CN111664289B - Method for controlling opening and closing process of hydraulic valve through database and pulse width modulation - Google Patents
Method for controlling opening and closing process of hydraulic valve through database and pulse width modulation Download PDFInfo
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- CN111664289B CN111664289B CN202010485844.5A CN202010485844A CN111664289B CN 111664289 B CN111664289 B CN 111664289B CN 202010485844 A CN202010485844 A CN 202010485844A CN 111664289 B CN111664289 B CN 111664289B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
- F16K31/00—Actuating devices; Operating means; Releasing devices
- F16K31/02—Actuating devices; Operating means; Releasing devices electric; magnetic
- F16K31/06—Actuating devices; Operating means; Releasing devices electric; magnetic using a magnet, e.g. diaphragm valves, cutting off by means of a liquid
- F16K31/0675—Electromagnet aspects, e.g. electric supply therefor
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K7/00—Modulating pulses with a continuously-variable modulating signal
- H03K7/08—Duration or width modulation ; Duty cycle modulation
Abstract
The invention discloses a method for controlling the opening and closing process of a hydraulic valve through a database and pulse width modulation. The control data and the opening and closing characteristic data of the hydraulic electromagnetic valve are stored by utilizing a database technology, a user can input the required opening and closing characteristic of the electromagnetic valve, and the controller matches proper electromagnetic valve control parameters from the stored array, so that the control of the electromagnetic valve is realized. The invention adopts PWM adjustment technology to realize the adjustment of voltage source output, two duty ratios are adopted in the opening stage (the closing stage is the same), the voltage source under the action of the first duty ratio enables the valve to be quickly opened (the valve is quickly closed in the closing stage), and the dynamic characteristic is improved; the voltage source under the action of the second duty ratio reduces the movement speed of the final valve core and reduces the loss of the valve core, thereby taking the dynamic characteristic and flexible opening and closing into consideration and prolonging the service life of the hydraulic electromagnetic valve.
Description
Technical Field
The invention belongs to the field of hydraulic valve control, and particularly relates to a method for controlling the opening and closing process of a hydraulic valve through a database and pulse width modulation.
Background
The hydraulic solenoid valve is also commonly called a hydraulic valve and a solenoid valve, and refers to an element used for controlling the pressure, the flow and the direction of liquid in hydraulic transmission. In order to realize the high-frequency control function of the hydraulic electromagnetic valve, the opening and closing speed of the hydraulic valve needs to be improved. When the valve is completely opened and closed, the valve core impacts on the valve body at a high speed to generate strong rigid impact, and damage is caused to machinery. For a high-frequency hydraulic valve, the higher the frequency is, the faster the corresponding opening and closing speed is, the higher the rigid impact frequency is, and the more serious the mechanical damage caused by the rigid impact is. Reducing the speed of the valve core when the valve core is completely opened and closed can reduce the rigid impact, but the reduction of the speed of the valve core can reduce the dynamic response characteristic of the hydraulic valve, so that the hydraulic valve cannot realize the function of high frequency response. How to give consideration to both dynamic characteristics and flexible opening and closing is a technical problem to be solved urgently in the prior art.
In the existing industrial control field, the application scene of the electromagnetic valve is generally stable, but the electromagnetic valve is required to be opened and closed at high frequency by tasting, the opening and closing characteristics (opening time, closing time and opening and closing delay time) are often adjusted according to the requirements of users, and how to effectively adjust the electromagnetic valve according to the requirements of the users is not reported.
Pulse width modulation is an analog control method, and when the pulse width modulation is used for regulating and controlling the output of a voltage source, a method for changing the equivalent output voltage is achieved by controlling the width (or the duty ratio) or the period (the method for changing the width of the voltage pulse is adopted in the invention). Most loads require a modulation frequency above 10Hz, typically between 1kHz and 200 kHz. Pulse width modulation is a very efficient technique for controlling analog circuits using digital signals from a microprocessor. Are widely used in many fields ranging from measurement, communication to power control and conversion.
The controller or control system allows the control strategy of the hydraulic solenoid valve to be stored in advance, but the controller outputs usually relevant execution parameters of the solenoid valve, such as the voltage magnitude of a voltage source, the execution parameters are usually not focused by a user, and the ordinary user cannot convert the control parameters according to the task requirement to be controlled. The main concerns of users are the opening and closing characteristics of the solenoid valve after being controlled, the service life of the solenoid valve and the like, and the performances can be measured by the opening and closing time of the solenoid valve and the movement speed of the valve core. Therefore, if a control method can be designed, specific control parameters of the solenoid valve can be given according to characteristics of the solenoid valve required by a user, so that the solenoid valve meets the requirements of the user, and the dynamic characteristics and flexible opening and closing of the solenoid valve can be considered, which is very significant for the field of industrial control.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a method for controlling the opening and closing process of a hydraulic valve through a database and pulse width modulation. The invention stores the control data of the electromagnetic valve by using the database technology, a user can input the required opening and closing characteristics of the electromagnetic valve, and the controller matches the proper electromagnetic valve control parameters from the stored arrays, thereby realizing the control of the electromagnetic valve. The control strategy of the invention gives consideration to the dynamic characteristic and the flexible opening and closing requirements of the electromagnetic valve.
The technical scheme of the invention is as follows:
the invention discloses a method for controlling the opening and closing process of a hydraulic valve through a database and pulse width modulation, wherein a coil of the hydraulic valve is connected with a voltage source, the voltage source is connected with a duty ratio controller, and a displacement sensor is installed in the hydraulic valve and used for acquiring the motion state of a valve core; the controller is connected with the displacement sensor to obtain the position and the movement speed of the valve core of the hydraulic valve; the controller is connected with the duty ratio controller; the controller stores characteristic data of an opening stage and characteristic data of a closing stage of the hydraulic valve in an array form;
the opening stage of the hydraulic valve is divided into a first opening stage and a second opening stage which are continuous in time, and the closing stage is divided into a first closing stage and a second closing stage which are continuous in time;
wherein each set of start-up stage characteristic data comprises a and SOpening device、V1、b、V2、TOpening deviceSix parameters; a is the duty cycle of the first turn-on phase; sOpening deviceThe valve core stroke is the percentage of the valve core stroke in the total stroke when the valve core stroke is switched from the first opening stage to the second opening stage; v1 is the initial opening buffer speed, which represents the speed of the valve core when switching from the first opening stage to the second opening stage, b is the duty ratio of the second opening stage, and V2 is the final opening buffer speed, which represents the speed when the valve core is completely opened; t isOpening deviceIs the total time of the opening stage;
each set of closing stage characteristic data comprises c and SClosing device、V3、d、V4、TClosing deviceSix parameters;
c is the duty cycle of the first off phase; s is closed as a valve core stroke, and the value of the valve core stroke represents the percentage of the total stroke when the first closing stage is switched to the second closing stage; v3 is the closing buffer initial speed, which represents the valve core speed when switching from the first closing stage to the second closing stage, d is the duty cycle of the second closing stage, V2 is the closing buffer final speed, which represents the speed when the valve core is completely closed; t isClosing deviceIs the total time of the shutdown phase;
the method specifically comprises the following steps: in the opening stage of the hydraulic valve, the controller searches a group of opening stage characteristic data in a matching way according to at least one parameter input by a user, and a and S in the group of opening stage characteristic dataOpening deviceAnd b; the controller firstly controls the output duty ratio of the duty ratio controller to be a, the voltage source outputs a voltage square wave with the duty ratio of a, the valve core starts to move under the action of the voltage square wave, and when the stroke of the valve core reaches SOpening deviceWhen the electromagnetic valve is completely opened, the opening stage is ended;
in the closing stage of the hydraulic valve, the controller searches a group of closing stage characteristic data in a matching way according to at least one parameter input by a user, and c and S in the group of closing stage characteristic dataClosing deviceAnd d; the controller firstly controls the output duty ratio of the duty ratio controller to be c, the voltage source outputs a voltage square wave with the duty ratio of c, the valve core starts to close under the action of the voltage square wave, and when the stroke of the valve core reaches SClosing deviceWhen the duty ratio controller is used, the controller controls the output duty ratio of the duty ratio controller to be d; the voltage source outputs a voltage square wave with a duty ratio of d, under the action of the voltage square wave, the speed of the valve core is reduced and the valve core continues to move until the electromagnetic valve is completely closed, and when the electromagnetic valve is completely closed, the closing stage is finished.
Preferably, before the starting stage, the method further comprises the following steps:
and controlling a duty ratio controller, wherein a voltage source outputs a voltage square wave with a constant duty ratio to enable the coil current of the hydraulic valve to maintain on a preset pre-loading current value to fluctuate, and the pre-loading current value is a preset value smaller than the opening current.
Preferably, before the closing stage, the method further comprises the following steps:
and controlling a duty ratio controller, wherein a voltage source outputs a voltage square wave with a constant duty ratio to enable the coil current of the hydraulic valve to be maintained on a preset opening maintaining current value to fluctuate, and the opening maintaining current value is a preset value larger than a closing current.
Preferably, in the on-phase or off-phase; when there are multiple sets of characteristic data in the opening stage or closing stage matching the input requirement of the user based on the input parameters of the user, selecting TOpening deviceOr TClosing deviceThe minimum array is used as the array executed by the controller, so that the opening and closing dynamic characteristics of the hydraulic valve are ensured.
Preferably, in the on-phase or off-phase; when according to the input parameters of the user, there are multiple sets of TOpening deviceOr TClosing deviceWhen the equal arrays match with the requirements of the user, selecting the array with the minimum V2 or V4 as the array executed by the controller; when there are still multiple sets of arrays matching the user's needs, the array that is executed by the controller is compared to the array with the smaller duty cycle value. The design aims at selecting a scheme with a lower final speed to better prolong the service life of the hydraulic electromagnetic valve when simultaneously meeting the requirements of users and having the same opening and closing dynamic characteristics; when the parameters are the same, the array with the smaller duty ratio is selected, so that the use of high voltage in the control process is reduced, the service lives of the voltage source and the hydraulic solenoid valve coil are prolonged, and the influence of inductance on the control process in the voltage switching process is reduced.
Preferably, in the opening stage, the input parameters of the user are preferably V1, V2 and TOpening deviceOne or more of; in the closing stage, the input parameters of the user are preferably V3, V4 and TClosing deviceOne or more of the above.
The characteristic data of the starting stage is obtained through pre-testing; during testing, selecting X test points from a within the selectable range, and selecting SOpening deviceSelecting Y test points in the optional range, performing Z test points in the optional range on b, and performing single-variable test to obtain V1, V2 and T corresponding to the total X, Y, Z group dataOpening device(ii) a And removing the arrays in which the hydraulic valve can not be completely opened, wherein the remaining arrays form characteristic data of the opening stage.
The characteristic data of the closing stage is obtained through pre-testing; in thatDuring testing, N test points are selected from c in the selectable range, and S is selectedClosing deviceSelecting M test points in the optional range, selecting L test points in the optional range from d, and testing by a single variable method to obtain V3, V4 and T corresponding to N M L group data in totalClosing device(ii) a And removing the array in which the electromagnetic valve can not be completely closed, wherein the residual array forms characteristic data in the closing stage.
Compared with the prior art, the invention has the beneficial effects that:
1) the pulse width modulation is adopted to realize the adjustment of the voltage source output voltage square wave, and the power supply requirement of the whole hydraulic valve control period can be met only by one voltage source, so that the switching process among different voltage sources is omitted, and the problem of control precision caused by the time required by the voltage source switching is avoided. When the pulse width modulation is adopted, signals from a processor to a controlled system are in a digital form, and digital-to-analog conversion is carried out. The noise impact can be minimized. Meanwhile, the invention reduces the configuration quantity of voltage sources in the system, lowers the cost and avoids the problem of equipment waste that only one voltage source works and other voltage sources are in a standby state in most control stages. The duty ratio is adjustable in the pulse width modulation, and the equivalent voltage output by the voltage source can change according to actual requirements, so that the voltage utilization rate is improved, and the energy consumption is reduced.
2) The invention adopts two duty ratios to modulate in an opening stage (the same principle in a closing stage), and the first opening (closing) stage mainly aims at quickly opening a valve (quickly closing in the closing stage), so that the dynamic characteristic is improved; when the valve is opened (closed) to a certain degree, the valve is switched to a second opening (closing) stage, and the purpose of the second opening (closing) stage is mainly to reduce the movement speed of the final valve core, so that the valve can be at an acceptable lower speed when being completely opened (closed), the loss of the valve core is reduced, the dynamic characteristic and the flexible opening and closing are considered, and the service life of the hydraulic electromagnetic valve is prolonged.
3) The invention tests the opening (closing) characteristics under various control combinations, and stores the test data into an array after screening, wherein the array comprises parameters which can be selected and input by a user and also comprises control parameters of a controller to a voltage source; therefore, a user can input required opening and closing characteristic parameters, and the controller searches the matched array from the array, so that the controller controls the voltage source to achieve the opening and closing characteristic and gives consideration to the movement speed of the valve core.
4) The array in the database provides accurate control parameters, and the opening and closing characteristics and the valve core speed of the hydraulic electromagnetic valve are accurate, searchable and repeatable, so that the control effect of the method can be expected, a user can completely search the corresponding array by matching the database according to the actually desired effect, and the method has high controllability.
Drawings
Fig. 1 is a schematic structural diagram of a specific system for implementing the control method of the present invention in the embodiment.
FIG. 2 is a graph of hydraulic valve dynamics under a certain set of data in a database.
Detailed Description
The invention will be further illustrated and described with reference to specific embodiments. The technical features of the embodiments of the present invention can be combined correspondingly without mutual conflict.
Fig. 1 is a schematic diagram of a control system structure of this embodiment, which is a specific system structure for implementing the control method of the present invention, and includes a hydraulic valve 4, a coil of the hydraulic valve 4 is connected to a voltage source 2 through a current detector 3, the voltage source is connected to a duty ratio controller 1, a coil current of the hydraulic valve is detected by the current detector 3, and a pressure state of each working port of the hydraulic valve 4 is obtained in real time by a pressure sensing system 6; a displacement sensor is arranged in the hydraulic valve 4 and used for acquiring the motion state of a valve core of the hydraulic valve; the controller 7 is connected with the pressure sensing system 6 to acquire data in the pressure sensing system 6 in real time, and the controller 7 is connected with the displacement sensor 5 to acquire the position and the movement speed of the valve core of the hydraulic valve; the controller 7 is connected with the duty ratio controller 1;
and the controller acquires data in the pressure sensing system in real time so as to calculate the system opening current and the system closing current in the current state. The controller generates a control signal 8 to participate in operations such as internal calculation and digital triggering of the controller. For ease of illustration, the control signals are depicted outside the controller in FIG. 1. The control signal is a square wave with adjustable frequency and duty ratio. Because the control signal is generated by the controller, the controller can also know the duty ratio, the frequency, the rising edge time and the falling edge time of the control signal in different states and know when the rising edge of the control signal in the next period comes.
The displacement sensor can obtain the displacement and the speed of the valve core in real time. When the valve core is displaced, the displacement of the valve core causes the resistance of the potentiometer in the displacement sensor to change. The amount of change in resistance reflects the magnitude of the displacement. After the displacement magnitude is obtained, the controller conducts derivation according to the obtained displacement magnitude to obtain the speed of the valve core.
The invention divides the opening phase of the hydraulic valve 4 into a first opening phase and a second opening phase which are continuous in time, and the closing phase is divided into a first closing phase and a second closing phase which are continuous in time.
The controller 7 stores characteristic data of the opening stage and the closing stage of the hydraulic valve in an array form;
wherein each set of start-up stage characteristic data comprises a and SOpening device、V1、b、V2、TOpening deviceSix parameters; a is the duty cycle of the first turn-on phase; sOpening deviceThe valve core stroke is the percentage of the valve core stroke in the total stroke when the valve core stroke is switched from the first opening stage to the second opening stage; v1 is the initial opening buffer speed, which represents the speed of the valve core when switching from the first opening stage to the second opening stage, b is the duty ratio of the second opening stage, and V2 is the final opening buffer speed, which represents the speed when the valve core is completely opened; t isOpening deviceIs the total time of the opening stage;
each set of closing stage characteristic data comprises c and SClosing device、V3、d、V4、TClosing deviceSix parameters;
c is the duty cycle of the first off phase; s is closed as a valve core stroke, and the value of the valve core stroke represents the percentage of the total stroke when the first closing stage is switched to the second closing stage; v3 is the closing buffer initial velocity, which is represented by the firstThe valve core speed when the closing stage is switched to the second closing stage, d is the duty ratio of the second closing stage, and V2 is the closing buffer end speed and represents the speed when the valve core is completely closed; t isClosing deviceIs the total time of the shutdown phase;
the problems to be solved and the expectations of implementation at the heart of the invention are: when the electromagnetic valve is completely opened and closed, in order to reduce the loss caused by rigid impact on the valve core, the instantaneous speed of the valve core at the moment of complete opening and complete closing needs to be reduced. The speeds of the valve core when the valve core is completely opened and closed are V2 and V4(V2 is the opening buffer end speed, and V4 is the closing buffer end speed), and the numerical values of the two speeds can be adjusted according to the opening and closing speed expected by a user.
The core control strategy of the invention is as follows: in the opening stage of the hydraulic valve 4, the controller 7 searches a group of opening stage characteristic data in a matching way according to at least one parameter input by a user, and a and S in the group of opening stage characteristic dataOpening deviceAnd b; the controller 7 firstly controls the output duty ratio of the duty ratio controller 1 to be a, the voltage source 2 accordingly outputs a voltage square wave with the duty ratio of a, under the action of the voltage square wave, the valve core starts to move, and when the stroke of the valve core reaches SOpening deviceWhen the electromagnetic valve is completely opened, the opening stage is finished after the electromagnetic valve is completely opened;
in the closing stage of the hydraulic valve 4, the controller 7 searches a group of closing stage characteristic data in a matching way according to at least one parameter input by a user, and c and S in the group of closing stage characteristic dataClosing deviceAnd d; the controller 7 firstly controls the output duty ratio of the duty ratio controller 1 to be c, the voltage source 2 accordingly outputs a voltage square wave with the duty ratio of c, under the action of the voltage square wave, the valve core starts to close and move, and when the stroke of the valve core reaches SClosing deviceWhen the duty ratio controller 1 outputs the duty ratio d, the controller 7 controls the output duty ratio of the duty ratio controller 1 to be d; the voltage source 2 outputs a voltage square wave with a duty ratio d, and under the action of the voltage square wave, the valve core reduces in speed and continues to move until the electromagnetic valve is completely closedWhen fully closed, the closing phase ends.
The database only needs to output an array according to the requirements of the user, and the array is in an opening stage or a closing stage; when there are multiple sets of characteristic data in the opening stage or closing stage matching the input requirement of the user based on the input parameters of the user, selecting TOpening deviceOr TClosing deviceThe smallest array serves as the array that the controller executes.
Preferably, in the on-phase or off-phase; when according to the input parameters of the user, there are multiple sets of TOpening deviceOr TClosing deviceWhen the equal arrays match with the requirements of the user, selecting the array with the minimum V2 or V4 as the array executed by the controller; when there are still multiple sets of arrays matching the user's needs, the array that is executed by the controller is compared to the array with the smaller duty cycle value.
In the present invention, V1, V2 and TOpening device、V3、V4、TClosing deviceThe characteristic parameters of the electromagnetic valve concerned by a user are opening and closing characteristic parameters and valve core motion parameters; and a, SOpening device、b、c、d、SClosing deviceThe control parameters (solenoid valve execution parameters) for directly or indirectly controlling the solenoid valve by the controller are parameters for controlling the duty ratio controller and the solenoid valve according to the requirements of users, and the users do not pay attention to the parameters. Therefore, in the opening stage, the input parameters of the user are preferably V1, V2 and TOpening deviceOne or more of; in the closing stage, the input parameters of the user are preferably V3, V4 and TClosing deviceOne or more of the above. Of course, if the user has a special requirement on the control parameter of the solenoid valve (for example, a requirement on the duty ratio), the control parameter of the solenoid valve can also be used as an input parameter for matching and searching.
The method of constructing the data set of the present invention is described below.
The characteristic data of the starting stage is obtained through pre-testing; during testing, X test points are selected according to the duty ratio a of the first starting stage in the selectable range, and S is selectedOpening deviceSelecting Y test points in the optional range, carrying out Z test points on the duty ratio b of the second opening stage in the optional range, and testing by a single variable method to obtain V1, V2 and T corresponding to the total X, Y and Z group dataOpening device(ii) a And removing the arrays in which the hydraulic valve can not be completely opened, wherein the remaining arrays form characteristic data of the opening stage.
The characteristic data of the closing stage is obtained through pre-testing; during testing, N test points are selected according to the duty ratio c of the first closing stage in the selectable range, and S is selectedClosing deviceSelecting M test points in the selectable range, selecting L test points in the selectable range according to the duty ratio d of the second closing stage, and testing by a single variable method to obtain V3, V4 and T corresponding to N M L group of dataClosing device(ii) a And removing the array in which the electromagnetic valve can not be completely closed, wherein the residual array forms characteristic data in the closing stage.
Taking the characteristic data of the starting stage as an example, SOpening deviceDividing by 100 equal parts, wherein values are respectively 1%, 2%,. and 100%; sOpening deviceWhen the value is 100%, the electromagnetic valve is completely opened, and the second variable voltage source is not connected in the opening stage;
the duty cycle a of the first switching-on phase varies over a range a0～100％(a0Is the duty cycle for the turn-on voltage). A is to0100% were aliquoted, taking each aliquot as Δ a. The voltage value at each bisector in the variation range is a0+iΔa，i＝0，1，2，3，...X-1，a0+(X-1)Δa＝1。
The driving voltage in the second starting stage is a voltage square wave with a duty ratio of b (also called as a starting buffer voltage), the variation range of b is-100%, and b is less than or equal to a. B is divided equally over its selectable range, taking each equal score as Δ b. The voltage value at each bisector within the range of variation is-1 + i Δ b, i ═ 0, 1, 2, 3.
Firstly, the duty ratio a output by the duty ratio controller in the first opening stage is determined as a0The output duty ratio of the voltage source is a0At a duty cycle of a0Under the excitation of the voltage square wave, the valve core starts to move, when the displacement of the valve core reaches 1% of the maximum stroke, the displacement sensor obtains the speed V1 (initial speed of opening buffer) of the valve core at the moment, the first opening stage is finished, the second opening stage is entered, and the duty ratio in the second opening stage is selected for controllingThe duty cycle b output by the controller is-100%, and the instantaneous speed V2 when the solenoid valve is fully opened under-100% is measured (if the solenoid valve can not be fully opened under the duty cycle, the data is recorded as invalid data). And measuring the time T from opening to full opening of the solenoid valve under the action of the duty ratios a and bOpening device(on time). Is recorded under (a)0、1％、V1、-1、V2、TOpening device)。
Keeping the duty ratio a output by the duty ratio controller in the first starting stage as a0And when the displacement of the valve core reaches 1% of the maximum stroke, the displacement sensor obtains the speed V1 of the valve core at the moment, the first opening stage is ended, the second opening stage is entered, and the duty ratio b output by the duty ratio controller in the second opening stage is taken as-1 + delta b. The instantaneous velocity V2 (end-of-opening buffer velocity) at which the solenoid valve was fully open under the influence of b being-1 + Δ b was measured. And the time T from opening to full opening of the solenoid valve under the action of the duty ratios a and bOpening device. Is recorded under (a)0、1％、V1、-1+Δb、V2、TOpening device). If the solenoid valve can not be completely opened under the combined action of the duty ratios, the data is recorded as invalid data.
Thirdly, because the duty ratio b of the second starting stage has Z test points, the duty ratio of the first starting stage is a0、SOpening deviceTaking 1% of cases, the measurement operation of step two needs to be repeated for Z times. Finally obtaining Z group (a)0、1％、V1、b、V2、TOpening device) Wherein invalid data is also denoted as a set of data.
Fourthly, the first to third steps are that in the first starting stage, the duty ratio of the first starting stage is a0、SOpening deviceThe test was carried out in 1% of cases, which were measured. Measuring the duty cycle as a in the first switching-on phase0Displacement of spool SOpening deviceTest data for the cases when 2%, 3%, 4% … 100% of the stroke was reached, respectively. Obtain 100 x Z groups (a)0、SOpening device、V1、b、V2、TOpening device) The data of (1).
Fifthly, when the duty ratio of the first opening stage is a0After the condition measurement is completed. Increasing the duty cycle to a0+ Δ a, the voltage of the repetitive turn-on phase is a0Measurement operation in case of + Δ a. Since X test points are selected for the duty cycle in the first start-up phase, the measurement operation of steps one to four needs to be repeated X times. Finally 100X Z X portions (a, S) are obtainedOpening device、V1、b、V2、TOpening device) And (4) data.
Sixth, since the duty ratio in the second opening stage may be an inverse value, the current is decreased to a value below the closing current, and the solenoid valve cannot be fully opened, or is closed early after being opened, and therefore, data is further detected. 100X Z X portions (a, S) were obtainedOpening device、V1、b、V2、TOpening device) After the data is processed, invalid data, namely data that the electromagnetic valve cannot be completely opened, is deleted, and all valid data are input into a database.
The acquisition of the dynamic characteristic data of the closing phase is similar to that of the opening phase. The duty cycle c of the first closing stage and the spool displacement are kept unchanged by 1%, and under the condition, the duty cycle d of the second closing stage is subjected to L test experiments. Then, keeping the duty cycle c of the first closing phase constant, the displacement of the valve core is increased from 1% to 100%, and 100 × L sets of experiments are performed in total. And then taking the duty ratio c of the first closing stage to test different test points for N times. A total of 100 × N × L experiments were performed; 100 portions of N, L (c, S) were obtainedClosing device、V3、d、V4、TClosing device) After the data, if the solenoid valve cannot be completely closed, the data is invalid and is discarded. All valid data is entered into the database. Said SClosing deviceDividing by 100 equal parts, and taking the value of 1% -100%; sClosing deviceWhen the value is 100%, the electromagnetic valve is completely closed, and the closing stage does not comprise a second closing stage.
The control method of the present invention may be based on an 8-stage solenoid valve control strategy, for example, a single duty cycle of the solenoid valve is divided into 8 stages, which are respectively represented by arabic numerals of (r) - (r). Wherein, the first represents a preloading excitation stage, the second represents a preloading maintenance stage, the third represents a first opening stage, the fourth represents a second opening stage (opening buffer stage), the fifth represents a maintenance stage, the sixth represents a first closing stage, the seventh represents a second closing stage (closing buffer stage), and the seventh represents a closing maintenance stage. The end time coincides with the rising edge time of the control signal, and the start time coincides with the falling edge of the control signal; the third and fourth are called opening stage, and the sixth and seventh are called closing stage.
The controller generates a control signal, before the rising edge of the control signal comes, the controller calculates the time required for increasing the coil current to the preloading current according to the current coil current state and the coil parameters, the time is used as the duration time of the preloading excitation stage, the first stage is carried out according to the duration time of the preloading excitation stage, the controller triggers the duty ratio controller in advance, the duty ratio controller outputs a high-frequency square wave signal with the duty ratio of 100% to a voltage source, the voltage source starts to output a voltage square wave with the duty ratio of 100%, and under the excitation of the voltage square wave, the coil current quickly reaches a preloading current state which surrounds a value slightly smaller than the starting current and does high-frequency small-amplitude fluctuation. The preload current is slightly less than the turn-on current, typically 90-95% of the turn-on current. The opening voltage and the opening current are the driving voltage and the coil current in the opening critical state of the hydraulic valve, and are parameters which are known in advance.
Because the duration of the first stage is calculated by the controller according to the current electrical parameters of the coil, when the duration of the first stage is over, the current of the coil is kept in a pre-loading current state slightly smaller than the starting current to do high-frequency small fluctuation. At the moment, the duration of the first stage is finished, the second stage is started, the controller triggers the duty ratio controller, the duty ratio controller outputs a high-frequency square wave signal with the duty ratio of e to the voltage source, the voltage source starts to output a voltage square wave with the duty ratio of e, wherein 0< e <1, and under the action of the preloading maintaining voltage, the coil current is always kept in a preloading current state, namely, the coil current surrounds a numerical value slightly smaller than the starting current and is in a preloading current state with high-frequency small fluctuation. (stage two, the value of the modulated voltage is slightly less than the product of the opening current and the resistance)
After the end of stage (II), when the control signal rising edge comes, it enters stage (III). The controller can open the buffer initial speed V1 and open the buffer end according to the requirement of the userSpeed V2, opening time TOpening device. Finding corresponding data (a, S) in a databaseOpening device、V1、b、V2、TOpening device). The controller triggers the duty ratio controller, the duty ratio controller outputs a high-frequency square wave signal with the duty ratio a to the voltage source, and the voltage source starts to output a voltage square wave with the duty ratio a, and the equivalent voltage value of the voltage square wave is U1. And step three, a is a fixed value. Under the action of the equivalent voltage U1 in the first opening stage, the current rises to the opening current, and the valve core starts to move. The current continues to rise, the valve core is in an acceleration state, and when the valve core stroke reaches SOpening device(the valve core speed reaches V1), the stage (III) is finished, and the stage (IV) is entered.
The initial valve core speed at the stage (iv) is V1, in order to make the valve core speed reach the opening buffer speed V2. The controller triggers the duty ratio controller, the duty ratio controller outputs a high-frequency square wave signal with the duty ratio b to the voltage source, the voltage source starts to output a voltage square wave with the duty ratio b, the equivalent voltage value is U2, and b is a fixed value in the fourth stage. Under the action of the opening buffer voltage U2, the current changes, the electromagnetic force changes, and the valve core begins to change to the V2 expected by a user. When the solenoid valve is fully open, the spool speed just changes to V2.
When the electromagnetic valve is fully opened, entering the stage (v). The displacement sensor outputs a signal to the controller, the duty ratio controller outputs a high-frequency square wave signal with the duty ratio of f (0< f <1) to the voltage source, and the voltage source starts to output a voltage square wave with the duty ratio of f, namely a maintaining voltage (the maintaining voltage is slightly larger than a closing voltage). Under this voltage, the current drops to a sustain current (sustain current — coil resistance — sustain voltage). Preferably, to improve the turn-off dynamics, the turn-on holding current value is slightly larger than the turn-off current, preferably 105-110% of the turn-off current.
When the control signal falling edge comes, enter stage (c). The controller can close the initial speed V3, the final speed V4 and the closing time T according to the requirements of the userClosing device. Finding corresponding data (c, S) in a databaseClosing device、V3、d、V4、TClosing device). The controller triggers a duty cycle controller which outputs a high frequency with a duty cycle of cThe square wave signal is sent to a voltage source, and the voltage source outputs a voltage square wave with the output duty ratio c, and the equivalent voltage value is U3. Under the action of the first closing stage equivalent voltage U3, the current drops to a closing current, and the valve core begins to close. The current continues to drop, the valve core is in an acceleration state, and when the valve core stroke reaches SClosing device(valve core speed reaches V3), the stage is finished, and the stage is entered.
Stage (c) the initial valve core speed is V3, so as to make the valve core speed reach closing buffer speed V4; the controller triggers the duty ratio controller, the duty ratio controller outputs a high-frequency square wave signal with the duty ratio d to the voltage source, and the voltage source outputs a voltage square wave with the duty ratio d, and the equivalent voltage value of the voltage square wave is U4. Under the action of the equivalent voltage U4 in the second closing stage, the current changes, the electromagnetic force changes, and the valve core speed changes towards the V4 value expected by a user. When the solenoid valve is fully closed, the spool speed just changes to V4.
When the hydraulic valve is completely closed, it enters the stage (b). The displacement sensor outputs a signal to the controller, the controller triggers the duty ratio controller, the duty ratio controller outputs a high-frequency square wave signal with the duty ratio of 0 to the voltage source, and the voltage source starts to output a voltage square wave with the duty ratio of 0, namely, power is not supplied. And repeating the process by the system until the phase (i) of the next period comes.
As shown in fig. 2, a dynamic characteristic curve of the hydraulic valve under a certain group of data in the database, as can be seen from the graph, one cycle of the graph is composed of 8 stages, each stage is controlled by a duty ratio, in this embodiment, the opening and closing characteristics and the valve core speed required by a user are realized by data called from the database, the dynamic characteristic curves of three cycles are the same, and the control is stable and reliable.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A method for controlling the opening and closing process of a hydraulic valve by a database and pulse width modulation is characterized in that,
a coil of the hydraulic valve (4) is connected with a voltage source (2), the voltage source is connected with the duty ratio controller (1), and a displacement sensor (5) is installed in the hydraulic valve (4) and used for acquiring the motion state of the valve core; the controller (7) is connected with the displacement sensor (5) to obtain the position and the movement speed of the valve core of the hydraulic valve; the controller (7) is connected with the duty ratio controller (1); the controller (7) stores characteristic data of an opening stage and characteristic data of a closing stage of the hydraulic valve in an array form;
the opening stage of the hydraulic valve (4) is divided into a first opening stage and a second opening stage which are continuous in time, and the closing stage is divided into a first closing stage and a second closing stage which are continuous in time;
wherein each set of start-up stage characteristic data comprises a and SOpening device、V1、b、V2、TOpening deviceSix parameters; a is the duty cycle of the first turn-on phase; sOpening deviceThe valve core stroke is the percentage of the valve core stroke in the total stroke when the valve core stroke is switched from the first opening stage to the second opening stage; v1 is the initial opening buffer speed, which represents the speed of the valve core when switching from the first opening stage to the second opening stage, b is the duty ratio of the second opening stage, and V2 is the final opening buffer speed, which represents the speed when the valve core is completely opened; t isOpening deviceIs the total time of the opening stage;
each set of closing stage characteristic data comprises c and SClosing device、V3、d、V4、TClosing deviceSix parameters;
c is the duty cycle of the first off phase; sClosing deviceThe valve core stroke is the percentage of the valve core stroke in the total stroke when the valve core stroke is switched from the first closing stage to the second closing stage; v3 is the closing buffer initial speed, which represents the valve core speed when switching from the first closing stage to the second closing stage, d is the duty cycle of the second closing stage, V4 is the closing buffer final speed, which represents the speed when the valve core is completely closed; t isClosing deviceFor the closing phaseWhen the total time is used;
the method specifically comprises the following steps: in the opening stage of the hydraulic valve (4), the controller (7) matches and searches a group of opening stage characteristic data according to at least one parameter input by a user, and a and S in the group of opening stage characteristic dataOpening deviceAnd b; the controller (7) firstly controls the duty ratio of the output voltage square wave of the duty ratio controller (1) to be a, the voltage source (2) outputs the voltage square wave with the duty ratio of a accordingly, the valve core starts to move under the action of the voltage square wave, and when the stroke of the valve core reaches SOpening deviceWhen the electromagnetic valve is completely opened, the opening stage is finished after the electromagnetic valve is completely opened;
in the closing stage of the hydraulic valve (4), the controller (7) matches and searches a group of closing stage characteristic data according to at least one parameter input by a user, and c and S in the group of closing stage characteristic dataClosing deviceAnd d; the controller (7) firstly controls the output duty ratio of the duty ratio controller (1) to be c, the voltage source (2) outputs a voltage square wave with the duty ratio of c, the valve core starts to close under the action of the voltage square wave, and when the stroke of the valve core reaches SClosing deviceWhen the voltage is in a high-voltage state, the controller (7) controls the duty ratio of the output voltage square wave of the duty ratio controller (1) to be d; the voltage source (2) outputs a voltage square wave with the duty ratio of d, under the action of the voltage square wave, the speed of the valve core is reduced and the valve core continues to move until the electromagnetic valve is completely closed, and when the electromagnetic valve is completely closed, the closing stage is finished.
2. The method for controlling the opening and closing process of a hydraulic valve according to claim 1, further comprising the steps of, prior to the opening phase:
and controlling a duty ratio controller, wherein a voltage source outputs a voltage square wave with a constant duty ratio to enable the coil current of the hydraulic valve to maintain on a preset pre-loading current value to fluctuate, and the pre-loading current value is a preset value smaller than the opening current.
3. The method for controlling the opening and closing process of a hydraulic valve according to claim 1 or 2, characterized by further comprising, before the closing phase, the steps of:
and controlling a duty ratio controller, wherein a voltage source outputs a voltage square wave with a constant duty ratio to enable the coil current of the hydraulic valve to be maintained on a preset opening maintaining current value to fluctuate, and the opening maintaining current value is a preset value larger than a closing current.
4. Method for controlling the opening and closing process of a hydraulic valve by means of a database and pulse width modulation according to claim 1, characterized in that in the opening phase or in the closing phase; when there are multiple sets of characteristic data in the opening stage or closing stage matching the input requirement of the user based on the input parameters of the user, selecting TOpening deviceOr TClosing deviceThe smallest array serves as the array that the controller executes.
5. The method for controlling the opening and closing process of a hydraulic valve according to claim 4, characterized in that in the opening phase or the closing phase; when according to the input parameters of the user, there are multiple sets of TOpening deviceOr TClosing deviceWhen the equal arrays match with the requirements of the user, selecting the array with the minimum V2 or V4 as the array executed by the controller; when there are still multiple sets of arrays matching the user's needs, the array that is executed by the controller is compared to the array with the smaller duty cycle value.
6. Method for controlling the opening and closing process of a hydraulic valve according to claim 1, wherein the user input parameters are preferably V1, V2, T during the opening phaseOpening deviceOne or more of; in the closing stage, the input parameters of the user are preferably V3, V4 and TClosing deviceOne or more of the above.
7. Passing database and pulse width modulation according to claim 1The method for controlling the opening and closing process of the hydraulic valve is characterized in that the characteristic data of the opening stage is obtained by pre-testing; during testing, selecting X test points from a within the selectable range, and selecting SOpening deviceSelecting Y test points in the optional range, performing Z test points in the optional range on b, and performing single-variable test to obtain V1, V2 and T corresponding to the total X, Y, Z group dataOpening device(ii) a And removing the arrays in which the hydraulic valve can not be completely opened, wherein the remaining arrays form characteristic data of the opening stage.
8. The method for controlling the opening and closing process of a hydraulic valve according to claim 1, wherein the closing phase characteristic data is obtained by pre-testing; during testing, c selects N test points in the selectable range, and SClosing deviceSelecting M test points in the optional range, selecting L test points in the optional range from d, and testing by a single variable method to obtain V3, V4 and T corresponding to N M L group data in totalClosing device(ii) a And removing the array in which the electromagnetic valve can not be completely closed, wherein the residual array forms characteristic data in the closing stage.
9. The method of claim 7, wherein S is a database and is a method for controlling the opening and closing of a hydraulic valve using pulse width modulationOpening deviceDividing by 100 equal parts, wherein values are respectively 1%, 2%,. and 100%; sOpening deviceWhen the value is 100%, the electromagnetic valve is completely opened, and the opening stage is only the first opening stage;
the equivalent voltage value of the voltage square wave with the duty ratio of a is larger than the opening voltage of the electromagnetic valve, the duty ratio b can select a positive value or a negative value, and the negative value represents that the direction of the output current of the second opening stage is opposite to that of the first opening stage.
10. The method of claim 8, wherein S is a database and is a pulse width modulation control for the opening and closing of the hydraulic valveClosing deviceDividing by 100 equal parts, wherein values are respectively 1%, 2%,. and 100%; sClosing deviceWhen the value is 100%, the electromagnetic valve is completely closed, the closing stage is only the first closing stage, the equivalent voltage value of the voltage square wave with the duty ratio of c is smaller than the closing voltage of the electromagnetic valve, and c and d can be selected to be positive values or negative values.
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