Damping method for a hydraulic system and a damped hydraulic system

Abstract

The application provides a damping method and a damping hydraulic system for a hydraulic system. The controller is used to control the hydraulic valve core to stay in the transition area for a preset time length to balance the pressure of the actuator. The damping method comprises the following steps: S1, after receiving the hydraulic actuator stop signal sent by the operating device, the controller sends a valve core moving signal to the hydraulic valve; S2, the hydraulic valve receives and responds to the valve core moving signal, moves the valve core from the first position to the cutoff area, and sends a valve core position feedback signal to the controller in real time; S3, the controller reads the valve core position feedback signal in real time, and when the valve core enters the transition area, the controller sends a valve core stop moving signal to the hydraulic valve, and the valve core stops at the second position and maintains for a preset time length; and S4, after the preset time length is maintained, the controller sends a valve core moving signal to the hydraulic valve again, and the valve core continues to move to the cutoff area.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of hydraulic control, in particular to a damping method of a hydraulic system and a damping hydraulic system. BACKGROUND

[0002] As the core power transmission unit of engineering machinery equipment, precision manufacturing equipment and heavy transport equipment, the hydraulic system controls the action of hydraulic cylinder, hydraulic motor and other actuators through hydraulic valve, realizes the movement, rotation or positioning of load, and has an irreplaceable position in industrial production and engineering operation. For example, the stopping control precision and stability of the hydraulic system of the aircraft de-icing vehicle are particularly harsh, and dramatic shaking or excessive response delay during stopping cannot be tolerated, because it is directly related to the safety of the aircraft skin.

[0003] In actual operation, the operator controls the conduction and cut-off of the hydraulic valve through the operating part (such as handle, button, etc.), and then drives the actuator to move the moving mechanism. When the operating part is pushed, the prior art usually sets a transition from slow motion to fast motion to avoid system vibration or personnel discomfort caused by sudden acceleration of the moving mechanism, and also meets the operator's mental expectation. However, when the operator releases the operating part to trigger the stop command, the prior art always faces the core contradiction that the response speed and the buffering effect cannot be considered: if a transition from slow motion to fast motion is set, the moving mechanism cannot stop as fast as the operator expects, which may cause a collision accident. Therefore, the motion buffer cannot be set when stopping, so when the operator releases the handle, the moving mechanism will stop suddenly, causing dramatic shaking, causing personnel discomfort or structural impact. This has become a key bottleneck restricting the safety, stability and operation precision of the hydraulic system. SUMMARY

[0004] In order to solve the above problems, the present application provides a damping method of a hydraulic system and a damping hydraulic system, which discharges the pressure of the working oil port by stopping the spool in the transition zone for a period of time. The present application accepts a small amount of time increase in exchange for significant damping effect.

[0005] The present application provides a damping method of a hydraulic system, comprising:

[0006] S1, after the controller receives the hydraulic actuator stop signal sent by the operating part, the controller sends a spool moving signal to the hydraulic valve;

[0007] S2, the hydraulic valve receives and responds to the spool moving signal, moves the spool from the first position to the cut-off zone, and sends a spool position feedback signal to the controller in real time, the first position is any point in the full open zone or the proportional zone;

[0008] S3, the controller reads the spool position feedback signal in real time, when detecting that the spool enters the transition zone, the controller sends a spool stop moving signal to the hydraulic valve, the spool stops at a second position and maintains for a preset time length, the second position is any point in the transition zone;

[0009] S4, after the maintenance of the preset time length, the controller sends a spool moving signal to the hydraulic valve again, the spool continues to move to the cutoff zone until the spool reaches the cutoff zone, and the hydraulic actuator stops moving;

[0010] Wherein, the path of the spool moving from the on position to the off position is in turn full open zone, proportional zone, transition zone and cutoff zone.

[0011] In one embodiment, the controller sends a spool moving signal or a spool stop moving signal to the driving unit of the hydraulic valve, and the driving unit of the hydraulic valve is used to drive the spool to move.

[0012] In one embodiment, the hydraulic actuator stop signal is an electrical signal generated when the operating member is released, and the controller generates a spool moving signal after receiving the hydraulic actuator stop signal, the spool moving signal contains target displacement and moving speed parameters.

[0013] In one embodiment, in S2, the spool position feedback signal is collected in real time by a linear encoder.

[0014] In one embodiment, the hydraulic actuator includes a hydraulic cylinder or a hydraulic motor, and the controller includes a PLC.

[0015] In one embodiment, in S3, the detection method of the spool entering the transition zone includes: calculating the displacement of the spool based on the real-time read spool position feedback signal, when detecting that the transition zone starting threshold < the displacement of the spool < the transition zone ending threshold, it is determined that the spool enters the transition zone, and the transition zone starting threshold and the transition zone ending threshold are preset based on the mechanical structure of the hydraulic valve.

[0016] In one embodiment, in S3, the preset time length is dynamically adjusted according to the load pressure or the movement speed of the hydraulic actuator, the greater the load pressure or the higher the speed, the longer the preset time length.

[0017] In one embodiment, in S3, during the time when the spool stops at the second position and maintains for a preset time length, the preset time length is 200-500 ms.

[0018] In one embodiment, in S4, after the maintenance of the preset time length, the controller detects the working oil port pressure through a pressure sensor, and sends a spool moving signal to the hydraulic valve again when the pressure drops to a preset pressure threshold.

[0019] The application further provides a damping hydraulic system for executing the damping method of the hydraulic system, comprising a controller, a hydraulic valve with a controllable spool position and position feedback, and a hydraulic actuator.

[0020] The controller receives a hydraulic actuator stop signal and outputs a spool control signal based on the spool position feedback signal to control the movement state of the spool;

[0021] The hydraulic valve receives the spool control signal output by the controller, sends a spool position feedback signal to the controller, and outputs a hydraulic valve control signal to control the movement state of the hydraulic actuator;

[0022] The hydraulic actuator receives the hydraulic valve control signal output by the hydraulic valve;

[0023] The control signal output by the controller comprises a spool movement signal and a spool stop movement signal, and the movement path of the spool comprises a full opening zone, a proportional zone, a transition zone and a cut-off zone in sequence, and the spool stays in the transition zone for a preset time when moving to the transition zone.

[0024] The damping method of the hydraulic system and the damping hydraulic system have the following beneficial effects:

[0025] The setting of the transition zone reduces the shaking amplitude of the movement mechanism when stopping, and the increase in the total stopping time is controlled within a range where there is no obvious delay perception, and the safety and precision improved by damping far exceed the influence of the slight increase in time. Meanwhile, the application is suitable for different loads and speeds and has strong versatility. The design of the transition zone for pressure relief fundamentally solves the contradiction between buffering and response speed in the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a graphical symbol schematic diagram of three working positions of a hydraulic valve.

[0027] Figure 2 It is a graphical symbol schematic diagram of the transition zone in the hydraulic valve of an embodiment of the application.

[0028] Figure 3 It is a schematic diagram of the relationship between the spool position and time of a hydraulic valve normally from the on position to the cut-off position.

[0029] Figure 4 It is a schematic diagram of the relationship between the spool position and time of a hydraulic valve from the on position to the transition zone and then to the cut-off position. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present application clearer, further detailed description will be made to the present application in combination with the accompanying drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and not used to limit the present application.

[0031] The present application provides a damping method for a hydraulic system, comprising:

[0032] S1, after the controller receives the hydraulic actuator stop signal sent by the operating device, the controller sends a spool moving signal to the hydraulic valve.

[0033] S2, the hydraulic valve receives and responds to the spool moving signal, and moves the spool from the first position to the cutoff area, and sends a spool position feedback signal to the controller in real time, the first position being any point in the full open area or the proportional area. In this embodiment, the spool position feedback signal is collected in real time by a linear encoder.

[0034] S3, the controller reads the spool position feedback signal in real time, and when it is detected that the spool enters the transition area, the controller sends a spool stop moving signal to the hydraulic valve, and the spool stops at the second position and maintains for a preset time length, the second position being any point in the transition area.

[0035] In one embodiment, the detection method of the spool entering the transition area comprises: calculating the displacement of the spool based on the spool position feedback signal read in real time, and determining that the spool enters the transition area when the transition area starting threshold < the displacement of the spool < the transition area ending threshold is detected. The transition area starting threshold and the transition area ending threshold are preset based on the mechanical structure of the hydraulic valve, such as the width of the spool shoulder and the distribution position of the oil port.

[0036] In a specific embodiment, the preset time length is dynamically adjusted according to the load pressure or the movement speed of the hydraulic actuator. For example, the load can be detected by a pressure sensor through the working oil port pressure, and the movement speed can be detected by an encoder through the displacement change rate of the actuator. The greater the load and the higher the speed, the longer the preset time length for stopping. In this embodiment, the preset time length is preferably 200-500 ms.

[0037] S4, after the maintenance of the preset time length ends, the controller sends a spool moving signal to the hydraulic valve again, and the spool continues to move to the cutoff area until the spool reaches the cutoff area, and the hydraulic actuator stops moving.

[0038] In a specific embodiment, after the maintenance of the preset time length ends, the controller detects the working oil port pressure through the pressure sensor, and sends a spool moving signal to the hydraulic valve again when the pressure drops to a preset pressure threshold.

[0039] Wherein, the path of the spool moving from the on position to the off position is in turn the full open zone, the proportional zone, the transition zone and the off zone. The moving speed of the spool is dynamically adjusted by the controller according to the first position.

[0040] When the spool is in the full open zone and the proportional zone, the working oil port is connected with the inlet port and the return port respectively, the hydraulic valve is on, and the hydraulic actuator is driven by the pressure oil. When the spool is in the off zone, the working oil port, the inlet port and the return port are not connected with each other, the hydraulic valve is off, and the hydraulic actuator stops moving. When the spool is in the transition zone, the inlet port is closed, and the working oil port is connected with the return port.

[0041] In a specific embodiment, the hydraulic valve of the present application comprises four oil ports, A port, B port, P port and T port. The A port and the B port are working oil ports, the P port is an inlet port, and the T port is a return port. Figure 1 The moving direction of the spool of a three-position four-way valve is disclosed. In the present application, a transition zone is set between the on position and the off position. Specifically, when the spool is in the first position, the P port is connected with the A port, and the B port is connected with the T port. When it is detected that the spool enters the transition zone, the spool stops at the second position and maintains for a preset time, at this time, the P port is closed, and the A port and the B port are both connected with the T port, see Figure 2 . The A, B and T ports of the transition zone hydraulic valve are on and pressure relief, and the range of the transition zone is very small. After the spool maintains for the preset time in the transition zone, the spool continues to move to the off position until the off position, at this time, the P port, the T port, the A port and the B port are all closed.

[0042] In a specific embodiment, the controller sends a spool moving signal or a spool stopping moving signal to the driving unit of the hydraulic valve, and the driving unit of the hydraulic valve is used to drive the spool to move.

[0043] The hydraulic actuator stopping signal is an electrical signal generated when the operating member is released. After receiving the hydraulic actuator stopping signal, the controller generates a spool moving signal, which contains a target displacement and a moving speed parameter. The target displacement refers to the position to which the spool needs to move, or the displacement amount by which the spool needs to move from the current position. The moving speed parameter is used to specify the moving speed of the spool.

[0044] In a specific embodiment, the hydraulic actuator comprises a hydraulic cylinder or a hydraulic motor. The controller is a control unit with logic operation and signal output functions, such as a PLC (Programmable Logic Controller).

[0045] In a hydraulic valve without a transition zone, the relationship between the flow rate and the time when the spool moves from the on position to the off position is as follows Figure 3As shown. It can be seen that in normal operation, the hydraulic pressure may not be fully released due to the spool passing through the transition zone too quickly, causing system shock. The preset duration of the transition zone in the present application can unload and balance the working oil port pressure before moving to the cutoff zone. As shown. Figure 4 As shown, where a is a range including the entire transition zone, L is in the range of 200-500 ms, and the value of K is the nature of the valve itself, i.e., the total time K from receiving the stop signal to the spool reaching the cutoff zone. In this way, the valve is kept in a certain opening degree for a certain time (preferably 200-500 ms) in the semi-conduction state, with an increased time within the range of no obvious delay perception, reducing the impact of the system and effectively solving the vibration problem of the motion mechanism.

[0046] The implementation process of the present application will be described in detail below in connection with a hydraulic cylinder and a hydraulic motor.

[0047] 1) Shock absorption control based on hydraulic cylinder:

[0048] This embodiment is applied to the lifting hydraulic system of the boom of an aircraft de-icing vehicle, the hydraulic actuator is a double-acting hydraulic cylinder, the controller is a PLC, and the hydraulic valve is an electro-hydraulic proportional directional valve. The oil port identification is as follows: the P port is connected to the hydraulic pump, the T port is connected to the oil tank, the A port is connected to the rodless cavity of the oil cylinder, and the B port is connected to the rod cavity of the oil cylinder.

[0049] S1, stop signal triggering:

[0050] The operator releases the handle controlling the boom to descend, and the built-in sensor in the handle generates a stop signal. After the PLC receives the signal, it calls the descending stop buffer program and generates a spool movement signal. The target displacement is from the full open zone to the cutoff zone, and the movement speed parameter is automatically matched.

[0051] S2, spool moving from full open zone to cutoff zone:

[0052] The drive unit of the hydraulic valve responds to the signal and drives the spool to move from the full open zone (current displacement 0 mm, A port connected to P port, B port connected to T port, oil cylinder rodless cavity filled with oil, boom descending) to the cutoff zone:

[0053] When moving to the proportional zone, the communication area of the A port and the P port decreases, and the descending speed of the boom slows down;

[0054] The linear encoder collects the spool position in real time and sends a feedback signal to the PLC.

[0055] S3, transition zone dwell pressure relief:

[0056] The PLC detects that the spool displacement reaches the starting threshold of the transition zone, and determines that it enters the transition zone:

[0057] At this time, the valve core shoulder seals P port, A port and B port are communicated with T port, the two cavities of the oil cylinder return oil through T port, the boom floats due to inertia, and the pressures of the two cavities gradually tend to be balanced.

[0058] The PLC sends a stop moving signal, and the valve core stays at the middle position of the transition zone for a preset time length 300 ms.

[0059] S4, the valve core continues to move to the cut-off zone:

[0060] After the stay ends, a continuation signal is sent, and the valve core moves to the cut-off zone. At this time, P port, T port, A port and B port are completely sealed, the oil cylinder is locked, the boom stops moving, and the swing amplitude of the end of the boom is reduced.

[0061] 2) Shock absorption control based on a hydraulic motor

[0062] The embodiment is applied to a walking system of a hydraulic carrying robot, a hydraulic actuator is a walking hydraulic motor, a controller is a microprocessor, and a hydraulic valve is a servo reversing valve.

[0063] S1-S2: after the robot stop signal is triggered, the valve core moves from the full open zone (the motor rotates in the forward direction, P port is communicated with A port, and B port is communicated with T port) to the cut-off zone, and the motor speed is reduced in the proportional zone stage.

[0064] S3: the valve core enters the transition zone and stays for 400 ms (which is adjusted according to the load), and the motor inlet and outlet pressures are balanced.

[0065] S4: the valve core reaches the cut-off zone, the motor is braked, and the impact acceleration of the robot when stopping is reduced.

[0066] The application also provides a shock absorption hydraulic system for performing the shock absorption method of the hydraulic system, which comprises a controller, a hydraulic valve with a controllable valve core position and a position feedback function, and a hydraulic actuator. The controller receives a hydraulic actuator stop signal and outputs a valve core control signal based on a valve core position feedback signal to control the motion state of the valve core. The hydraulic valve receives the valve core control signal output by the controller, sends a valve core position feedback signal to the controller, and outputs a hydraulic valve control signal to control the motion state of the hydraulic actuator. The hydraulic actuator receives the hydraulic valve control signal output by the hydraulic valve. The control signal output by the controller comprises a valve core moving signal and a valve core stop moving signal, the moving path of the valve core comprises a full open zone, a proportional zone, a transition zone and a cut-off zone in sequence, and the valve core stays in the transition zone for a preset time when the valve core moves to the transition zone.

[0067] The shock absorption method of the hydraulic system and the shock absorption hydraulic system have the following beneficial effects:

[0068] The setting of the transition zone makes the shaking range of the moving mechanism reduced when stopping, and the increase of the total stopping time is controlled within the range that no obvious delay is perceived, the safety and precision brought by the damping are improved, and the value is far more than the influence of the micro time increase. Meanwhile, the application is suitable for different loads and speeds, and has strong universality. The embodiment realizes pressure balance by using the pressure relief characteristics of the transition zone of the hydraulic valve, and fundamentally solves the contradiction between the buffering and the response speed in the prior art.

[0069] The above embodiments are only further descriptions of the application, and do not limit the application in other forms. The application can have other various embodiments. Those skilled in the art can make various corresponding modifications and changes according to the application without departing from the spirit and essence of the application, and the corresponding modifications and changes shall fall within the protection scope of the application.

Claims

1. A method of damping a hydraulic system, characterized by, The method comprises the following steps: S1, after the controller receives a hydraulic actuator stop signal sent by the operating tool, the controller sends a spool moving signal to the hydraulic valve; S2, the hydraulic valve receives and responds to the spool moving signal, and moves the spool from a first position to a cutoff area, and sends a spool position feedback signal to the controller in real time, wherein the first position is any point in the full open area or the proportional area; S3, the controller reads the spool position feedback signal in real time, and when it is detected that the spool enters the transition area, the controller sends a spool stop moving signal to the hydraulic valve, the spool stops at a second position and maintains for a preset time, and the second position is any point in the transition area; S4, after the preset time is maintained, the controller sends the spool moving signal to the hydraulic valve again, and the spool continues to move to the cutoff area until the spool reaches the cutoff area, and the hydraulic actuator stops moving; The path of the spool from the on position to the cutoff position is in sequence of the full open area, the proportional area, the transition area and the cutoff area.

2. The hydraulic system damping method of claim 1, wherein The controller sends the spool moving signal or the spool stop moving signal to the driving unit of the hydraulic valve, and the driving unit of the hydraulic valve is used to drive the spool to move.

3. The hydraulic system damping method of claim 1, wherein The hydraulic actuator stop signal is an electrical signal generated when the operating tool is released, the controller generates the spool moving signal after receiving the hydraulic actuator stop signal, and the spool moving signal contains target displacement and moving speed parameters.

4. The hydraulic system damping method of claim 1, wherein In S2, the spool position feedback signal is collected in real time by a linear encoder.

5. The hydraulic system damping method of claim 1, wherein The hydraulic actuator comprises a hydraulic cylinder or a hydraulic motor, and the controller comprises a PLC.

6. The hydraulic system damping method of claim 1, wherein In S3, the detection method of the spool entering the transition area comprises: calculating the displacement of the spool based on the spool position feedback signal read in real time, and when the transition area starting threshold value < the displacement of the spool < the transition area ending threshold value is detected, it is determined that the spool enters the transition area, and the transition area starting threshold value and the transition area ending threshold value are preset based on the mechanical structure of the hydraulic valve.

7. The hydraulic system damping method of claim 1, wherein In S3, the preset time is dynamically adjusted according to the load pressure or the moving speed of the hydraulic actuator, and the greater the load pressure or the higher the speed, the longer the preset time.

8. The hydraulic system damping method of claim 1, wherein In S3, the spool stops at the second position and maintains for a preset time, and the preset time is 200-500 ms.

9. The hydraulic system damping method of claim 1, wherein In S4, after the preset time is maintained, the controller detects the working oil port pressure through a pressure sensor, and sends the spool moving signal to the hydraulic valve again when the pressure drops to a preset pressure threshold value.

10. A shock absorbing hydraulic system characterized by, The damping method for executing the hydraulic system according to any one of claims 1-9 comprises a controller, a hydraulic valve with a controllable spool position and position feedback, and a hydraulic actuator; The controller receives a hydraulic actuator stop signal, and outputs a spool control signal based on the spool position feedback signal to control the movement state of the spool; The hydraulic valve receives the spool control signal output by the controller, sends a spool position feedback signal to the controller, and outputs a hydraulic valve control signal to control the movement state of the hydraulic actuator; The hydraulic actuator receives the hydraulic valve control signal output by the hydraulic valve; The control signal output by the controller comprises a valve core moving signal and a valve core stopping moving signal, and the moving path of the valve core comprises a full opening zone, a proportional zone, a transition zone and a cut-off zone in sequence, and the valve core stays in the transition zone for a preset time when moving to the transition zone.

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