CN1804747A - Method for controlling continuous adjustment of flow by using electromagnetic on-off valve - Google Patents

Abstract

The invention relates to a method for using electromagnetic switch valve to control the flow which can period open and close electromagnetic switch valve before achieving the object value, wherein f(t) is the input signal of the electromagnetic switch valve, when f(t)=1, the electromagnetic switch valve opens; t is the real time; tn=(deltax/B)2*KT is the logic 1 time of the control switch valve; n is the period number; T is the minimum switch period of the switch valve; K>=1 is the adjusting factor; deltax is object value differential value; B is the adjusting factor of the enclosed ring control factor.

Description

With the continuously adjustable method of electromagnetic switch valve Control Flow

Affiliated technical field

The invention belongs to fluid flow control field, a kind of specifically with the continuously adjustable method of electromagnetic switch valve Control Flow, relate to the method that physical quantity targets such as position, pressure, flow reach certain precision prescribed control.

Background technology

In industries such as metallurgy, water conservancy, environmental protection, by the accurate control of hydraulic system to physical quantity targets such as flow, pressure, positions, often adopt LINEAR CONTINUOUS topworkies such as proportioning valve, servo-valve, the rate-of flow that flows through its valve by stepless control is finished, as the disclosed electro-hydraulic servo position control of Chinese patent CN2646748 just the continuous adjusting of flow is realized position control by servo-valve.But proportioning valve, servo-valve often need corresponding configuration one cover electrical servo system could work, so the complex structure of its valve, failure rate is also high, expensive accordingly, maintenance cost is high, also higher to the requirement of environment for use.In addition, linear valves such as proportioning valve, servo-valve are very easy to take place situations such as spool is stuck, component wear, and its serviceable life is shorter.There is not the deficiency of above-mentioned linear valve in electromagnetic switch valve (or claiming the logic switch valve), and control is simple, reliability is higher, but it only possesses switching function, can not carry out continuity control to rate-of flow, therefore, when being carried out the continuity closed-loop control, the physical quantity target do not adopt switch valve at present.

Summary of the invention

Technical matters to be solved by this invention is: overcome the existing complex structures of linear actuator such as usage ratio valve, servo-valve in the prior art, reliability is not high, maintenance cost is high, environment for use is required high deficiency, provide a kind of with the continuously adjustable method of electromagnetic switch valve Control Flow, this method can be adjustable continuously to rate-of flow, and control accuracy is higher.

The technical scheme that addresses the above problem is: what provided is as follows with the continuously adjustable method of electromagnetic switch valve Control Flow:

Electromagnetic switch valve consecutive periods ground carries out opening and closing before arriving given fluid aim parameter;

1) each unlatching, the unlatching of closing electromagnetic switch valve in the cycle, shut-in time are determined by following formula;

$f\left(t\right)=\left\{\begin{array}{cc}1;& t\∈[(n-1)\mathrm{KT},(n-1)\mathrm{KT}+t_n]\\ 0;& t\∈((n-1)\mathrm{KT}+t_n,\mathrm{nKT})\end{array}\right.$

In the formula:

F (t) is the input signal of electromagnetic switch valve, f (t)=1 o'clock, and the electromagnetic switch opening of valves; F (t)=0 o'clock, electromagnetic switch valve was closed;

T is a real-time time;

t _nBe the logical one time of gauge tap valve;

N is a periodicity, and n is the positive integer more than or equal to 1, i.e. n=1, and 2,3,

T is the minimum switch periods of switch valve;

K is for adjusting coefficient, K 〉=1, it is relevant with the minimum switch periods T of switch valve and the system inertia controlled, the value of K should make system inertia reduce to be as the criterion, if the system inertia of control is bigger, adjust the desirable higher value of COEFFICIENT K, the K value is the adjusting time of conference increase control system too, generally speaking, the value of adjustment COEFFICIENT K is: 5 〉=K 〉=2;

2) the logical one time t of gauge tap valve in the following formula _nDetermine by following expression:

t _n＝(Δx÷B) ²×KT

In the formula:

Δ x is aim parameter difference (referring to the poor of fluid aim parameter given in the closed-loop control system and actual amount);

B is the adjustment coefficient of closed-loop control system, and it is relevant with control accuracy, and it is more little to adjust coefficient B within the specific limits, and the degree of regulation of system is just high more, and generally speaking, the value of adjusting coefficient B is: 1 〉=B 〉=0.1.

From the above mathematical model of setting up as can be known: aim parameter difference DELTA x is big more, the service time t of switch valve in one-period _nJust long more; X is more little for the aim parameter difference DELTA, the service time t of switch valve in one-period _nJust short more.In real process, along with reducing of aim parameter difference DELTA x, the service time t of switch valve in one-period _nReduce gradually, until reaching desired precision.

Compared with prior art, the present invention is owing to adopted electromagnetic switch valve, and not only implementation cost is lower, and implements simple, reliable.In addition, the present invention is less demanding to environment for use, so range of application is wider, as can be used for the control of hydraulic jack plunger positioning system, water factory's pipeline valve control, the control of slurry transportation pipeline valve of plant equipment etc.Use the present invention can the substitute proportion valve, linear valve parts such as servo-valve, not only reduced use cost, and have should not stop up, more not easy to wear, advantages such as the parts functions of use is reliable more, longer service life.

Description of drawings

Fig. 1 is a control principle block diagram of the present invention.

Fig. 2 is the control block diagram of an example of the present invention.

Fig. 3 is the test result curve map of the embodiment of the invention.

Embodiment

Control principle of the present invention is as shown in Figure 1: aim parameter difference DELTA x input t _n=(Δ x ÷ B) ²In * KT the computing module 21, obtain t _nWith real-time time t and KT complementation (being t%KT), obtain a numerical value rt, again t from 0 to KT range _nCompare by comparer 22 with numerical value rt, if t _nDuring 〉=rt, the output signal f of its output module 23 (t) is 1, if t _nDuring＜rt, output signal f (t) is 0; Output signal f (t) controls electromagnetic switch valve 24: when f (t) was 1, switch valve 24 was opened, and when f (t) was 0, switch valve 24 cut out; For by the medium total amount S in the system of switch valve 24 control, be the integration of the rate-of flow relevant with its physical arrangement parameter P.

Fig. 2 has provided the control block diagram that the present invention is used for conticaster liquid cylinder pressure piston position closed-loop system.The present invention controls the piston position of hydraulic cylinder by the three-position switch solenoid valve, and the fluid pressure source of system is constant.

During this control system work, at first set the position given of expectation, control system obtains the feedback signal of displacement transducer 36, and according to the output of mathematical model control figure template card 33 of the present invention, the break-make of output signal control electromagnetic switch valve 34 is controlled hydraulic cylinder 35 position of piston.

The minimum switch periods T of electromagnetic switch valve is 250 milliseconds (inertia of system is very big) in this example; Adjust values of factor K and be made as 4, can reduce the switch number of times of valve like this, help reducing oil cylinder inertia, also help the serviceable life that prolongs valve; It is more little to adjust coefficient B, and the degree of regulation of system is just high more, adjusts coefficient B in this example and is set at 0.5; The switch periods KT=1000 millisecond of electromagnetic switch valve when system moves.According to t _n=(Δ x ÷ B) ²* KT, when aim parameter difference DELTA x=0.5 millimeter, t _n=KT=1000 millisecond, that is to say when aim parameter difference DELTA x be that switch valve is in opening state always before 0.5 millimeter, the aim parameter difference is less than reducing the service time t of solenoid valve along with the aim parameter difference after 0.5 millimeter _nReduce gradually.For example, during aim parameter difference DELTA x=0.4 millimeter, the service time t of solenoid valve _nBe 640 milliseconds, the time of closing is 360 milliseconds; During aim parameter difference DELTA x=0.3 millimeter, the service time t of solenoid valve _nBe 360 milliseconds, the shut-in time is 640 milliseconds.Final solenoid valve cuts out fully, and hydraulic cylinder piston stops on the desired position.

Electromagnetic switch valve has a work dead band τ in actual motion, and promptly when switching time was in this work dead zone range, valve was less than action.(if Δ x ÷ B) ²During * KT＜τ, final objective amount difference DELTA x can satisfy accuracy requirement, then needn't consider the work dead-time problem of electromagnetic switch valve.

If further improve control accuracy, can consider the work dead-time problem of electromagnetic switch valve.That is:

As τ/C≤(Δ x ÷ B) ²During * KT＜τ, make t _n=τ;

As (Δ x ÷ B) ²During * KT＜τ/C, make t _n=0;

τ is the work dead band of electromagnetic switch valve in the formula, and C is the coefficient greater than 1.

The work dead band of electromagnetic switch valve is 20 milliseconds in this example, and coefficient C is set at 2, that is: when service time of the electromagnetic switch valve that calculates less than 20 milliseconds, and during more than or equal to 10 milliseconds, make t _n=20 milliseconds; When service time of the electromagnetic switch valve that calculates during, just think that the aim parameter difference is 0, makes t less than 10 milliseconds _n=0.

The hydraulic cylinder piston position set-point that this example sets is 20 millimeters, the data such as the table 1 of surveying in system's actual motion, and data and curves is as shown in Figure 3.

Table 1

Physical location (millimeter)	Desired location (millimeter)	t n(millisecond)	KT (millisecond)
				14.97	20	1000	1000
19.5	20	1000	1000
				19.515	20	941	1000
19.89	20	48	1000
				19.955	20	0	1000

From table 1 and Fig. 3 as can be seen, hydraulic cylinder piston moves since 15 millimeter places, switch valve is always for opening state before the aim parameter difference is 0.5 millimeter (physical location is 19.5 millimeters), and the aim parameter difference is less than reducing t along with the aim parameter difference after 0.5 _nReduce gradually.Finally through 9 seconds time, physical location arrived 19.955 millimeters, and the position deviation of hydraulic cylinder piston is within 0.05 millimeter.

Claims (3)

1, with the continuously adjustable method of electromagnetic switch valve Control Flow, it is characterized in that:

The electromagnetic switch valve consecutive periods carries out opening and closing before arriving given fluid aim parameter;

1) each unlatching, the unlatching of closing electromagnetic switch valve in the cycle, shut-in time are determined by following formula;

$f\left(t\right)=\left\{\begin{array}{cc}1;& t\∈[(n-1)\mathrm{KT},(n-1)\mathrm{KT}+t_n]\\ 0;& t\∈((n-1)\mathrm{KT}+t_n,\mathrm{nKT})\end{array}\right.$

In the formula:

F (t) is the input signal of electromagnetic switch valve, f (t)=1 o'clock, and the electromagnetic switch opening of valves; F (t)=0 o'clock, electromagnetic switch valve was closed;

T is a real-time time;

t _nBe the logical one time of gauge tap valve;

N is a periodicity, and n is the positive integer more than or equal to 1;

T is the minimum switch periods of switch valve;

K is for adjusting coefficient, K 〉=1;

2) the logical one time t of gauge tap valve in the following formula _nDetermine by following expression:

t _n＝(Δx÷B) ²×KT

In the formula:

Δ x is the aim parameter difference;

B is the adjustment coefficient of closed-loop control system.

2, control method as claimed in claim 1, the span that it is characterized in that said adjustment COEFFICIENT K is 5 〉=K 〉=2, the span of adjusting coefficient B is 1 〉=B 〉=0.1.

3, control method as claimed in claim 1 or 2 is characterized in that:

As τ/C≤(Δ x ÷ B) ²During * KT＜τ, make t _n=τ;

As (Δ x ÷ B) ²During * KT＜τ/C, make t _n=0;

τ is the work dead band of electromagnetic switch valve in the formula, and C is the coefficient greater than 1.

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