Patent ID: 12221767

It should be understood that the dimensions of various parts shown in the accompanying drawings are not drawn according to actual proportional relations. In addition, the same or similar components are denoted by the same or similar reference signs.

DETAILED DESCRIPTION

Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and is in no way intended as a limitation to the present disclosure, its application or use. The present disclosure may be implemented in many different forms, which are not limited to the embodiments described herein. These embodiments are provided to make the present disclosure thorough and complete, and fully convey the scope of the present disclosure to those skilled in the art. It should be noticed that: relative arrangement of components and steps, material composition, numerical expressions, and numerical values set forth in these embodiments, unless specifically stated otherwise, should be explained as merely illustrative, and not as a limitation.

The use of the terms “first”, “second” and similar words in the present disclosure do not denote any order, quantity or importance, but are merely used to distinguish between different parts. A word such as “comprise”, “include” or variants thereof means that the element before the word covers the element(s) listed after the word without excluding the possibility of also covering other elements. The terms “up”, “down”, “left”, “right”, or the like are used only to represent a relative positional relationship, and the relative positional relationship may be changed correspondingly if the absolute position of the described object changes.

In the present disclosure, when it is described that a particular device is located between the first device and the second device, there may be an intermediate device between the particular device and the first device or the second device, and alternatively, there may be no intermediate device. When it is described that a particular device is connected to other devices, the particular device may be directly connected to said other devices without an intermediate device, and alternatively, may not be directly connected to said other devices but with an intermediate device.

All the terms (including technical and scientific terms) used in the present disclosure have the same meanings as understood by those skilled in the art of the present disclosure unless otherwise defined. It should also be understood that terms as defined in general dictionaries, unless explicitly defined herein, should be interpreted as having meanings that are in line with their meanings in the context of the relevant art, and not to be interpreted in an idealized or extremely formalized sense.

Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, these techniques, methods, and apparatuses should be considered as part of this specification.

In some related technologies, the passive energy storage type travel stability system developed by the hydro-pneumatic suspension technology is used to solve the vibration problem. After studies, it has been found that, when the passive energy storage type travel stability system is turned on, since the pressure of the energy storage is not necessarily balanced with the pressure of the rodless cavity of the boom hydraulic cylinder in the operation device after the system is turned on, it is easily to cause the piston rod of the boom cylinder to move back and forth, so that the operation device cannot always remain in a set position but change in position, thereby resulting in spillage of the material in the bucket or other safety risks.

The setting position here refers to a specific position where the operation device may remain (for example, an open end of the bucket remains horizontal, and the distance from the connection hinge point of the bucket to the ground is about 300 mm) when the construction machinery such as a backhoe loader capable of performing transfer or operation by carrying the material travels and performs a transfer operation by carrying the material, so that the whole vehicle has a low center of gravity, thereby improving the stable operation and smooth travel of the vehicle.

In addition, due to the differences in the road roughness and the weight of the material in the bucket, the damping required for vibration reduction also varies, so that the passive energy storage type travel stability system in the related art is difficult to adjust the damping of the system in real time according to the road roughness and the weight of the material in the bucket.

In view of this, the present disclosure provides a travel stability system, a backhoe loader, and a control method, which can improve the safety during the travelling process.

As shown inFIG.1, it is a schematic view of hydraulic principles in some embodiments of the travel stability system according to the present disclosure.FIG.2is a schematic block diagram in some embodiments of the travel stability system according to the present disclosure. Referring toFIGS.1and2, in some embodiments, the travel stability system includes: a hydraulic actuator1, a first hydraulic oil source B, an energy storage element A, and a controller E. The hydraulic actuator1may be an operation unit of the operation vehicle to which the travel stability system is applied. In some embodiments, the hydraulic actuator1can carry the material when the construction machinery vehicle travels. For example, in the backhoe loader where the embodiment of the travel stability system of the present disclosure is used, the hydraulic actuator1may be a boom cylinder.

The first hydraulic oil source B is operatively connected with the hydraulic actuator1and configured to provide pressure oil to the hydraulic actuator1. The first hydraulic oil source B may provide hydraulic oil to the hydraulic actuator1through the first oil supply path r1as necessary, and stop the supply of hydraulic oil to the hydraulic actuator1as necessary.

Referring toFIG.1, in some embodiments, the first hydraulic oil source B includes a hydraulic source, for example the oil pump7inFIG.1. In some embodiments, the first hydraulic oil source B may further include an electromagnetic change valve3provided in the first oil supply path r1to realize the operability of oil supply. The first hydraulic oil source B may also include an overflow valve4arranged between the first oil supply path r1and the oil return oil path to provide overload protection of the system or realize functions such as constant pressure of the hydraulic source.

InFIG.1, the oil pump7may be driven by the electric motor5or the engine to pump hydraulic oil from the oil tank6. The oil inlet and the oil return port of the electromagnetic change valve3are respectively connected to the outlet of the oil pump7and the oil tank6, and the two operation oil ports of the electromagnetic change valve3are respectively connected to the rodless cavities of the two hydraulic actuators1, so as to realize start and stop of the hydraulic actuator1as well as operations in different running directions by the switching of the electromagnetic change valve3. In other embodiments, the first hydraulic oil source B may also use an oil supply mechanism configured to drive own operation units in an existing operation machine.

The energy storage element A is operatively connected with the first oil supply path r1between the first hydraulic oil source B and the hydraulic actuator1. The energy storage element A may include one or more energy storages, such as a gas-type energy storage, a spring-type energy storage or a piston-type energy storage. The energy storage element A can effectively absorb the shock and vibration in the associated hydraulic path of the hydraulic actuator1, thereby effectively solving the problems such as permeation of the oil in the hydraulic pipeline fitting, severe vibration of the operator cabin and the vehicle body structure, and easy spillage of the carried material in some operation vehicles where the travel stability system is applied, and improving the reliability, operation comfort, travel stability and operation efficiency of the operation vehicle.

Referring toFIG.2, in some embodiments, the controller E can compare the oil pressures of the hydraulic actuator1with the energy storage element A after the travel stability system is turned on, and achieve a balance between the oil pressures of the energy storage element A and the hydraulic actuator1before the energy storage element A is accessed to the first oil supply path r1. In this embodiment, the pressure of the energy storage element is adjusted so that it remains consist with the pressure of the hydraulic actuator to ensure that after the travel stability system is turned on, the operation device may still remain at the set position before the system is turned on, thereby improving the stable operation and smooth travel of the operation vehicle.

The controller E may be an electronic controller that operates in a logical manner to perform operations, execute control algorithms, store and query data, and other required operations. The controller E may include or is capable of accessing a memory, an auxiliary storage device, a processor, and any other assembly for running an application program. The memory and the auxiliary storage device may be in the form of read only memory (ROM), random access memory (RAM), or an integrated path that may be accessed by the controller. Various other paths (such as power supply paths, signal conditioning paths, driver paths, and other types of paths) may be associated with the controller E.

Referring toFIGS.1and2, in some embodiments, the travel stability system further includes: a second hydraulic oil source C and an oil drainage element D. The second hydraulic oil source C is operatively connected with the energy storage element A, and can supply pressure oil to the energy storage element A through the second oil supply path r2, so as to raise the oil pressure of the energy storage element A. For example, when the pressure of the energy storage element A is lower than that of the hydraulic actuator1, the second hydraulic oil source C supplies the pressure oil to the energy storage element A so that the oil pressure of the energy storage element A is raised and tends to be in consistence with the pressure of the hydraulic actuator1.

InFIG.1, the second hydraulic oil source C includes: an oil pump7and a first control valve8. The oil pump7communicates with the energy storage element A through the second oil supply oil path r2. The first control valve8which is connected in series with the second oil supply oil path r2, and signally connected with the controller E, is configured to cause the second oil supply oil path r2to be in communication or be disconnected according to a control instruction of the controller E. In some embodiments, the first hydraulic oil source B and the second hydraulic oil source C use the same oil pump to provide hydraulic oil. In other embodiments, the first hydraulic oil source B and the second hydraulic oil source C use different oil pumps to provide hydraulic oil.

The oil drainage element D is operatively connected with the energy storage element A, and configured to unload the energy storage element A through the oil drainage path r3so as to reduce the oil pressure of the energy storage element A. For example, when the pressure of the energy storage element A is higher than that of the hydraulic actuator1, the energy storage element A can be unloaded by the oil drainage element D, so that the oil pressure of the energy storage element A is reduced, and tends to be in consistence with the pressure of the hydraulic actuator1.

InFIG.1, the oil drainage element D includes an oil tank6and a second control valve14. The oil tank6communicates with the energy storage element A through the oil drainage path r3. The second control valve14is connected in series with the oil drainage path r3and signally connected with the controller E, and configured to cause the oil drainage path r3to be in communication or be disconnected according to a control instruction of the controller E.

In order to effectively obtain the pressures of the energy storage element A and the hydraulic actuator1, referring toFIGS.1and2, in some embodiments, the travel stability system further includes a first pressure sensor2and a second pressure sensor16. The first pressure sensor2may be arranged on the energy storage element A or connected to the outlet of the energy storage element A. The first pressure sensor2is configured to detect the oil pressure of the energy storage element A. The second pressure sensor16may be arranged on the hydraulic actuator1or connected to the oil port of the hydraulic actuator1. The second pressure sensor16is configured to detect the oil pressure of the hydraulic actuator1.

Referring toFIG.1, in some embodiments, the travel stability system further includes a third control valve9. The third control valve9is located in the oil path between the first oil supply path r1and the energy storage element A, and signally connected with the controller E. The third control valve9can cause an oil path between the first oil supply path r1and the energy storage element A to be in communication or be disconnected according to a control instruction of the controller E. InFIG.1, the third control valve9may be located in the oil path r4that communicates the first oil supply path r1with the second oil supply path r2. Before the energy storage element A is accessed to the first oil supply path r1, the oil path between the energy storage element A and the first oil supply path r1is disconnected through the third control valve9. After the pressure of the energy storage element A is in consistence with that of the hydraulic actuator1through the second hydraulic oil source C or the oil drainage element D, the third control valve9is turned on, so that the energy storage element A is communicated with the first oil supply path r1, thereby providing protection against shock and vibration to the hydraulic actuator1through the energy storage element A.

The road roughness on which the operation vehicle travels may change with the travel process. For example, the operation environment of the backhoe loader is generally a non-pavement off-road surface. In order to reduce the effect of the variation in the road roughness of the road on the comfort of the driver and the smooth travel, referring toFIG.1, in some embodiments, the travel stability system further includes: an electro-hydraulic proportional throttle valve11and a one-way valve12. The electro-hydraulic proportional throttle valve11is signally connected with the controller E, and configured to change the throttle diameter of the electro-hydraulic proportional throttle valve11according to a control instruction of the controller E. The one-way valve12after connection with the electro-hydraulic proportional throttle valve11in parallel, is arranged in series with the second oil supply path r2, and configured to realize one-way communication in an oil filling direction of the energy storage element A.

In this embodiment, the electro-hydraulic proportional throttle valve11and the one-way valve12can constitute a one-way throttle valve configured to control the flow of the pressure oil between the energy storage element A and the first oil supply path r1, while the throttle diameter of the electro-hydraulic proportional throttle valve11is adjusted by controlling the current so that the damping of the system can be changed.

Regarding the adjustment of the throttle diameter of the electro-hydraulic proportional throttle valve11, referring toFIG.2, in some embodiments, the travel stability system further includes: a road roughness detecting element G, an operation end load detecting element F and a database H. The road roughness detecting element G may include an acceleration sensor or an inclination sensor arranged on the vehicle body, and is signally connected with the controller E. The road roughness detecting element G may be configured to detect a signal characterizing the road roughness of the currently traveled road. The road roughness refers to the degree of deviation of the road from the reference plane, which may be characterized by wavelength and amplitude.

The operation end load detecting element F may use a load sensor to weigh the weight of the material carried by the operation end as the current load of the hydraulic actuator. The operation end load detecting element F is signally connected with the controller E, and configured to detect the current load of the hydraulic actuator1. The database H is located within the controller E or signally connected with the controller E, and configured to store the road roughness level and/or the mapping data between the load of the hydraulic actuator and the throttle orifice diameter of the electro-hydraulic proportional throttle valve11.

The controller E can determine the road roughness level according to the signal characterizing the road roughness of the currently traveled road, and query the database H according to the road roughness level and/or the current load of the hydraulic actuator1, and then send a control instruction to the electro-hydraulic proportional throttle valve11according to the queried throttle diameter of the electro-hydraulic proportional throttle valve11, so that the electro-hydraulic proportional throttle valve11adjusts the throttle diameter.

The mapping data stored within the database may be calculated in advance according to a simulation model. Correspondingly, in some embodiments, the travel stability system further includes a model building unit I. The model building unit I is signally connected with the database H, and configured to take different loads of the hydraulic actuator and different levels of road surface spectrum information as an input, the throttle diameter of the electro-hydraulic proportional throttle valve11as an independent variable and travel smoothness as a target function to perform iterative optimization through neural network algorithms, so as to fit a set of curves of an optimal throttling diameter of the electro-hydraulic proportional throttle valve11respectively corresponding to different loads of the hydraulic actuator under different road roughness levels, and save fitting data to the database H.

When a model is built, it is possible to build simulation models corresponding to a plurality of road surface levels, to input the values of a plurality of throttle diameters are input for different hydraulic brake loads in the simulation model of each road level, and find out a set of curves of the optimal throttle diameter corresponding to the best travel smoothness under different loads. The curve may include a curve of the optimal throttle diameter during that the hydraulic brake is in idling.

In this way, when the energy storage element A is accessed to the first oil supply path r1, the controller may detect the current load of the hydraulic actuator1and the signal characterizing the road roughness of the currently traveled road, and determine the road roughness level according to the signal characterizing the road roughness of the currently traveled road. The controller may further query the database H according to the road roughness level and/or the current load of the hydraulic actuator1, and cause the electro-hydraulic proportional throttle valve11to adjust the throttle diameter according to the queried throttle diameter of the electro-hydraulic proportional throttle valve11.

The road roughness level here represents a certain range of road roughness. After the travel stability system is turned on, the road roughness detecting element G may monitor the road roughness in real time. When the road roughness is within a range corresponding to a certain road roughness level, there is no need to adjust the throttle diameter of the electro-hydraulic proportional throttle valve11. When it is detected that the road roughness level where the current road roughness is situated changes, the corresponding throttle diameter is adjusted according to the level of the current road roughness. The optimal throttle diameter stored within the database is used to reduce the adverse effects of vibration and impact on the operation vehicle during the traveling process, and improve the comfort of the driver and the travel smoothness.

For the operation vehicle, the loads of the operation end under idling and full-load conditions are greatly distinctive, so that there is a certain difference in the demand for vibration reduction. In order to cause the operation vehicle to have a favorable vibration reduction effect in these two conditions, referring toFIG.1, in some embodiments, the energy storage element A includes: a first energy storage18, a second energy storage19and a fourth control valve17. The first energy storage18has a first maximum operation oil pressure, the second energy storage19has a second maximum operation oil pressure, wherein the second maximum operation oil pressure is greater than the first maximum operation oil pressure. The first energy storage18is equivalent to a low-pressure energy storage and is mainly applied in an idling state, while the second energy storage19is equivalent to a high-pressure energy storage and is mainly applied in a loaded state.

The fourth control valve17is connected to the second hydraulic oil source C, the oil drainage element D, the first energy storage18and the second energy storage19respectively. The fourth control valve17can switch the oil paths from the second hydraulic oil source C to the first energy storage18or the second energy storage19, and switch the oil paths from the first energy storage18or the second energy storage19to the oil drainage element D. The fourth control valve17may implement switching the operations of pressurizing and unloading of any one of the first energy storage18and the second energy storage19and the buffering of the hydraulic actuator.

In some embodiments, the controller E is signally connected with the fourth control valve17. The controller E can determine whether the hydraulic actuator1is in an idling condition when the travel stability system is turned on. If it is in the idling condition, the controller E sends a control instruction to the fourth control valve17to switch it to cause the first energy storage18to be connected with the first oil supply path r1via the second oil supply path r2, and otherwise, sends a control instruction to the fourth control valve17to switch it to cause the second energy storage19to be connected with the first supply oil path r1via the second oil supply path r2.

In some embodiments, the initial oil pressure of the first energy storage18before the travel stability system is turned on is equal to the oil pressure of the hydraulic actuator1in an idling condition, so that it is possible to save the time consumed in balancing the pressures of the energy storage18and the hydraulic actuator1, raise the response speed of the system and improve the sensitivity in reaction. Moreover, the rigidity and damping of the first energy storage18are relatively small, so that it is possible to provide a better damping effect to the hydraulic actuator for an idling condition.

In some embodiments, the initial oil pressure of the second energy storage19before the travel stability system is turned on is equal to the oil pressure of the hydraulic actuator1in a full-load condition. Since the second energy storage19has a relatively large air inflation pressure and volume, it is possible to meet the vibration reduction requirements in a loaded or even full-load condition. For some operation vehicles, full-load operation is usually used. The initial oil pressure of the second energy storage19is equal to the oil pressure of the hydraulic actuator1in a full-load condition, so that it is possible to reduce the time consumed in balancing the pressures of the second energy storage19and the hydraulic actuator1, raise the response speed of the system and improve the sensitivity in reaction.

In the above-described embodiments, each control valve may be an electromagnetic switching valve, or a hydraulic control switching valve, an electro-hydraulic switching valve, and the like.

Referring toFIG.1, in some embodiments, the travel stability system further includes: a safety valve15located between the energy storage element A and the oil tank6. The safety valve15can unload the energy storage element A via the safety valve15when the oil pressure of the energy storage element A exceeds a preset maximum oil pressure. When the road surface is excessively excited, it is possible to exceed the maximum load-bearing capacity of the energy storage element. At this time, the oil may flow into the oil tank6through the safety valve15so as to achieve overload protection of the energy storage element and its pipeline. InFIG.1, the second oil supply line may also be connected in series with an electromagnetic on-off valve10. The electromagnetic on-off valve10may be configured to cause the energy storage element A to be connected or disconnected with the first oil supply path r1and the second oil supply path r2.

Take into account that in some operation conditions (for example, the shovel loading and unloading operations of the backhoe loader), the travel time is very short and the vehicle speed also varies relatively frequently, so that there is no need to use the travel stability system. Therefore, referring toFIG.2, in some embodiments, the travel stability system further includes: a speed sensor J. The speed sensor J is signally connected with the controller E, and configured to test the speed of the vehicle body K where the travel stability system is situated. The controller E can turn on the travel stability system when the speed of the vehicle body where the travel stability system is situated exceeds a preset speed (for example, 5 KM/h or the like) for a preset time period (for example, 10s). In the state that the travel stability system is turned on, the controller E can turn off the travel stability system so as to save the recourses of the system when the speed of the vehicle body does not meet the condition that the speed of the vehicle body exceeds the preset speed within a preset time period.

The above-described travel stability system may be applied to various operation vehicles, such as a backhoe loader, a loader, a skid steer loader and a fork loaders. As shown inFIG.3, it is a schematic structural diagram in some embodiments of the backhoe loader according to the present disclosure. InFIG.3, the backhoe loader includes a vehicle body K and any of the above-described embodiments of the travel stability system. In some embodiments, the hydraulic actuator1may include a boom cylinder of the backhoe loader. The boom cylinder is connected with a loading mechanism (for example, a bucket) and may be configured to lift the material.

Based on the above-described embodiments of the travel stability system, the present disclosure also provides a control method of the system. As shown inFIG.4, it is a schematic flowchart in some embodiments of the control method according to the present disclosure. Referring toFIG.4, in some embodiments, the control method includes:Step100: after the travel stability system is turned on, comparing the oil pressure of the hydraulic actuator1with the oil pressure of the energy storage element A;Step200: achieving a balance between the oil pressure of the energy storage element A and the oil pressure of the hydraulic actuator1;Step300: accessing the energy storage element A to the first oil supply path r1.

In this embodiment, the above-described steps may be implemented by the controller E in the travel stability system. In this embodiment, the pressure of the energy storage element is adjusted to cause it to remain in consistence with the pressure of the hydraulic actuator, so as to ensure that after the travel stability system is turned on, the operation device can still remain at the set position before the system is turned on without change or a significant change, thereby improving the handling stability and travel smooth of the operation vehicle.

In some embodiments, the step200may include: if the oil pressure of the energy storage element A is higher than that of the hydraulic actuator1, the energy storage element A is unloaded through the oil drainage path r3, so as to reduce the oil pressure of the energy storage element A to balance with the oil pressure of the hydraulic actuator1. If the oil pressure of the energy storage element A is lower than that of the hydraulic actuator1, the pressure oil is supplied to the energy storage element A through the second oil supply path r2, so as to raise the oil pressure of the energy storage element A to balance with the oil pressure of the hydraulic actuator1.

Referring toFIGS.1and2, in some embodiments, the travel stability system further includes: a second hydraulic oil source C, an electro-hydraulic proportional throttle valve11, a one-way valve12, and a database H. The second hydraulic oil source C is operatively connected with the energy storage element A, and configured to supply the pressure oil to the energy storage element A through the second oil supply path r2. The electro-hydraulic proportional throttle valve11and the one-way valve12which are connected in parallel, are arranged in series in the second oil supply path r2. The one-way valve12is configured to realize one-way communication in an oil filling direction of the energy storage element A, and the electro-hydraulic proportional throttle valve11and the database H are both signally connected with the controller E.

Referring toFIG.5, correspondingly, the control method further includes steps400to700for realizing automatic adjustment of the throttle diameter of the electro-hydraulic proportional throttle valve11. In step400, when the energy storage element A is accessed to the first oil supply path r1, the current load of the hydraulic actuator1and the signal characterizing the road roughness of the current road are detected. In step500, the road roughness level is determined according to the signal characterizing the road roughness of the current road. In step600, the database H is queried according to the road roughness level and/or the current load of the hydraulic actuator1. In step700, the throttle diameter of the electro-hydraulic proportional throttle valve11is adjusted according to the queried throttle diameter of the electro-hydraulic proportional throttle valve11.

In some embodiments, the control method may further include: taking different loads of the hydraulic actuator and different levels of road surface spectrum information as an input, the throttle diameter of the electro-hydraulic proportional throttle valve11as an independent variable and travel smoothness as a target function to perform iterative optimization through neural network algorithms, so as to fit a set of curves of an optimal throttling diameter of the electro-hydraulic proportional throttle valve (11) respectively corresponding to different loads of the hydraulic actuator under different road roughness levels, and save fitting data to the database H.

Referring toFIG.1, in some embodiments, the energy storage element A includes: a first energy storage18, a second energy storage19, and a fourth control valve17. The first maximum operation oil pressure of the first energy storage18is lower than the second maximum operation oil pressure of the second energy storage19. Correspondingly, the control method may further include: determining whether the hydraulic actuator1is in an idling condition when the travel stability system is turned on; switching the fourth control valve17to cause the first energy storage18to communicate with the first oil supply path r1if the hydraulic actuator1is in the idling condition; and switching the fourth control valve17to cause the second energy storage19to communicate with the first oil supply oil path r1if the hydraulic actuator1is in a loaded condition.

In some embodiments, the control method further includes: turning on the travel stability system when a time period during which the speed of the vehicle body K where the travel stability system is situated remains in exceeding a first preset value for a first time period in the state that the travel stability system is not turned on; and turning off the travel stability system when a time period during which the speed of the vehicle body K remains in not exceeding a second preset value for a second time period in the state that the travel stability system is turned on.

Next, the control process of an example of the travel stability system applied to the backhoe loader inFIG.6will be described in conjunction withFIGS.1to3.

In step S101, when the backhoe loader performs a load operation in a short-to-medium distance or an idling travel in a high speed, the controller may determine whether the speed of the vehicle body meets the condition that the speed of the vehicle body exceeds the limit value of 5 Km/h for a time period of more than 10 seconds according to the speed signal returned by the speed sensor located in the wheel assembly. If meeting the condition, step S102is performed, that is, the travel stability system is turned on by the controller. If not meeting the condition, step S120is performed, and the travel stability system is not turned on or is turned off.

The driver may operate the handle to energize the left or right position of the three-position four-way electromagnetic change valve3to fill the boom cylinder with oil through the oil pump7, thereby controlling the boom cylinder1to perform a telescopic action so as to complete the shovel loading operation. In addition, the travel stability system may be set to a manual on-off mode, such that the controller receives a control instruction of the driver through the control panel to realize the turn-on or turn-off of the travel stability system, thereby preventing failure of the automatic mode and improving the safety of the system.

After step S102, in step S103, whether it is in an idling condition is determined by a load sensor mounted at the bottom of the bucket. If it is in an idling condition, step S104is performed. In step S104, the fourth control valve17is selected to communicate with the first energy storage18. Since the initial pressure of the first energy storage18is set to be the same as the pressure of the rodless cavity of the boom cylinder during idling, the balance between the pressures of the first energy storage18and the pressure of the rodless cavity of the boom cylinder is achieved, without variation in the position of the operation device after the connection.

Subsequently, in step S105, the signal of the road roughness is collected in real time by the acceleration sensor mounted at the position of the axle, and is fed back to the controller so as to further determine the level of the current road roughness. According to the road roughness level, the database is queried for a value of the throttle diameter of the electro-hydraulic proportional throttle corresponding to the level of the current road roughness in an idling condition.

Next, in step S106, the controller adjusts the throttle diameter of the electro-hydraulic proportional throttle valve11according to the queried result. If the level of the road surface does not change in step S107, step S117is performed such that the electromagnetic on-off valve10is energized and turned on, and the third control valve9is switched from a turn-off state to a turn-on state to maintain the smoothness of the oil path r4, thereby forming a hydraulic passage from the first energy storage18to the rodless cavity of the boom cylinder via the fourth control valve17, the electro-hydraulic proportional throttle valve11, the electromagnetic on-off valve10and the third control valve9. If the level of the road surface changes, step S105is returned to determine the value of the throttle diameter of the alternative electro-hydraulic proportional throttle valve again.

When it is determined not in an idling condition in step S103, that is, in a loaded operation condition, step S108is performed. In step S108, the fourth control valve17is selected to communicate with the second energy storage19. Then, step S109is performed to determine whether the pressure Nenergy-storageof the second energy storage19is equal to the pressure Noperationof the boom cylinder at the operation end. If Nenergy-storageis not equal to Noperation, step S110is performed to determine whether the pressure Nenergy-storageof the second energy storage19is greater than the pressure Noperationof the boom cylinder at the operation end. If Nenergy-storage>Noperation, step S115is performed such that the oil fluid of the second energy storage19flows back to the oil tank6via the fourth control valve17, the second control valve14and the throttle valve13through the oil drainage path, so as to realize the unloading operation. If Nenergy-storage<Noperation, the second energy storage19is supplemented with oil through the second oil supply path so as to realize the pressurization operation. During the pressurization, the pressure oil pumped by the oil pump7flows into the second energy storage19via the first control valve8, the electromagnetic on-off valve10, the one-way valve12and the fourth control valve17.

After the steps S115and S116, both return to perform the step S108again. After one or more cycles, step S109is performed until the pressure Nenergy-storageof the second energy storage19is equal to the pressure Noperationof the boom cylinder at the operation end.

If the pressure Nenergy-storageof the second energy storage19is equal to the pressure Noperationof the boom cylinder at the operation end, step S111is performed. For example, if the initial oil pressure of the second energy storage19before the travel stability system is turned on is equal to the oil pressure of the hydraulic actuator1in a full-load condition, then step S111may be performed directly after the determination in the step S108in a full-load state.

In step S111, the current load of the hydraulic actuator is detected. Such operation may also be performed before the step of determining whether it is in the idling state. According to the current load and the road roughness level corresponding to the signal of the road roughness, the database is queried in step S112, and then the operation of adjusting the electro-hydraulic proportional throttle is performed according to the queried value of the throttle diameter of the electro-hydraulic proportional throttle in step S113.

If the level of the road surface in step S114does not change, step S117is performed so that the electromagnetic on-off valve10is energized and turned on, and the third control valve9is switched from an turn-off state to an turn-on state so as to maintain the smoothness of the oil path r4, thereby forming a hydraulic passage from the second energy storage19to the rodless cavity of the boom cylinder via the fourth control valve17, the electro-hydraulic proportional throttle valve11, the electromagnetic on-off valve10and the third control valve9. If the level of the road surface changes, step S112is returned to determine the value of the throttle diameter of the alternative electro-hydraulic proportional throttle valve again.

After step S117, if the speed of the vehicle body K does not meet the condition of remaining in exceeding 5 Km/h within 10s, step S119may be performed to disconnect the communication oil path between the energy storage element and the first oil supply path, and further turn off the travel stability system through step S120.

Hereto, various embodiments of the present disclosure have been described in detail. Some details well known in the art are not described in order to avoid obscuring the concept of the present disclosure. According to the above description, those skilled in the art would fully understand how to implement the technical solutions disclosed here.

Although some specific embodiments of the present disclosure have been described in detail by way of examples, those skilled in the art should understand that the above examples are only for the purpose of illustration but not for limiting the scope of the present disclosure. It should be understood by those skilled in the art that modifications to the above embodiments and equivalently substitution of part of the technical features may be made without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.