JP3138028B2 - Flow control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow control device for feedback controlling the speed and position of a hydraulic actuator by a flow control valve.

[0002]

2. Description of the Related Art As a device for feedback-controlling the speed of a hydraulic actuator by a flow control valve, FIG.
As shown in the indicated flow rate Q _r valve controller 1 is previously set, and a measured flow rate Q _i measured by the flow meter 3, the flow control valve 2 in accordance with the measured flow rate Q _i and indicated flow rate Q _r correcting the opening degree, the indicated flow rate Q _r and controls the speed of the hydraulic actuator 4 performs feedback control to match are known.

[0003]

[SUMMARY OF THE INVENTION However, when such a temperature or viscosity of the hydraulic oil is changed, the actual flow rate even with the same valve opening changes, also the measured flow rate Q _i also changes in the flow meter 3 and a problem that the indicated flow rate Q _r is is not performed accurate feedback control in order not actually necessarily match the actual flow rate Q flowing into the hydraulic actuator 4 has occurred.

Accordingly, the present invention corrects a measurement error of the flow sensor due to a change in the temperature of the hydraulic oil or the like, and performs high-accuracy feedback control by matching the actual flow rate with the measured flow rate.

[0005]

According to a first aspect of the present invention, as shown in FIG. 1, a flow control valve 2 which is interposed in a hydraulic oil passage of a hydraulic actuator 31 and opens and closes in response to a drive signal is provided with a preset instruction flow rate. valve driving means 32 for driving the flow control valve 2 in accordance with Q _r and the feedback flow Q _f
When a flow rate measuring means 33 for measuring a flow rate Q _i of the operating oil of the flow control valve 2, the displacement sensor 34 for measuring the displacement of the hydraulic actuator 31, the displacement amount L ₀ output is in a predetermined displacement sensor 34 a time measuring means 35 for measuring the time ΔT to reach, the indicated flow rate Q hydraulic actuator 31 based on the _r reaches a predetermined displacement amount L ₀ target time T ₀
, A measured time ΔT and a target time T
A means 36 for correcting the measured flow rate Q _i in accordance with _0, feedback flow the correction value to the valve drive means 32 Q _f
Means 37 for outputting as

A second invention, the displacement sensor 34 measures the displacement of the predetermined interval L ₀ of the hydraulic actuator 31.

A third invention, the displacement sensor 34 measures the displacement of the predetermined each unit interval L ₀ of the hydraulic actuator 31 continuously.

[0008] The fourth invention is to correct the measured flow rate Q _i of the next displacement on the basis of the measurement time ΔT of the correction means 36 is required to last displacement of the predetermined interval L ₀ of the hydraulic actuator 31.

According to a fifth aspect of the present invention, the correction means 36 continuously measures the time required for displacement of the hydraulic actuator 31 for each predetermined unit section L ₀ , and measures the measurement time ΔT _{n-1 of the} previous section.
_{Is used} to correct the measured flow rate Qi in the next section.

[0010]

[Action] A first aspect of the present invention is measured hydraulic actuator 31 in response to an indicated flow rate Q _r target time T ₀ which is calculated from that previously set and the time ΔT that required to displace the predetermined displacement amount L ₀ flow rate Q _i the eliminating an error between the actual flow rate Q supplied to the actual hydraulic actuator 31 to correct, add feedback control to the valve drive means 32 calculates the feedback flow rate Q _f from the measured flow rate Q _i that this correction.

A second aspect of the present invention, the displacement sensor 34 measures the displacement of the predetermined interval L ₀ of the hydraulic actuator 31, the time required for the displacement and [Delta] T.

A third aspect of the present invention, the displacement sensor 34 is a displacement amount for each predetermined unit interval L ₀ continuously measured hydraulic actuator 31, the time required for the displacement of the unit sections L ₀ and [Delta] T.

[0013] The fourth invention is to correct the measured flow rate Q _i of the next displacement based correction means 36 the previous predetermined interval L measurement time ΔT and the target time T ₀ required for the displacement of the ₀ of the hydraulic actuator 31 .

According to a fifth aspect of the present invention, the correction means 36 continuously measures the time required for displacement of the hydraulic actuator 31 for each predetermined unit section L ₀ , and measures the measurement time ΔT _{n−1 of} the previous section and the target time T Based on ₀ , the measured flow rate Q _{in the} next section is corrected.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows a first embodiment, in which 2 is a flow control valve for controlling the flow rate of hydraulic oil supplied from a hydraulic supply source 21, and 3 is installed downstream of the flow control valve 2 to control the hydraulic oil. A flow meter 4 for measuring the flow rate is a hydraulic cylinder that expands and contracts a rod 5 according to the supply amount of hydraulic oil.

[0017] 6 and 7, a limit switch provided in proximity to the rod 5 is fixed at a predetermined distance L _0, the switch is turned on when the tip of the rod 5 passes.

[0018] 1 in the valve controller, and opening and closing the flow control valve 2 in accordance with the indicated flow rate Q _r set in advance,
The flow rate is measured from the output signal of the flow meter 3, the time ΔT from when the limit switch 6 is turned on until the limit switch 7 is turned on is measured, and the measured flow rate Q _i in which an error with respect to the actual flow rate Q is corrected. Is performed based on the feedback control.

First, an outline of the control will be given based on the theory of control, and then specific control will be described in detail.

Generally, the discharge flow rate for the same opening degree of the valve changes depending on the operating temperature and viscosity of the hydraulic oil, and the detection output itself of the flow meter 3 for the same flow rate also depends on the operating temperature, viscosity and other disturbances of the hydraulic oil. fluctuate. That is, the measured flow rate Q _i is

(Equation 1)

It is known that the measured value of the measured flow rate Q _i changes with changes in the temperature and viscosity of the hydraulic oil.

Here, when the hydraulic oil is supplied to the hydraulic cylinder 4 and the rod 5 is extended, the rod 5 is turned on after passing through the limit switch 6 and then moved by a predetermined length L ₀ to turn on the limit switch 7. I do. Assuming that a predetermined time required for the displacement of the predetermined displacement L ₀ when the rod 5 extends at the predetermined speed at the designated flow rate Q _r is the target time T ₀ , the predetermined displacement L ₀ and the valve flow rate Q (hereinafter referred to as the actual flow rate) Q) is expressed by the following equation.

(Equation 2)

The operating speed of the hydraulic cylinder 4 is always the actual flow rate Q
In the above equation, when the feedback control is performed when the measured flow rate Q _i does not match the actual flow rate Q, the time required for passing the predetermined displacement L ₀ is not T ₀ ,
The difference between the measured flow rate Q _i and the actual flow rate Q can be known from the change in the time required for the predetermined displacement L ₀ .

The measured flow rate Q _i ≠ the actual flow rate Q time required for the displacement of a known interval L ₀ in the [Delta] T, whereas, the indicated flow rate Q _r = measured flow rate Q _i = the time to displace the L ₀ when the actual flow rate Q Is the target time T ₀ , ΔT and T ₀ are different as in the following equation.
Incidentally, the L ₀ is calculated based on the indicated flow rate Q _r as described below (6).

(Equation 3)

Therefore, a correction constant K _C shown in the following equation is calculated as a constant for correcting an error between the measured flow rate Q _{i and} the actual flow rate Q.

(Equation 4)

Next, the feedback flow Q _f which eliminated the measurement error becomes Uri measured flow rate Q _i and the correction constant K _C from the shown in the following equation.

(Equation 5)

According to the above equation (4), the valve controller 1
It is indicated flow rate Q so the flow control valve 2 by adding a feedback flow Q _f may be opening and closing as _r and the actual flow rate Q matches, from the above expressions (3) and (4), the measured flow rate Q _i the feedback flow Q _f corrected is determined by the following equation.

(Equation 6)

That is, the feedback flow rate Q obtained by correcting the error of the measured flow rate Q _{i from} the actual flow rate Q by the above equation (5).
By matching the _f the indicated flow rate Q _r, it is possible to match the actual flow rate Q in the indicated flow rate Q _r.

When the target time T ₀ is set as the stroke cross-sectional area S of the hydraulic cylinder 4, T ₀ is obtained from the above equation (2) by the following equation.

(Equation 7)

An example of the flow control to which the above theory is applied will be described with reference to the flowchart of FIG.

[0031] When the start by setting the indicated flow rate Q _r to the valve controller 1 supplies hydraulic fluid to the hydraulic cylinder 4 by opening the flow control valve 2 according to the valve controller 1 is indicated flow rate Q _r.

[0032] reads the indicated flow rate Q _r, the indicated flow rate Q _r
, The target time T ₀ is calculated by the equation (7). (Steps 49 and 50)

[0033] When the tip rod 5 is extended to pass through the limit switch 6, and detects the passage the time T ₁ starts measuring time (step 51) and reads the output of the flow meter 3 (step 53).

When the rod 5 has moved the predetermined displacement L ₀ , the limit switch 7 is turned on, the time T ₂ is detected in step 54, and the time ΔT required for the displacement of L ₀ is calculated (step 55).

At a preset indicated flow rate _Qr , the rod 5
There a predetermined target time T ₀ required for the displacement of the L _0, to calculate the correction constant K _C to correct the measured flow rate Q _i from the calculated time ΔT by the formula (3), the feedback flow from the equation (5) _Qf is calculated (steps 56 and 57).

[0036] The feedback flow Q _f calculated at step 57, the valve controller 1 while maintaining indicated flow rate Q _r and controls the opening and closing of the flow control valve 2 (step 58-61), known under this instruction flow Q _r of the error of the measured flow rate Q _i and the actual flow rate Q and a ΔT obtained in target time T ₀ and the step 55 is monitored, and setting the feedback flow rate Q _f and corrects the error of the measured flow rate Q _i by the correction coefficient K _C Further, when there is a change in indicated flow rate Q _r is always predetermined speed the displacement velocity of the rod 5 by repeating cycle of resetting in accordance with the variation ΔQ in indicated flow rate Q _r in step 59 and 61 I will keep it.

By repeating the above control cycle,
High-precision feedback control is possible without being affected by measurement errors of the flow meter 3 due to disturbances such as changes in the temperature and viscosity of the hydraulic oil and overload, and the hydraulic cylinder 4 can be constantly driven at a predetermined speed. Therefore, the warm-up operation of the hydraulic device is not required, and the productivity can be improved, and the flow rate control with high reliability can be performed even with the aging.

[0038] Figure 4 shows a second embodiment, n aliquoted stroke range of the hydraulic cylinder 4 at a predetermined distance L ₀ in place of the limit switch 6 and 7 of the first embodiment,
At every predetermined interval, n + 1 digital displacement sensors 8
Is provided. This digital displacement sensor 8
For example, it is constituted by a position detector such as a digital stroke sensor or the like, generates a pulse by the displacement of the tip of the rod 5, sends a pulse to the valve controller 1, and other configurations and controls are the same as those of the first embodiment. .

[0039] With the extension of the rod 5, the digital displacement sensor 8 as shown in FIG. 5 generates a sequential pulses from n _1, formed of a predetermined distance L ₀ in the same manner as in the first embodiment each each time displacing the section corrects the error of the measured flow rate Q _i compare the indicated flow rate Q _r time required for the actual displacement a predetermined target time T ₀ which is displaced a predetermined distance L ₀ when the [Delta] T _n Thus, the feedback flow rate _Qf is calculated.

Here, when the tip of the rod 5 passes through the digital displacement sensor 8 of n _i where n = i-th, measurement of ΔT _i is started. At this time, the feedback flow rate Q _fi for controlling the flow control valve 2 is calculated in the section of ΔT _i−1 , which is the n = i−1 th, and is set in an arbitrary section n
Feedback flow Q _fn in is determined from the following equation based on the equation (4) and (5).

(Equation 8)

Therefore, the time ΔT _n for displacing the predetermined interval L ₀ , which is a continuous measurement section, is sequentially measured, and the correction coefficient K _Cn is calculated for each measurement section, and the measured flow rate Q _in and the actual flow rate Q _in are calculated.
To control the flow control valve 2 by the feedback flow Q _fn removing the error between _n, the actual flow rate Q _n match always to the instruction flow Q _r with it is possible to displace the rods 5 at a predetermined speed, the The flow rate control with higher accuracy than in the first embodiment can be performed.

[0042] Figure 6 shows a third embodiment, in the second embodiment the predetermined distance L ₀ to stroke range of the hydraulic cylinder 4 by using an analog displacement sensor 9 in place of the digital displacement sensor 8 The displacement amount is continuously detected by dividing into n equal parts, and is constituted by, for example, a potentiometer or the like. Other configurations and controls are the same as in the first embodiment.

With the extension of the rod 5, the analog displacement sensor 9 detects the displacement as shown in FIG. 7, and the valve controller 1 calculates a predetermined displacement L ₀ , as shown in FIG. spacing rod 5 of the predetermined in the same manner as L ₀
Each time the section consisting of is displaced, a predetermined target time T ₀ for displacing the predetermined interval L ₀ at the indicated flow rate Q _r is compared with a time ΔT _n required for the actual displacement, and the measured flow rate Q _in and calculates the feedback flow rate Q _f to correct the error.

[0044] Here, when the front end of the rod 5 passes through the position of the _i-1 L ₀ is n = i-1 th, measuring the [Delta] T _i is started. At this time, the feedback flow rate Q _fi for controlling the flow control valve 2 is calculated in the immediately preceding section of ΔT _i−1 , and the feedback flow rate Q _fn in an arbitrary section n is calculated by the above equation (8). More required.

[0045] Thus, continuous sequentially measuring the time [Delta] T _n which is displaced a predetermined distance _n L ₀ is the measured segment, calculates the correction coefficient K _Cn for each measurement interval, measures the flow rate Q _in the actual flow rate Q _n to control the flow control valve 2 by the feedback flow Q _fn removing the error between the actual flow rate Q _n match always to the instruction flow Q _r it is possible to displace the rods 5 at a predetermined speed, further predetermined by spacing _n L ₀ of the minute displacement can further perform accurate flow control than the second embodiment.

In the above embodiment, an example in which the linear displacement by the hydraulic cylinder 4 is measured has been described. However, if the actuator is a hydraulic actuator, the same control as in the above embodiment can be performed. , using the hydraulic motor as a hydraulic actuator, in the case of using a rotary encoder as a displacement sensor, with a predetermined rotation angle theta ₀ on behalf of a predetermined length L ₀ of the embodiment, when the indicated flow rate Q _r A correction constant K _C is obtained from the difference between the target time T ₀ required to rotate θ ₀ and the time ΔT required for the actual displacement,
By performing the feedback control in the measured flow rate Q _i of the corrected seek feedback flow rate Q _f, drives the hydraulic actuators at all times at a predetermined speed again to match the indicated flow rate Q _r and actual flow rate Q as Example Becomes possible.

In the above embodiment, the flow meter 3 is provided after the flow control valve 2. However, although not shown, the flow control valve 2 is provided with a flow meter to simplify the structure of the hydraulic circuit. Can be.

That is, by measuring the valve differential pressure of the flow control valve 2 by the pressure sensor and detecting the valve opening area by the valve controller 1, the measured flow rate Q _i can be obtained by the following equation.

(Equation 9)

[0049] By treating the measured flow rate Q _i as in the above embodiment, with a simple configuration, it is possible to match the indicated flow rate Q _r and actual flow rate Q.

[0050]

According to the present invention as described above, according to the present invention, hydraulic actuator indicated flow rate Q _r time required for the actual displacement a predetermined target time T ₀ required to displace a predetermined interval L ₀ when the The measured flow rate Q _i is calculated using the correction coefficient K _C from the difference from ΔT.
The error with the actual flow rate Q is eliminated, and the feedback flow rate Q _f
To perform feedback control to the flow control valve, which enables highly accurate flow control without being affected by disturbances such as changes in the temperature and viscosity of the hydraulic oil and overload.
A hydraulic actuator can be driven at a predetermined speed at all times, which eliminates the need for warming up hydraulic equipment, improving productivity, and ensuring a reliable flow control device even over time. Can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims of the present invention.

FIG. 2 is a configuration diagram showing an embodiment of the present invention.

FIG. 3 is a flowchart of control.

FIG. 4 is a configuration diagram showing another embodiment.

FIG. 5 is a diagram illustrating a relationship between an output pulse and time.

FIG. 6 is a configuration diagram showing another embodiment.

FIG. 7 is a diagram showing a relationship between displacement and time.

FIG. 8 is a configuration diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Valve controller 2 Flow control valve 3 Flow meter 4 Hydraulic cylinder 6 Limit switch 7 Limit switch 31 Hydraulic actuator 32 Valve driving means 33 Flow measuring means 34 Displacement sensor 35 Time measuring means 36 Measured flow correcting means 37 Signal generating means 38 Target time calculation means

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-93101 (JP, A) JP-A-57-116911 (JP, A) JP-A-2-190601 (JP, A) 32367 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) F15B 9/09 F15B 11/04 G05D 7/06 G05D 16/20

Claims (5)

(57) [Claims] 1. A flow control valve interposed in a hydraulic oil passage of a hydraulic actuator and opened and closed according to a drive signal, valve driving means for driving the flow control valve according to a preset instruction flow rate and a feedback flow rate, Flow rate measuring means for measuring the flow rate of the hydraulic oil of the flow rate control valve,
A displacement sensor for measuring a displacement amount of the hydraulic actuator, time measuring means for measuring a time until an output of the displacement sensor reaches a predetermined displacement amount, and a hydraulic actuator reaching the predetermined displacement amount based on the indicated flow rate Means for calculating a target time, means for correcting the measured flow rate according to the measured time and the target time, and means for outputting the correction value to the valve driving means as a feedback flow rate. Flow control device. 2. The apparatus according to claim 1, wherein said displacement sensor measures a displacement amount of a hydraulic actuator in a predetermined section.
A flow control device as described. 3. The flow control device according to claim 1, wherein the displacement sensor continuously measures a displacement amount of the hydraulic actuator for each predetermined unit section. 4. The flow control device according to claim 2, wherein said correction means corrects the measured flow rate at the time of the next displacement based on the previous measurement time of the hydraulic actuator. 5. The flow control device according to claim 3, wherein said correction means corrects a measured flow rate in a next section based on a measurement time in a previous section at the same displacement of the hydraulic actuator.