CN119196216A

CN119196216A - A controllable stroke oil-gas suspension cylinder and control method thereof

Info

Publication number: CN119196216A
Application number: CN202411132427.7A
Authority: CN
Inventors: 张宏如
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-07-31
Filing date: 2015-07-31
Publication date: 2024-12-27
Also published as: CN106704441A

Abstract

The present invention discloses a controllable stroke oil-gas suspension cylinder and a control method thereof, which comprises a cylinder barrel, a piston rod, a piston, an internal control valve group, a sealing seat ring, an accumulator, a control valve, a gas-liquid booster pump and a flow control cylinder, a piston is arranged in the cylinder barrel, a piston rod is connected to the piston, the piston rod is sealed and connected to the upper part of the cylinder barrel through a sealing seat ring, the inner cavity of the cylinder barrel and the inner cavity of the piston rod are connected through a damping channel on the internal control valve group to form an independent suspension cylinder inner cavity system; the cylinder barrel, the piston rod and the piston form a suspension cylinder inner cavity inside the suspension cylinder, the cylinder barrel, the sealing seat ring, the piston rod and the piston form a secondary oil cavity between the side walls of the waist of the suspension cylinder, and the secondary oil cavity is connected to the control valve and the accumulator through a pipeline to form an independent external control loop. The present invention forms a dual-channel equal pressure and synchronous control system structure with the constructed dual-circuit system through the gas-liquid booster pump and the flow control cylinder, which can realize reliable and stable stroke control, and at the same time, it is accompanied by stiffness and height control.

Description

Stroke-controllable hydro-pneumatic suspension cylinder and control method thereof

Technical Field

The invention relates to the technical field of hydro-pneumatic suspension cylinders, in particular to a stroke-controllable hydro-pneumatic suspension cylinder and a control method thereof.

Background

The hydro-pneumatic suspension cylinder integrates the structural principles and the use functions of an air spring and a hydraulic damper, and has better mechanical properties and application range. The inside of the hydro-pneumatic suspension cylinder is filled with nitrogen and hydraulic oil. The nitrogen is used as an elastic medium and an energy storage medium, has the variable stiffness characteristic, and has a larger energy storage ratio than a metal elastic material. The hydraulic oil is used as a damping medium, and damping force is generated through a damping structure inside the suspension cylinder.

The hydro-pneumatic suspension cylinders have a greater operating pressure and capacity than air springs due to the encapsulation of nitrogen within the cylinder structure. Similar to the conventional hydraulic cylinder structure, the hydro-pneumatic suspension cylinder is also composed of a cylinder barrel assembly and a piston rod assembly according to a movement relation and a mounting structure, an inner volume separation cavity comprises a rod cavity and a rodless cavity, and the piston rod is generally of a hollow structure. The rodless cavity is called a suspension cylinder cavity and consists of a cylinder barrel cavity and a piston rod cavity. The rod-containing chamber is called a secondary oil chamber and is an annular space surrounded by the cylinder tube assembly and the piston rod assembly between the waist side walls of the suspension cylinder.

When the inner cavity of the suspension cylinder is used as a cavity, hydraulic oil and nitrogen are filled in the suspension cylinder, and the suspension cylinder is also called an oil-gas mixing cavity or a mixing oil cavity. The greatest amplitude of the volume spatial variation of the secondary oil chamber during use is typically used as a source of damping flow within the suspension cylinder. The auxiliary oil cavity is filled with hydraulic oil, and a damping channel is arranged on the side wall of the piston rod at the inner side of the auxiliary oil cavity and communicated with the inner cavity of the suspension cylinder.

As shown in fig. 1 and 2, two typical structural types of single-chamber double-oil chamber hydro-pneumatic suspension cylinders are shown. Fig. 1 is a piston rod upper structure, and fig. 2 is a piston rod lower structure. The oil chamber filled with hydraulic oil alone is called a pure oil chamber, and includes a variable pure oil chamber and an invariable pure oil chamber. The variable pure oil cavity is communicated with the mixed oil cavity to form a damping channel. When the suspension cylinder compresses or draws the god, the volumes and pressures of the variable pure oil cavity and the mixed oil cavity change to generate damping flow. The auxiliary oil cavity is used as a variable pure oil cavity and is communicated with the suspension inner cavity. The area of the suspension cylinder inside system pressure providing elastic force to the outside is called the pressure acting area. The area where damping flow occurs with the suspension cylinder compression or extension speed is referred to as the damping flow area. The elastic force of the suspension cylinder is determined by the pressure of the system in the suspension cylinder and the pressure acting area. The damping flow of the system is determined by the damping flow area and the suspension cylinder compression or extension speed. In the single-air-chamber double-oil-chamber structure, the pressure acting area is the outer circle area of a piston rod of a suspension cylinder, and the stiffness curve is shown in fig. 13. The damping flow area is the cross-sectional area of the variable oil chamber, i.e., the annular area of the secondary oil chamber cavity, and the damping characteristics are shown in fig. 15.

As shown in fig. 3-6, the three-oil cavity structure with four typical single air chambers has a pressure acting area which is the area of the piston rod, and the stiffness curve is shown in fig. 13. The three-oil cavity structure divides the suspension cylinder cavity into a cylinder barrel cavity and a piston rod cavity through a piston or valve plate structure. The hydraulic oil is independently filled into a main oil cavity, the hydraulic oil and nitrogen are simultaneously filled into a mixed oil cavity, a damping structure is arranged on a piston or a valve plate and is communicated with an inner cavity of a cylinder barrel and an inner cavity of a piston rod to form an inner cavity damping channel, and an auxiliary oil cavity is communicated with an inner cavity of a suspension cylinder through the damping structure on the side wall of the piston rod to form an auxiliary oil cavity damping channel, wherein the damping characteristic is shown in figure 15.

Fig. 3 shows a piston rod overhead structure, the inner cavity of the cylinder (main oil cavity) and the auxiliary oil cavity are both variable pure oil cavities, and are respectively communicated with the inner cavity of the piston rod (mixed oil cavity) to form two parallel damping channels, the damping structure on the side wall of the piston rod and the damping structure on the piston or the valve plate are also usually combined structures of a one-way valve and a damping hole, the damping flow area of the main oil cavity channel is the inner cavity area of the cylinder, and the damping flow area of the auxiliary oil cavity channel is the annular area of the auxiliary oil cavity.

Fig. 4 shows a piston rod lower structure, the auxiliary oil cavity is a variable pure oil cavity, the inner cavity of the piston rod (main oil cavity) is an invariable pure oil cavity, the auxiliary oil cavity is communicated with the inner cavity of the cylinder barrel (mixed oil cavity) through the inner cavity of the piston rod, a damping channel is synthesized, and the damping flow area is the annular area of the auxiliary oil cavity.

Fig. 5 shows another piston rod lower structure, wherein the inner cavity of the piston rod separates oil/gas parts through a floating piston to form a mixed oil cavity, the inner cavity of the cylinder barrel (main oil cavity) and the auxiliary oil cavity are all variable pure oil cavities, the variable pure oil cavities are respectively communicated with the inner cavity of the piston rod to form two parallel damping channels, the damping flow area of the main oil cavity channel is the inner cavity area of the cylinder barrel, and the damping flow area of the auxiliary oil cavity channel is the annular area of the auxiliary oil cavity.

Fig. 6 shows a piston rod overhead pressure compensation structure, wherein a cylinder barrel inner cavity (a main oil cavity) and an auxiliary oil cavity are both variable pure oil cavities, a piston rod inner cavity is a mixed oil cavity, the auxiliary oil cavity, the main oil cavity and the mixed oil cavity are sequentially communicated to form two damping channels connected in series, a pressure and flow complementary relation is formed between the auxiliary oil cavity and the main oil cavity, the system negative pressure phenomenon of the hydro-pneumatic suspension cylinder is eliminated, and the application range of the damping coefficient of the system is remarkably improved. The damping flow area of the main oil cavity channel is the outer circle area of the piston rod, and the damping flow area of the auxiliary oil cavity channel is the annular area of the auxiliary oil cavity.

As shown in fig. 7, 8 and 9, three typical structures of the double-chamber three-oil chamber hydro-pneumatic suspension cylinder are provided, and the piston rod is arranged below.

FIG. 7 shows a dual air chamber forward series structure, the cylinder cavity and the piston rod cavity each comprise a mixed oil cavity, the mixed oil cavities are communicated through a damping structure, the auxiliary oil cavity is used as a variable pure oil cavity to be communicated with the piston rod cavity, the main damping flow of the system is provided, the damping flow area is the auxiliary oil cavity area, additional damping flow can be generated between the two mixed oil cavities, the size and the flow direction depend on initial inflation parameters of the upper air chamber and the lower air chamber, the auxiliary oil cavity, the cylinder cavity and the two mixed oil cavities in the piston rod cavity form a full-through hydraulic circuit, the two damping channels are included, the integral pressure acting area of the suspension cylinder is the piston rod area, the stiffness curve is shown in FIG. 13, and the damping characteristic is shown in FIG. 15.

Fig. 8 is a diagram showing a structure in which the two air chambers are oppositely arranged, the inner cavity of the suspension cylinder is isolated by a piston with a closed structure into a cylinder cavity and a piston rod cavity which are independent of each other, the cylinder cavity and the piston rod cavity respectively comprise a mixed oil cavity, the pressure of the piston rod cavity is led into the auxiliary oil cavity through a set of pipelines to form a back pressure opposite structure with the cylinder cavity, the elastic force output is the difference between the pressure output of the area of the cylinder cavity and the pressure output of the area of the auxiliary oil cavity, and the rigidity curve is shown in fig. 14. The auxiliary oil cavity is used as a variable pure oil cavity, a damping channel is formed through a connecting pipeline with the inner cavity of the piston rod, so that the damping flow of the system is formed, the damping flow area of the system is the area of the auxiliary oil cavity, and the damping characteristic is shown in fig. 15.

Fig. 9 is another inverted opposed dual plenum structure with stiffness characteristics similar to those of fig. 8, see fig. 14. The difference with the structure of FIG. 8 is that the inner cavity of the cylinder barrel is a variable pure oil cavity, an energy accumulator is added outside and used as a mixed oil cavity, the middle is connected with a damping valve through a pipeline to form a damping channel of a main oil cavity, the damping flow area of the channel of the main oil cavity is the inner cavity area of the cylinder barrel, and the damping flow area of the channel of the auxiliary oil cavity is the annular area of the auxiliary oil cavity.

It should be noted that:

1. Besides the basic structure (fig. 1 and 2) with single air chamber and double oil chambers, the structure with the upper piston rod and the structure with the lower piston rod do not have the same mechanical model and mechanical relationship (as shown in fig. 3 and 4), and the structure of the packaging structure, the position and the damping channel of hydraulic oil and nitrogen are different, so that the hydro-pneumatic suspension cylinder with one structure cannot be used after being inverted, which is also a characteristic of the hydro-pneumatic suspension cylinder.

2. The damping flow of the suspension cylinder is derived from the volume change of the variable pure oil chamber when the suspension cylinder is compressed or stretched, and the generation of the damping flow must connect the variable pure oil chamber to the mixed oil chamber or finally connect the variable pure oil chamber to the mixed oil chamber through another pure oil chamber to form a damping channel, otherwise, the mechanical relationship inside the suspension cylinder is not established.

From the various application structures in the prior art (fig. 1-9), the auxiliary oil cavity is taken as a main source of the damping flow of the system, and is communicated with the inner cavity of the suspension cylinder without exception, so that an externally closed hydraulic circuit is formed.

3. Fig. 8 and 9 show counter-pressure opposite structures with the piston rod arranged below, and although good rigidity characteristics are obtained (fig. 14), the two structures are required to be based on physical isolation of the cylinder cavity and the piston rod cavity, so that important structural, position, speed, flow and pressure relations between the cylinder cavity and the piston rod cavity are lost, and a conduit structure with a complex piston rod cavity occupies an effective space inside, so that a variable damping structure based on the control relation of position, flow and pressure in the suspension cylinder cavity cannot be arranged and applied.

4. The nine structures shown in fig. 1-9 are main structural forms of the existing hydro-pneumatic suspension cylinder on the rigidity structure, under the conventional structure, a damping structure of the system consists of damping holes and one-way valves, the damping structure is not adjustable in the use process, and the damping characteristic of the system is a quadratic curve f=f (v) based on speed terms and forward and reverse differences, and is shown in fig. 15.

The structure of fig. 1-7 has substantially uniform stiffness characteristics, and the characteristic curve, see fig. 13, is a forward nonlinear curve with hard spots at the starting points of the curve. The whole suspension cylinder internal system is a closed loop, and external input cannot be introduced for control, but variable damping control can be realized to a certain extent based on the internal space and structural arrangement of a variable damping mechanism.

Although the structures of fig. 8 and 9 obtain relatively good rigidity characteristics and eliminate hard points (the rigidity characteristic curve is shown in fig. 14), the control targets and control links of external control are lacking, the external control on the rigidity and the state of the system is difficult to realize, and the following variable damping control cannot be realized due to the physical isolation of the structure to the inner cavity of the suspension cylinder.

Active and semi-active control suspension systems, which are aimed at active or semi-active integrated control of system stroke, state, rigidity and damping, are in existence in various hydro-pneumatic suspension cylinder structures, and lack of structural foundation and conditions for complete realization.

5. The existing hydro-pneumatic suspension cylinders with various structures are focused on the collocation of the internal rigidity and damping characteristics of the suspension cylinder and the integrity and reliability of independent operation, an external input port for active control applied from outside and an internal control link are not considered, and an internal oil cavity and an air chamber are mutually related and mutually controlled and are also commonly used independently as independent components. But as the whole chassis, especially the active and semi-active suspension, the active or semi-active control is required according to different road conditions, running states and different driving and operating environments, and the whole hydro-pneumatic suspension cylinder does not construct an independent link for external control or combined control of multiple suspension cylinders, so that the excellent performance and combined potential of the hydro-pneumatic suspension cylinder are not fully exerted, and the external active control applied to the existing suspension cylinder structure can cause the disturbance of the flow and pressure in the suspension cylinder, thereby causing the problems of system stability and reliability.

The active and semi-active suspensions are well applied to high-end products such as cars, business cars and the like, mainly based on the combination of leaf springs, spiral springs, air springs and the like and an electric control damper, and an electric control system is introduced for control, but the problems of working capacity, control capacity, system precision and cost of the suspension components and the electric control system are limited, and the application of large-sized vehicles and popular products is greatly limited. Applications in hydro-pneumatic suspension based engineering, heavy duty and popular vehicles are still blank. Among them, the stroke control and the height and the state control of the suspension system are the most basic functional requirements, and it is highly demanded to propose a basic hydro-pneumatic suspension cylinder structure for active and semi-active control system, and a basic system structure scheme for stroke and state control.

Disclosure of Invention

The invention aims to provide a controllable stroke hydro-pneumatic suspension cylinder and a control method thereof, which are used for constructing a basic structure for external active control and combined control among a plurality of suspension cylinders and implementing a structural scheme for stroke, height and state control. The core is to construct an internal/external two independent hydraulic circuit system, an external active control target link, a control form and a structural scheme for implementing control so as to solve the problems in the prior art.

In order to solve the technical problems, the invention adopts the following technical scheme:

The invention discloses a stroke-controllable hydro-pneumatic suspension cylinder which comprises a cylinder barrel, a piston rod, a piston, an internal control valve group, a sealing seat ring, an energy accumulator, a control valve, a gas-liquid booster pump and a flow control cylinder, wherein the piston is arranged in the cylinder barrel, the piston rod is connected to the piston, and the piston rod is in sealing connection with the upper part of the cylinder barrel through the sealing seat ring;

The cylinder barrel, the piston rod and the piston enclose a suspension cylinder cavity in the suspension cylinder, the suspension cylinder cavity is a rodless cavity, the bottom of the piston rod is provided with the internal control valve group, the internal control valve group divides the suspension cylinder cavity into a cylinder barrel cavity and a piston rod cavity, the cylinder barrel cavity is filled with hydraulic oil, the bottom of the cylinder barrel cavity is provided with an external control interface, the piston rod cavity is filled with hydraulic oil and nitrogen, and the cylinder barrel cavity and the piston rod cavity are communicated through a damping channel on the internal control valve group to form an independent suspension cylinder cavity system;

The cylinder barrel, the seal seat ring, the piston rod and the piston form an auxiliary oil cavity in a surrounding mode between the side wall of the waist of the suspension cylinder, the auxiliary oil cavity is a rod cavity, hydraulic oil is filled in the auxiliary oil cavity and is completely isolated from the inner cavity of the suspension cylinder, a connecting port is arranged at the position, close to the seal seat ring, of the cylinder barrel, and the auxiliary oil cavity is externally connected with the control valve and the energy accumulator through pipelines to form an independent external control loop;

The gas-liquid booster pump comprises a reversing valve capable of implementing oil way reversing and closing control, is communicated with a rodless cavity of the flow control cylinder internally, is provided with an external control interface, is connected with an external control interface of the suspension cylinder inner cavity system, is provided with an external control interface, is arranged in the rod cavity and is connected with an external control interface of the external control loop, and therefore two independent closed systems are formed, and two independent channels for synchronously controlling the stroke, the rigidity and the height of the suspension cylinder are formed.

Further, the control valve is an input port for external control of suspension cylinder travel, stiffness and height, and acts as a damping/flow control element inside the external control circuit and is provided with an external control interface.

Further, the auxiliary oil cavity in the external control loop and the inner cavity of the cylinder barrel in the suspension cylinder inner cavity system form a double-air-chamber back pressure opposite structure.

Further, hydraulic oil and nitrogen are filled in the energy accumulator.

Still further, the suspension cylinder chamber maintains a complete chamber structure and pressure/flow correlation, and the internal control valve train acts as a damping control assembly between the cylinder chamber and the piston rod chamber.

The invention also provides a control method of the stroke-controllable hydro-pneumatic suspension cylinder, which comprises the following steps:

1) When the stroke of the suspension cylinder needs to be reduced, the reversing valve is arranged at a storage position, the gas-liquid booster pump is started, quantitative hydraulic oil in an inner cavity system of the suspension cylinder is injected into a rodless cavity of the flow control cylinder, and quantitative hydraulic oil in a rod cavity of the flow control cylinder is injected into an auxiliary oil cavity of the suspension cylinder through an external control loop;

2) When the stroke of the suspension cylinder needs to be increased, the reversing valve is arranged at a release position, the gas-liquid booster pump is started, hydraulic oil in the rodless cavity of the flow control cylinder is reversely injected into the suspension cylinder inner cavity system, and meanwhile, quantitative hydraulic oil in the auxiliary oil cavity of the suspension cylinder is discharged back into the rod cavity of the flow control cylinder through the external control loop by means of pressure difference between two loops/systems;

3) When the stroke of the suspension cylinder does not need to be controlled and changed, the gas-liquid booster pump is closed and started, and the reversing valve is placed at the stop position.

When the suspension cylinder is compressed or stretched, the volumes of the inner cavity of the cylinder barrel and the auxiliary oil cavity are all changed, and the inner cavity and the auxiliary oil cavity are all variable oil cavities. For the suspension cylinder inner cavity system, flow exchange is carried out between the cylinder inner cavity and the piston rod inner cavity, and the damping flow area is the cylinder inner cavity area. For an external control loop, flow exchange is carried out between the auxiliary oil cavity and the energy accumulator, and the damping flow area is the area of the auxiliary oil cavity. The suspension cylinder inner cavity system and the external control loop form a double-air-chamber back pressure opposite structure through the cylinder inner cavity (main oil cavity) and the auxiliary oil cavity. The pressure acting area of the suspension cylinder inner cavity system is the inner cavity area of the cylinder barrel. The pressure acting area of the external control loop is the area of the auxiliary oil cavity. The total elastic force output of the suspension cylinder is the pressure superposition of the area of the inner cavity of the cylinder barrel and the area of the auxiliary oil cavity. See fig. 20. Curve 1 is the stiffness curve of the suspension cylinder inner cavity system, curve 2 is the stiffness curve of the external control loop, and curve 3 is the integrated stiffness curve of the suspension cylinder system. As can be seen from fig. 20, the external control loop well corrects the stiffness characteristic of the suspension cylinder inner cavity system in the initial stage, and forms a positive-negative zero-crossing balance position.

The inside of the gas-liquid booster pump is of a cylinder/plunger cylinder combined structure, hydraulic oil in the inner cavity of the suspension cylinder is injected into the rodless cavity of the flow control cylinder at high pressure and pulsation flow by means of the reciprocating motion of the piston/plunger combined with the one-way valve, and the hydraulic oil in the rod cavity at the other side is pushed to enter the auxiliary oil cavity of the suspension cylinder, so that the stroke and the height of the suspension cylinder are controlled. The piston in the flow control cylinder still plays a role in isolating the suspended cylinder inner cavity system from the external control loop. The area ratio of the rod cavity/rodless cavity of the flow control cylinder and the area ratio of the auxiliary oil cavity/cylinder barrel cavity of the suspension cylinder are kept in a certain proportional relation so as to realize a specific control effect. When releasing, the release switch between the gas-liquid booster pump and the flow control cylinder is opened, and the flow control cylinder returns in a differential mode. The piston rod of the flow control cylinder is used for adjusting the control characteristic, and also is used as a signal acquisition component and a control triggering component for suspending the position and the state of the cylinder. Fig. 17 is a graph showing the pressure characteristics of the dual circuit/system of the present invention. Curve 1 is the external control loop pressure characteristic curve and curve 2 is the suspension cylinder inner chamber system pressure characteristic curve. The two circuit/system pressures reach the balance of elastic force at the balance position through the respective pressure acting areas.

When the height of the suspension cylinder needs to be reduced or the suspension cylinder needs to be retracted, a gas-liquid booster pump is started, quantitative hydraulic oil in an inner cavity system of the suspension cylinder is injected into a rodless cavity of the flow control cylinder, and meanwhile quantitative hydraulic oil in a rod cavity is injected into an auxiliary oil cavity of the suspension cylinder. The height of the hydro-pneumatic suspension cylinder is reduced, and the balance position is changed until a new balance position is reached. The suspension cylinder is shown in a retracted state in fig. 26. The flow control cylinder selects proper diameter ratio of the piston rod/the cylinder barrel, and can achieve an isobaric control state. As shown in fig. 19, the system pressure characteristic curve under the isobaric control is shown. The curve 1/curve 2 is the pressure characteristic curve of the external control loop and the suspension cylinder inner cavity system in the original balance position state, and the curve 3/curve 4 is the pressure characteristic curve of the external control loop and the suspension cylinder inner cavity system in the new balance position state. Fig. 24 shows the system stiffness characteristic under isostatic control. Curve 1 is the system stiffness characteristic curve in the original equilibrium state, and curve 2 is the system stiffness characteristic curve in the new equilibrium state. As can be seen from fig. 19 and 24, the height of the suspension cylinder is adjusted under the isostatic control, each working position of the suspension cylinder synchronously descends along with the balance position, and the working stroke is changed.

When the original height of the suspension cylinder needs to be restored or the suspension cylinder needs to be released, the position of the reversing valve is switched, and the gas-liquid booster pump is started, so that the hydraulic oil in the rodless cavity of the flow control cylinder can be reversely injected into the suspension cylinder inner cavity system. Meanwhile, the quantitative hydraulic oil in the auxiliary oil cavity is discharged back to the rod cavity of the flow control cylinder by means of the pressure difference between the two loops/systems. When restoring the suspension cylinder height, the weight of the sprung mass of the vehicle needs to be overcome and raised to the original working height. Additional pressure in the two circuits/systems also needs to be overcome in the case of non-isobaric control. As shown in fig. 27, a system configuration diagram for restoring from a compressed state to an initial state is shown.

When the diameter ratio of the piston rod/the cylinder barrel of the flow control cylinder is not the diameter ratio corresponding to the piston rod/the cylinder barrel of the suspension cylinder, a non-isobaric control state is formed. The configuration shown in fig. 11 is a case where the diameter of the piston rod of the flow control cylinder is zero. Fig. 23 shows the variation of the stiffness curve of the height and stroke control of the non-isobaric structure, curve 1 is the original stiffness curve, and curve 2 is the stiffness curve of the new equilibrium position. As can be seen from fig. 23, the non-isobaric structure, despite the corresponding control in the balance of the suspension cylinders, is significantly weakened in both the actual height and stroke control in the empty/full load condition.

Fig. 12 shows another limit condition, namely, the flow exchange channel of the suspended cylinder inner cavity system is disconnected, and the gas-liquid booster pump adopts an open structure to form a single-loop control structure. The pressure characteristics of this control structure underslung cylinder chamber system and the external control circuit are shown in fig. 18. In fig. 18, curve 1 is the original balance position external control loop pressure characteristic curve, curve 3 is the new balance position external control loop pressure characteristic curve, and curve 2/4 is the suspension cylinder inner chamber system pressure characteristic curve. As can be seen from fig. 18, the suspension cylinder chamber system pressure characteristics remain unchanged during control. Fig. 21 and 22 show the change of the stiffness curve of the suspension cylinder under two control forces, wherein the curve 1 is the original stiffness curve, and the curve 2 is the stiffness curve under the new balance position. As can be seen from fig. 21 and 22, the control of the actual working height of the suspension cylinder by the single-loop control structure is still weaker, and the control of the working stroke of the suspension cylinder is more remarkable, but the system stiffness value in the idle and full states is also obviously changed. For a specific vehicle, the no-load state and the full-load state are relatively fixed, so that the single-loop control structure has a certain influence on the smoothness of the running of the vehicle.

The dual-loop isobaric control structure disclosed by the invention, as shown in fig. 19 and 24, has the advantages of accurate and consistent control of balance positions and actual working positions, small additional pressure and stable process, keeps the original empty/full load stiffness characteristic unchanged, and ensures that the initial state and each intermediate transition state of the control are kept very good in consistency, thus ensuring the smoothness and stability of single use and multi-system combined application of the system.

The controllable stroke hydro-pneumatic suspension cylinder disclosed by the invention is characterized in that an external control loop and a suspension cylinder inner cavity system are closed systems. The gas-liquid booster pump/flow control cylinder, the external control loop and the suspension cylinder inner cavity system are isolated type step-by-step control, and are reversible and safe control.

Fig. 28 is a system configuration diagram in a normal operation and no-load state, and fig. 29 is a system configuration diagram in a normal operation and full-load state. As can be seen from fig. 28 and 29, during normal operation, the flow is exchanged between the cylinder tube inner cavity and the piston rod inner cavity in the suspension cylinder inner cavity system, the flow is exchanged between the auxiliary oil cavity and the energy accumulator in the external control loop, and the flow is not exchanged between the gas-liquid booster pump/flow control cylinder, the external control loop and the suspension cylinder inner cavity system, and the reversing valve in the gas-liquid booster pump/flow control cylinder is in a full-cut state, so that the stability and reliability of the system operation are ensured. In FIG. 28, the internal control valve train inside the suspension cylinder is in an unloaded state, and in FIG. 29, the internal control valve train is in a fully loaded state. FIGS. 30 and 31 are detailed block diagrams of the internal control valve arrangement in the unloaded and fully loaded states, respectively.

The internal control valve group is an automatic damping-changing structure component controlled by internal pressure, which can sense and judge the working state of a suspension cylinder according to the pressure of a suspension cylinder inner cavity system and automatically adjust and control the flow and damping coefficient between a cylinder barrel inner cavity (main oil cavity) and a piston rod inner cavity (mixed oil cavity). As shown in FIG. 16, the damping characteristic curve of the internal control valve train is automatically controlled according to the internal pressure of the system.

Compared with the prior art, the invention has the beneficial technical effects that:

1. The controllable stroke hydro-pneumatic suspension cylinder completely isolates the hydro-pneumatic suspension cylinder auxiliary oil cavity from the suspension cylinder inner cavity (comprising the cylinder inner cavity and the piston rod inner cavity), and takes the auxiliary oil cavity as a target link for external control so as to realize active or semi-active control on the stroke, the length and the rigidity of the suspension cylinder;

2. The invention discloses a suspension cylinder inner cavity in a stroke-controllable hydro-pneumatic suspension cylinder, which uses an internal control valve group as a core to control an inner cylinder inner cavity (a main oil cavity) and an inner cavity (a combined oil cavity) of a mixed piston rod, so as to construct a complete and independent pressure/flow control system, provide main body rigidity/damping mechanical parameters of the suspension cylinder, realize variable damping active control in the system, and ensure that the pressure acting area and the damping flow area are both the inner cavity area of the cylinder;

3. The controllable stroke hydro-pneumatic suspension cylinder is provided with an accumulator, a control valve and a pipeline outside the hydro-pneumatic suspension cylinder, is connected with a secondary oil cavity of the suspension cylinder to construct an independent external control loop, and can achieve the following three purposes that ① uses the accumulator (a mixed oil cavity) to construct complete pressure and flow relation of the external control loop with the secondary oil cavity, ② uses the control valve to construct an external control input port and simultaneously serves as a damping element of the external control loop, and ③ uses the external control loop and the suspension cylinder inner cavity system to form novel and complete double-air-chamber back pressure opposite structure relation through the secondary oil cavity;

4. the external control loop constructed by the controllable stroke hydro-pneumatic suspension cylinder is independent of the suspension cylinder inner cavity system, and the mechanical parameters of the suspension cylinder inner cavity system are supplemented and corrected through the auxiliary oil cavity, and the suspension cylinder inner cavity system is reversely controlled on the parameters such as rigidity, stroke, state, pressure and the like. The pressure acting area and the damping flow area are the annular area of the auxiliary oil cavity;

5. The stroke-controllable hydro-pneumatic suspension cylinder disclosed by the invention is used for constructing a complete suspension cylinder inner cavity structure on the basis of realizing a double-air-chamber back-pressure opposite structure. And establishing complete structural and parameter association of the relative position, speed, pressure, flow and the like between the inner cavity of the cylinder barrel and the inner cavity of the piston rod through the internal control valve assembly. The automatic damping-changing function of the suspended cylinder inner cavity system based on the double-air-chamber back-pressure opposite structure is realized for the first time, and a brand new basic framework is provided for various damping-changing active control in the future;

6. The controllable stroke hydro-pneumatic suspension cylinder is connected with a suspension cylinder inner cavity system and an external control loop respectively by a gas-liquid booster pump/a flow control cylinder to form a closed double-loop constant pressure control system. The gas-liquid booster pump is used as the control executing mechanism of the invention, and the internal reversing valve is used for forward and reverse control and cut-off and closure during normal operation.

In summary, the stroke-controllable hydro-pneumatic suspension cylinder constructs a suspension cylinder inner cavity system and an external control loop by structurally isolating the auxiliary oil cavity from the suspension cylinder inner cavity, forms a double-channel isobaric and synchronous control system structure with the constructed double-loop system through the hydraulic booster pump/the flow control cylinder, realizes reliable and stable height and state control, constructs a novel double-air chamber back-pressure hydro-pneumatic suspension cylinder structure, realizes automatic damping change control under the empty/full load state of the system, and opens up a novel technical structure for active and semi-active control hydro-pneumatic suspension.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings that are needed in the embodiments will be briefly described below, it being obvious that the drawings in the following description are only some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a prior art hydro-pneumatic suspension cylinder with a single air chamber and double oil chambers on a piston rod;

FIG. 2 is a schematic diagram of a prior art single chamber double chamber hydro-pneumatic suspension cylinder with a piston rod down set;

FIG. 3 is a schematic diagram of a prior art three-chamber hydro-pneumatic suspension cylinder with a single air chamber on the piston rod;

FIG. 4 is a schematic diagram of a prior art three-chamber hydro-pneumatic suspension cylinder with a single air chamber under the piston rod;

FIG. 5 is a schematic diagram of a prior art three-chamber hydro-pneumatic suspension cylinder with a single air chamber under the piston rod;

FIG. 6 is a schematic diagram of a prior art three-chamber/pressure compensated hydro-pneumatic suspension cylinder with a single air chamber on the piston rod;

FIG. 7 is a schematic diagram of a prior art three-oil chamber hydro-pneumatic suspension cylinder with a double air chamber arranged below a piston rod and connected in series in the forward direction;

FIG. 8 is a schematic diagram of a prior art dual chamber inverted three chamber hydro-pneumatic suspension cylinder with a lower piston rod;

FIG. 9 is a schematic diagram of a prior art dual chamber inverted three chamber hydro-pneumatic suspension cylinder with a lower piston rod;

FIG. 10 is a schematic diagram of the construction of a controllable stroke hydro-pneumatic suspension cylinder of the present invention;

FIG. 11 is a schematic diagram of the structure of the non-isobaric control in the controllable stroke hydrocarbon suspension cylinder of the present invention;

FIG. 12 is a schematic diagram of the architecture of a single channel control in a controllable stroke hydro-pneumatic suspension cylinder of the present invention;

FIG. 13 is a graph of a conventional hydro-pneumatic suspension cylinder stiffness characteristic;

FIG. 14 is a graph of stiffness characteristics of a dual plenum counter-pressure opposed structure hydro-pneumatic suspension cylinder;

FIG. 15 is a graph of damping characteristics for a conventional hydro-pneumatic suspension cylinder;

FIG. 16 is a graph of the variable damping characteristics for a controllable stroke hydro-pneumatic suspension cylinder of the invention;

FIG. 17 is a system pressure profile for a controllable stroke hydro-pneumatic suspension cylinder of the invention;

FIG. 18 is a graph of pressure characteristics of a single channel control architecture stroke control system in a controllable stroke hydro-pneumatic suspension cylinder of the present invention;

FIG. 19 is a graph of the pressure characteristics of the controllable stroke hydro-pneumatic suspension cylinder height/state control system of the invention;

FIG. 20 is a graph of the stiffness characteristics of a controllable stroke hydro-pneumatic suspension cylinder of the present invention;

FIG. 21 is a graph of the stroke control stiffness characteristics of a single channel control structure in a controllable stroke hydro-pneumatic suspension cylinder of the present invention;

FIG. 22 is a graph of the stroke control stiffness characteristics of a single channel control structure in a controllable stroke hydro-pneumatic suspension cylinder of the present invention;

FIG. 23 is a graph of stroke control stiffness characteristics of a non-isobaric control architecture in a controllable stroke hydrocarbon suspension cylinder of the present invention;

FIG. 24 is a graph of pressure control structure height/state control stiffness characteristics in a controllable stroke hydro-pneumatic suspension cylinder of the present invention;

FIG. 25 is a system configuration diagram of a controllable stroke hydro-pneumatic suspension cylinder of the invention;

FIG. 26 is a block diagram of a controllable stroke hydro-pneumatic suspension cylinder stowed state system of the invention;

FIG. 27 is a block diagram of a controlled stroke hydro-pneumatic suspension cylinder release state system of the present invention;

FIG. 28 is a block diagram of a controlled stroke hydro-pneumatic suspension cylinder no-load condition system of the present invention;

FIG. 29 is a block diagram of a controllable stroke hydro-pneumatic suspension cylinder full load system of the invention;

FIG. 30 is a partial enlarged view of an empty state of a pressure controlled variable damping structure of an internal control valve bank in a controllable stroke hydro-pneumatic suspension cylinder of the present invention;

FIG. 31 is a partial enlarged view of the full load condition of the pressure controlled variable damping structure of the internal control valve train in a controllable stroke hydro-pneumatic suspension cylinder of the present invention.

The reference numerals are 10, a piston rod, 11, a piston, 12, an internal control valve group, 13, a cylinder barrel, 14, a sealing seat ring, 15, an energy accumulator, 16, a control valve, 17, a gas-liquid booster pump, 18, a flow control cylinder, 19, a reversing valve, 20, a suspension cylinder inner cavity, 21, a secondary oil cavity, 22, a cylinder barrel inner cavity, 23, a piston rod inner cavity, 25, a pipeline, 30, a suspension cylinder inner cavity system, 31, an external control interface, 32, an external control interface, 40, an external control loop, 41, an external control interface, 42 and an external control interface.

Detailed Description

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention.

In the description of the present invention, it should be understood that the terms "length," "width," "inner," "outer," and the like indicate an orientation or a positional relationship based on that shown in the drawings, and are merely for convenience of description and simplification of the description, and do not indicate or imply that the apparatus or element in question must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the present invention, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.

In the description of the present invention, unless explicitly stated and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected, directly connected, indirectly connected via an intermediate medium, or in communication between two elements or in an interaction relationship between two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

The embodiment of the specification provides a controllable stroke hydro-pneumatic suspension cylinder, including cylinder, piston rod, piston, internal control valve group, sealed seat circle, energy storage, control valve, gas-liquid booster pump and flow control jar, be provided with the piston in the cylinder, be connected with the piston rod on the piston, pass through sealed seat circle sealing connection between piston rod and the cylinder upper portion.

The cylinder barrel, the piston rod and the piston enclose a suspension cylinder inner cavity inside the suspension cylinder, the suspension cylinder inner cavity is a rodless cavity, an internal control valve group is arranged at the bottom of the piston rod, the suspension cylinder inner cavity is divided into a cylinder barrel inner cavity and a piston rod inner cavity by the internal control valve group, hydraulic oil is filled in the cylinder barrel inner cavity, an external control interface is arranged at the bottom of the cylinder barrel inner cavity, hydraulic oil and nitrogen are filled in the piston rod inner cavity, and the cylinder barrel inner cavity and the piston rod inner cavity are communicated through damping channels on the internal control valve group to form an independent suspension cylinder inner cavity system.

And, cylinder, sealed seat circle, piston rod and piston enclose into the auxiliary oil pocket between the lateral wall of suspension cylinder waist, and the auxiliary oil pocket is for having the pole chamber, and auxiliary oil pocket fills hydraulic oil and keeps apart completely with suspension cylinder inner chamber, and the auxiliary oil pocket sets up the connector in the position that the cylinder is close to sealed seat circle, and auxiliary oil pocket passes through pipeline external control valve and accumulator, forms independent external control circuit.

The gas-liquid booster pump comprises a reversing valve capable of implementing oil way reversing and closing control, the interior of the reversing valve is communicated with a rodless cavity of the flow control cylinder, the gas-liquid booster pump is provided with an external control interface, the external control interface of the gas-liquid booster pump is connected with an external control interface of the suspension cylinder inner cavity system, the flow control cylinder is provided with an external control interface, and the external control interface of the flow control cylinder is arranged in the rod cavity and is connected with an external control interface of an external control loop, so that two independent closed systems are formed, and two independent channels for synchronously controlling the stroke, rigidity and height of the suspension cylinder are formed.

At this point, the control valve is an input port for external control of suspension cylinder travel, stiffness and height, and acts as a damping/flow control element inside the external control circuit, and is provided with an external control interface.

And the auxiliary oil cavity in the external control loop and the inner cavity of the cylinder barrel in the suspension cylinder inner cavity system form a double-air-chamber back pressure opposite structure.

In addition, the accumulator is filled with hydraulic oil and nitrogen.

At this point, the suspension cylinder chamber maintains a complete chamber structure and pressure/flow correlation, and the internal control valve train acts as a damping control assembly between the cylinder chamber and the piston rod chamber.

The control method of the controllable stroke hydro-pneumatic suspension cylinder comprises the following steps:

The following describes in detail the technical solutions provided by the embodiments of the present invention with reference to the accompanying drawings.

Example 1

The invention relates to a stroke-controllable hydro-pneumatic suspension cylinder in an embodiment 1, which comprises a piston rod 10, a piston 11, an internal control valve group 12, a cylinder barrel 13, a sealing seat ring 14, an energy accumulator 15, a control valve 16, a gas-liquid booster pump 17, a flow control cylinder 18, a reversing valve 19 and a pipeline 25. The cylinder tube 13, the piston rod 10 and the piston 11 enclose a suspension cylinder inner chamber 20 (no rod chamber) inside the suspension cylinder. The cylinder tube 13, the seal ring 14, the piston rod 10, and the piston 11 define a sub-oil chamber 21 (rod chamber) in the suspension cylinder waist side wall. The auxiliary oil chamber 21 is filled with hydraulic oil and is completely isolated from the suspension cylinder inner chamber 20. The suspension cylinder chamber 20 is divided into a cylinder chamber 22 and a piston rod chamber 23 by the internal control valve train 12 at the bottom of the piston rod 10. The cylinder cavity 22 is filled with hydraulic oil, and the piston rod cavity 23 is filled with hydraulic oil and nitrogen. The cylinder bore 22 and piston rod bore 23 communicate through a damping passage on the internal control valve train 12 to form a complete, independent suspension cylinder bore system 30. The auxiliary oil chamber 21 is provided with an external connection port at a position of the cylinder 13 close to the seal ring 14, and is externally connected with the accumulator 15 and the control valve 16 through a pipeline 25 to form an independent external control circuit 40.

The suspension cylinder inner cavity system 30 is sealed in the suspension cylinder inner cavity 20 and consists of a piston rod inner cavity 23, a cylinder barrel inner cavity 22 and an internal control valve group 12, and an external control interface 31 is arranged at the bottom of the cylinder barrel inner cavity 22. The external control circuit 40 is composed of the auxiliary oil cavity 21, the energy accumulator 15, the control valve 16 and the pipeline 25, and the control valve 16 is provided with an external control interface 41. The external control circuit 40 is completely isolated from the suspension cylinder chamber system 30, independent of each other.

The secondary oil chamber 21 in the external control circuit 40 is in a double-chamber counter-pressure opposing relationship with the cylinder bore 22 in the suspension cylinder bore system 30. The accumulator 15 is filled with hydraulic oil and nitrogen gas. The sub oil chamber 21 serves as a target link for externally controlling the height and stroke of the suspension cylinder. The control valve 16, in addition to acting as an input port for external control of suspension cylinder height, travel and stiffness, also acts as a damping/flow control element for the external control circuit 40 itself.

The gas-liquid booster pump 17 contains a reversing valve 19 inside, and forms a component for controlling the stroke and height of the suspension cylinder with the flow control cylinder 18. The internal control interface of the gas-liquid booster pump 17 is communicated with the rodless cavity of the flow control cylinder 18, and the external control interface 32 can be controlled in real time. An external control interface 42 of the flow control cylinder 18 is provided in the rod chamber. The reversing valve 19 can perform reversing and closing control of the oil passage. The external control interface 32 of the gas-liquid booster pump 17 and the external control interface 42 of the flow control cylinder 18 are respectively connected with the external control interface 31 of the suspension cylinder inner cavity system 30 and the external control interface 41 of the external control loop 40 to form two independent closed systems, so that two channels for continuously and synchronously controlling the height/stroke of the suspension cylinder in equal pressure are formed. As shown in fig. 25, a block diagram of a controllable stroke hydro-pneumatic suspension cylinder system is shown. Fig. 10 is a schematic structural view.

When the suspension cylinder is compressed or stretched, the volumes of the cylinder barrel inner cavity 22 and the auxiliary oil cavity 21 are changed, and the volumes are all variable oil cavities. For the suspension cylinder inner cavity system 30, flow exchange is carried out between the cylinder barrel inner cavity 22 and the piston rod inner cavity 23, and the damping flow area is the sectional area of the cylinder barrel inner cavity 22. For the external control circuit 40, flow exchange is performed between the secondary oil chamber 21 and the accumulator 15, and the damping flow area is the sectional area of the secondary oil chamber 21. The damping flow of the suspension cylinder is the sum of the damping flow of the suspension cylinder inner chamber system 30 and the external control circuit 40. The suspension cylinder chamber system 30 and the external control circuit 40 form a double-air-chamber counter-pressure opposing structure through the cylinder chamber 22 and the auxiliary oil chamber 21. The pressure area of the suspension cylinder chamber system 30 is the cross-sectional area of the cylinder chamber 22. The pressure acting area of the external control circuit 40 is the sectional area of the sub oil chamber 21. The overall stiffness of the suspension cylinder is formed by the superposition of the pressure of the suspension cylinder inner chamber system 30 and its pressure area of application and the pressure of the external control circuit 40 and its pressure area of application. See fig. 20. Curve 1 is the stiffness curve of the suspension cylinder inner chamber system 30, curve 2 is the stiffness curve of the outer control loop 40, and curve 3 is the integrated stiffness curve of the suspension cylinder system. As can be seen from fig. 20, the external control circuit 40 favorably corrects the rigidity characteristics of the suspension cylinder inner chamber system 30 at the initial stage.

An internal control valve train 12, which is a pressure controlled automatic variable damping control assembly, is mounted at the bottom of the piston rod 10. Automatic variable damping control in the empty/full suspension cylinder state is achieved by sensing the system pressure of the suspension cylinder chamber system 30. Referring to fig. 16, the air/full load automatic variable damping control characteristic of the present invention. FIGS. 30 and 31 are structural state diagrams of the internal control valve arrangement 12 in the empty/full condition. As can be seen in fig. 30 and 31, the internal control valve train 12 is based on the complete structure of the suspension cylinder bore 20 and its complete position/velocity and pressure/flow relationship between the inner cylinder bore 22 and the piston rod bore 23. Fig. 28 and 29 are system configuration diagrams of the controllable stroke hydro-pneumatic suspension cylinder of the present invention in the empty/full state.

When the suspension cylinder height needs to be reduced or the suspension cylinder needs to be retracted, the reversing valve 19 is placed in the retracted position, the gas-liquid booster pump 17 is started, the quantitative hydraulic oil in the suspension cylinder inner cavity system 30 is injected into the rodless cavity of the flow control cylinder 18, and meanwhile the quantitative hydraulic oil in the rod cavity on the other side is injected into the auxiliary oil cavity 21 of the external control loop 40. The suspension cylinder height is reduced and the balance position is changed until a new balance position is reached. Fig. 26 is a system configuration diagram showing a retracted state of the suspension cylinder. The area ratio of the piston rod/cylinder barrel selected by the flow control cylinder 18 is consistent with the area ratio of the piston rod 10/cylinder barrel 13 of the suspension cylinder, and the constant pressure control state is realized. As shown in fig. 19, the system pressure characteristic under the isobaric control. Curve 1/curve 2 is the pressure characteristic curves of the external control circuit 40 and the suspension cylinder inner chamber system 30 in the original balance state, and curve 3/curve 4 is the pressure characteristic curves of the external control circuit 40 and the suspension cylinder inner chamber system 30 in the new balance state. Fig. 24 shows the system stiffness characteristic under isostatic control. Curve 1 is the system stiffness characteristic curve in the original equilibrium state, and curve 2 is the system stiffness characteristic curve in the new equilibrium state. As can be seen from fig. 19 and 24, the height of the suspension cylinder is adjusted in the isobaric control state, and each working position of the suspension cylinder is synchronously lowered with the balance position, so that the working stroke is changed.

When it is necessary to restore the original height of the suspension cylinder or release the suspension cylinder, the reversing valve 19 is placed in the release position, the gas-liquid booster pump 17 is started, and the hydraulic oil in the rodless chamber of the flow control cylinder 18 is reversely injected into the suspension cylinder inner chamber system 30. At the same time, the quantitative hydraulic oil in the auxiliary oil chamber 21 of the external control circuit 40 is discharged back to the rod chamber of the flow control cylinder 18 by means of the pressure difference between the two circuits/systems. As shown in fig. 27, a system configuration diagram is shown for the suspension cylinder release state.

When there is no need to adjust the suspension cylinder height or the vehicle is operating normally, the start gas-liquid booster pump 17 is turned off and the reversing valve 19 is placed in the cut-off position.

The controllable stroke hydro-pneumatic suspension cylinder disclosed by the invention is characterized in that an isolation auxiliary oil cavity is used as a target link of external control, and two independent control loop systems of a suspension cylinder inner cavity system and an external control loop are constructed to form two equal-pressure and synchronous control channels for controlling the height and stroke of the suspension cylinder. The control input port of the external control loop and the suspension cylinder inner cavity system and the damping control structure of the loop/system are comprehensively set, the integrity of the suspension cylinder inner cavity and the complete association structure of the position, the speed, the pressure, the flow and the like between the piston rod inner cavity and the cylinder inner cavity are maintained, the combined functions of active external control, a double-air-chamber back pressure opposite structure, internal active variable damping control and the like are realized, the defects of the traditional structure are eliminated, and the complete and excellent mechanical characteristics are realized. The whole function and the structure of the suspension cylinder are complete, the internal structure is simple, and the structural efficiency of the hydro-pneumatic suspension cylinder is furthest excavated. The stability and reliability of the operation of the suspension cylinder inner cavity system are ensured while the external active control is effectively implemented.

The invention provides a stroke-controllable hydro-pneumatic suspension cylinder structure, which is the first time in the prior literature and products from the key technical functions of isolation of a secondary oil cavity and a suspension cylinder cavity, an independent double-loop system, equal-pressure and synchronous double-channel control, a double-air-chamber opposite structure, variable rigidity, variable damping and the like, and provides a novel basic suspension cylinder structure with complete and reliable structure and function for further expanding an active and semi-active hydro-pneumatic suspension.

The technical proposal of the invention is based on the hydro-pneumatic suspension structure, and has obvious advantages in the aspects of bearing capacity, control capacity, cost composition and the like. The chassis performance of various products such as common vehicles, load-carrying vehicles and special vehicles is improved by the method, and the method has high-efficiency and economical technical means and product directions.

The closed double-loop isobaric control system constructed by the invention comprises active control of the height and state of a suspension cylinder, automatic variable damping control of no-load and full-load, and a double-air-chamber counter-pressure opposite structure established by an external control loop and a suspension cylinder inner cavity system, and can be independently controlled and operated in a combined mode.

When the height and the state of the vehicle are adjusted, the gas-liquid booster pump/the flow control cylinder are respectively synchronous with the suspension cylinder inner cavity/the auxiliary oil cavity and perform equal pressure flow exchange (figure 24). The initial position and the intermediate state transition smoothly.

When the vehicle is running, the flow exchange is carried out between the inner cavity of the cylinder barrel and the inner cavity of the piston rod in the inner cavity system of the suspension cylinder, and the flow exchange is carried out between the auxiliary oil cavity and the energy accumulator in the external control loop. The external control loop completely supplements and corrects the mechanical parameters of the suspension cylinder inner cavity system, and outputs good rigidity characteristics (figure 20). Suspension cylinder bore systems rely on internal control valve trains to output good variable damping characteristics based on internal integrity (fig. 16).

When the vehicle is in an idle operation, the working pressure of the inner cavity of the suspension cylinder is in a low pressure state. The internal control valve group opens the variable damping channel, and the suspension cylinder inner cavity system is in a low damping coefficient state. When the device runs fully, the working pressure of the inner cavity of the suspension cylinder is in a high-pressure state. The internal control valve group closes the variable damping channel, and the suspension cylinder inner cavity system is in a high damping coefficient state. The suspension cylinder can output good damping characteristics when in empty/full operation.

2. The double-air-chamber back-pressure opposite suspension cylinder structure disclosed by the invention keeps complete and concise suspension cylinder inner cavity structure, and complete association between the cylinder barrel inner cavity and the piston rod inner cavity is realized, a complete suspension cylinder inner cavity system and an independent external control loop are constructed, the suspension cylinder inner cavity system provides main body parameters of the suspension cylinder, the external control loop provides control parameters of the system, and the independent suspension cylinder inner cavity system and the external control loop structure ensure the stability and the reliability of the operation of the suspension system.

3. The pressure acting area and the damping flow area of the suspension cylinder inner cavity system are the cylinder barrel inner cavity area, the pressure acting area and the damping flow area of the external control loop are the auxiliary oil cavity area, the external control loop and the suspension cylinder inner cavity system form a back pressure opposite structure, hard points in the stroke are eliminated, zero crossing balance points of the suspension cylinder are formed, and good rigidity characteristics are output.

4. The invention relates to variable damping self-adaptive control, which is based on a complete structure of a suspension cylinder inner cavity, and a complete structure and correlation of relative positions, speeds, pressures, flow rates and the like between a cylinder inner cavity and a piston rod inner cavity, wherein an internal control valve group is a variable damping control mechanism based on the internal pressure of a system, the variable damping flow control of a double-point and steady state is realized, F=f (p, v) is realized, fig. 16 is two damping characteristic curves of automatic matching of the system in an empty/full load state, the variable damping control flow area of the invention is the cylinder inner cavity area, and the maximum state of the cylinder structure is reached.

The core of the internal control valve group is to construct a valve core component taking internal pressure as control input and a variable damping structure to form an internal variable damping channel. The valve core assembly comprises a closed pressure cavity for system identification, and a spring is used for providing valve core reference pressure to push the valve core to move. The spool reference pressure is set between the suspension cylinder no-load pressure and the full-load pressure. The valve core is provided with an inner/outer two groups of damping holes and a one-way valve, the inner/outer two groups of damping holes and the one-way valve are matched with a valve core seat ring to form a fixed damping channel and a controllable damping channel, the fixed damping channel is long-pass, the controllable damping channel is opened when the valve core extends, and the controllable damping channel is closed when the valve core retracts. The valve core assembly also comprises a damping cavity and a damping ring, and is used for controlling the steady-state response of the valve core. FIGS. 30 and 31 are block diagrams of the operation of the internal control valve arrangement in the empty/full condition.

For the internal control valve group, 1) a variable damping structure, a variable damping channel and an automatic control structure are constructed in the cylinder body, the pressure of the inner cavity system of the suspension cylinder is used as an input parameter of variable damping control, F=f (p, v), and 2) the reference pressure of the valve core is used for identifying the idle pressure and the full pressure in the system and pushing the valve core to extend and retract by overlapping with the system pressure. Therefore, the invention is a typical double-point variable damping control, see FIG. 16, 3) a damping cavity and a damping ring in a valve core assembly are used for controlling the steady-state response of the valve core, and the pressure fluctuation and the pressure impact in the system can not cause the transient starting and the rigid impact of the valve core, so that the system is steady-state control, and 4) the invention is a suspension cylinder structure which is based on the double-air chamber back pressure opposite structure at present and realizes the external active control and the internal variable damping automatic control, and provides a brand new basic oil-gas suspension cylinder structure for the future technical development.

The invention is used as a structural scheme for actively controlling the height and the state of the oil gas suspension in a mechanical/hydraulic control mode, and has obvious innovative characteristics and application value.

Example 2

The control method of the controllable stroke hydro-pneumatic suspension cylinder of the embodiment 2 of the invention comprises the following steps:

1) When the height of the suspension cylinder is required to be lowered or the suspension cylinder is required to be retracted, the reversing valve 19 is arranged at the retraction position, the gas-liquid booster pump 17 is started, quantitative hydraulic oil in the suspension cylinder inner cavity system 30 is injected into the rodless cavity of the flow control cylinder 18, and meanwhile quantitative hydraulic oil in the rod cavity on the other side is injected into the auxiliary oil cavity 21 of the external control loop 40;

2) When the original height of the suspension cylinder needs to be restored or the suspension cylinder needs to be released, the reversing valve 19 is placed in a release position, the gas-liquid booster pump 17 is started, hydraulic oil in the rodless cavity of the flow control cylinder 18 is reversely injected into the suspension cylinder inner cavity system 30, and meanwhile, the quantitative hydraulic oil in the auxiliary oil cavity 21 of the external control circuit 40 is discharged back into the rod cavity of the flow control cylinder 18 by means of the pressure difference between the two circuits/systems;

3) When there is no need to adjust the suspension cylinder height or the vehicle is operating normally, the start gas-liquid booster pump 17 is turned off, and the reversing valve 19 is placed in the cut-off position.

The above embodiments are only illustrative of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art to the technical solutions of the present invention should fall within the protection scope defined by the claims of the present invention without departing from the design spirit of the present invention.

Claims

1. The stroke-controllable hydro-pneumatic suspension cylinder is characterized by comprising a cylinder barrel, a piston rod, a piston, an internal control valve group, a sealing seat ring, an energy accumulator, a control valve, a gas-liquid booster pump and a flow control cylinder, wherein the piston is arranged in the cylinder barrel, the piston rod is connected to the piston, and the piston rod is in sealing connection with the upper part of the cylinder barrel through the sealing seat ring;

2. The controllable-stroke hydro-pneumatic suspension cylinder as recited in claim 1 wherein said control valve is an input port for external control of suspension cylinder stroke, stiffness and height and acts as a damping/flow control element within an external control circuit and is provided with an external control interface.

3. The controllable-stroke hydro-pneumatic suspension cylinder of claim 1 wherein said secondary oil chamber in said external control circuit forms a double plenum counter-pressure opposed configuration with said cylinder bore in said suspension cylinder bore system.

4. The controllable-stroke hydro-pneumatic suspension cylinder of claim 1 wherein the accumulator is internally charged with hydraulic oil and nitrogen.

5. The controllable-stroke hydro-pneumatic suspension cylinder of any one of claims 1-4 wherein the suspension cylinder chamber maintains a complete chamber configuration and pressure/flow correlation and wherein the internal control valve train acts as a damping control assembly between the cylinder chamber and the piston rod chamber.

6. A method of controlling a controllable stroke hydro-pneumatic suspension cylinder comprising: