenoid valves E and G to the T end. The main oil circuits Lc and Ld of the cockpit are connected, and the hydraulic cylinders A and B are interconnected in reverse on the left and right. The oil in the rodless chamber c1 of the hydraulic cylinder C flows into the rodless chamber d1 of the hydraulic cylinder D through the solenoid valve E, and the oil in the rodless chamber e1 flows into the rodless chamber f1 of the hydraulic cylinder F through the solenoid valve G. At this time, the hydraulic cylinders C and D are interconnected on the left and right, and the hydraulic cylinders E and F are interconnected on the left and right. Due to the continuous steering on the winding mountain road, the vehicle body will roll over for a long time, and due to the large steering angle of some sections, there is a risk of rollover. At this time, its roll stiffness needs to be improved. Assuming that the vehicle is going up along the winding mountain road, the body tilts to the right, the left hydraulic cylinders A, C and E of the whole vehicle are running upward at the same time, and the right hydraulic cylinders B, D and F are running downward at the same time. The oil pressure in the rodless chamber a1 of the oil-gas hydraulic cylinder A in the cockpit increases, pushing the oil in a1 to flow to b2 through the oil line Lc, giving the oil-gas hydraulic cylinder B an upward force, causing the oil-gas hydraulic cylinder B to move upward, inhibiting the downward movement of the oil-gas hydraulic cylinder B. The oil pressure in the hydraulic cylinder chambers d1 and f1 of the truck box decreases, thereby pumping the oil in the hydraulic cylinder chambers c1 and e1 to flow to the hydraulic cylinder chambers d1 and f1 through the solenoid valve and hydraulic pipeline, causing the hydraulic cylinders D and F to move upward, inhibiting the downward movement of the hydraulic cylinders D and F, and vice versa. At this time, the oil in the rodless chamber a1 and the rod chamber b2 of the cockpit hydraulic cylinder flows through the spiral tube and the electromagnetic proportional valve and then is interconnected. The oil in the rod chamber a2 and the rodless chamber b1 of the cockpit hydraulic cylinder flows through the spiral tube and the electromagnetic proportional valve and then is interconnected. The high-speed moving oil generates inertia, and the PID control strategy can be used to control the opening size of the electromagnetic proportional valve.When the vehicle body attitude monitoring device sends the detected longitudinal and lateral acceleration and angular velocity signals of the vehicle body into the PLC controller, if it is analyzed that the vehicle is vibrating at a low frequency, that is, f0 < f1, the PLC controller sends a command to the electromagnetic proportional valve, making the electromagnetic proportional valve reduce its opening degree according to the control strategy, promoting the corresponding increase in the flow rate through the solenoid tube, so as to make full use of the attenuation advantage of the inertance container in low-frequency vibration. During this process, the flow sensor is responsible for detecting the oil volume in the parallel oil circuit. The vehicle body attitude monitoring device collects the vehicle body state information again and feeds it back to the PLC controller for analyzing its working condition and vibration frequency. The reversing valve changes its working position again according to the analysis result, and the electromagnetic proportional valve adjusts the opening degree again according to the set control strategy according to the size of the vehicle body vibration frequency, so as to make the suspension output appropriate inertial force and damping force. This cycle repeats to suppress suspension bounce and vehicle body roll, coordinate handling stability and ride comfort, and improve driving safety.

[0088] In summary, the present invention can switch among three working conditions of the suspension to cope with different driving and road conditions; at the same time, it can achieve semi-active control of the suspension through the electromagnetic proportional valve to cope with complex working conditions, improve the ride comfort and handling stability of the vehicle; and according to the vehicle body attitude monitoring system, it can avoid damage to the hinge point due to excessive roll or pitch angle, and improve the driving safety of the vehicle.

Claims

1. A semi-active control method for the body posture of an articulated vehicle with oil-gas interconnected ISD suspension, characterized in that: The following steps are involved: Step 1, design the oil-gas interconnected ISD suspension system, arrange its oil circuit, and establish the kinematic model of the articulated vehicle with the hinge point located at the midpoint of the rear axle of the tractor and the mathematical model of the electromagnetic proportional valve as a reference model. The kinematic model includes the tractor and the semi-trailer; Step 2, using a gyroscope sensor, an acceleration sensor and a vehicle height sensor to construct a vehicle posture monitoring device to obtain road information and vehicle posture information in real time; Step 3, adding a PLC controller, taking corresponding control strategies according to the different vehicle body posture information obtained in step 2, and controlling each electromagnetic reversing valve in the system through the PLC controller to change the different flow directions of the oil in the oil-gas circuit, realize the change of the oil-gas ISD suspension interconnection mode, and achieve the purpose of coping with the three working conditions of muddy, mining area, and winding mountain roads, and avoid the cockpit and cargo compartment of the articulated vehicle from being damaged due to the articulation point being greater than the limit angle due to bumps on unstructured roads; Step 4: embed a spiral tube inertial container in the oil-gas interconnection circuit to store oil kinetic energy and improve the low-frequency vibration isolation performance of the vehicle; Step 5, connect an electromagnetic proportional valve in parallel with the spiral tube, and the PLC controller changes the oil flow through the spiral tube by adjusting the opening of the electromagnetic proportional valve, thereby comprehensively adjusting the damping force and inertia force of the suspension system, realizing the adjustable suspension output force, thereby realizing semi-active control of the vehicle body posture; Step 6: The vehicle body posture monitoring device collects the vehicle body status information again and feeds it back to the PLC controller to analyze its working condition and vibration frequency. The reversing valve changes its working position again according to the analysis results, and the electromagnetic proportional valve adjusts the opening size again according to the size of the vehicle body vibration frequency according to the set control strategy.

2. The method according to claim 1, characterized in that The design of the oil-gas interconnected ISD suspension system is realized through the following steps. The system includes a two-position two-way solenoid valve, a two-position four-way solenoid valve, a three-position four-way solenoid valve, a spiral tube, an electromagnetic proportional valve, a flow sensor, a PLC controller, a vehicle body posture monitoring device and six oil-gas hydraulic cylinders; Six oil-gas hydraulic cylinders are installed at the suspension positions corresponding to the six wheels, among which oil-gas hydraulic cylinder A and oil-gas hydraulic cylinder B are installed between the cockpit body and the wheel where the cockpit is located. The rodless chambers of these two oil-gas hydraulic cylinders are connected to two different oil circuits, and the rod chambers are connected to one oil circuit. One of the oil circuits of the rodless chamber of oil-gas hydraulic cylinder A and the oil circuit of the rod chamber are respectively connected to two ports of the three-position four-way electromagnetic reversing valve. After passing through the electromagnetic valve, the other two ports of the electromagnetic valve are connected in series with the two middle spiral tubes. The other end of the spiral tube is connected to one of the oil circuits of the rodless chamber of oil-gas hydraulic cylinder B and the oil circuit of the rod chamber, so as to realize the connection of the chambers of the corresponding hydraulic cylinders under different working modes, and the two spiral tubes are connected in parallel with an electromagnetic proportional valve, and a flow sensor is connected in series with the electromagnetic proportional valve in the branch to check the flow of the relevant oil channel; The oil-gas hydraulic cylinder C, the oil-gas hydraulic cylinder D, the oil-gas hydraulic cylinder E and the oil-gas hydraulic cylinder F are installed between the cargo compartment and the wheels where the cargo compartment is located; another oil circuit of the rodless chamber of the oil-gas hydraulic cylinder A is connected to the rodless chamber of the oil-gas hydraulic cylinder C through a two-position two-way solenoid valve D, and another oil circuit of the rodless chamber of the oil-gas hydraulic cylinder B is connected to the rodless chamber of the oil-gas hydraulic cylinder D through a two-position two-way solenoid valve F; at the same time, the rodless chambers of the oil-gas hydraulic cylinder C and the oil-gas hydraulic cylinder D are connected through a two-position two-way solenoid valve E, and the rodless chambers of the oil-gas hydraulic cylinder E and the oil-gas hydraulic cylinder F are connected through a two-position two-way solenoid valve G; then the rodless chambers and rod chambers of the oil-gas hydraulic cylinder C and the oil-gas hydraulic cylinder D are respectively connected to the two ends of the two-position four-way solenoid valves B and C, and the other two ends of the solenoid valves B and C are respectively connected to the rodless chambers and rod chambers of the oil-gas hydraulic cylinder F and the oil-gas hydraulic cylinder E; Solenoid valve A, solenoid valve B, solenoid valve C, solenoid valve D, solenoid valve E, solenoid valve F, solenoid valve G and solenoid proportional valve A, solenoid proportional valve B are all connected to the PLC controller and are controlled by the controller to change the working position of the solenoid reversing valve and adjust the opening size of the solenoid proportional valve.

3. The method according to claim 1, characterized in that The kinematic model of an articulated vehicle with the hinge point located at the midpoint of the rear axle of the tractor is established. The kinematic model includes the tractor and the semi-trailer. f , rear axle midpoint O g , trailer axle midpoint O g and hinge point A r The vehicle kinematic model is derived from the geometric relationship in the geodetic coordinate system; then, the mathematical model of the electromagnetic proportional valve is established, and the relationship between the flow rates flowing through the electromagnetic proportional valve and the spiral tube is derived; in this suspension system, the electromagnetic proportional valve plays the role of an actuator in a semi-active control system. By connecting it in parallel with the spiral tube, the opening of the electromagnetic proportional valve can be adjusted to change the flow rates in the electromagnetic proportional valve itself and the spiral tube, thereby changing the suspension output force through the diversion method.

4. The method according to claim 1, characterized in that: The vehicle body posture monitoring device is composed of a gyroscope sensor, an acceleration sensor and a vehicle body height sensor. The two gyroscopes are used to measure the angular velocity of the cockpit and cargo compartment's roll or pitch in a certain period of time, and then the roll or pitch angle is obtained by integrating the angular velocity. The acceleration sensor is used to assist in calculating the attitude angle of the cockpit and cargo compartment. At this time, the calculated data is sent to the controller for analysis to obtain the angle θ1 caused by the body roll, the angle δ1 caused by the simultaneous pitch, and the body vibration frequency f0.

5. The method according to claim 1, characterized in that It also includes a controller, which is composed of a PLC controller, a lithium battery, and a power detection module. The power supply end and the power detection module of the PLC controller are electrically connected to the power supply end of the lithium battery respectively. The PLC controller and the power detection module are electrically connected, and the control ends of each solenoid valve, solenoid proportional valve, flow sensor, and vehicle body posture detection device are electrically connected to the I / O port of the PLC controller respectively.

6. The method according to claim 1, characterized in that In step 3, the switching of interconnection modes to cope with the three working conditions is that the body posture monitoring device collects the longitudinal, lateral acceleration and angular velocity signals of the body and sends them to the PLC controller. The controller compares the current vehicle state parameters with the thresholds set in the system to determine whether it is a muddy road condition, a complex road condition in a mining area, or a winding mountain road condition, and then controls the solenoid valve according to the working condition.

7. The method according to claim 6, characterized in that In step 3, the PLC controller is used to control each solenoid reversing valve in the system to change the different flow directions of the oil in the oil and gas circuit, realize the change of the oil and gas ISD suspension interconnection mode, and achieve the purpose of coping with muddy, mining area, and winding mountain road conditions: 1). Muddy road conditions: When the vehicle is driving on a muddy road, the articulated vehicle is prone to damage to the hinge point due to road subsidence. The PLC controller switches the solenoid valve A to the working end T, the oil and gas hydraulic cylinders A and B are interconnected in the forward direction, the solenoid valves D and F are placed at the upper end, the solenoid valves E and G are placed at the lower end, and the solenoid valves B and C are both at the T end. The oil and gas hydraulic cylinders A and B are interconnected with the oil and gas hydraulic cylinders C and D front and back, respectively. At this time, the oil channels at the corresponding positions are connected, effectively controlling the hinge point to not exceed the limit angle; 2). Complex road conditions in mining areas: When the vehicle is driving on the road surface in the mining area, the road surface in the mining area is relatively complex, and there are many road subsidence or protrusions. At this time, the PLC controller switches the solenoid valve A to the working end T, and the oil and gas hydraulic cylinders A and B are interconnected in the forward direction. Magnetic valve A switches to the working end P, and the oil-gas hydraulic cylinders A and B at the location of the cockpit are reversely interconnected through the intermediate oil circuit. Solenoid valves D, E, F, and G are all placed at the lower end, and solenoid valves B and C are placed at the P end. The four oil-gas hydraulic cylinders C, D, E, and F at the cargo compartment are interconnected in an X-shaped manner. At this time, the oil channels at the corresponding positions are connected, which effectively improves their roll stiffness and pitch stiffness; 3). Winding mountain road working conditions: When the vehicle is driving on a winding mountain road, the vehicle is prone to long-term roll due to frequent steering. The PLC controller switches the solenoid valve A to the working end P, the solenoid valves B and C to the T end, the solenoid valves D and F are placed in the lower position, and the solenoid valves E and G are placed in the upper position. At this time, the oil-gas hydraulic cylinders A and B at the location of the cockpit are reversely interconnected left and right through the intermediate oil circuit, and the oil-gas hydraulic cylinders C and E at the cargo compartment are interconnected with D and F on the left and right respectively, and the oil channels at the corresponding positions are connected, which effectively improves its roll stiffness; the relevant oil channels do not interfere with each other under the three working conditions.

8. The method according to claim 1, characterized in that In step 4, a spiral tube is embedded in the interconnected loop. The slender spiral tube acts as an inertia element to provide inertia force and parasitic damping force. The damping valve and the electromagnetic proportional valve act as damping elements to provide damping force for vibration reduction, which is equivalent to the shock absorber in the mechanical suspension. The two accumulators are filled with a certain amount of high-pressure inert gas to provide suspension elastic force, which is equivalent to the spring in the mechanical suspension and plays the role of supporting the vehicle body and buffering.

9. The method according to claim 1, characterized in that: In step 5, an electromagnetic proportional valve and a flow sensor are connected in parallel with the spiral tube, which can detect the flow in the oil circuit and adjust the oil flow through the spiral tube by controlling the opening of the electromagnetic proportional valve, thereby comprehensively adjusting the damping force and inertia force of the suspension system; when the vehicle vibrates at a low frequency, the attenuation advantage of the inertia container in low-frequency vibration can be fully utilized to effectively suppress the influence of low-frequency vibration on vehicle stability; when the vehicle is in high-frequency vibration, the opening is adjusted to avoid the negative effect of the inertia container in high-frequency vibration.

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