JPH07301208A - Oil pressure valve spool control method - Google Patents

Abstract

PURPOSE:To compensate for the pilot pressure shortage and maintain a normal learning control, when a plurality of oil pressure valves having a common pilot pressure supply source are simultaneously operated, by controlling the oil pressure through adding the preliminary found short pulse width to a learnt and compensated pulse width. CONSTITUTION:A solenoid valve 2, which is equipped with a pair of changeover valves 2a, 2b, applies the position control of a spool 3 by controlling supply of pilot pressure from a common pilot pressure supply source to an operating chamber on both sides of a spool 3 drive cylinder. The displacement of the spool 3 is fed back to a control device 1 and adopted as a basic data for learning by a position detector 4. When changeover valves 2a, 2b are similtaneously operated, control is accomplished by adding short pulse width corresponding to the preliminary found simultaneously operating mode to the learnt and compensated pulse width. As a result, simultaneous operation of oil pressure valves of respective series become practicable and deterioration of response speed relating to the control operation can be avoided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of controlling a hydraulic circuit used for driving a boom of a construction machine or a work platform for aerial work. More specifically, it relates to a method for controlling a spool of a hydraulic valve such as a hydraulic switching valve that constitutes the hydraulic circuit.

[0002]

2. Description of the Related Art As a conventional control method for a hydraulic valve used in a hydraulic circuit of this type, learning is performed on the basis of immediately preceding data such as a deviation between a immediately preceding command value and a feedback value, and based on the learning result. Using the control pulse with the pulse width corrected, for example, a solenoid valve including a pair of solenoid type directional control valves is on / off controlled, and the spool position is controlled through the control of the solenoid valve to control the boom and other actuators. There is known a control method for controlling hydraulic pressure supply, which has a so-called learning function (Japanese Patent Publication No. 3-81001).

By the way, in controlling the operation of a boom or the like, for example, a multiple hydraulic circuit including a turning hydraulic circuit, a telescopic hydraulic circuit, and an undulating hydraulic circuit is formed. The control pilot pressure used for each hydraulic valve in such a multiple hydraulic circuit is normally supplied from a common pilot pressure supply source that reduces the original pressure. In this case, due to downsizing of the pressure reducing valve and the like, when the multiple hydraulic circuits are simultaneously operated, the flow rate and pressure related to the pilot pressure are actually restricted.

FIG. 2 is a control block diagram of a generally used hydraulic valve unit. As shown in the figure, at least a command signal and a feedback signal from the operation lever or the like are input to the control device 1, and calculation is performed according to an appropriate learning procedure on the basis of deviations thereof,
On / off control of the solenoid valve 2 is performed using a control pulse whose pulse width is corrected based on the learning result. The solenoid valve 2 is composed of a pair of solenoid type switching valves and the like, and spools pilot pressure from a common pilot pressure supply source obtained by reducing the original pressure.
The position of the spool 3 is controlled by controlling the supply to the working chambers on both sides of the drive cylinder.
Then, based on the result of the position control of the spool 3, the hydraulic pressure switching valve (not shown) is switched, the hydraulic pressure supply control to the actuator portion is performed, and the target drive for the boom or the like is performed. The displacement of the spool 3 is detected by the position detector 4 and the control device 1
Is used as basic data for learning in the control device 1.

FIGS. 3 to 5 show the state of pilot pressure in the conventional multiple control, that is, the relationship between the pilot pressure and the operation relationship between the solenoid valves 2a and 2b of each hydraulic valve in the hydraulic circuit of the multiple configuration. It is a thing. In this case, the solenoid valves 2a and 2b are respectively
For example, it is composed of a pair of solenoid type switching valves, and as described above, the position of the spool 3 is controlled by controlling the supply of the pilot pressure P to the working chambers on both sides of the drive cylinder of the spool 3. The pilot pressure P refers to a pilot pressure from a common supply source obtained by reducing the original pressure. In FIG. 3, only the first solenoid valve 2a operates and the second solenoid valve 2b operates.
3 shows a change in pilot pressure P when there is no simultaneous operation state with. In the figure, Pa indicates a pilot pressure (hereinafter simply referred to as a necessary pressure) necessary for accurately pulse-driving the spool 3 of each hydraulic valve in accordance with the control pulse. As shown, in this case, the pilot pressure P fluctuates according to the on / off state of the first solenoid valve 2a.
It does not fall below a. Therefore, in this case, the pilot pressure P does not become insufficient, so that normal learning control is executed.

FIG. 4 shows the first solenoid valves 2a and 2
This shows changes in the pilot pressure P when the continuous solenoid valves 2b are controlled independently of each other and are irregularly operated simultaneously as a result.
As shown in the figure, in this case, the simultaneous operation state of both solenoids 2a and 2b, that is, the range in which the ON states overlap (a)
In (b), since the depressurization gradient of the pilot pressure P is further increased, the pressure may fall below the required pressure Pa.
Therefore, in this case, since the pilot pressure P is insufficient, the flow rate and pressure to the drive cylinders of the corresponding spools 3 are insufficient, resulting in a large error in the position control, and normal learning control is continued. In many cases, it will not be possible.

Therefore, in order to avoid this shortage of pilot pressure P, the first solenoid valve 2a and the second solenoid valve 2b are kept on standby until the other pulse driving is completed so that the solenoid valves 2a and 2b do not operate simultaneously. There are known control methods. FIG. 5 shows a case according to this control method. In this case, the pilot pressure P is prevented from falling below the required pressure Pa as shown in the figure. However, in the case of this control method, there is a drawback that the response speed of each operation is lowered because it is necessary to wait so that they do not operate simultaneously.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above technical circumstances and has the following objects. (1) Assuming that a common supply source is used as a pilot pressure source for controlling each hydraulic valve in a multiple hydraulic circuit, downsizing of pilot pressure supply means such as a pressure reducing valve that constitutes the supply source is achieved. Provided is a control method capable of supplementing a lack of pilot pressure while maintaining normal learning control. (2) To provide a control method that enables simultaneous operation of each hydraulic valve and avoids a decrease in response speed related to the control operation.

[0009]

According to the present invention, a plurality of hydraulic valves having a common pilot pressure supply source are provided, and the position of each spool is controlled by correcting the pulse width based on learning. In a continuous hydraulic circuit, when the hydraulic valves are simultaneously operated, the pulse width corrected by learning is added with a deficient pulse width corresponding to a mode of simultaneous operation, which is controlled. And

[0010]

In the present invention, the shortage pulse width added to the control pulse obtained by the learning operation based on the immediately preceding data is determined by the actual multiple hydraulic circuit for each mode of simultaneous operation. Ask. That is, a specific combination of hydraulic valves operating at the same time, or the total number of stations operating at the same time is changed to experimentally measure the pilot pressure drop for each mode in advance, and an insufficient pulse that can supplement the pilot pressure drop. Find the width and enter it as a control map. In executing the control, a predetermined insufficient pulse width corresponding to the mode of simultaneous operation at each time is selected, the position control of each spool is executed by the control pulse added with the insufficient pulse width, and the control result is fed back. Then, the learning control is continued by using it as basic data.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the solenoid valves 2a, 2 of each hydraulic valve in a multiple structure when the present control method is applied.
b shows the relationship between the operational relationship between each other and the pilot pressure. In this embodiment, when the operation commands are simultaneously output to the first solenoid valve 2a and the second solenoid valve 2b, the control pulse generation points are synchronized with each other. did. A in the figure
Is the deficient pulse width previously obtained by the above-mentioned method, and in this example, the deficient pulse width A corresponding to the case where the number of stations operating simultaneously is two is used. In the present control method, as shown in the figure, it is assumed that the pilot pressure P when the solenoid valves 2a and 2b are simultaneously operated is reduced to the required pressure Pa or less, and this is calculated by adding the insufficient pulse width A. It has a feature in complementing it.

Then, each solenoid valve 2
In the on / off control of a and 2b, when a predetermined insufficient pulse width A is added to each control pulse that operates simultaneously and the control is executed, naturally the on state of each solenoid valve 2a and 2b becomes longer for a predetermined time. Therefore, the supply time of the pilot pressure P to each spool 3 also becomes longer accordingly. The miso of the present invention lies in that the decrease of the pilot pressure P is complemented by the excess of the supply time of the pilot pressure P to each spool 3. As a result, the amount of decrease in the pilot pressure P is not always exactly complemented to all control pulses. However, as described above, the insufficient pulse width A was previously tested in accordance with an actual hydraulic circuit. Since it is what is sought after, the average complement will be within a range that does not pose a problem. The error in the individual control pulses due to the complementary action is
It is fed back in the form of an error in the position control of, and is included in the basic data in the learning operation for the next control pulse. As a result, the error in the complementary action will be corrected in the next control pulse via the learning operation. In this way, normal learning control can be continued.

In the above description of the embodiment, 2
Although the description has been made by focusing on the control relationship between the series of hydraulic valves, it goes without saying that the number of stations can be increased or decreased. Further, in the above embodiment, the case where the control pulses are synchronized with each other at the time of generation of the pulse has been illustrated, but the present invention is not necessarily limited to this. Further, when the insufficient pulse width is made to correspond to each mode of simultaneous operation, as a standard for subdividing the mode, only a specific combination of hydraulic valves is used as a reference, or only the total number of stations operating simultaneously is used as a reference. It is also possible to set it.

[0014]

According to the present invention, the following effects can be obtained. (1) A pilot supply source uses a common supply source as a pilot pressure source for controlling each hydraulic valve in a hydraulic circuit of multiple structure, and further, while maintaining miniaturization of a supply means such as a pressure reducing valve constituting the supply source, a pilot By supplementing the lack of pressure, normal learning control can be continued. (2) As a result, the hydraulic valves of each series can be simultaneously operated, and the standby time as in the above-mentioned conventional technique can be eliminated, so that the reduction of the response speed regarding the control operation can be avoided. (3) The size of the pilot pressure supply means such as the pressure reducing valve can be kept small, so that the cost can be suppressed.

[Brief description of drawings]

FIG. 1 is a state explanatory view showing changes in pilot pressure in an embodiment of the present invention.

FIG. 2 is a control block configuration diagram of a hydraulic valve unit.

FIG. 3 is a state explanatory view showing changes in pilot pressure in a conventional example.

FIG. 4 is a state explanatory view showing changes in pilot pressure in a conventional example.

FIG. 5 is a state explanatory view showing changes in pilot pressure in a conventional example.

[Explanation of symbols]

1 ... Control device, 2 ... Solenoid valve, 3 ... Spool,
4 ... Position detector, P ... Pilot pressure, Pa ... Required pressure, A
… Insufficient pulse width

Claims (1)

[Claims] 1. A multiple hydraulic circuit having a plurality of hydraulic valves having a common pilot pressure supply source and correcting the pulse width based on learning to control the position of each spool. When operating the hydraulic valves at the same time, a spool control method for the hydraulic valves is characterized in that the pulse width corrected by learning is controlled by adding a shortage pulse width corresponding to a previously determined mode of simultaneous operation. .