CN112551398B - Self-weight dropping hydraulic control method and system and crane - Google Patents
Self-weight dropping hydraulic control method and system and crane Download PDFInfo
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- CN112551398B CN112551398B CN202011444918.7A CN202011444918A CN112551398B CN 112551398 B CN112551398 B CN 112551398B CN 202011444918 A CN202011444918 A CN 202011444918A CN 112551398 B CN112551398 B CN 112551398B
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66C—CRANES; LOAD-ENGAGING ELEMENTS OR DEVICES FOR CRANES, CAPSTANS, WINCHES, OR TACKLES
- B66C23/00—Cranes comprising essentially a beam, boom, or triangular structure acting as a cantilever and mounted for translatory of swinging movements in vertical or horizontal planes or a combination of such movements, e.g. jib-cranes, derricks, tower cranes
- B66C23/62—Constructional features or details
- B66C23/82—Luffing gear
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
- F15B11/02—Systems essentially incorporating special features for controlling the speed or actuating force of an output member
- F15B11/04—Systems essentially incorporating special features for controlling the speed or actuating force of an output member for controlling the speed
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
- F15B11/08—Servomotor systems without provision for follow-up action; Circuits therefor with only one servomotor
Abstract
The invention relates to the technical field of engineering machinery, and provides a self-weight amplitude-falling hydraulic control method, a self-weight amplitude-falling hydraulic control system and a crane. The self-weight amplitude falling hydraulic control method comprises the following steps: acquiring the pressure of a rodless cavity of the luffing cylinder in real time, and correcting the maximum control current in real time according to the pressure of the rodless cavity; acquiring the opening of an electric control handle, and determining a control current according to the corrected maximum control current and the opening of the electric control handle; and the amplitude-variable balance valve communicated with the rodless cavity adjusts the opening degree of a valve core of the amplitude-variable balance valve according to the control current. According to the self-weight amplitude falling hydraulic control method provided by the invention, the maximum control current is corrected in real time according to the real-time pressure of the rodless cavity, so that any opening of the electric control handle corresponds to a constant amplitude falling speed, and the operation of uniform amplitude falling is greatly simplified under the condition of ensuring uniform amplitude falling.
Description
Technical Field
The invention relates to the field of engineering machinery, in particular to a self-weight amplitude-falling hydraulic control method and system and a crane.
Background
The dropping amplitude performance of the automobile crane is one of important indexes for measuring the controllability of the automobile crane. At present, medium and small tonnage automobile cranes all adopt a dead weight amplitude falling mode, namely, a rod cavity of an amplitude-changing oil cylinder does not feed oil, and amplitude falling is realized by generating a vertically downward component force completely depending on the gravity of a large arm. In the amplitude falling process, the amplitude falling speed is adjusted by adjusting the opening degree of a valve core of an amplitude variation balance valve communicated with the rodless cavity of the amplitude variation oil cylinder.
Under the condition that the opening of the variable amplitude balance valve is unchanged, the downward component force of the gravity of the large arm is gradually increased along with the change of the angle of the large arm, and the amplitude falling speed is gradually increased. In order to ensure uniform amplitude falling, the opening degree of the amplitude-variable balance valve needs to be adjusted in real time along with the reduction of the amplitude-falling angle. The opening degree of the variable amplitude balance valve is determined by the opening degree of the electric control handle, namely the opening degree of the electric control handle needs to be adjusted in real time. However, in actual operation, it is difficult to realize uniform width falling through manual operation of the electric control handle, and the operation difficulty of uniform width falling is high.
Disclosure of Invention
The invention provides a self-weight amplitude-falling hydraulic control method and system and a crane, which are used for solving the problem that a crane self-weight amplitude-falling system in the prior art is difficult to realize uniform amplitude falling through manual operation of an electric control handle.
The invention provides a self-weight amplitude-falling hydraulic control method, which comprises the following steps:
acquiring the pressure of a rodless cavity of the variable amplitude oil cylinder at preset time intervals, and correcting the maximum control current in real time according to the pressure of the rodless cavity;
acquiring the opening of an electric control handle, and determining a control current according to the corrected maximum control current and the opening of the electric control handle;
and the amplitude-variable balance valve communicated with the rodless cavity adjusts the opening degree of a valve core of the amplitude-variable balance valve according to the control current.
According to the self-weight amplitude falling hydraulic control method provided by the invention, the maximum control current is corrected in real time according to the pressure of the rodless cavity, and a current compensation coefficient is determined according to the pressure of the rodless cavity and a preset maximum amplitude falling speed;
correcting the maximum control current in real time according to the current compensation coefficient, preferably, the maximum control current corrected in real time is:
wherein the content of the first and second substances,
the corrected maximum control current of the electric control handle at the ith moment,
is the original maximum control current, P, corresponding to the maximum opening of the electric control handle i Pressure of said rodless chamber, K, obtained for moment i i The current compensation factor determined for the instant i,i is more than or equal to 1 and less than or equal to n, i is a positive integer, and the pressure of the rodless cavity is collected for n times in the whole amplitude falling process.
According to the self-weight amplitude-falling hydraulic control method provided by the invention, the current compensation coefficient is determined according to the pressure of the rodless cavity and the preset maximum amplitude-falling speed, and the method specifically comprises the following steps:
respectively according to the pressure P of the rodless cavity obtained at the current moment i And the pressure P of the rodless chamber obtained at the previous moment i-1 Determining the control current I required for maintaining the maximum amplitude falling speed at the current moment i And a control current I required for maintaining the maximum amplitude falling speed at the last moment i-1 ；
The pressure P of the rodless cavity obtained according to the current moment i Last moment obtained pressure P of said rodless chamber i-1 The control current I required for keeping the maximum amplitude falling speed at the current moment i And a control current I required for maintaining the maximum falling speed at the last moment i-1 Determining the current compensation coefficient, preferably the current compensation coefficient is:
according to the self-weight amplitude-falling hydraulic control method provided by the invention, the pressure P of the rodless cavity is respectively obtained according to the current moment i And the pressure P of the rodless chamber obtained at the previous moment i-1 Determining the control current I required for maintaining the maximum amplitude falling speed at the current moment i And a control current I required for maintaining the maximum falling speed at the last moment i-1 The method specifically comprises the following steps:
determining the maximum flow demand of the rodless cavity according to the size of the amplitude-variable oil cylinder and the preset maximum amplitude-falling speed;
according to the flow formula
And the flow area A and the control current I of the amplitude variation balance valveRelation, determining the control current I required for maintaining the maximum falling speed at the current moment i And a control current I required for maintaining the maximum falling speed at the last moment i-1 ；
Q is the flow of the rodless cavity, C is the flow coefficient, A is the flow area of the variable amplitude balance valve, rho is the density of hydraulic oil, and P is the pressure of the rodless cavity.
According to the self-weight amplitude-falling hydraulic control method provided by the invention, the maximum flow demand of the rodless cavity is determined according to the size of the amplitude-changing oil cylinder and the preset maximum amplitude-falling speed, and the method specifically comprises the following steps:
determining the cropping time according to the preset maximum cropping speed;
and determining the maximum flow demand of the rodless cavity according to the cylinder diameter of the luffing cylinder, the cylinder stroke and the luffing time.
The invention also provides a self-weight amplitude-falling hydraulic system, which comprises an amplitude-changing oil cylinder, an amplitude-changing balance valve, a pressure detection unit, an electric control handle and a controller;
the rod cavity of the variable-amplitude oil cylinder is communicated with an oil tank, the rodless cavity of the variable-amplitude oil cylinder is communicated with the working oil port of the variable-amplitude balance valve, the pressure detection unit is used for detecting the pressure of the rodless cavity of the variable-amplitude oil cylinder, and the variable-amplitude balance valve, the pressure detection unit and the electric control handle are respectively connected with the controller;
the controller is used for acquiring the pressure of the rodless cavity of the luffing cylinder at preset time intervals and correcting the maximum control current in real time according to the pressure of the rodless cavity; and the control circuit is also used for acquiring the opening of the electric control handle and determining the control current according to the corrected maximum control current and the opening of the electric control handle.
According to the self-weight amplitude-falling hydraulic system provided by the invention, the pressure detection unit is a pressure sensor.
The self-weight amplitude-falling hydraulic system further comprises an electric proportional pressure reducing valve, the electric proportional pressure reducing valve is in communication connection with the controller, and a working oil port of the electric proportional pressure reducing valve is communicated with a pilot oil port of the amplitude-changing balance valve.
The self-weight amplitude-falling hydraulic system further comprises an electro-hydraulic proportional reversing valve, a working oil port of the electro-hydraulic proportional reversing valve is communicated with an oil inlet of the amplitude-changing balance valve, and a pilot oil port of the electro-hydraulic proportional reversing valve is communicated with a pilot oil port of the amplitude-changing balance valve to form the same pilot oil.
The invention also provides a crane which comprises any one of the self-weight falling-amplitude hydraulic systems.
According to the self-weight amplitude falling hydraulic control method, the system and the crane, the maximum control current is corrected in real time according to the real-time pressure of the rodless cavity, so that the control current corresponding to any opening of the electric control handle is corrected, and uniform amplitude falling is ensured without manually adjusting the opening of the electric control handle in real time. Any opening degree of the electric control handle corresponds to a constant amplitude falling speed, and during operation, the amplitude falling speed is determined and the electric control handle is adjusted to the corresponding opening degree. And the operation of uniform amplitude falling is greatly simplified under the condition of ensuring uniform amplitude falling.
Drawings
In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings needed for the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
FIG. 1 is a flow chart diagram of a hydraulic control method for self-weight amplitude falling provided by the invention;
FIG. 2 is a schematic structural diagram of a self-weight amplitude-falling hydraulic system provided by the invention;
FIG. 3 is a block diagram of a self-weight drop hydraulic system provided by the invention;
reference numerals:
1. a variable amplitude oil cylinder; 11. a rod cavity; 12. a rodless cavity; 2. a variable amplitude balance valve; 3. a pressure sensor; 4. an electric control handle; 5. a controller; 6. an oil tank; 7. an electro-hydraulic proportional directional valve; 8. an electro proportional pressure reducing valve.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without inventive step based on the embodiments of the present invention, are within the scope of protection of the present invention.
The following describes the self-weight drop amplitude hydraulic control method, system and crane of the invention with reference to fig. 1-3.
The embodiment of the invention provides a self-weight amplitude-falling hydraulic control method for realizing uniform amplitude falling control. Fig. 1 is a schematic flow chart of a hydraulic control method for self-weight amplitude falling provided by the present invention, and the hydraulic control method for self-weight amplitude falling comprises the following steps:
s100, acquiring the pressure of a rodless cavity of the luffing cylinder according to a preset time interval, and correcting the maximum control current in real time according to the pressure of the rodless cavity.
S200, acquiring the opening of an electric control handle, and determining a control current according to the corrected maximum control current and the opening of the electric control handle;
and S300, adjusting the opening degree of a valve core of the variable amplitude balance valve communicated with the rodless cavity according to the control current.
Specifically, a certain opening degree of the electric control handle corresponds to a certain control current and a certain opening degree of the variable amplitude balance valve. According to the embodiment of the invention, the maximum control current is corrected in real time according to the real-time pressure of the rodless cavity, so that the maximum control current is changed along with the change of the pressure of the rodless cavity, namely the maximum control current is corrected to be gradually reduced along with the gradual increase of the pressure of the rodless cavity in the process of gradually increasing the pressure of the rodless cavity; because the maximum control current corresponds to the opening degree of the handle, the corrected maximum control current is multiplied by the opening degree value to obtain the control current corresponding to the opening degree value, and the control current corresponding to the opening degree value is reduced, so that the real-time correction of the control current corresponding to any opening degree value of the electric control handle is realized. And the amplitude variation balance valve adjusts the opening of the valve core of the amplitude variation balance valve according to the corrected control current so as to realize uniform amplitude variation. At the moment, different opening degrees of the electric control handle correspond to different amplitude falling speeds.
According to the self-weight amplitude falling hydraulic system provided by the embodiment of the invention, the maximum control current is corrected in real time according to the real-time pressure of the rodless cavity, so that the maximum control current is gradually reduced along with the increase of the pressure of the rodless cavity, and the control current corresponding to any opening of the electric control handle is also gradually reduced along with the increase of the pressure of the rodless cavity, so that any opening of the electric control handle corresponds to a constant amplitude falling speed, and the uniform amplitude falling is ensured without manually adjusting the opening of the electric control handle in real time. During operation, the required amplitude falling speed is determined and the electric control handle is adjusted to the corresponding opening. Under the condition of ensuring uniform amplitude falling, the operation of uniform amplitude falling is simplified to a great extent, and the operation difficulty is reduced.
In step S100, the correcting the maximum control current in real time according to the pressure of the rod-less cavity specifically includes:
s110, determining a current compensation coefficient according to the pressure of the rodless cavity and a preset maximum amplitude falling speed;
and S120, correcting the maximum control current in real time according to the current compensation coefficient.
In a self-weight amplitude-falling hydraulic system, under the action of the gravity of a large arm, the rodless cavity returns oil to the amplitude-falling balance valve, and the amplitude-falling speed can be ensured to be uniform due to the constant flow of the rodless cavity. The pressure in the rodless cavity gradually increases as the angle of the large arm decreases. According to the flow formula:
q is the flow of the rodless cavity, C is the flow coefficient, A is the flow area of the variable amplitude balance valve, rho is the density of hydraulic oil, and P is the pressure of the rodless cavity.
It can be known that, when the pressure of the rodless cavity is gradually increased, the opening degree of the variable amplitude balance valve needs to be reduced to ensure the constant flow of the rodless cavity, and then the control current needs to be reduced.
The preset maximum amplitude falling speed is a value manually set according to actual operation needs and corresponds to the control current corresponding to the maximum opening of the electric control handle. The embodiment of the invention aims to ensure that the maximum control current of the electric control handle at the maximum opening degree can always ensure the maximum amplitude falling speed to be constant, and corrects the maximum control current in real time.
Specifically, the maximum control current corrected in real time is:
wherein, the first and the second end of the pipe are connected with each other,
is the maximum control current after the modification at the ith moment,
is the original maximum control current, P, corresponding to the maximum opening of the electric control handle i Pressure of said rodless chamber, K, obtained for moment i i And (3) determining a current compensation coefficient for the ith moment, wherein i is more than or equal to 1 and less than or equal to n, i is a positive integer, and acquiring the pressure of the rodless cavity for n times in the whole amplitude falling process.
The pressure of a rodless cavity of the variable amplitude oil cylinder can be acquired in real time through a pressure sensor, a real-time compensation coefficient is calculated according to the real-time pressure, then the maximum control current is corrected in real time through the correction formula on the basis of the original maximum control current corresponding to the maximum opening of the electric control handle according to the real-time pressure value and the real-time compensation coefficient of the rodless cavity, the maximum control current which is gradually reduced along with the gradual increase of the pressure of the rodless cavity is obtained, on the basis, the uniform amplitude falling at the set maximum amplitude falling speed can be ensured when the electric control handle is at the maximum opening, and similarly, the uniform amplitude falling at a certain speed which is less than the maximum amplitude falling speed can be ensured when the handle is at any other opening.
In step S110, the determining a current compensation coefficient according to the pressure of the rodless cavity and a preset maximum amplitude-falling speed specifically includes:
s111, respectively obtaining the pressure P of the rodless cavity at the current moment i And the pressure P of the rodless chamber obtained at the previous moment i-1 Determining the control current I required for maintaining the maximum amplitude falling speed at the current moment i And a control current I required for maintaining the maximum falling speed at the last moment i-1 。
S112, obtaining the pressure P of the rodless cavity according to the current moment i Last time the pressure P of the rodless chamber i-1 And a control current I required for maintaining the maximum amplitude falling speed at the current moment i And a control current I required for maintaining the maximum falling speed at the last moment i-1 Determining the current compensation factor.
After the pressure of the rodless cavity is collected at each moment, the control current required for keeping the maximum amplitude falling speed at the moment is calculated according to the pressure, and the pressure of the rodless cavity and the corresponding control current at each moment are stored for calling when the current compensation coefficient is calculated at the next moment.
Specifically, in the embodiment of the present invention, the current compensation coefficient is:
i before the rodless cavity pressure is collected at the first moment 0 And P 0 The initial control current of the system and the initial voltage of the rodless cavity, respectively. When the maximum control current is corrected at each moment, the pressure of the rodless cavity at the current moment is collected, the control current required for keeping the maximum amplitude falling speed at the current moment is calculated according to the pressure, the pressure of the rodless cavity at the previous moment and the corresponding control current are obtained at the same time, the current compensation coefficient at each moment is calculated according to the formula, and the corrected maximum control current at each moment can be obtained.
In step S111, the pressure P of the rodless chamber is obtained according to the current time i And the pressure P of the rodless chamber obtained at the previous moment i-1 DeterminingThe control current I required for maintaining the maximum amplitude falling speed at the current moment i And a control current I required for maintaining the maximum falling speed at the last moment i-1 The method specifically comprises the following steps:
determining the maximum flow demand of the rodless cavity according to the size of the amplitude-variable oil cylinder and the preset maximum amplitude-falling speed;
according to the flow formula
And determining the control current I required for keeping the maximum amplitude falling speed at the current moment according to the relation between the overcurrent area A of the amplitude variation balance valve and the control current I i And a control current I required for maintaining the maximum amplitude falling speed at the last moment i-1 ；
Q is the flow of the rodless cavity, C is the flow coefficient, A is the flow area of the variable amplitude balance valve, rho is the density of hydraulic oil, and P is the pressure of the rodless cavity.
Specifically, the relationship between the flow area of the variable amplitude balance valve and the control current can be determined according to a valve core displacement-flow area curve of the variable amplitude balance valve and the relationship between the valve core displacement of the variable amplitude balance valve and the control current, namely A = kappa.I, wherein kappa is a flow area coefficient, and I is the control current. There is a definite relationship between the control current and the pressure in the rodless chamber with a constant flow in the rodless chamber.
The method comprises the following steps of determining the maximum flow demand of the rodless cavity according to the size of the luffing cylinder and the preset maximum amplitude falling speed, and specifically comprises the following steps:
determining the cropping time according to the preset maximum cropping speed;
and determining the maximum flow demand of the rodless cavity according to the cylinder diameter of the luffing cylinder, the cylinder stroke and the luffing time.
Specifically, the maximum amplitude falling speed corresponds to the maximum flow of the rodless cavity;
wherein Q is m The maximum flow of the rodless cavity is shown, D is the cylinder diameter of the amplitude-variable oil cylinder, L is the stroke of the amplitude-variable oil cylinder, and T is the amplitude falling time.
The invention also provides a self-weight amplitude-falling hydraulic system, which is shown in fig. 2 as a schematic structural diagram of the self-weight amplitude-falling hydraulic system provided by the invention, and comprises an amplitude-changing oil cylinder 1, an amplitude-changing balance valve 2, a pressure detection unit, an electric control handle 4 and a controller 5. The rod cavity 11 of the variable amplitude oil cylinder 1 is communicated with the oil tank 6, and the rodless cavity 12 of the variable amplitude oil cylinder 1 is communicated with the working oil port of the variable amplitude balance valve 2. The pressure detection unit is used for detecting the pressure of the rodless cavity 12 of the luffing cylinder 1. The amplitude variation balance valve 2, the pressure detection unit and the electric control handle 4 are respectively connected with a controller 5. The controller 5 is used for acquiring the pressure of the rodless cavity 12 of the luffing cylinder 1 according to a preset time interval and correcting the maximum control current in real time according to the pressure of the rodless cavity 12; and the control circuit is also used for obtaining the opening of the electric control handle and determining the control current according to the corrected maximum control current and the opening of the electric control handle.
Wherein the pressure detection unit may be a pressure sensor 3. The amplitude variation balance valve 2 can be an electric proportional balance valve which is directly in communication connection with the controller 5, directly receives control current output by the controller 5, and adjusts the opening of the valve core according to the control current. In the embodiment of the invention, the variable amplitude balance valve further comprises an electric proportional pressure reducing valve 8 serving as a pilot valve, the electric proportional pressure reducing valve 8 is in communication connection with the controller 5, a working oil port of the electric proportional pressure reducing valve 8 is communicated with a pilot oil port of the variable amplitude balance valve 2, the controller 5 transmits control current to the electric proportional pressure reducing valve 8, and the pilot oil is controlled by the electric proportional pressure reducing valve 8 to adjust the valve core opening of the variable amplitude balance valve 2.
As shown in fig. 2, a working oil port of the electro-hydraulic proportional reversing valve 7 is communicated with an oil inlet of the variable amplitude balance valve 2, a pilot oil port of the variable amplitude balance valve 2 is communicated with a pilot oil port of the electro-hydraulic proportional reversing valve 7, for example, a working oil port of the electro-proportional pressure reducing valve 8 is respectively communicated with the variable amplitude balance valve 2 and the pilot oil port of the electro-hydraulic proportional reversing valve 7. The oil drain ports of the variable amplitude oil cylinder 1, the variable amplitude balance valve 2 and the electro-hydraulic proportional reversing valve 7 are all communicated with an oil tank 6.
When the self-weight amplitude falling hydraulic system provided by the embodiment works, an operator controls the opening of the electric control handle 4. The controller 5 reads the pressure value of the rodless cavity 12 acquired by the pressure detection unit in real time, and corrects the maximum control current in real time according to the pressure value. Meanwhile, the controller 5 reads the opening value of the electric control handle 4, calculates a control current according to the opening value of the electric control handle 4 and the maximum control current of the electric control handle 4, and outputs the control current to the electro-proportional pressure reducing valve 8. The electric proportional pressure reducing valve 8 adjusts the opening degrees of the variable amplitude balance valve 2 and the electro-hydraulic proportional reversing valve 7 according to the control current, so that the crane boom falls at a constant speed in the vertical direction. For the method for correcting the maximum control current by the controller 5, reference may be made to the above embodiments, and details are not repeated herein.
The invention also provides a crane which comprises the self-weight amplitude-falling hydraulic system. The maximum control current can be corrected in real time, so that the control current corresponding to any opening of the electric control handle is corrected, and uniform amplitude falling is ensured without manually adjusting the opening of the electric control handle in real time. Any opening degree of the electric control handle corresponds to a constant amplitude falling speed, and during operation, the amplitude falling speed is determined and the electric control handle is adjusted to the corresponding opening degree. Under the condition of ensuring uniform amplitude falling, the operation of uniform amplitude falling is also simplified to a great extent.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, and not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (8)
1. A self-weight amplitude-falling hydraulic control method is characterized by comprising the following steps:
the method comprises the following steps of obtaining the pressure of a rodless cavity of a luffing cylinder according to a preset time interval, and correcting the maximum control current in real time according to the pressure of the rodless cavity, and specifically comprises the following steps:
determining a current compensation coefficient according to the pressure of the rodless cavity and a preset maximum amplitude falling speed, and correcting the maximum control current in real time according to the current compensation coefficient; the real-time corrected maximum control current is:
wherein the content of the first and second substances,
the maximum control current of the electric control handle corrected at the ith moment,
is the original maximum control current, P, corresponding to the maximum opening of the electric control handle i Pressure, K, of said rodless chamber obtained for moment i i The current compensation coefficient determined at the ith moment is that i is more than or equal to 1 and less than or equal to n, i is a positive integer, and the pressure of the rodless cavity is collected for n times in the whole amplitude falling process;
the determining of the current compensation coefficient according to the pressure of the rodless cavity and the preset maximum amplitude falling speed specifically comprises the following steps:
respectively according to the pressure P of the rodless cavity obtained at the current moment i And the pressure P of the rodless chamber obtained at the previous moment i-1 Determining the control current I required for maintaining the maximum amplitude falling speed at the current moment i And a control current I required for maintaining the maximum falling speed at the last moment i-1 ；
The pressure P of the rodless cavity obtained according to the current moment i Last moment obtained pressure P of said rodless chamber i-1 The control current I required for keeping the maximum amplitude falling speed at the current moment i And a control current I required for maintaining the maximum amplitude falling speed at the last moment i-1 Determining the currentThe compensation coefficient of the current is as follows:
acquiring the opening degree of an electric control handle, and determining a control current according to the corrected maximum control current and the opening degree of the electric control handle, wherein the control current corresponding to the opening degree value is obtained by multiplying the maximum control current by the opening degree value of the electric control handle;
and the amplitude-variable balance valve communicated with the rodless cavity adjusts the opening degree of a valve core of the amplitude-variable balance valve according to the control current.
2. The hydraulic control method for self-weight amplitude drop according to claim 1, wherein the pressure P of the rodless chamber obtained from the current time is respectively obtained i And the pressure P of the rodless chamber obtained at the previous moment i-1 Determining the control current I required for maintaining the maximum amplitude falling speed at the current moment i And a control current I required for maintaining the maximum falling speed at the last moment i-1 The method specifically comprises the following steps:
determining the maximum flow demand of the rodless cavity according to the size of the luffing oil cylinder and the preset maximum luffing speed;
according to the flow formula
And determining the control current I required for keeping the maximum amplitude falling speed at the current moment according to the relation between the overcurrent area A of the amplitude variation balance valve and the control current I i And a control current I required for maintaining the maximum amplitude falling speed at the last moment i-1 ；
Q is the flow of the rodless cavity, C is the flow coefficient, A is the flow area of the variable amplitude balance valve, rho is the density of hydraulic oil, and P is the pressure of the rodless cavity.
3. The self-weight amplitude-dropping hydraulic control method according to claim 2, wherein the determining of the maximum flow demand of the rodless chamber according to the size of the amplitude-dropping cylinder and a preset maximum amplitude-dropping speed specifically comprises:
determining the cropping time according to the preset maximum cropping speed;
and determining the maximum flow demand of the rodless cavity according to the cylinder diameter of the luffing cylinder, the cylinder stroke and the luffing time.
4. A self-weight amplitude-falling hydraulic system comprises an amplitude-changing oil cylinder and is characterized by further comprising an amplitude-changing balance valve, a pressure detection unit, an electric control handle and a controller;
the rod cavity of the variable-amplitude oil cylinder is communicated with an oil tank, the rodless cavity of the variable-amplitude oil cylinder is communicated with the working oil port of the variable-amplitude balance valve, the pressure detection unit is used for detecting the pressure of the rodless cavity of the variable-amplitude oil cylinder, and the variable-amplitude balance valve, the pressure detection unit and the electric control handle are respectively connected with the controller;
the controller is used for acquiring the pressure of the rodless cavity of the luffing oil cylinder according to a preset time interval;
the controller is further used for determining a current compensation coefficient according to the pressure of the rodless cavity and a preset maximum amplitude falling speed, and specifically comprises the following steps: respectively according to the pressure P of the rodless cavity obtained at the current moment i And the pressure P of the rodless chamber obtained at the previous moment i-1 Determining the control current I required for maintaining the maximum amplitude falling speed at the current moment i And a control current I required for maintaining the maximum amplitude falling speed at the last moment i-1 (ii) a The pressure P of the rodless cavity obtained according to the current moment i Last moment obtained pressure P of said rodless chamber i-1 The control current I required for keeping the maximum amplitude falling speed at the current moment i And a control current I required for maintaining the maximum falling speed at the last moment i-1 Determining the current compensation coefficient, wherein the current compensation coefficient is as follows:
the controller is also used for correcting the maximum control current in real time according to the current compensation coefficient; the real-time corrected maximum control current is:
wherein, the first and the second end of the pipe are connected with each other,
the corrected maximum control current of the electric control handle at the ith moment,
is the original maximum control current, P, corresponding to the maximum opening of the electric control handle i Pressure, K, of said rodless chamber obtained for moment i i The current compensation coefficient determined at the ith moment is that i is more than or equal to 1 and less than or equal to n, i is a positive integer, and the pressure of the rodless cavity is collected for n times in the whole amplitude falling process;
the controller is also used for obtaining the opening of the electric control handle and determining the control current according to the corrected maximum control current and the opening of the electric control handle.
5. The self-gravity amplitude-falling hydraulic system according to claim 4, wherein the pressure detection unit is a pressure sensor.
6. The self-weight amplitude-falling hydraulic system according to claim 4, further comprising an electro-proportional pressure reducing valve, wherein the electro-proportional pressure reducing valve is in communication connection with the controller, and a working oil port of the electro-proportional pressure reducing valve is communicated with a pilot oil port of the amplitude-falling balance valve.
7. The self-weight amplitude-falling hydraulic system according to claim 4, further comprising an electro-hydraulic proportional reversing valve, wherein a working oil port of the electro-hydraulic proportional reversing valve is communicated with an oil inlet of the amplitude-changing balance valve, and a pilot oil port of the electro-hydraulic proportional reversing valve is communicated with a pilot oil port of the amplitude-changing balance valve to form the same pilot oil.
8. A crane, comprising a deadweight boom lowering hydraulic system as claimed in any one of claims 4 to 7.
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| CN113479800B (en) * | 2021-07-30 | 2023-08-22 | 三一汽车起重机械有限公司 | Amplitude falling control method and system and crane |
| CN114542534A (en) * | 2022-02-25 | 2022-05-27 | 三一汽车起重机械有限公司 | Amplitude falling hydraulic control method, amplitude falling hydraulic control system and engineering machinery |
| CN114876902A (en) * | 2022-07-11 | 2022-08-09 | 中联重科股份有限公司 | Speed real-time tracking hydraulic control method and system and engineering machinery |
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