WO2023005475A1

WO2023005475A1 - Falling control method and system, and crane

Info

Publication number: WO2023005475A1
Application number: PCT/CN2022/098888
Authority: WO
Inventors: 陈宇; 谭磊
Original assignee: 三一汽车起重机械有限公司
Priority date: 2021-07-30
Filing date: 2022-06-15
Publication date: 2023-02-02
Also published as: CN113479800A; CN113479800B

Abstract

A falling control method and system, and a crane. The falling control system is connected to a variable amplitude cylinder (610) of the crane, and a rod cavity of the variable amplitude cylinder (610) is connected to an electrical proportional overflow valve (640). The falling control method comprises: obtaining a rodless cavity pressure value within a rodless cavity of the variable amplitude cylinder (610) when a crane performs a falling operation; calculating a difference between the rodless cavity pressure value and a preset standard pressure value of the rodless cavity; and when the difference does not fall within a preset range, controlling the electrical proportional overflow valve (640) to adjust the pressure of the rod cavity. On the basis of this arrangement, it is possible to ensure the uniformity and stability of a falling speed of the crane.

Description

Fall amplitude control method, system and crane

technical field

The present application relates to the technical field of engineering machinery, in particular to a fall control method, system and crane.

Background of the invention

The fall performance of a crane is one of the important indicators to measure its maneuverability. The amplitude control principle of the existing small and medium-sized tonnage cranes is divided into two types: a rod chamber plus a constant pressure fall and a fall by the boom’s own weight. Non-electric proportional relief valve, the relief pressure is the initial setting value, during the falling process, the falling speed is adjusted by adjusting the opening of the luffing joint valve stem of the main valve; the rod chamber of the luffing cylinder does not Pressurization, relying entirely on the gravity of the boom to generate a vertical downward component force to achieve the fall, during the fall process, adjust the fall speed by adjusting the spool opening of the luffing balance valve.

However, both of the above-mentioned two falling forms have the problem that as the elevation angle of the boom changes, the downward component of the boom gravity gradually increases, resulting in a gradual increase in the falling speed. In order to ensure uniform falling speed, it is necessary to adjust the opening of the luffing balance valve in real time as the falling angle decreases. Since the opening of the luffing balance valve is determined by the opening of the operating handle, manual real-time adjustment is required. However, in actual operation, it is very difficult to realize the uniform falling speed by manually operating the operating handle, and the uniform and stable falling speed cannot be guaranteed.

Contents of the invention

In order to solve the above-mentioned technical problems, the present application is proposed. The embodiments of the present application provide a fall control method, system and crane, which can ensure uniform and stable fall speed of the crane.

According to one aspect of the present application, a fall control method is provided, which is applied to the fall control system. The fall control system is connected to the luffing cylinder of the crane, and the rod chamber of the luffing cylinder is connected to the electric proportional overflow valve; the amplitude control method includes: obtaining the pressure value of the rodless cavity in the rodless cavity of the luffing cylinder during the crane performing the amplitude drop operation; calculating the pressure value of the rodless cavity and the preset value the difference between the standard pressure values of the rodless cavity; and when the difference is not within the preset range, control the electric proportional overflow valve to adjust the pressure of the rod cavity.

In one embodiment, the controlling the electric proportional relief valve to adjust the pressure of the rod chamber includes: continuously adjusting the current of the electric proportional relief valve to adjust the pressure of the rod chamber; During the pressure adjustment of the rod chamber, the pressure value of the rodless chamber is acquired according to a preset time interval; and when the difference between the pressure value of the rodless chamber and the standard pressure value is within the preset range , stop adjusting the current of the electric proportional overflow valve to stop adjusting the pressure of the rod cavity.

In one embodiment, the controlling the electric proportional relief valve to adjust the pressure of the rod chamber includes: continuously adjusting the current of the electric proportional relief valve to adjust the pressure of the rod chamber; During the pressure adjustment of the rod chamber, the pressure value of the rodless chamber is obtained in real time; and when the difference between the pressure value of the rodless chamber and the standard pressure value is within the preset range, the adjustment of the electric chamber is stopped. Proportional relief valve current to stop adjusting the rod chamber pressure.

In one embodiment, the standard pressure value is obtained through the following methods: determining the current angle of the boom of the crane; determining the angle interval in which the current angle is located; determining the target rod cavity corresponding to the angle interval a pressure value; and determining the standard pressure value according to the target rod chamber pressure value.

In an embodiment, the determining the target rod chamber pressure value corresponding to the angle interval includes: determining the angle interval based on the pre-calibrated correspondence between the angle interval and the target rod chamber pressure value The corresponding target has the rod cavity pressure value.

In an embodiment, the determining the standard pressure value according to the target rod chamber pressure value includes: based on the target rod chamber pressure value, the pre-calibrated target rod chamber pressure value and the The corresponding relationship of the standard pressure value is used to determine the standard pressure value.

In one embodiment, the controlling the electric proportional relief valve to adjust the pressure of the rod chamber includes: determining the current coefficient according to the pressure value of the rodless chamber and the current working current; and adjusting the current coefficient according to the current coefficient The control current of the electro-proportional overflow valve is used to adjust the pressure of the rod cavity.

In an embodiment, the adjusting the control current of the electric proportional relief valve according to the current coefficient includes: calculating the control current by the following formula:

Im=Io-Ki×Pi;

Wherein, Im is the control current, Io is the maximum current of the electric proportional relief valve, Pi is the pressure value of the rodless chamber obtained at the ith moment, and Ki is the current at the ith moment Coefficient, i is a positive integer.

In an embodiment, the determining the current coefficient according to the pressure value of the rodless chamber and the current working current includes: calculating the current coefficient according to the following formula:

Wherein, Ki is the current coefficient, Ii is the operating current of the electric proportional overflow valve at the i moment, and Pi is the rodless chamber pressure value of the rodless chamber at the i moment; For the operating current of the electric proportional overflow valve, the hth moment is the previous moment of the i-th moment, and Ph is the pressure value of the rodless chamber in the rodless chamber at the hth moment.

According to another aspect of the present application, a fall control system is provided, the fall control system is connected to the luffing cylinder of the crane, and the rod chamber of the luffing cylinder is connected to an electric proportional overflow valve; the fall The control system includes a controller and a pressure sensor; the pressure sensor is used to measure the pressure value of the rodless chamber in the rodless chamber of the luffing cylinder during the amplitude drop operation of the crane; the controller is used to During the crane's falling operation, the pressure value of the rodless chamber is obtained from the pressure sensor, and the difference between the pressure value of the rodless chamber and the preset standard pressure value of the rodless chamber is calculated; when the When the difference is not within the preset range, the electric proportional relief valve is controlled to adjust the pressure of the rod cavity.

In one embodiment, the pressure sensor is installed in the rodless cavity, the electric proportional overflow valve is installed in the rod cavity, and both the pressure sensor and the electric proportional overflow valve are compatible with the The above controller communication connection.

In an embodiment, when the controller performs the control of the electric proportional relief valve to adjust the pressure of the rod cavity, it specifically performs: continuously adjust the current of the electric proportional relief valve to adjust the the pressure of the rod chamber; during the pressure adjustment of the rod chamber, obtain the pressure value of the rodless chamber from the pressure sensor according to the preset time interval; and when the pressure value of the rodless chamber is consistent with the When the difference of the standard pressure value is within the preset range, stop adjusting the current of the electric proportional relief valve to stop adjusting the pressure of the rod cavity.

In an embodiment, when the controller performs the control of the electric proportional relief valve to adjust the pressure of the rod cavity, it specifically performs: continuously adjust the current of the electric proportional relief valve to adjust the the pressure of the rod chamber; during the pressure adjustment of the rod chamber, obtain the pressure value of the rodless chamber from the pressure sensor in real time; and when the difference between the pressure value of the rodless chamber and the standard pressure value When the value is within the preset range, stop adjusting the current of the electric proportional overflow valve to stop adjusting the pressure of the rod cavity.

According to another aspect of the present application, a crane is provided, comprising: any one of the fall control systems described above and a crane body.

According to another aspect of the present application, a non-transitory computer-readable storage medium is provided, on which a computer program is stored, and when the computer program is executed by a processor, the droop control method described in the first aspect is implemented.

The application provides a method, system, and crane for controlling amplitude drop. During the amplitude drop operation of the crane, the pressure value of the rodless cavity in the rodless cavity of the luffing cylinder is obtained, and the pressure value of the rodless cavity is calculated to be the same as the preset value. The difference between the standard pressure values in the rodless cavity when the amplitude is falling at a constant speed. If the difference between the pressure value of the rodless chamber and the standard pressure value is not within the preset range, it means that the falling speed is not uniform, and the pressure of the rodless chamber is controlled by the electric proportional overflow valve to maintain the pressure value of the rodless chamber Keep within the preset range, so as to achieve uniform and stable falling speed. To sum up, in each embodiment of the present application, according to the feedback pressure value of the rodless chamber, the pressure of the rodless chamber is adjusted through the electric proportional relief valve to keep the pressure of the rodless chamber constant, which ensures the control of the falling speed. Constant velocity.

Brief description of the drawings

The above and other objects, features and advantages of the present application will become more apparent through a more detailed description of the embodiments of the present application in conjunction with the accompanying drawings. The accompanying drawings are used to provide a further understanding of the embodiments of the present application, and constitute a part of the specification, and are used together with the embodiments of the present application to explain the present application, and do not constitute limitations to the present application. In the drawings, the same reference numerals generally represent the same components or steps.

Fig. 1 is a schematic flowchart of a method for controlling fall amplitude provided by an exemplary embodiment of the present application.

Fig. 2 is a schematic flow chart of a method for controlling the pressure of a chamber with a rod provided by an exemplary embodiment of the present application.

Fig. 3 is a schematic flowchart of another method for controlling the pressure of a chamber with a rod provided by an exemplary embodiment of the present application.

Fig. 4 is a schematic flowchart of another method for controlling the pressure of a cavity with a rod provided by an exemplary embodiment of the present application.

Fig. 5 is a schematic structural diagram of a fall control system provided by an exemplary embodiment of the present application.

Fig. 6 is a schematic structural diagram of another fall control system provided by an exemplary embodiment of the present application.

Fig. 7 is a schematic structural diagram of a crane provided by an exemplary embodiment of the present application.

Modes of Carrying Out the Invention

Hereinafter, exemplary embodiments according to the present application will be described in detail with reference to the accompanying drawings. Apparently, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. It should be understood that the present application is not limited by the exemplary embodiments described here.

The uniform and stable falling speed is very important to the safety and stability of the crane operation. The fall control principle of the existing small and medium-sized tonnage cranes is divided into two types: rod cavity plus constant pressure drop and lift arm self-weight fall. The common relief valve is used instead of the electric proportional relief valve, and the relief pressure is the initial set value.

In the above two falling forms, the falling speed will become faster and faster as the elevation angle of the boom decreases, rather than at a constant speed. It is necessary for the operator to adjust the opening of the tie rod or handle according to the angle.

As shown in Figure 1, an embodiment of the present application provides a fall control method, which is applied to the fall control system. The fall control system is connected to the luffing cylinder of the crane, and the rod chamber of the luffing cylinder is connected to the electric proportional overflow valve, the method includes the steps of:

Step 110: Acquiring the pressure value of the rodless chamber in the rodless chamber of the luffing cylinder during the amplitude drop operation of the crane.

Specifically, when the crane performs a drop operation, the angle of the boom decreases, resulting in a shift in the center of gravity, and the speed of the drop will become faster as the elevation angle of the boom decreases, instead of falling at a constant speed. During the crane's falling operation, its falling speed is related to the pressure value in the rodless chamber, so during the crane's falling operation, the pressure in the rodless chamber of the luffing cylinder is measured to obtain the pressure value of the rodless chamber .

Step 120: Calculate the difference between the pressure value of the rodless chamber and the preset standard pressure value of the rodless chamber.

Specifically, during the amplitude drop process, when the jib angle continuously changes to cause the center of gravity to shift, the pressure in the rodless cavity (that is, the component force of the jib gravity along the direction of the cylinder piston rod and the hydraulic oil in the rod cavity acting on the The sum of the forces on the piston and the area of the rodless chamber) can be kept constant to ensure uniform and stable falling speed. Therefore, in a short period of time during the constant-velocity fall, the pressure value in the rodless chamber is a calibrated and always constant standard pressure value, and the difference between the pressure value in the rodless chamber and the standard pressure value can be used to determine the falling Whether the web speed remains uniform and stable. If the difference is within the preset range, it can be considered that the falling speed at this time is uniform and stable.

Step 130: When the difference is not within the preset range, control the electric proportional overflow valve to adjust the pressure of the rod cavity.

Specifically, when the difference is not within the preset range, it means that the pressure in the rodless cavity is far from the standard pressure value, and the uniform and stable falling speed cannot be maintained. The rod chamber of the luffing oil tank is connected with the electric proportional relief valve. When the difference is not within the preset range, the pressure in the rod chamber is controlled through the electric proportional relief valve, so as to maintain the force of the rod chamber hydraulic oil acting on the piston. In a suitable range, when the boom angle changes, the sum of the weight of the boom along the piston rod of the oil cylinder is constant. As the pressure in the rodless chamber increases, the pressure in the rod chamber decreases. The pressure in the rod cavity, so as to keep the pressure in the rodless cavity stable as close as possible to the standard pressure value or the difference with the standard pressure value is less than the preset range, so as to achieve uniform and constant falling speed.

As shown in FIG. 2 , an embodiment of the present application provides a method for controlling the pressure of a chamber with a rod, and step 130 may include the following steps.

Step 210: Continuously adjust the current of the electric proportional overflow valve to adjust the pressure of the rod cavity.

Specifically, as mentioned above, the rod chamber is connected to the electric proportional relief valve. As the boom angle decreases, the center of gravity shifts, causing the falling speed to drop faster and faster, and the pressure in the rodless chamber will increase in response and cannot be maintained. Uniform rate of decline. Therefore, the current of the electric proportional relief valve is continuously controlled, the pressure in the rod chamber is adjusted, and the reaction force is applied through the piston to prevent the pressure in the rodless chamber from further increasing and gradually tend to be stable.

Step 220: During the pressure adjustment of the rod chamber, obtain the pressure value of the rodless chamber according to a preset time interval.

Specifically, a pressure sensor is connected to the rodless cavity, and the pressure sensor can detect the pressure in the rodless cavity, which can be detected in real time, and can also be detected according to a preset detection cycle when it takes a long time to complete the fall. , such as checking every 2 seconds. Through the detection result of the pressure sensor, the overflow valve arranged on the rod cavity is fed back in real time or according to the detection cycle. According to the detection result of the pressure sensor, it can be intuitively seen that adjusting the pressure in the rod chamber can reduce the pressure in the rodless chamber.

Step 230: When the difference between the pressure value of the rodless chamber and the standard pressure value is within the preset range, stop adjusting the current of the electric proportional overflow valve to stop adjusting the pressure of the rod chamber.

Specifically, according to the feedback of the pressure sensor, when the difference between the pressure value of the rodless chamber and the standard pressure value is within the preset range, the pressure value of the rodless chamber can maintain the stability of the fall speed, and at this time, the electric ratio can be adjusted by stopping The current to the relief valve stops adjusting the pressure in the chamber with the rod.

In an embodiment of the present application, the controlling the electric proportional relief valve to adjust the pressure of the rod chamber may include: continuously adjusting the electric current of the electric proportional relief valve to adjust the pressure of the rod chamber ; during the pressure adjustment of the rod chamber, acquire the pressure value of the rodless chamber in real time; and when the difference between the pressure value of the rodless chamber and the standard pressure value is within the preset range, stop Adjust the current of the electric proportional overflow valve to stop adjusting the pressure of the rod cavity.

As shown in Figure 3, an embodiment of the present application provides a method for obtaining a standard pressure value, and the method may include the following steps.

Step 310: Determining the current angle of the jib of the crane.

Specifically, in the process of the crane performing the falling operation, the elevation angle of the boom will gradually decrease, so in the whole falling process, the angles of the boom are different at different time points, so in each To detect the point in time, it is necessary to determine the current angle of the boom.

Step 320: Determine the angle interval where the current angle is located; wherein, each angle interval corresponds to a pressure value of the rod chamber.

Step 330: Determine the target rod chamber pressure value corresponding to the angle interval.

Specifically, as the angle of the boom changes, the force of the hydraulic oil in the rod chamber acting on the piston is also different, that is, to maintain the pressure value of the rodless chamber within the preset range of the standard pressure value, the pressure required by the rod chamber is also Different, therefore, the angle can be divided into several intervals by means of calibration, each interval corresponds to a pressure value of the rod chamber, and the pressure value of the rod chamber corresponding to each interval indicates that the pressure value of the rod chamber in this interval is approximately The difference between the pressure value of the rodless chamber and the standard pressure value will be within the preset range. Therefore, the target rod chamber pressure value corresponding to the angle interval where the current angle is located is determined. That is, the target rod chamber pressure value corresponding to the angle interval may be determined based on the pre-calibrated correspondence between the angle interval and the target rod chamber pressure value.

Step 340: Determine a standard pressure value according to the target rod chamber pressure value.

Specifically, according to the target pressure value of the rod chamber, the pressure of the rod chamber is adjusted through the electric proportional overflow valve. During the adjustment process, since the relationship between the target rod chamber pressure value and the standard pressure value is calibrated, it is not necessary to obtain The real-time feedback of the pressure sensor only needs to directly determine the standard pressure value and adjust it according to the target rod chamber pressure value. That is, the standard pressure value may be determined based on the target rod chamber pressure value, a pre-calibrated correspondence between the target rod chamber pressure value and the standard pressure value.

As shown in FIG. 4 , an embodiment of the present application provides another method for controlling the pressure of a cavity with a rod. Step 130 may include the following steps.

Step 410: Determine the current coefficient according to the pressure value of the rodless cavity and the current working current.

Specifically, when the crane falls, under the action of the gravity of the boom, the pressure in the rodless chamber can be kept constant to ensure uniform falling speed. When the pressure in the rodless chamber changes, the flow rate in the rodless chamber must be guaranteed. Constant, so it is necessary to adjust the control current of the electric proportional relief valve. After obtaining the rodless chamber pressure through the pressure sensor, since the working current is related to the preset falling speed, the control current required to maintain the preset falling speed at the current moment can be calculated according to the pressure value of the rodless chamber, and stored The pressure value of the rodless cavity at each moment and the corresponding control current are called for the calculation of the current coefficient at the next moment.

Step 420: Adjust the control current of the electric proportional overflow valve according to the current coefficient, so as to adjust the pressure of the rod cavity.

Specifically, the pressure value of the rodless chamber is collected by the pressure sensor, and the current coefficient can be determined according to the pressure value of the rodless chamber. On this basis, the control current is corrected according to the pressure value of the rodless chamber and the current coefficient,

The control current that changes with the pressure of the rodless cavity is obtained, and the electromagnetic force of the electric proportional relief valve spool is controlled by the control current to ensure a uniform fall at the preset falling speed.

In addition, the preset falling speed is an artificially set value according to actual operation needs. For example, if the crane is required to complete the falling operation in one minute, then the preset falling speed is performed according to the falling time of one minute combined with the actual parameters of the crane. The speed setting ensures that the crane can complete the falling operation within one minute while maintaining the preset falling speed. The adjustment of the electric proportional relief valve will be carried out with the goal of always ensuring the preset falling speed Control to adjust the control current.

In an embodiment of the present application, adjusting the control current of the electric proportional overflow valve according to the current coefficient includes:

The control current is calculated by the following formula:

Im=Io-Ki×Pi;

Among them, Im is the control current, Io is the maximum current of the electric proportional relief valve, Pi is the rodless chamber pressure value obtained at the i-th moment, Ki is the current coefficient at the i-th moment, and i is a positive integer.

Specifically, the pressure sensor is used to collect the pressure of the rodless chamber of the luffing cylinder in real time, and the real-time current coefficient is calculated according to the real-time pressure. Corrected in real time, a control current that gradually changes with the pressure of the rodless cavity is obtained.

In an embodiment of the present application, determining the current coefficient according to the pressure value of the rodless cavity and the current working current includes:

The current coefficient is calculated by the following formula:

Among them, Ki is the current coefficient, Ii is the operating current of the electric proportional relief valve at the i-th moment, Pi is the pressure value of the rodless chamber at the i-th moment; Ih is the working current of the electric proportional relief valve at the h-th moment Current, the moment h is the previous moment of the i moment, and Ph is the pressure value of the rodless chamber at the hth moment.

Specifically, when the control current is corrected at each moment, the pressure value of the rodless cavity at the current moment is collected, and the control current required at the current moment is calculated according to the pressure, and the pressure of the rodless cavity at the previous moment and the corresponding For the control current, the current coefficient at each moment is calculated according to the above formula, that is, the adjusted control current at each moment can be obtained.

As shown in Figure 5, an embodiment of the present application provides a fall control system, the fall control system is connected to the luffing cylinder of the crane, and the rod chamber of the luffing cylinder is connected to the electric proportional overflow valve; the fall control system includes A controller 510 and a pressure sensor 520.

The pressure sensor 520 is used to measure the pressure value of the rodless chamber in the rodless chamber of the luffing cylinder during the amplitude drop operation of the crane.

The controller 510 is used to obtain the pressure value of the rodless chamber from the pressure sensor during the amplitude drop operation of the crane, and calculate the difference between the pressure value of the rodless chamber and the preset standard pressure value of the rodless chamber, when the difference When it is not within the preset range, the electric proportional relief valve is controlled to adjust the pressure in the rod cavity.

To sum up, in this application, the electric proportional relief valve is used as the secondary relief valve of the luffing cylinder with the rod cavity, and the pressure sensor is installed in the rodless cavity. Through the real-time feedback of the pressure sensor and the control logic, the electric proportional relief valve connected to the rod chamber is controlled to maintain the force of the hydraulic oil acting on the piston in the rod chamber. When the angle of the boom changes, the sum of the force of the hydraulic oil in the rod chamber acting on the piston and the component force of the gravity of the boom along the direction of the piston rod of the cylinder is constant. The component force increases with the decrease of the boom angle, and the overflow pressure of the rodless chamber overflow valve decreases accordingly. The control logic can realize the function in the form of real-time feedback calculation of the rodless chamber pressure, or can realize the function by calibrating the relief pressure of the electric proportional relief valve at different angles of the boom.

Specifically, the pressure fed back by the pressure sensor in the rodless chamber is calculated and processed through the control logic, and the electric proportional relief valve in the rod chamber is controlled to solve the problem that the falling speed decreases with the boom angle, and the center of gravity shifts to cause the falling speed to decrease. The faster problem, in this application, the secondary relief valve of the luffing cylinder with the rod chamber adopts the electric proportional relief valve, and the pressure sensor is installed in the rodless chamber of the oil cylinder to monitor the pressure of the rodless chamber, the flow pressure, and the During the process, when the angle of the boom continuously changes and the center of gravity shifts, keep the pressure in the rodless chamber (equal to the sum of the component force of the gravity of the boom along the direction of the piston rod of the cylinder and the force of the hydraulic oil in the rod chamber acting on the piston) and then divide Rodless chamber area), when the opening of the main valve luffing valve stem (such as a manual pull rod or handle) is constant, according to the pressure difference flow formula, the pressure difference remains unchanged, the flow area remains unchanged, and the flow rate does not change. Therefore, the falling speed can be guaranteed to be uniform and stable.

As shown in Figure 5, in one embodiment of the present application, the pressure sensor 520 is installed in the rodless cavity, the overflow valve is installed in the rod cavity, and both the pressure sensor 520 and the electric proportional overflow valve are connected to the controller 510 in communication .

In an embodiment of the present application, when the controller 510 controls the electric proportional relief valve to adjust the pressure of the rod chamber, it executes: continuously adjusting the current of the electric proportional relief valve to adjust the pressure of the rod chamber; During the pressure adjustment period, the pressure value of the rodless chamber is obtained from the pressure sensor according to the preset time interval; when the difference between the pressure value of the rodless chamber and the standard pressure value is within the preset range, stop adjusting the current of the electric proportional relief valve to stop adjusting the pressure in the rod cavity.

In an embodiment of the present application, the controller 510 obtains the standard pressure value through the following methods: determine the current angle of the boom of the crane; determine the angle interval in which the current angle is located; wherein, each angle interval corresponds to a rod chamber pressure value ; Determining a target rod chamber pressure value corresponding to the angle interval; and determining a standard pressure value according to the target rod chamber pressure value.

In an embodiment of the present application, controlling the electric proportional relief valve to adjust the pressure of the rod chamber by the controller 510 includes: determining the current coefficient according to the pressure value of the non-rod chamber and the current operating current; adjusting the electric proportional relief valve according to the current coefficient The current is controlled to adjust the pressure in the rod cavity.

In an embodiment of the present application, when the controller 510 adjusts the control current of the relief valve according to the current coefficient, it specifically executes:

The control current is calculated by the following formula:

Im=Io-Ki×Pi;

Among them, Im is the control current, Io is the maximum current of the electric proportional relief valve, Pi is the pressure value of the rodless chamber obtained at the i-th moment, Ki is the current coefficient at the i-th moment, and i is a positive integer.

In an embodiment of the present application, when the controller 510 determines the current coefficient according to the pressure value of the rodless chamber and the current working current, it executes:

The current coefficient is calculated by the following formula:

Among them, Ki is the current coefficient, Ii is the operating current of the electric proportional overflow valve 530 at the i-th moment, Pi is the pressure value of the rodless cavity of the rodless cavity at the i-th moment; Ih is the electric proportional overflow valve 530 at the h-th moment The working current of the hth moment is the previous moment of the ith moment, and Ph is the pressure value of the rodless chamber at the hth moment.

As shown in Figure 6, an embodiment of the present application provides another amplitude control system, including: luffing cylinder 610, pressure sensor 620, luffing balance valve 630, electric proportional relief valve 640 and main valve luffing joint 650.

Specifically, the fall control principle of the existing small and medium-sized tonnage cranes is divided into two types: rod cavity plus constant pressure drop and lift arm self-weight drop control. The ordinary relief valve is used instead of the electric proportional relief valve. The overflow pressure is the initial setting value. For the two types of falling width, the falling speed will become faster and faster with the decrease of the boom elevation angle, instead of a constant speed, the operator needs to adjust the opening degree of the pull rod or handle according to the angle, that is, adjust the opening degree of the luffing joint of the main valve. In this application, the secondary overflow valve of the luffing oil cylinder with the rod cavity adopts an electric proportional overflow valve, and the pressure sensor is installed in the rodless cavity. Through the control logic, the pressure fed back by the sensor in the rodless chamber is calculated and processed, and the overflow of the electric proportional relief valve in the rod chamber is controlled to solve the problem that the falling speed decreases with the angle of the boom, and the center of gravity shifts, causing the falling speed to fall faster In this application, the secondary relief valve of the luffing cylinder with the rod chamber adopts an electric proportional relief valve, and the pressure sensor is installed in the rodless chamber of the oil cylinder to monitor the pressure and flow pressure of the rodless chamber. , when the center of gravity shifts due to the continuous change of the boom angle, maintain the pressure in the rodless chamber (equal to the sum of the component force of the boom gravity along the direction of the cylinder piston rod and the force of the hydraulic oil in the rod chamber acting on the piston and divide the rodless chamber Cavity area), when the opening of the main valve luffing valve stem is constant, according to the pressure difference flow formula, the pressure difference remains unchanged, the flow area remains unchanged, and the flow rate remains unchanged, so the falling speed can be guaranteed to be uniform and stable . Therefore, in the solutions provided by the various embodiments of the present application, under the condition that the luffing balance valve and the main valve luffing joint are in a certain state, the pressure in the rod cavity can be directly adjusted through the electric proportional overflow valve, and the electric proportional The overflow valve can be automatically adjusted according to the control working current, which is more accurate than manual adjustment.

Through the real-time feedback of the sensor and the control logic, the electric proportional relief valve with the rod chamber is controlled to maintain the force of the hydraulic oil acting on the piston with the rod chamber. When the angle of the boom changes, the sum of the force of the hydraulic oil in the rod chamber acting on the piston and the component force of the gravity of the boom along the direction of the piston rod of the cylinder is constant. The component force increases with the decrease of the boom angle, and the overflow pressure of the rodless chamber overflow valve decreases accordingly. The control logic can realize the function in the form of real-time feedback calculation of the rodless chamber pressure, or can realize the function by calibrating the overflow pressure of the electric proportional overflow valve at different angles of the boom. It should be noted that the form of the main valve is not limited to hand lever, hydraulic control, or electric control. The main valve shown in Figure 6 is in the form of a hand lever, which is only an expression of the principle.

As shown in FIG. 7 , an embodiment of the present application provides a crane, including: the fall control system 710 described in any one of the above embodiments and a crane body 720 . Wherein, the fall control system 710 is configured to execute the fall control methods provided in the above-mentioned embodiments.

An embodiment of the present application provides a non-transitory computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the fall control methods provided in the foregoing embodiments are implemented.

The solutions provided by various embodiments of the present application have the following advantages and progress:

1. The secondary overflow valve of the rod cavity of the luffing cylinder adopts an electric proportional overflow valve to realize variable and controllable pressure of the rod cavity of the luffing cylinder during the luffing.

2. A pressure sensor is placed in the rodless cavity of the luffing cylinder, and the electric proportional overflow valve installed on the falling side of the main valve is controlled through the real-time feedback of the pressure in the rodless cavity, or the electric ratio of the falling amplitude is calibrated twice at different angles of the boom The overflow pressure is used to control the pressure of the rodless chamber of the luffing cylinder to keep constant. Under the condition of a certain opening of the luffing valve stem, the flow velocity of the rodless chamber is guaranteed to be constant, that is, the uniform falling speed is constant.

The basic principles of the present application have been described above in conjunction with specific embodiments, but it should be pointed out that the advantages, advantages, effects, etc. mentioned in the application are only examples rather than limitations, and these advantages, advantages, effects, etc. Various embodiments of this application must have. In addition, the specific details disclosed above are only for the purpose of illustration and understanding, rather than limitation, and the above details do not limit the application to be implemented by using the above specific details.

The block diagrams of devices, devices, devices, and systems involved in this application are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, devices, devices, systems may be connected, arranged, configured in any manner. Words such as "including", "comprising", "having" and the like are open-ended words meaning "including but not limited to" and may be used interchangeably therewith. As used herein, the words "or" and "and" refer to the word "and/or" and are used interchangeably therewith, unless the context clearly dictates otherwise. As used herein, the word "such as" refers to the phrase "such as but not limited to" and can be used interchangeably therewith.

It should also be pointed out that in the devices, equipment and methods of the present application, each component or each step can be decomposed and/or reassembled. These decompositions and/or recombinations should be considered equivalents of this application.

The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the scope of the application. Thus, the present application is not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

The foregoing description has been presented for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of the application to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

A fall control method, applied to a fall control system, the fall control system is connected to a luffing oil cylinder of a crane, and the rod chamber of the luffing oil cylinder is connected to an electric proportional overflow valve; the fall control method includes :

Obtaining the pressure value of the rodless chamber in the rodless chamber of the luffing cylinder during the amplitude drop operation of the crane;

calculating the difference between the pressure value of the rodless chamber and the preset standard pressure value of the rodless chamber; and

When the difference is not within the preset range, the electric proportional overflow valve is controlled to adjust the pressure of the rod cavity.
The fall control method according to claim 1, wherein the controlling the electric proportional overflow valve to adjust the pressure of the rod cavity comprises:

Continuously adjust the current of the electric proportional relief valve to adjust the pressure of the rod cavity;

During the pressure adjustment of the rod chamber, acquiring the pressure value of the rodless chamber according to a preset time interval; and

When the difference between the pressure value of the rodless chamber and the standard pressure value is within the preset range, stop adjusting the current of the electric proportional overflow valve to stop adjusting the pressure of the rod chamber.
The fall control method according to claim 1, wherein the controlling the electric proportional overflow valve to adjust the pressure of the rod cavity comprises:

Continuously adjust the current of the electric proportional relief valve to adjust the pressure of the rod cavity;

Obtaining the pressure value of the rodless chamber in real time during the pressure adjustment of the rod chamber; and

When the difference between the pressure value of the rodless chamber and the standard pressure value is within the preset range, stop adjusting the current of the electric proportional overflow valve to stop adjusting the pressure of the rod chamber.
The fall control method according to any one of claims 1 to 3, wherein the standard pressure value is obtained by the following method:

determining a current angle of the boom of the crane;

determining the angle interval in which the current angle is located;

determining a target rod chamber pressure value corresponding to the angle interval; and

The standard pressure value is determined according to the target rod chamber pressure value.
The fall control method according to claim 4, wherein said determining the target rod chamber pressure value corresponding to the angle interval comprises:

Based on the pre-calibrated correspondence between the angle interval and the target rod chamber pressure value, the target rod chamber pressure value corresponding to the angle interval is determined.
The amplitude control method according to claim 4, wherein said determining said standard pressure value according to said target rod chamber pressure value comprises:

The standard pressure value is determined based on the target rod chamber pressure value, a pre-calibrated correspondence between the target rod chamber pressure value and the standard pressure value.
The fall control method according to claim 1, wherein the controlling the electric proportional overflow valve to adjust the pressure of the rod cavity comprises:

determining a current coefficient according to the pressure value of the rodless chamber and the current operating current; and

The control current of the electric proportional overflow valve is adjusted according to the current coefficient to adjust the pressure of the rod cavity.
The amplitude control method according to claim 7, wherein said adjusting the control current of said electric proportional relief valve according to said current coefficient comprises:

The control current is calculated by the following formula:

Im=Io-Ki×Pi;

Wherein, Im is the control current, Io is the maximum current of the electric proportional relief valve, Pi is the pressure value of the rodless chamber obtained at the ith moment, and Ki is the current at the ith moment Coefficient, i is a positive integer.
The amplitude control method according to claim 7, wherein said determining the current coefficient according to the pressure value of the rodless cavity and the current working current comprises:

The current coefficient is calculated by the following formula:

Wherein, Ki is the current coefficient, Ii is the operating current of the electric proportional overflow valve at the i moment, and Pi is the rodless chamber pressure value of the rodless chamber at the i moment; For the operating current of the electric proportional overflow valve, the hth moment is the previous moment of the i-th moment, and Ph is the pressure value of the rodless chamber in the rodless chamber at the hth moment.
A fall control system, the fall control system is connected to a luffing cylinder of a crane, and the rod chamber of the luffing cylinder is connected to an electric proportional overflow valve; the fall control system includes a controller and a pressure sensor;

The pressure sensor is used to measure the pressure value of the rodless chamber in the rodless chamber of the luffing cylinder during the amplitude drop operation of the crane;

The controller is configured to obtain the pressure value of the rodless chamber from the pressure sensor during the amplitude drop operation of the crane, and calculate the pressure value of the rodless chamber and the preset standard of the rodless chamber The difference of the pressure value; when the difference is not within the preset range, the electric proportional overflow valve is controlled to adjust the pressure of the rod chamber.
The fall control system according to claim 10, wherein the pressure sensor is installed in the rodless cavity, the electric proportional overflow valve is installed in the rod cavity, and the pressure sensor and the The electric proportional relief valves are all communicated with the controller.
The fall control system according to claim 10 or 11, wherein, when the controller executes the control of the electric proportional overflow valve to adjust the pressure of the rod chamber, it specifically executes:

Continuously adjust the current of the electric proportional relief valve to adjust the pressure of the rod cavity;

During the pressure adjustment of the rod chamber, acquiring the pressure value of the rodless chamber from the pressure sensor according to a preset time interval; and

When the difference between the pressure value of the rodless chamber and the standard pressure value is within the preset range, stop adjusting the current of the electric proportional overflow valve to stop adjusting the pressure of the rod chamber.
The fall control system according to claim 10 or 11, wherein, when the controller executes the control of the electric proportional overflow valve to adjust the pressure of the rod chamber, it specifically executes:

Continuously adjust the current of the electric proportional relief valve to adjust the pressure of the rod cavity;

Obtaining the pressure value of the rodless chamber from the pressure sensor in real time during the pressure adjustment of the rod chamber; and

When the difference between the pressure value of the rodless chamber and the standard pressure value is within the preset range, stop adjusting the current of the electric proportional overflow valve to stop adjusting the pressure of the rod chamber.
A crane, comprising: the fall control system according to any one of claims 10-13 and a crane body.