Positive flow system and method for controlling compound stability of uppercarriage and undercarriage

Abstract

A positive flow system and a method for controlling compound stability of uppercarriage and undercarriage are provided. The positive flow system includes: a first main pump (1); a second main pump (2); a first valve body (1) and a second valve body (2). The first valve body (1) has a first main oil inlet path, which includes a linear travel valve (1.2) and a bypass overflow valve (1.1), a left travel valve (1.3), a first uppercarriage mechanism control valve (1.4), a second uppercarriage mechanism control valve (1.5) and a first neutral position unloading valve (1.6). The second valve body has a second main oil inlet path, which includes a right travel valve (2.1), a third uppercarriage mechanism control valve (2.2), a fourth uppercarriage mechanism control valve (2.3), a fifth uppercarriage mechanism control valve (2.4) and a second neutral position unloading valve (2.5). Figure 1

Description

A positive flow vehicle getting on and off composite stability control system and method

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is based on and claims priority to an application with CN application number 202010986416.0 and application date September 18, 2020. The disclosed content of the CN application is hereby introduced as a whole into this application. Technical Field

[0003] The present disclosure belongs to the field of networking technology, and in particular relates to a positive flow vehicle boarding and absorptive composite stability control system and system. Background Art

[0004] Mobile hydraulic machinery in industries such as engineering, construction, and mining often requires the coordinated movement of multiple actuators during operation. This has led to the development of different types of control systems for mobile hydraulic machinery. These systems have evolved into two main types: negative flow control systems, primarily developed in Japan, and load-sensing systems, primarily developed in Europe and the United States. However, with the advancement of electronic technology, electrical control components have become capable of the high-speed computation and control required for mobile hydraulics. Traditional negative flow systems have gradually been replaced by positive flow systems. Modern control technologies have significantly improved the controllability of these systems and reduced fuel consumption.

[0005] Traditional negative flow control primarily uses the negative feedback port of the main valve to feed back a signal to the pump's displacement control port. When the main valve is inactive, the negative feedback port reaches the relief valve's set pressure, at which point the corresponding main pump reaches minimum displacement. During the main valve's reversal process, the negative feedback port area gradually decreases, reducing the pressure fed back to the pump, and the main pump's displacement gradually increases. When the valve stem reaches its maximum position, the negative feedback channel closes, and the corresponding main pump's displacement reaches its maximum. Because feedback pressure is inversely proportional to pump displacement, this system is called a negative feedback control system. When multiple actuators are combined, coordination is maintained through priority valves or back pressure on the main valve port area.

[0006] In a negative flow system, when the disembarkation actuator is activated and the onboard actuator is not engaged, the negative feedback signals from the left and right travel motors are fed back to the first and second main pumps, respectively. When the onboard actuator engages, the corresponding onboard main valve disconnects the Px circuit, causing the linear travel valve's signal activation port to build up pressure and initiate reversal. During the reversal process, the main valve corresponding to the left travel motor disconnects the neutral negative feedback signal, ensuring that the first main pump maintains maximum displacement. The main valve corresponding to the onboard actuator completes reversal first, while the linear travel valve delays its reversal through damping to mitigate deceleration and shock. While this is effective, it does not completely address the deceleration and shock issues. After the onboard actuators complete their combined actions and the onboard actuator exits, the main valve corresponding to the onboard actuator begins closing. At this point, the Px circuit and the linear travel valve remain in the switching position. Only when the main valve corresponding to the onboard actuator approaches the closed position does the Px circuit connect to the tank, and the linear travel valve begins its reset action. During this process, the main valve opening of the upper vehicle actuator gradually closes, and the first main pump always maintains the maximum displacement, causing the upper vehicle actuator to be subjected to a large impact when it stops. The rapid rise in pressure of the first main pump causes the lower vehicle actuator to be subjected to a large impact when the linear travel valve is reset.

[0007] Load sensing is categorized as pre-valve-compensated load sensing and post-valve-compensated load sensing. When flow reaches saturation with pre-valve-compensated load sensing, the main pump's flow tends to flow to the lower load side, causing disharmony in the combined action of the actuators. Post-valve-compensated load sensing compensates for the inability of pre-valve-compensated load sensing to achieve proportional flow distribution when flow is saturated. Therefore, post-valve-compensated load sensing is often chosen for excavator systems. Load feedback is provided via the load feedback channel on the main valve to the pressure compensation valve and the pressure feedback port of the main pump. The pressure differential across the main valve and the valve core opening area adjust the pump displacement, thereby achieving the desired flow rate for the actuators. When multiple actuators are in combined action, the main pump and each compensation valve feedback the highest load pressure to maintain a constant pressure differential across each main valve. When the main pump's flow reaches saturation, the pressure differential across the main valve drops to the same value, ensuring a uniform proportional reduction in actuator flow and ensuring coordination.

[0008] For a load-sensing system, when the disembarkation actuator is activated and the onboard actuator is not engaged, the load feedback signals from the left and right travel motors are fed back to the first and second main pumps, respectively. When the onboard actuator engages, the linear travel valve switches. At this point, the load feedback signal from the left travel motor to the first main pump decreases or is lost, significantly reducing the displacement of the first main pump. As the main valve opening corresponding to the onboard actuator gradually increases, the onboard load feedback signal gradually feeds back to the first main pump, gradually increasing its displacement. The rapid decrease in displacement of the first main pump during the linear travel valve switching process causes the disembarkation actuator to decelerate rapidly, generating a corresponding inertial shock, which severely impacts handling comfort.

[0009] Summary of the Invention

[0010] In view of this, the embodiment of the present disclosure provides a positive flow boarding and disembarking compound stability control system, which can reduce the impact on the boarding actuator when it stops and alleviate the impact on the disembarking actuator when the linear travel valve is reset.

[0011] In one aspect of the present disclosure, a positive flow boarding and disembarking compound stability control system is provided, comprising: a first main pump; a second main pump; a first valve body, having a first main oil inlet circuit, and comprising a first connection, a second connection, a third connection, a fourth connection and a fifth connection, wherein the first main oil inlet circuit comprises a linear travel valve and a bypass overflow valve arranged in the first connection of the first valve body, a left travel valve arranged in the second connection of the first valve body, a first boarding mechanism control valve arranged in the third connection of the first valve body, a second boarding mechanism control valve arranged in the fourth connection of the first valve body and a first mid-position unloading valve arranged in the fifth connection of the first valve body; and a second valve body, having a second main oil inlet circuit, and comprising a first connection, a second connection, a third connection, a fourth connection and a fifth connection, wherein the second main oil inlet circuit comprises a right travel valve arranged in the first connection of the second valve body, a third boarding mechanism control valve arranged in the second connection of the second valve body, a fourth boarding mechanism control valve arranged in the third connection of the second valve body Mechanism control valve, the fifth boarding mechanism control valve arranged in the fourth connection of the second valve body and the second mid-position unloading valve arranged in the fifth connection of the second valve body; wherein, the first main pump is connected to the first main oil inlet circuit, and the first main oil inlet circuit is divided into three paths in the first valve body, the first path leads to the bypass relief valve, the second path leads to the oil inlet of the linear travel valve, and the third path leads to the left travel valve, the first boarding mechanism control valve, the second boarding mechanism control valve and the oil inlet of the mid-position unloading valve; the linear travel valve is respectively connected to the oil inlets of the third boarding mechanism control valve, the fourth boarding mechanism control valve, the fifth boarding mechanism control valve and the second mid-position unloading valve; the second main pump is connected to the second main oil inlet circuit, and the second main oil inlet circuit is divided into three paths in the second valve body, the first path leads to the bypass relief valve, the second path leads to the oil inlet of the linear travel valve, and the third path leads to the oil inlet of the right travel valve.

[0012] In some embodiments, the left travel valve and the right travel valve both include a three-position four-way reversing structure, and the middle position function of the three-position four-way reversing structure is Y-type.

[0013] In some embodiments, the first boarding mechanism control valve, the second boarding mechanism control valve, the third boarding mechanism control valve, the fourth boarding mechanism control valve and the fifth boarding mechanism control valve all include a three-position four-way reversing structure, and the middle position function of the three-position four-way reversing structure is type O.

[0014] In some embodiments, the left travel valve and the right travel valve both include a three-position six-way reversing structure.

[0015] In some embodiments, the linear travel valve is a two-position four-way solenoid reversing valve.

[0016] In some embodiments, when the linear travel valve is in an initial state without power, the first main oil inlet circuit supplies oil to the oil inlet of the left travel valve through the linear travel valve, the first main oil inlet circuit also supplies oil to the oil inlets of the first boarding mechanism control valve, the second boarding mechanism control valve and the first mid-position unloading valve, the second main oil inlet circuit supplies oil to the oil inlet of the right travel valve, and the second main oil inlet circuit also supplies oil to the oil inlet of the third boarding mechanism control valve, the fourth boarding mechanism control valve, the fifth boarding mechanism control valve and the second mid-position unloading valve through the linear travel valve; and

[0017] When the linear travel valve is in the reversing state after being energized, the first main oil inlet circuit supplies oil to the oil inlets of the third boarding mechanism control valve, the fourth boarding mechanism control valve, the fifth boarding mechanism control valve and the second mid-position unloading valve through the linear travel valve. The first main oil inlet circuit also supplies oil to the oil inlets of the first boarding mechanism control valve, the second boarding mechanism control valve and the first mid-position unloading valve. The second main oil inlet circuit supplies oil to the oil inlet of the left travel valve through the linear travel valve. The second main oil inlet circuit also supplies oil to the oil inlet of the right travel valve.

[0018] In some embodiments, a one-way conducting structure is provided in the linear motion valve, and is configured to make the bypass oil passage from the first main oil inlet passage to the second main oil inlet passage one-way conducting when the linear motion valve is in a reversing state.

[0019] In some embodiments, the return oil ports of the bypass relief valve, the linear travel valve, the left travel valve, the first boarding mechanism control valve, the second boarding mechanism control valve and the first mid-position unloading valve are all connected to the first main return oil circuit of the first valve body, and the first main return oil circuit is connected to the oil tank through the return oil port T; the return oil ports of the right travel valve, the third boarding mechanism control valve, the fourth boarding mechanism control valve, the fifth boarding mechanism control valve and the second mid-position unloading valve are all connected to the second main return oil circuit of the second valve body, and the second main return oil circuit is connected to the first main return oil circuit.

[0020] In one aspect of the present disclosure, a positive flow vehicle boarding and disembarking composite stability control method based on the aforementioned positive flow vehicle boarding and disembarking composite stability control system is provided, comprising:

[0021] When it is detected that the pilot pressures of the left and right travel valves reach the main valve opening pressure, the vehicle exit pressure switch Ps_d is activated to gradually increase the pilot pressures of the left and right travel valves to the maximum set pressure, increase the displacement of the first and second main pumps to the maximum displacement, and gradually switch the first and second center unloading valves to the closed position.

[0022] When it is detected that the pilot pressure of any boarding mechanism control valve reaches the main valve opening pressure, the boarding pressure switch Ps_u is activated to gradually increase the pilot pressure of the boarding mechanism control valve to the maximum set pressure;

[0023] When it is detected that both the getting-off pressure switch Ps_d and the getting-on pressure switch Ps_u are activated, the linear travel valve is activated by sending an Xptr signal to the linear travel valve;

[0024] When the Xptr control pressure of the linear motion valve increases to a value greater than the spring pressure in the valve, the linear motion valve starts to switch direction. When the Xptr control pressure increases to the set pressure, the linear motion valve completes the switching.

[0025] During the switching process of the linear travel valve, the first main pump and the second main pump are always kept at the maximum displacement, and the first main pump and the second main pump are communicated with each other, so that the displacement of the first main pump is gradually divided to the first boarding mechanism control valve, the second boarding mechanism control valve, the third boarding mechanism control valve, the fourth boarding mechanism control valve, and the fifth boarding mechanism control valve;

[0026] After the linear travel valve completes the reversal, the displacement of the second main pump is supplied to the left travel valve and the right travel valve, and the first main pump provides flow to the vehicle loading mechanism.

[0027] In some embodiments, the method further comprises:

[0028] When the pilot pressure of the control valve of the boarding mechanism gradually decreases, the output displacement of the first main pump is reduced accordingly;

[0029] When the pilot pressure drops to the main valve opening pressure, the displacement of the first main pump is reduced to 1 / 2 of the maximum displacement and the vehicle pressure switch Ps_u is closed;

[0030] When the vehicle pressure switch Ps_u is closed, the Xptr control pressure of the linear travel valve is gradually reduced to 0 to reset the linear travel valve, and the displacement of the first main pump is gradually increased from 1 / 2 of the maximum displacement to the maximum displacement;

[0031] When the linear travel valve is completely reset, the first main pump is caused to supply the left travel valve with a maximum displacement, and the second main pump is caused to supply the right travel valve with a maximum displacement.

[0032] In some embodiments, the method further comprises:

[0033] When it is detected that the pilot pressures of the left travel valve and the right travel valve gradually decrease, the displacements of the first main pump and the second main pump are gradually reduced;

[0034] When the pilot pressure of the left travel valve and the right travel valve is reduced to the main valve opening pressure, the vehicle getting off pressure switch Ps_d is closed, so that the first main pump and the second main pump are reduced to the minimum displacement, and the first center unloading valve and the second center unloading valve are reset to achieve unloading of the first main pump and the second main pump.

[0035] In some embodiments, the method also includes: after the linear travel valve completes the reversal, the first main pump provides flow to the first boarding mechanism control valve, the second boarding mechanism control valve, the third boarding mechanism control valve, the fourth boarding mechanism control valve and the fifth boarding mechanism control valve, while also providing flow to the left travel valve and the right travel valve through the linear travel valve.

[0036] Based on the disclosed embodiments, after the dismounting actuator is activated, the first master pump always maintains maximum displacement during the intervention of the onboard actuator, thereby effectively mitigating the deceleration and impact of the dismounting after the linear travel valve is switched. When the onboard actuator performs a combined action with the dismounting actuator, the switched linear travel valve allows the second master pump to supply displacement to the left and right travel valves, and the first master pump to supply displacement to the control valves of the various mechanisms of the onboard. In some embodiments, when the onboard actuator exits the state of combined action with the dismounting actuator, the displacement of the first master pump decreases in response to the decrease in the pilot pressure signal of the onboard actuator, thereby reducing the stopping impact of the onboard actuator and mitigating the impact on the dismounting actuator after the linear travel valve is reset. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG1 is a schematic diagram of the hydraulic principle of some embodiments of the positive flow on-and-off composite stability control system disclosed herein;

[0038] FIG2 is a schematic diagram of logic control signals for a boarding actuator and a disembarking actuator to perform a composite action in some embodiments of the positive flow boarding and disembarking composite stability control method disclosed herein;

[0039] FIG3 is a schematic diagram showing the relationship between various signals when a boarding actuator and an alighting actuator perform a compound action in some embodiments of the positive flow boarding and alighting compound stability control method disclosed herein. DETAILED DESCRIPTION

[0040] The following will be combined with the accompanying drawings in the embodiments of the present disclosure to clearly and completely describe the technical solutions in the embodiments of the present disclosure. Obviously, the embodiments described are only part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present disclosure.

[0041] With reference to Figures 1-3, in some embodiments, the present disclosure provides a positive flow combined boarding and disembarking stability control system, comprising: a first main pump P1, a second main pump P2, a first valve body 1, and a second valve body 2. The first valve body 1 has a first main oil inlet circuit, comprising a first, second, third, fourth, and fifth connections. The first main oil inlet circuit includes a linear travel valve 1.2 and a bypass relief valve 1.1 disposed in the first connection of the first valve body 1; a left travel valve 1.3 disposed in the second connection of the first valve body 1; a first boarding mechanism control valve 1.4 disposed in the third connection of the first valve body 1; a second boarding mechanism control valve 1.5 disposed in the fourth connection of the first valve body 1; and a first center unloading valve 1.6 disposed in the fifth connection of the first valve body 1. The linear travel valve 1.2 enables the disembarking vehicle to maintain a linear travel function when the boarding and disembarking actuators are in combined motion. The first center unloading valve 1.6 is capable of unloading pressure from the first main oil inlet circuit during idle operation.

[0042] Second valve body 2 has a second main oil inlet circuit, comprising a first, second, third, fourth, and fifth connections. This second main oil inlet circuit includes a right travel valve 2.1 provided in the first connection of second valve body 2, a third boarding mechanism control valve 2.2 provided in the second connection of second valve body 2, a fourth boarding mechanism control valve 2.3 provided in the third connection of second valve body 2, a fifth boarding mechanism control valve 2.4 provided in the fourth connection of second valve body 2, and a second center unloading valve 2.5 provided in the fifth connection of second valve body 2. Second center unloading valve 2.5 is capable of unloading pressure from the second main oil inlet circuit during idle operation.

[0043] The first main pump P1 is connected to the first main oil inlet circuit, which branches into three paths within the first valve body 1. The first path leads to the bypass relief valve 1.1, which controls and protects the system pressure. The second path leads to the oil inlet of the linear travel valve 1.2. The third path leads to the oil inlets of the left travel valve 1.3, the first and second boarding mechanism control valves 1.4 and 1.5, and the first center unloading valve 1.6. The linear travel valve 1.2 is connected to the oil inlets of the third, fourth, and fifth boarding mechanism control valves 2.2, 2.3, and 2.4, respectively, and the second center unloading valve 2.5.

[0044] The second main pump P2 is connected to the second main oil inlet circuit, which is divided into three paths inside the second valve body 2. The first path leads to the bypass relief valve 1.1, which plays a role in system pressure control and protection. The second path leads to the oil inlet of the linear travel valve 1.2. The third path leads to the oil inlet of the right travel valve 2.1.

[0045] In this embodiment, the first boarding mechanism control valve 1.4, the second boarding mechanism control valve 1.5, the third boarding mechanism control valve 2.2, the fourth boarding mechanism control valve 2.3, and the fifth boarding mechanism control valve 2.4 constitute the boarding mechanism operating system. The linear travel valve 1.2, the left travel valve 1.3, and the right travel valve 2.1 constitute the disembarkation travel system. When the positive flow boarding and disembarkation composite stability control system is applied to construction machinery (e.g., an excavator), the first boarding mechanism control valve 1.4, the second boarding mechanism control valve 1.5, the third boarding mechanism control valve 2.2, the fourth boarding mechanism control valve 2.3, and the fifth boarding mechanism control valve 2.4 can respectively correspond to multiple boarding actuators of the construction machinery, such as the excavator's bucket, boom, dipper arm, and slewing mechanism.

[0046] Referring to Figure 1 , in some embodiments, the left travel valve 1.3 and the right travel valve 2.1 both comprise a three-position, four-way reversing structure, with the neutral position functioning in a Y-shape. In other words, when the left travel valve 1.3 and the right travel valve 2.1 are in the neutral position, both operating oil ports of the left travel motor are connected to the oil return port, and both operating oil ports of the right travel motor are connected to the oil return port.

[0047] Referring to Figure 1, in some embodiments, the first boarding mechanism control valve 1.4, the second boarding mechanism control valve 1.5, the third boarding mechanism control valve 2.2, the fourth boarding mechanism control valve 2.3 and the fifth boarding mechanism control valve 2.4 all include a three-position four-way reversing structure, and the middle position function of the three-position four-way reversing structure is O type.

[0048] 1 , in some embodiments, the left travel valve 1.3 and the right travel valve 2.1 both include a three-position six-way reversing structure.

[0049] 1 , in some embodiments, the linear motion valve 1 . 2 is a two-position four-way solenoid directional valve.

[0050] When the linear travel valve 1.2 is in an initial state without power, the first main oil inlet circuit supplies oil to the oil inlet of the left travel valve 1.3 through the linear travel valve 1.2. The first main oil inlet circuit also supplies oil to the oil inlets of the first boarding mechanism control valve 1.4, the second boarding mechanism control valve 1.5, and the first mid-position unloading valve 1.6. The second main oil inlet circuit supplies oil to the oil inlet of the right travel valve 2.1. The second main oil inlet circuit also supplies oil to the oil inlets of the third boarding mechanism control valve 2.2, the fourth boarding mechanism control valve 2.3, the fifth boarding mechanism control valve 2.4, and the second mid-position unloading valve 2.5 through the linear travel valve 1.2.

[0051] When the linear travel valve 1.2 is in the reversing state after being energized, the first main oil inlet circuit supplies oil to the oil inlets of the third boarding mechanism control valve 2.2, the fourth boarding mechanism control valve 2.3, the fifth boarding mechanism control valve 2.4 and the second mid-position unloading valve 2.5 through the linear travel valve 1.2. The first main oil inlet circuit also supplies oil to the oil inlets of the first boarding mechanism control valve 1.4, the second boarding mechanism control valve 1.5 and the first mid-position unloading valve 1.6. The second main oil inlet circuit supplies oil to the oil inlet of the left travel valve 1.3 through the linear travel valve 1.2. The second main oil inlet circuit also supplies oil to the oil inlet of the right travel valve 2.1.

[0052] Referring to Figure 1 , in some embodiments, a one-way flow structure 1.21 is provided within the linear motion valve 1.2. This structure is configured to provide one-way flow from the bypass oil passage from the first main oil inlet to the second main oil inlet when the linear motion valve 1.2 is in the switching state. This allows a portion of the flow from the first main oil inlet to flow to the next vehicle via the one-way flow structure.

[0053] With reference to Figure 1 , in some embodiments, the oil return ports of the bypass relief valve 1.1, the linear travel valve 1.2, the left travel valve 1.3, the first boarding mechanism control valve 1.4, the second boarding mechanism control valve 1.5, and the center unloading valve 1.6 are all connected to the first main oil return circuit, which is connected to the fuel tank via the oil return port T. The oil return ports of the right travel valve 2.1, the third boarding mechanism control valve 2.2, the fourth boarding mechanism control valve 2.3, the fifth boarding mechanism control valve 2.4, and the second center unloading valve 2.5 are all connected to the second main oil return circuit of the second valve body 2, which is connected to the first main oil return circuit.

[0054] With reference to FIG1 and the aforementioned embodiments of the positive flow vehicle boarding and exiting composite stability control system, the present disclosure further provides a positive flow vehicle boarding and exiting composite stability control method based on the aforementioned positive flow vehicle boarding and exiting composite stability control system, including:

[0055] 1) Sensors collect pilot pressure information corresponding to the left and right travel motors and convert this pilot pressure information into pilot pressures corresponding to the left and right travel valves 1.3 and 2.1. When the pilot pressures of the left and right travel valves 1.3 and 2.1 reach the main valve opening pressures, the vehicle exit pressure switch Ps_d is activated, gradually increasing the pilot pressures of the left and right travel valves 1.3 and 2.1 to their maximum set pressures. This increases the displacement of the first and second main pumps P1 and P2 to their maximum capacity, and gradually switches the first and second center unloading valves 1.6 and 2.5 to their closed positions.

[0056] 2) Detect the pilot pressure information of each boarding mechanism through a sensor and convert the pilot pressure information into the corresponding pilot pressure of the boarding mechanism control valve of each boarding mechanism. When it is detected that the pilot pressure of any boarding mechanism control valve (the first boarding mechanism control valve 1.4, the second boarding mechanism control valve 1.5, the third boarding mechanism control valve 2.2, the fourth boarding mechanism control valve 2.3, and the fifth boarding mechanism control valve 2.4) reaches the main valve opening pressure, activate the boarding pressure switch Ps_u, and gradually increase the pilot pressure of the boarding mechanism control valve to the maximum set pressure;

[0057] 3) When both the exit pressure switch Ps_d and the entry pressure switch Ps_u are detected to be activated, an Xptr signal is sent to the linear motion valve 1.2 to activate the linear motion valve 1.2. When the Xptr control pressure of the linear motion valve 1.2 increases to a value greater than the spring pressure within the valve, the linear motion valve 1.2 begins to switch direction. When the Xptr control pressure increases to the set pressure, the linear motion valve 1.2 completes the switching.

[0058] 4) During the switching process of the linear travel valve 1.2, the first main pump P1 and the second main pump P2 are always maintained at their maximum displacement, and the first main pump P1 and the second main pump P2 are communicated with each other, so that the displacement of the first main pump P1 is gradually distributed to the first boarding mechanism control valve 1.4, the second boarding mechanism control valve 1.5, the third boarding mechanism control valve 2.2, the fourth boarding mechanism control valve 2.3, and the fifth boarding mechanism control valve 2.4;

[0059] 5) After the linear travel valve 1.2 completes the reversal, the displacement of the second main pump P2 is supplied to the left travel valve 1.3 and the right travel valve 2.1, and the first main pump P1 provides flow to the vehicle raising mechanism.

[0060] In some embodiments, the positive flow vehicle boarding and disembarking combined stability control method further includes:

[0061] 6) When the pilot pressure of the boarding mechanism control valve gradually decreases, the displacement of the first main pump P1 is reduced accordingly; when the pilot pressure drops to the main valve opening pressure, the displacement of the first main pump P1 is reduced to 1 / 2 of the maximum displacement and the boarding pressure switch Ps_u is closed;

[0062] 7) When the vehicle pressure switch Ps_u is closed, the Xptr control pressure of the linear travel valve 1.2 is gradually reduced to 0, thereby resetting the linear travel valve 1.2, and the displacement of the first main pump P1 is gradually increased from 1 / 2 of the maximum displacement to the maximum displacement;

[0063] 8) When the linear travel valve 1.2 is reset, the first main pump P1 is operated at maximum displacement to supply the left travel valve 1.3, and the second main pump P2 is operated at maximum displacement to supply the right travel valve 2.1.

[0064] In some embodiments, the positive flow vehicle boarding and disembarking combined stability control method further includes:

[0065] 9) When it is detected that the pilot pressure of the left travel valve 1.3 and the right travel valve 2.1 gradually decreases, the displacement of the first main pump P1 and the second main pump P2 is gradually reduced; when the pilot pressure of the left travel valve 1.3 and the right travel valve 2.1 drops to the main valve opening pressure, the vehicle disembarkation pressure switch Ps_d is closed, the first main pump P1 and the second main pump P2 are reduced to the minimum displacement, and the first center unloading valve 1.6 and the second center unloading valve 2.5 are reset to achieve unloading of the first main pump P1 and the second main pump P2.

[0066] In some embodiments, after the linear travel valve 1.2 completes the reversal, the first main pump P1 provides flow to the first boarding mechanism control valve 1.4, the second boarding mechanism control valve 1.5, the third boarding mechanism control valve 2.2, the fourth boarding mechanism control valve 2.3 and the fifth boarding mechanism control valve 2.4, while also providing flow to the left travel valve 1.3 and the right travel valve 2.1 through the linear travel valve 1.2.

[0067] Figure 2 illustrates the logic control signals for the combined actions of the boarding and disembarking actuators in certain embodiments of the presently disclosed positive flow combined stability control method. In Figure 2 , the inputs are the detection signals from various sensors: the disembarkation pressure switch Ps_d provides the pressure monitoring control signal for disembarkation; the boarding pressure switch Ps_u provides the pressure monitoring control signal for boarding; Xptr is the control pressure signal for the linear travel valve; and Q_p1 is the displacement control signal for the first main pump P1.

[0068] Figure 3 is a schematic diagram showing the relationship between the various signals of the boarding and disembarking actuators when performing a compound action in some embodiments of the positive flow boarding and disembarking compound stability control method disclosed herein. Xp_d is the pilot pressure signal of the disembarking actuator, and Xp_u is the pilot pressure signal of the boarding actuator.

[0069] In order to solve the problem of excessive deceleration and certain impact when getting off the vehicle during the intervention of the on-board actuator, the embodiment of the present disclosure enables the first main pump to always maintain the maximum displacement during the intervention of the on-board actuator, extends the switching time of the main valve corresponding to the on-board actuator, and effectively reduces the deceleration and impact problems of getting off the vehicle after the linear travel valve is switched.

[0070] The above is only a preferred embodiment of the present disclosure. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present disclosure. These improvements and modifications should also be regarded as within the scope of protection of the present disclosure.

Claims

1. A positive flow vehicle entry and exit compound stability control system, comprising: First main pump (P1); Second main pump (P2); A first valve body (1) has a first main oil inlet circuit and includes a first connection, a second connection, a third connection, a fourth connection, and a fifth connection, wherein the first main oil inlet circuit includes a linear travel valve (1.2) and a bypass relief valve (1.1) provided in the first connection of the first valve body (1), a left travel valve (1.3) provided in the second connection of the first valve body (1), a first boarding mechanism control valve (1.4) provided in the third connection of the first valve body (1), a second boarding mechanism control valve (1.5) provided in the fourth connection of the first valve body (1), and a first mid-position unloading valve (1.6) provided in the fifth connection of the first valve body (1); and The second valve body (2) has a second main oil inlet circuit and includes a first connection, a second connection, a third connection, a fourth connection and a fifth connection, wherein the second main oil inlet circuit includes a right travel valve (2.1) arranged in the first connection of the second valve body (2), a third boarding mechanism control valve (2.2) arranged in the second connection of the second valve body (2), a fourth boarding mechanism control valve (2.3) arranged in the third connection of the second valve body (2), a fifth boarding mechanism control valve (2.4) arranged in the fourth connection of the second valve body (2) and a second mid-position unloading valve (2.5) arranged in the fifth connection of the second valve body (2); The first main pump (P1) is connected to the first main oil inlet circuit, and the first main oil inlet circuit is divided into three circuits in the first valve body (1), the first circuit leading to the bypass relief valve (1.1), the second circuit leading to the oil inlet of the linear travel valve (1.2), and the third circuit leading to the oil inlets of the left travel valve (1.3), the first boarding mechanism control valve (1.4), the second boarding mechanism control valve (1.5), and the mid-position unloading valve (1.6); the linear travel valve (1.2) is respectively connected to the oil inlets of the third boarding mechanism control valve (2.2), the fourth boarding mechanism control valve (2.3), the fifth boarding mechanism control valve (2.4), and the second mid-position unloading valve (2.5); The second main pump (P2) is connected to the second main oil inlet circuit, and the second main oil inlet circuit is divided into three circuits in the second valve body (2), the first circuit leading to the bypass relief valve (1.1), the second circuit leading to the oil inlet of the linear travel valve (1.2), and the third circuit leading to the oil inlet of the right travel valve (2.1).

2. The positive flow vehicle entry and exit compound stability control system according to claim 1, wherein: The left travel valve (1.3) and the right travel valve (2.1) both comprise a three-position four-way reversing structure, and the middle position function of the three-position four-way reversing structure is Y-type.

3. The positive flow vehicle entry and exit compound stability control system according to claim 1, wherein: The first boarding mechanism control valve (1.4), the second boarding mechanism control valve (1.5), the third boarding mechanism control valve (2.2), the fourth boarding mechanism control valve (2.3) and the fifth boarding mechanism control valve (2.4) all comprise a three-position four-way reversing structure, wherein the middle position function of the three-position four-way reversing structure is type O.

4. The positive flow vehicle entry and exit compound stability control system according to claim 1, wherein: The left travel valve (1.3) and the right travel valve (2.1) both include a three-position six-way reversing structure.

5. The positive flow vehicle entry and exit compound stability control system according to claim 1, wherein: The linear travel valve (1.2) is a two-position four-way electromagnetic reversing valve.

6. The positive flow vehicle entry and exit compound stability control system according to claim 5, wherein: When the linear travel valve (1.2) is in an initial state without power, the first main oil inlet path supplies oil to the oil inlet of the left travel valve (1.3) through the linear travel valve (1.2), and the first main oil inlet path also supplies oil to the oil inlets of the first boarding mechanism control valve (1.4), the second boarding mechanism control valve (1.5), and the first mid-position unloading valve (1.6), the second main oil inlet path supplies oil to the oil inlet of the right travel valve (2.1), and the second main oil inlet path also supplies oil to the oil inlet of the third boarding mechanism control valve (2.2), the fourth boarding mechanism control valve (2.3), the fifth boarding mechanism control valve (2.4), and the second mid-position unloading valve (2.5) through the linear travel valve (1.2); and When the linear travel valve (1.2) is in a reversing state after being energized, the first main oil inlet path supplies oil to the oil inlets of the third boarding mechanism control valve (2.2), the fourth boarding mechanism control valve (2.3), the fifth boarding mechanism control valve (2.4) and the second mid-position unloading valve (2.5) through the linear travel valve (1.2). The first main oil inlet path also supplies oil to the oil inlets of the first boarding mechanism control valve (1.4), the second boarding mechanism control valve (1.5) and the first mid-position unloading valve (1.6). The second main oil inlet path supplies oil to the oil inlet of the left travel valve (1.3) through the linear travel valve (1.2). The second main oil inlet path also supplies oil to the oil inlet of the right travel valve (2.1).

7. The positive flow vehicle entry and exit compound stability control system according to claim 6, wherein: A one-way conducting structure (1.21) is provided in the linear travel valve (1.2), and is configured to allow the bypass oil passage from the first main oil inlet passage to the second main oil inlet passage to be one-way conducting when the linear travel valve (1.2) is in a switching state.

8. The positive flow vehicle entry and exit compound stability control system according to claim 1, wherein: The oil return ports of the bypass relief valve (1.1), the linear travel valve (1.2), the left travel valve (1.3), the first boarding mechanism control valve (1.4), the second boarding mechanism control valve (1.5), and the first mid-position unloading valve (1.6) are all connected to the first main oil return circuit of the first valve body (1), and the first main oil return circuit is connected to the oil tank via the oil return port T; The oil return ports of the right travel valve (2.1), the third boarding mechanism control valve (2.2), the fourth boarding mechanism control valve (2.3), the fifth boarding mechanism control valve (2.4) and the second mid-position unloading valve (2.5) are all connected to the second main oil return circuit of the second valve body (2), and the second main oil return circuit is in communication with the first main oil return circuit.

9. A positive flow vehicle boarding and disembarking composite stability control method based on the positive flow vehicle boarding and disembarking composite stability control system according to any one of claims 1 to 8, comprising: When it is detected that the pilot pressure of the left travel valve (1.3) and the right travel valve (2.1) reaches the main valve opening pressure, the vehicle disembarkation pressure switch Ps_d is activated, so that the pilot pressure of the left travel valve (1.3) and the right travel valve (2.1) gradually increases to the maximum set pressure, the displacement of the first main pump (P1) and the second main pump (P2) increases to the maximum displacement, and the first center unloading valve (1.6) and the second center unloading valve (2.5) are gradually switched to the closed position; When it is detected that the pilot pressure of any boarding mechanism control valve reaches the main valve opening pressure, the boarding pressure switch Ps_u is activated to gradually increase the pilot pressure of the boarding mechanism control valve to the maximum set pressure; When it is detected that both the getting-off pressure switch Ps_d and the getting-on pressure switch Ps_u have been activated, an Xptr signal is sent to the linear travel valve (1.2) to activate the linear travel valve (1.2); When the Xptr control pressure of the linear motion valve (1.2) increases to be greater than the spring pressure in the valve, the linear motion valve (1.2) starts to switch direction, and when the Xptr control pressure increases to the set pressure, the linear motion valve (1.2) completes the switching; During the switching process of the linear travel valve (1.2), the first main pump (P1) and the second main pump (P2) are always kept at maximum displacement, and the first main pump (P1) and the second main pump (P2) are communicated with each other, so that the displacement of the first main pump (P1) is gradually divided to the first boarding mechanism control valve (1.4), the second boarding mechanism control valve (1.5), the third boarding mechanism control valve (2.2), the fourth boarding mechanism control valve (2.3), and the fifth boarding mechanism control valve (2.4); After the linear travel valve (1.2) completes the reversal, the displacement of the second main pump (P2) is supplied to the left travel valve (1.3) and the right travel valve (2.1), and the first main pump (P1) provides flow to the vehicle loading mechanism.

10. The method according to claim 9, further comprising: When the pilot pressure of the vehicle boarding mechanism control valve gradually decreases, the displacement of the first main pump (P1) is correspondingly reduced; When the pilot pressure drops to the main valve opening pressure, the displacement of the first main pump (P1) is reduced to 1 / 2 of the maximum displacement and the vehicle pressure switch Ps_u is closed; When the vehicle pressure switch Ps_u is closed, the Xptr control pressure of the linear travel valve (1.2) is gradually reduced to 0, so that the linear travel valve (1.2) is reset, and the displacement of the first main pump (P1) is gradually increased from 1 / 2 of the maximum displacement to the maximum displacement; When the linear travel valve (1.2) is reset, the first main pump (P1) supplies power to the left travel valve (1.3) at a maximum displacement, and the second main pump (P2) supplies power to the right travel valve (2.1) at a maximum displacement.

11. The method according to claim 10, further comprising: When it is detected that the pilot pressures of the left travel valve (1.3) and the right travel valve (2.1) gradually decrease, the displacements of the first main pump (P1) and the second main pump (P2) are gradually reduced; When the pilot pressures of the left travel valve (1.3) and the right travel valve (2.1) are reduced to the main valve opening pressure, the vehicle disembarkation pressure switch Ps_d is closed, so that the first main pump (P1) and the second main pump (P2) are both reduced to the minimum displacement, and the first mid-position unloading valve (1.6) and the second mid-position unloading valve (2.5) are both reset, thereby achieving unloading of the first main pump (P1) and the second main pump (P2).

12. The method according to claim 9, further comprising: After the linear travel valve (1.2) completes the reversal, the first main pump (P1) provides flow to the first boarding mechanism control valve (1.4), the second boarding mechanism control valve (1.5), the third boarding mechanism control valve (2.2), the fourth boarding mechanism control valve (2.3) and the fifth boarding mechanism control valve (2.4), while also providing flow to the left travel valve (1.3) and the right travel valve (2.1) through the linear travel valve (1.2).