CN115817098A - A trailing arm type oil-air suspension control system and control method thereof - Google Patents

Abstract

The invention discloses a trailing arm type hydro-pneumatic suspension control system and a control method thereof, wherein the control method comprises the following steps: the oil-gas suspension system, the brake system and the power unit assembly; the hydro-pneumatic suspension system and the braking system are respectively connected with the power unit assembly. The hydro-pneumatic suspension system includes: a plurality of pairs of axle suspension systems; the axle suspension system comprises a left suspension oil cylinder, a left suspension energy accumulator, a left through valve, a left posture adjusting valve, a right suspension oil cylinder, a right suspension energy accumulator, a right through valve and a right posture adjusting valve; the brake system includes: brake accumulator, inverse proportion brake valve, brake, pressure sensor and oil-supplementing valve. The advantages are that: the real-time synchronous lifting action of the multi-shaft hydro-pneumatic suspension is realized by the braking assistance of a hydraulic braking system without adding any complex hydraulic valve set and control strategy; the hydro-pneumatic suspension system does not increase any additional control element, and the hydro-pneumatic suspension can realize any one-key leveling within the stroke range through the built-in position sensor of the suspension oil cylinder.

Description

A trailing arm type oil-air suspension control system and its control method

technical field

The invention relates to a trailing arm type oil-gas suspension control system and a control method thereof, belonging to the technical field of suspension control.

Background technique

There are mainly two types of suspension structure layout for off-road vehicles: cross arm type and longitudinal arm type. The cross-arm suspension refers to the suspension structure in which the wheels swing in the transverse plane of the vehicle, and the trailing arm suspension refers to the suspension structure in which the wheels swing in the longitudinal plane of the vehicle. Oil-air suspension is a suspension device that integrates elastic elements and shock absorbers. It overcomes the linear characteristics of leaf springs. It is applied to engineering vehicles and special vehicles. It has good vibration reduction performance, ride comfort and vehicle driving stability, and can realize Adjustability of ride height. The upper end of the trailing arm type oil-pneumatic suspension is hinged with the vehicle frame, and the lower end is hinged with the swing leg of the trailing arm. With the expansion and contraction of the suspension oil cylinder, the vehicle frame and the trailing arm swing legs move relative to each other, so that the upper body of the vehicle can be raised and lowered relative to the ground.

The automatic leveling of the oil-pneumatic suspension means that each suspension cylinder reaches a different designated position, or reaches the same designated position, so that the bodywork is level. The commonly used method is to control the opening and closing time of the switch valve through position sensors and angle sensors, so that Control the expansion and contraction of each suspension cylinder.

The synchronous lifting of oil and gas suspension means that the oil cylinders move at the same time and the speed is synchronized. At present, the synchronous lifting and lowering of the oil and gas suspension is generally realized through synchronous pumps, gear splitters, speed control valves, diversion and confluence valves, etc. A more accurate system is a post-valve compensation system composed of electromagnetic proportional valves and hydraulic control directional valves to achieve synchronous action.

The automatic leveling of oil and gas suspension is easy, but the synchronous lifting is difficult. Auto-leveling requires results, and synchronization requires processes. During the lifting and lowering process of the multi-axis trailing arm suspension, due to the interaction force between the front and rear axles, the tires on the swing legs of the trailing arm will roll relative to the ground, which makes it difficult to synchronize the lifting and lowering movements of the suspension and affects the stability of the body. .

To sum up, the existing technology has the following disadvantages: (1) The synchronization and leveling system of the oil-air suspension is complicated; (2) The leveling system of the oil-air suspension cannot achieve the leveling of any displacement; (3) The synchronization accuracy is limited by the valve group The manufacturing accuracy has a great influence, and on-site debugging is difficult.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the defects of the prior art, provide a trailing arm type oil-air suspension control system and its control method, and realize the off-road vehicle attitude adjustment action, driving brake and parking brake; the present invention can quickly It realizes independent control of suspension cylinders, synchronous control of coaxial suspension cylinders, synchronous control of suspension cylinders on the same side, and synchronous adjustment of vehicle lifting, which can meet the needs of various driving conditions. The solution of the invention can improve the driving safety and mobility of the off-road vehicle.

In order to solve the above technical problems, the present invention provides a trailing arm oil-air suspension control system, including: oil-air suspension system, braking system and power unit assembly; the oil-air suspension system and braking system are respectively connected to the power unit assembly;

The oil-pneumatic suspension system includes: several pairs of axle suspension systems, the number of the axle suspension systems is consistent with the number of vehicle axles; the axle suspension system includes a left suspension oil cylinder, a left suspension accumulator, a left through valve , the left attitude control valve and the right suspension oil cylinder, the right suspension accumulator, the right through valve, and the right attitude adjustment valve; wherein, the left suspension oil cylinder is respectively connected with the left through valve and the left attitude adjustment valve, and the left suspension accumulator is connected with the left through valve , the left attitude control valve is also connected to the power unit assembly and the left through valve; the right suspension cylinder is connected to the right through valve and the right attitude control valve respectively, the right suspension accumulator is connected to the right through valve, and the right attitude control valve is also connected to the power unit Assembly and right through valve; left suspension cylinder and right suspension cylinder are built with displacement sensors;

The braking system includes: a brake accumulator, an inverse proportional brake valve, a brake, a pressure sensor, and an oil replenishment valve; The assembly is connected to the fuel supply valve, the inverse proportional brake valve is connected to the brake, and the brake is set on the tire rim for braking the vehicle;

The pressure sensor is used to collect the oil pressure in the brake accumulator, and convert it into an electrical signal and transmit it to the power unit assembly; the inverse proportional brake valve has pressure output when it is not powered, and has no pressure output when it is powered; the brake has a pressure hold Dead, no pressure to release; inverse proportional brake valve is not powered when the whole vehicle brakes, and when the power is on, the whole vehicle brakes are released.

Further, there are two brake accumulators and two inverse proportional brake valves, forming a pair of control modules;

One of the control modules controls the brake on the left side of the axle and the other control module controls the brake on the right side of the axle.

Further, the power unit assembly adopts a hydraulic power unit assembly, which is used to control the oil-pneumatic suspension system and the braking system through hydraulic oil to perform suspension cylinder action and braking action.

Further, the lower hinge points of the left and right suspension oil cylinders of the axle suspension system are symmetrically arranged on the corresponding swing legs of the axle, and the upper hinge points of the oil cylinders are arranged on the vehicle body.

Further, the oil inlet port of the inverse proportional brake valve is connected to the brake accumulator, the oil return port of the inverse proportional brake valve is connected to the oil tank of the power unit assembly, and the output port of the inverse proportional brake valve is connected to the brake.

Further, the suspension accumulators in all the axle suspension systems have the same volume and the same pre-charging pressure.

A hydraulic braking method for a trailing arm type oil-pneumatic suspension control system, comprising:

In the initial state, the inverse proportional brake valve is not powered, the pressure oil in the brake accumulator is input to the brake through the oil inlet of the inverse proportional brake valve, and the brake locks the rim under the action of hydraulic oil to realize the braking of the whole vehicle;

When the pressure sensor detects that the pressure in the brake accumulator is lower than the set value, the power unit assembly supplies oil to the brake accumulator until the pressure of the brake accumulator reaches the set value, the power unit assembly to stop fuel supply;

When the brake needs to be released, a certain current is continuously given to the inverse proportional brake valve to control the hydraulic oil in the brake to flow back to the oil tank through the oil return port, and the brake is separated from the brake disc under the action of the spring force, so that the whole vehicle is completely released from the brake. move.

A coaxial suspension synchronous lifting control method for a trailing arm type oil-air suspension control system, comprising:

The hydraulic braking system is in the initial state, all tires are in the braking state, the swing arm of the vehicle rotates around the contact point between the tire and the ground, and the frame rotates around the swing arm;

If the suspension of a certain bridge needs to be raised or lowered synchronously, the power unit assembly controls the corresponding left attitude control valve and the right attitude control valve of the bridge to be energized, and the rodless chambers of the left suspension oil cylinder and the right suspension oil cylinder enter oil and have a The rod cavity returns oil, and the left suspension oil cylinder and the right suspension oil cylinder are extended synchronously under the joint action of their respective swing arms and the frame, driving the bodywork to move upwards synchronously, and the left suspension oil cylinder is detected by the built-in displacement sensors in the left suspension oil cylinder and the right suspension oil cylinder. The stroke positions of the oil cylinder and the right suspension cylinder are adjusted at any position within the stroke range of the suspension cylinder according to the detected stroke position.

A method for synchronous lifting and lowering control of the suspension on the same side of a trailing arm type oil-air suspension control system, comprising:

The hydraulic braking system is in the initial state, all tires are in the braking state, the swing arm of the vehicle rotates around the contact point between the tire and the ground, and the frame rotates around the swing arm;

If the suspension on one side needs to be raised or lowered synchronously, all the attitude control valves on the same side are controlled to be energized at the same time through the power unit assembly. Under the joint action of their respective swing arms and frame, the suspension cylinders elongate synchronously, driving the bodywork to move upwards synchronously, and detect the stroke position of each suspension cylinder through the built-in displacement sensors of all suspension cylinders. Leveling at any position within the range; all attitude control valves on the same side refer to all left or right attitude adjustment valves on the same side, and all suspension cylinders on the same side refer to all left suspension cylinders or all right suspension cylinders on the same side cylinder.

A method for synchronous lifting and lowering control of a vehicle suspension of a trailing arm type oil-air suspension control system, comprising:

The hydraulic braking system is in the initial state, all tires are in the braking state, the swing arm of the vehicle rotates around the contact point between the tire and the ground, and the frame rotates around the swing arm;

If the suspension of the whole vehicle needs to be raised or lowered synchronously, all the attitude control valves of the whole vehicle are controlled to be powered on at the same time through the power unit assembly. Under the joint action of their respective swing arms and frame, the oil cylinders elongate synchronously, driving the bodywork to move upwards synchronously, and detect the stroke position of each suspension cylinder through the built-in displacement sensors of all suspension cylinders of the whole vehicle, and according to the detected stroke position in the suspension cylinder Leveling is performed at any position within the stroke range; all attitude control valves of the vehicle refer to all left and right attitude control valves of the vehicle, and all suspension cylinders of the vehicle refer to all left suspension cylinders and all right suspension cylinders of the vehicle. Suspension cylinder.

Leveling at any position within the stroke range of the cylinder can be achieved. When the suspension is lowered synchronously, the reversing valve DT3 is energized, and the other valves are energized in the same way as when the suspension is lowered synchronously.

The beneficial effect that the present invention reaches:

(1) Without adding any complex hydraulic valve groups and control strategies, the real-time synchronous lifting action of multi-axis oil-air suspension can be realized through the braking assistance of the hydraulic braking system;

(2) The oil-pneumatic suspension system does not add any additional control components. The built-in position sensor of the suspension cylinder enables the oil-pneumatic suspension to achieve any one-key leveling within the travel range.

Description of drawings

Fig. 1 is oil-pneumatic suspension and brake hydraulic principle diagram of the present invention;

Figure 2 is a structural layout diagram of the trailing arm oil-air suspension.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings. The following examples are only used to illustrate the technical solution of the present invention more clearly, but not to limit the protection scope of the present invention.

The solution of the present invention provides a trailing arm type oil-air suspension control system, which performs oil-air suspension synchronization and leveling. In this embodiment, it is applied to off-road vehicles to realize attitude adjustment actions, driving brakes and parking brakes of off-road vehicles. The present invention can quickly realize the independent control of the suspension oil cylinder, the synchronous control of the coaxial suspension oil cylinder, the synchronous control of the suspension oil cylinder on the same side and the synchronous adjustment of the lifting of the whole vehicle, and can meet the requirements of various driving conditions. The solution of the invention can improve the driving safety and mobility of the off-road vehicle.

Example 1:

As shown in FIG. 1 , it is a schematic diagram of the hydro-pneumatic suspension and braking described in this solution, and the hydro-pneumatic suspension system and the braking system share a power unit assembly 1 . The oil-air suspension system includes suspension cylinders 311/312/313/321/322/323, suspension accumulator 4, through valve 5, left attitude adjustment valve 7, right attitude adjustment valve 8; the braking system includes brake accumulator 9 , Inverse proportional brake valve 10, brake 11, pressure sensor 12, oil filling valve 13 and other components. Among them, there are 6 suspension oil cylinders, suspension accumulators 4, through valves 5, and brakes 11. The 6 suspension oil cylinders are symmetrically arranged on the 6 swing legs. Each suspension oil cylinder has a built-in displacement sensor (the displacement sensor used in this embodiment It is a magnetic position sensor 6), which can continuously monitor the stroke of the oil cylinder. The installation form of the suspension oil cylinder is shown in Figure 2. The layout of the longitudinal arm type oil-pneumatic suspension: 6 suspension oil cylinders. The shaft 14 is connected to the vehicle body 15 and the swing arm 16 respectively. Swing arm 16 is connected with tire 17, and brake is installed on the rim motor.

Brake accumulator 9, two inverse proportional brake valves 10; power unit assembly 1, fuel supply valve 13, pressure sensor 12, left attitude control valve 7, right attitude control valve 8 each. The power unit assembly includes an air filter 101, a gear pump 104, a motor 105, a hydraulic oil tank 108, an oil suction filter 102, an air filter 109, an overflow valve 103, a one-way valve 106, an unloading valve 2, and a reversing valve 107 ; The left attitude control valve 7 and the right attitude control valve 8 respectively include 6 normally closed switch valves; the 6 through valves in different positions have different numbers and the same function, including through valves DT31/DT32/DT33/DT34/DT35/DT36, through The valve is normally open by default. The on-off valve numbers in the left attitude control valve are DT11/DT12/DT13/DT14/DT15/DT16, and the on-off valve numbers in the right attitude control valve are DT21/DT22/DT23/DT24/DT25/DT26. 6 Each brake 11 is installed on six tire rims respectively, and the pressure sensor 12 is installed between the fuel supply valve 13 and the inverse proportional brake valve 10 . The inverse proportional brake valve 10 has pressure output when it is not energized, and has no pressure output when it is energized; the brake 11 is locked with pressure and released without pressure. The inverse proportional brake valve 10P is connected to the brake accumulator 9, the T port is connected to the oil tank of the power unit assembly 1, and the output port A is connected to the brake 11. When the inverse proportional brake valve 10 is not powered, the vehicle is braked, and when the power is supplied, the vehicle brake is released. The six suspension accumulators 4 have the same volume and the same precharge pressure.

Example 2:

A hydraulic braking method for a trailing arm type oil-pneumatic suspension control system, comprising:

The initial state is that the two inverse proportional brake valves 10 are not powered. At this time, the pressure oil in the brake accumulator 9 is input to the six brakes 11 through the P of the inverse proportional brake valve, and the brakes 11 lock the rim under the action of hydraulic oil. Realize vehicle braking; because the inverse proportional brake valve 10 has internal leakage, the parking brake can only be maintained for a period of time. When the pressure sensor 12 detects that the pressure of any one of the brake accumulators 9 is lower than the set value, the motor 105 of the power unit assembly 1 is started, the switching valves DT1 and DT4 are energized, and the electromagnet DT2 of the reversing valve 107 is energized , to supply oil to the brake accumulator 9, until the pressure of the brake accumulator 9 reaches the set value, the switch valve DT1 and DT4 are de-energized at the same time, the electromagnet DT2 of the reversing valve 107 is also de-energized, and the power unit assembly The motor 105 of 1 cuts off the power subsequently and stops fuel supply. The brake needs to be released before the vehicle runs normally. At this time, a certain current needs to be continuously supplied to the two inverse proportional brake valves 10. The hydraulic oil in the brake 11 flows back to the oil tank through the T port, and the brake 11 contacts the brake disc under the action of the spring force Disengage, so that the vehicle is completely released from the brakes.

Example 3:

A coaxial suspension synchronous lifting control method for a trailing arm type oil-air suspension control system, comprising:

The hydraulic braking system is in the initial state. At this time, the six tires are in the braking state, the swing arm rotates around the contact point between the tire and the ground, and the vehicle frame rotates around the swing arm. Taking the synchronous lifting of the first axle suspension as an example, the motor 105 is started, the gear pump 104 outputs hydraulic oil, the switch valve DT1 is energized, the electromagnet DT2 of the reversing valve 107 is energized, the left attitude adjustment valve DT11, DT12 and the right attitude adjustment valve DT21 , DT22 is powered on, the left suspension oil cylinder 311 of the first axle and the right suspension oil cylinder 321 of the first axle enter the oil into the rodless chamber and return the oil from the rod chamber. The bodywork moves upwards in sync. Through the position detection function of the built-in displacement sensor 6 of the oil cylinder, leveling at any position within the stroke range of the coaxial oil cylinder can be realized. When the first bridge suspension 311 and 321 are lowered synchronously, the electromagnet DT3 of the reversing valve 107 is energized, and the energized situation of other valves is the same as the synchronous rise.

Example 4:

A method for synchronous lifting and lowering control of the suspension on the same side of a trailing arm type oil-air suspension control system, comprising:

The hydraulic braking system is in the initial state. At this time, the six tires are in the braking state, the swing arm rotates around the contact point between the tire and the ground, and the vehicle frame rotates around the swing arm. Taking the synchronous lifting of the left suspension as an example, the motor 105 is started, the gear pump 104 outputs hydraulic oil, the switch valve DT1 is energized, the reversing valve electromagnet DT2 is energized, and the left attitude adjustment valves DT11, DT12, DT13, DT14, DT15, DT16 Powered at the same time, the rodless cavity of the three suspension cylinders 311/312/313 on the left enters oil and the rod cavity returns oil. Under the joint action of their respective swing arms and frame, the three oil cylinders elongate synchronously, driving the bodywork synchronously upward movement. Through the position detection function of the built-in displacement sensor 6 of the oil cylinder, leveling at any position within the stroke range of the oil cylinder on the same side can be realized. When the left side suspension is lowered synchronously, the electromagnet DT3 of the reversing valve 107 is energized, and the energized situation of other valves is the same as that of the synchronous rise.

Example 5:

A method for synchronous lifting and lowering control of a vehicle suspension of a trailing arm type oil-air suspension control system, comprising:

The hydraulic braking system is in the initial state. At this time, the six tires are in the braking state, the swing arm rotates around the contact point between the tire and the ground, and the vehicle frame rotates around the swing arm. The motor 105 starts, the gear pump 104 outputs hydraulic oil, the on-off valve DT1 is energized, the reversing valve electromagnet DT2 is energized, the left attitude adjustment valves DT11, DT12, DT13, DT14, DT15, DT16 are energized at the same time, and the right attitude adjustment valve DT21 . Under the combined action of the frame, they elongate synchronously and drive the upper body to move upwards synchronously. Through the position detection function of the built-in displacement sensor 6 of the oil cylinder, leveling at any position within the stroke range of the oil cylinder can be realized. When the suspension is lowered synchronously, the reversing valve DT3 is energized, and the other valves are energized in the same way as when the suspension is lowered synchronously.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the present invention, some improvements and modifications can also be made. It should also be regarded as the protection scope of the present invention.

Claims (10)

1. A trailing arm hydro-pneumatic suspension control system, comprising: the system comprises an oil-gas suspension system, a braking system and a power unit assembly; the hydro-pneumatic suspension system and the braking system are respectively connected with the power unit assembly;

the hydro-pneumatic suspension system includes: the number of the axle suspension systems is consistent with that of the axles; the axle suspension system comprises a left suspension oil cylinder, a left suspension energy accumulator, a left through valve, a left posture adjusting valve, a right suspension oil cylinder, a right suspension energy accumulator, a right through valve and a right posture adjusting valve; the left suspension oil cylinder is respectively connected with the left through valve and the left posture adjusting valve, the left suspension energy accumulator is connected with the left through valve, and the left posture adjusting valve is also respectively connected with the power unit assembly and the left through valve; the right suspension oil cylinder is respectively connected with the right through valve and the right posture adjusting valve, the right suspension energy accumulator is connected with the right through valve, and the right posture adjusting valve is also respectively connected with the power unit assembly and the right through valve; displacement sensors are arranged in the left suspension oil cylinder and the right suspension oil cylinder;

the brake system includes: the brake system comprises a brake energy accumulator, an inverse proportion brake valve, a brake, a pressure sensor and an oil supplementing valve; the braking energy accumulator is respectively connected with the pressure sensor, the oil supplementing valve and the inverse proportion braking valve, the power unit assembly is connected with the oil supplementing valve, the inverse proportion braking valve is connected with the brake, and the brake is arranged on a tire rim and used for braking a vehicle;

the pressure sensor is used for acquiring the oil pressure in the brake accumulator, converting the oil pressure into an electric signal and transmitting the electric signal to the power unit assembly; when the inverse proportion brake valve is not electrified, pressure is output, and when the inverse proportion brake valve is electrified, no pressure is output; the brake is locked by pressure and released without pressure; the brake of the whole vehicle is realized when the inverse proportion brake valve is electrified, and the brake of the whole vehicle is released when the inverse proportion brake valve is electrified.

2. The trailing arm hydro-pneumatic suspension control system of claim 1, wherein there are two each of the brake accumulator and the anti-proportional brake valve, forming a pair of control modules;

one of the control modules controls the brakes on the left side of the axle and the other control module controls the brakes on the right side of the axle.

3. The trailing arm hydro-pneumatic suspension synchronizing and leveling system of claim 1 wherein the power unit assembly employs a hydraulic power unit assembly for controlling the hydro-pneumatic suspension system and the braking system with hydraulic oil for suspension cylinder actuation and braking actuation.

4. The trailing arm hydro-pneumatic suspension synchronizing and leveling system of claim 1, wherein lower hinge points of a left suspension cylinder and a right suspension cylinder of the axle suspension system are symmetrically arranged on corresponding swing legs of an axle, and upper hinge points of the cylinders are arranged on a vehicle body.

5. The trailing arm hydro-pneumatic suspension synchronizing and leveling system of claim 1, wherein an oil inlet of the anti-proportional brake valve is connected to a brake accumulator, an oil return port of the anti-proportional brake valve is connected to an oil tank of the power unit assembly, and an output port of the anti-proportional brake valve is connected to a brake.

6. The trailing arm hydro-pneumatic suspension synchronizing and leveling system of claim 1 wherein suspension accumulators in all of the axle suspension systems are of the same volume and the same pre-charge pressure.

7. A hydraulic braking method based on the trailing arm type hydro-pneumatic suspension control system of any one of claims 1 to 6, comprising:

in an initial state, the inverse proportion brake valve is not electrified, pressure oil in the brake energy accumulator is input into the brake through an oil inlet of the inverse proportion brake valve, and the brake locks the rim under the action of hydraulic oil to realize the braking of the whole vehicle;

when the pressure sensor detects that the pressure in the brake energy accumulator is lower than a set value, the power unit assembly supplies oil to the brake energy accumulator, and the power unit assembly stops supplying the oil until the pressure of the brake energy accumulator reaches the set value;

when the braking needs to be relieved, a certain current is continuously supplied to the inverse proportion braking valve, hydraulic oil in the brake is controlled to flow back to the oil tank through the oil return port, and the brake is separated from the brake disc under the action of the spring force, so that the whole vehicle is completely relieved from braking.

8. The coaxial suspension synchronous lifting control method of the trailing arm type hydro-pneumatic suspension control system according to any one of claims 1 to 6, comprising:

the hydraulic braking system is in an initial state, all tires are in a braking state, the swing arm of the vehicle rotates around a contact point between the tires and the ground, and the frame rotates around the swing arm;

if a certain bridge is hung and needs to synchronously lift or descend, a power unit assembly controls a left posture adjusting valve and a right posture adjusting valve corresponding to the bridge to be powered on, rodless cavities of a left hanging oil cylinder and a right hanging oil cylinder feed oil, and rod cavity return oil, the left hanging oil cylinder and the right hanging oil cylinder extend synchronously under the combined action of respective swing arms and a frame to drive the upper assembly to move upwards synchronously, the stroke positions of the left hanging oil cylinder and the right hanging oil cylinder are detected through displacement sensors arranged in the left hanging oil cylinder and the right hanging oil cylinder, and leveling is carried out at any position in the stroke range of the hanging oil cylinders according to the detected stroke positions.

9. The same-side suspension synchronous lifting control method of the trailing arm type hydro-pneumatic suspension control system according to any one of claims 1 to 6, comprising the following steps:

the hydraulic braking system is in an initial state, all tires are in a braking state, the swing arm of the vehicle rotates around a contact point between the tires and the ground, and the frame rotates around the swing arm;

if one side of the suspension needs to synchronously lift or synchronously descend, all the attitude adjusting valves on the same side are controlled to be simultaneously powered through the power unit assembly, oil is fed into rodless cavities and returned into rod cavities of all the suspension oil cylinders on the same side, all the suspension oil cylinders on the same side synchronously extend under the combined action of respective swing arms and the frame to drive the upper part to synchronously move upwards, the stroke position of each suspension oil cylinder is detected through displacement sensors arranged in all the suspension oil cylinders, and leveling is carried out at any position in the stroke range of the suspension oil cylinders according to the detected stroke position; all the posture adjusting valves on the same side refer to all the left posture adjusting valves or right posture adjusting valves on the same side, and all the suspension oil cylinders on the same side refer to all the left suspension oil cylinders or all the right suspension oil cylinders on the same side.

10. The whole vehicle suspension synchronous lifting control method based on the trailing arm type hydro-pneumatic suspension control system of any one of claims 1-6 is characterized by comprising the following steps:

the hydraulic braking system is in an initial state, all tires are in a braking state, the swing arm of the vehicle rotates around a contact point between the tires and the ground, and the frame rotates around the swing arm;

if the whole vehicle needs to be synchronously lifted or synchronously lowered in a suspension way, all the attitude adjusting valves of the whole vehicle are controlled to be simultaneously powered by the power unit assembly, oil is fed into rodless cavities and returned into rod cavities of all suspension oil cylinders of the whole vehicle, all the suspension oil cylinders of the whole vehicle synchronously extend under the combined action of respective swing arms and a vehicle frame to drive the upper part to synchronously move upwards, the stroke position of each suspension oil cylinder is detected by displacement sensors arranged in all the suspension oil cylinders of the whole vehicle, and the leveling is carried out at any position in the stroke range of the suspension oil cylinders according to the detected stroke position; all the attitude adjusting valves of the whole vehicle refer to all the left attitude adjusting valves and all the right attitude adjusting valves of the whole vehicle, and all the suspension oil cylinders of the whole vehicle refer to all the left suspension oil cylinders and all the right suspension oil cylinders of the whole vehicle.

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