JPS61233204A - Service life predicting device of servo valve - Google Patents

Abstract

PURPOSE:To facilitate prediction of the service life of spool upto the limit of usage through motion of neutral point by detecting the neutral point of the spool of servo valve every predetermined time then comparing the detected level with a normal level under initial adjusting. CONSTITUTION:The displacement of the spool 5 of servo valve is detected through a displacement gauge 6 then compared with a setting level in an amplifier 2 and fed back to the spool 5. The neutral point of spool 5 is compared with the normal level provided from an initial level setter 10 every predetermined time set through a timer 11 to operate the time elapsed until the motion of the neutral point will reach to the limit of usage through an arythmetic unit 12 thus to indicate the time on an indicator 14.

Description

[Detailed description of the invention] [°Industrial field of application] This invention predicts the life time due to wear of the spool of a servo valve, thereby making it possible to prevent trouble with the servo valve and grasp the replacement time. The present invention relates to a servo valve life prediction device.

[Conventional technology]

The spool has a built-in spool that controls the amount of oil. The mechanical zero point of the spool that adjusts the flow rate of oil passing through the servo valve changes depending on usage conditions due to manufacturing errors and spool wear.

In order to maintain this mechanical neutral position of the spool, electrical neutral adjustment (zero point adjustment) is performed while detecting the spool position and applying electrical feedback.

FIG. 3 is a schematic diagram showing the configuration of a conventional automatic zero point adjustment device for sage pulp. In FIG. 3, the setting signal 1 and the feedback signal of the spool position are matched by a matching amplifier 762, and the setting signal is converted into a current by the power amplifier 3.The moving coil 4 (?-&:
A current is passed through the moving coil 4 to energize the moving coil 4.

With this, sir? The pulp spool 5 operates. This operation of the spool 5 controls the amount of oil flowing through the servo valve. The spool position is detected by the displacement meter 6, and the detection signal is amplified by the displacement meter amplifier f7 and fed back to the butt amplifier f2.
゛In the matching amplifier 2, the setting signal 1 and the feedback signal output from the displacement meter amplifier f7 are matched, and the displacement meter amplifier f7 is matched so that the deviation becomes zero.
I am trying to control 7.

[Problem that the invention seeks to solve]

In this way, the neutral point adjustment (zero point adjustment) of the servo valve is performed by adjusting the displacement meter so that the feedback signal output from the displacement meter amplifier f7 becomes zero when the setting signal 1'' is zero. After this adjustment, if the position of the spool 5 moves from the time of adjustment due to aging, the amount corresponding to the difference in movement is fed back to the matching amplifier 2 via the displacement meter jar. .

Therefore, a flow rate corresponding to the difference flows into the control system, which changes the initial state and deteriorates control accuracy. It also becomes uncontrollable.

Therefore, a device has been proposed that has a circuit that detects a change in the neutral point of the spool 5 and automatically adjusts the zero point.

However, since the neutral point change amount must maintain the high-speed response characteristic of servo valves, and mechanical control limits are determined, automatic zero point adjustment alone does not have the ability to determine when the control limit has been reached. If the system is used at its limits, it has the disadvantage that it will not be possible for the system to utilize its original characteristics.

This invention was made to eliminate the above-mentioned conventional drawbacks, and provides a servo valve life prediction device that is capable of preventing troubles in the servo valve system and predicting the life of the servo valve, and is useful for process control. The purpose is to provide.

[Means for solving problems]

Sir of this invention? The pulp life time prediction device is driven by a setting signal, and the servo operates the spool of female pulp by comparing the detection signal that detects the position of the coil and the spool with the setting signal, zeroing out the deviation, and neutralizing the spool. The neutral point is moved by a feedback control system that automatically adjusts the point, and by detecting the neutral point position of the spool at predetermined time intervals when the adjustment is completed, and comparing and calculating the detected signal with the normal value at the time of initial adjustment. This system is provided with means for detecting the amount and current spool position and predicting the time until the use limit value is reached by moving the neutral point of the spool.

[Effect]

This invention depends on the setting signal) The pulp servo energizes the coil to operate the spool, and by this spool operation, the detection signal that detects the spool position is matched with the setting signal, the deviation is zeroed, and the spool neutral point is automatically adjusted. , detect the neutral position of the spool at predetermined time intervals and compare and calculate the detected signal with the normal value at the time of initial adjustment to detect the movement amount of the neutral point and the current spool position; Predict the time required to reach the usage limit due to movement of the spool's neutral point.

〔Example〕

Below is the sir of this invention? An embodiment of the pulp life prediction device will be described based on the drawings.

FIG. 1 is a block diagram showing the configuration of one embodiment.

In FIG. 1, parts that are the same as those in FIG. 3 are given the same reference numerals, and their explanations will be omitted, and the parts that are different from those in FIG. 3 will be mainly described.

As is clear from comparing Figure 1 with Figure 3,
In the figure, the parts indicated by numerals 1 to 7 shown in FIG. 3 are the same as those shown in FIG. 3, and the parts indicated by numerals 8 and after are newly added to the configuration of FIG. 83.

That is, the position of the spool 5 is detected by a displacement meter 6, and the detection signal is inputted to a spool neutral point automatic adjustment circuit 8 through a displacement meter angua. The output of this spool neutral point automatic adjustment circuit 8 is fed back to the matching amplifier f2 through a D/A (digital/analog) converter 9.
The data is sent to the arithmetic unit 12.

Further, the initial value setter 10 outputs the spool neutral point position upon completion of adjustment to the calculator 12. A timer setting time signal is input from the timer 11 to the arithmetic unit 12 . The data of the initial value setter 10 is read and stored in the memory 13 at regular intervals for each timer set time.

Further, the calculator 13 predicts the time until the servo valve reaches the control limit position, and displays the result on the display 14.

Next, the operation of the servo valve life prediction device of the present invention configured as described above will be explained. In explaining this operation, the parts indicated by reference numerals 1 to 7 are the same as those shown in FIG. 3, and the explanation thereof will be omitted.

By the way, normally, if servo pulp is in a controlled state,
With the spool 5 located at the neutral point, a) deviation control is performed such that the spool operates only when a command value is received, and returns to the neutral point again after the command is set.

Therefore, during the control state, since the spool 5 is always located at the neutral point, the position detection signal of the spool 5, which is detected at regular intervals by the displacement meter 5, is used as the spool position signal when the initial adjustment is completed. By performing a comparison calculation with , it is detected as the neutral point movement amount.

In addition, since the servo valve's spool neutral point fluctuation has a characteristic that it deviates in proportion to the frequency of use, the time required to reach the control limit can be further predicted and calculated based on the calculated amount of fluctuation within a certain period of time. I have to.

Next, this series of general operations will be explained in more detail. The neutral point of the spool shifts in a certain direction based on past performance in proportion to the frequency of use.

Therefore, by using this feature, first set the spool neutral point position when the adjustment is completed by setting the initial value setting device 1.
011C and an arithmetic unit 1211C are provided.

The neutral point during the subsequent control is determined by inputting a timer setting time signal from the timer 11 at regular intervals for each timer setting time, reading data from the initial value setter 10, and storing the value in the memory 13.

Next, in the arithmetic unit 12, Perform the calculation.

The relationship expressed by equation (1) is shown in FIG. 2, where the horizontal axis shows the timer setting time and the vertical axis shows the initial value. In FIG. 2 and equation (1), dn is the current measurement value, dn-1 is the previous measurement value, Tn is the current measurement time, and rh-1 is the previous measurement time.

This equation (1) is calculated, the time required to reach the control limit position d is predicted, and the result is displayed on the display 14. Note that this control limit position d is set in advance in the computing unit 12.

〔Effect of the invention〕

As described above, according to the servo pulp life prediction device of the present invention, the spool position of the servo pulp is detected at certain fixed time intervals in a steady state controlled using the servo pulp, and the detected signal is detected. The amount of movement of the neutral point and the current spool position are detected by comparing and calculating the normal value at the time of initial adjustment, and the time required to reach the usage limit due to movement of the spool's neutral point is predicted. It is possible to predict the life time due to wear and other factors.

Therefore, it is useful for process control.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the servo pulp life prediction device of the present invention, and FIG. FIG. 3 is a diagram showing the relationship between the timer setting time and the initial value for explaining the operation of the pulp life prediction device. FIG. 3 is a block diagram of a conventional automatic neutral point adjustment device for a servo valve. 2...Matching amplifier, 4...Sir is a coil, 6
... Spool, 6... Displacement meter, 7... Displacement meter amplifier, 8... Spool neutral point automatic adjustment circuit, 9...
・D/A converter, 10...Initial value setter, 1 no.
...Timer, 12...Arithmetic unit, 13...Memory, 1
4--Display device. Applicant Sub-Agent Takehiko E Takehiko 1F41, Patent Attorney

Claims (1)

[Claims] Feedback control that automatically adjusts the spool neutral point by comparing a servo coil that is driven by a setting signal to operate the spool of the servo valve, and a detection signal that detects the position of the spool and the setting signal to zero the deviation. The system detects the neutral point position of the spool at predetermined intervals when the adjustment is completed, and compares and calculates the detected signal with the normal value at the time of initial adjustment to determine the amount of movement of the neutral point and the current spool position. A servo valve life time prediction device, comprising means for detecting the spool's neutral point and predicting the time until the service limit value is reached by moving the neutral point of the spool.