JPS61228108A - Automatic zero point adjuster of servo valve - Google Patents

Abstract

PURPOSE:To decrease adjusting work, by arithmetically comparing a detected signal of a spool position in a servo valve with the normal value, obtained when it is initially adjusted, and detecting a movement of the neutral point so as to automatically correct it feeding back the detected signal. CONSTITUTION:A device provides a servo coil 4 being driven by a preset signal and actuating a spool 5 in a servo valve. While the device provides a feedback system which collates a detected signal of a position of the spool with the preset signal to control the deviation to zero. Further the device provides a memory means 10 which stores the spool position detected signal after the spool 5 completes its neutral point to be adjusted. While the device, arithmetically comparing the spool position detected signal through a time constant circuit in the initial time of adjustment with the value stored in the memory means 10 and giving the deviation to the feedback system, corrects the neutral point. By this constitution, adjusting work is decreased.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention monitors the position of the neutral point using a spool position detector signal when a servo valve is in a controlled state, and monitors the spool position signal after initial adjustment is completed. The present invention relates to an automatic zero point adjustment device for a servo valve that detects movement of a neutral point and feeds back a deviation signal from the neutral point.

[Conventional technology]

The servo valve has a built-in spool that controls the amount of oil. The mechanical zero point of the spool that adjusts the flow rate varies 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.

When used in this state, the neutral point may change over time due to wear of the spool, etc., resulting in poor control accuracy and an uncontrollable state. Currently, these countermeasures include conducting both adjustments by inspecting the neutral point when it exceeds a certain limit or periodically.

FIG. 2 is a block diagram of such an automatic zero point adjustment device for a servo valve. In this figure 2, the setting signal 1 and the feedback signal of the spool position are matched together.
Match at f2 and get the deviation signal.
The current is converted into a current, and the current is passed through the tz coil 4 (moving coil).

This allows spool 5 to operate and? - Control the amount of oil passing through the gel pulp. At this time, the position of the spool 5 is detected by the displacement meter 6, and the detection signal is fed back to the butt amplifier 2 via the displacement meter amplifier f7, and control is performed so that the deviation between the setting signal 1 and the feedback signal becomes O. are doing.

[Problem that the invention seeks to solve]

Here, to adjust the neutral point (zero point) of the saab pulp, adjust the displacement meter amplifier f1 so that the feedback signal output from the displacement meter differential becomes O when the setting signal 1 is at the set value O. After this adjustment, if the position of the spool 5 moves from the time of adjustment due to aging, the amount of the movement is transferred to the butt ring I2 via the displacement meter ring f7.
will be given feedback.

For this reason, a flow rate corresponding to the difference flows into the control system, and the controlled object is controlled in a balanced manner, which results in a change from the initial state, and the control accuracy deteriorates by that amount. Also, the situation becomes uncontrollable.

This invention was made in order to eliminate the above-mentioned conventional drawbacks, and it is possible to reduce the adjustment work, prevent deterioration of control accuracy, enable normal control, and prevent uncontrollable conditions. The purpose is to provide an automatic adjustment device.

[Means for solving problems]

The automatic zero point adjustment device for Serb pulp of the present invention compares a servo coil that is driven by a setting signal to operate a spool of Serb pulp, a detection signal that detects the position of the spool, and a setting signal to reduce the deviation to zero. The feedback system to control, the storage means for storing the spool position detection signal after the spool neutral point adjustment is completed, and the spool position detection signal passed through the time constant circuit during the initial adjustment are compared with the value stored in the storage means. and a means for automatically correcting the neutral point by applying the deviation to a feedback system.

[For production]

In this invention, a servo coil is energized by a setting signal to move a spool of servo pulp, and a detection signal that detects the position of the spool is fed back through a feedback system and matched with a setting signal so that the deviation becomes zero. In addition, the spool position detection signal after the neutral point adjustment of the spool is completed is stored in the storage means, and the spool position detection signal passed through the time constant circuit at the time of initial adjustment is compared with the value stored in the storage means. The deviation is given to the feedback system to automatically correct the neutral point.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the automatic zero point adjustment device for saab pulp of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an example thereof. In FIG. 1, in order to avoid duplication, parts that are the same as those in FIG. 2 will be given the same reference numerals and their explanations will be omitted, and parts that are different from those in FIG. 2 will be mainly described.

As is clear from comparing Figure 1 with Figure 2,
In the figure, the parts indicated by reference numerals 1 to 1 are the same as those in FIG. 1, and the parts indicated by reference numeral 8 and after are newly added parts from FIG. 1, and are the parts that are characteristic of the present invention. That is, the present invention has the structure shown in FIG. 1 with the addition of the parts indicated by reference numeral 8 and thereafter.

A movable terminal C of the changeover switch 8 is connected to the output end of the displacement meter Angua. The changeover switch 8 has a movable terminal C and two fixed terminals a and b, and the fixed terminals a and b are connected to the input terminals of analog/digital converters 9 and 11, respectively. .

The output ends of both A/l) converters 9 and 11 are connected to an input end of an initial value memory 100 and an input end of a time constant circuit 120, respectively. The output of the initial value memory 10 and the output of the time constant circuit 12 are sent to an arithmetic circuit 13. This arithmetic circuit 13 performs a comparison operation between an initial value and a current value, and its output is sent to a matching amplifier f2 via a D/A (differential/analog) converter 14.

This arithmetic circuit 13, initial value memory 10, and time constant circuit 12 constitute a position detection signal monitoring circuit. Note that the neutral point movement does not change suddenly, so the stool is in a controlled state. In order to avoid transient error movements, the position detection signal monitoring circuit is designed to have a large time constant.

Next, an explanation will be given of the operation of the search/route automatic zero adjustment device of the present invention constructed as described above. In explaining this operation, the parts indicated by reference numerals 1 and 2 are the same as those shown in FIG. 2, and the explanation thereof will be omitted.

Normally, when the servo valve is in the control state, the stool 5 is located at the neutral point, and the stool operates only when the command value arrives, and the command setting is also a deviation control that returns to the neutral point. Is going. Therefore, since the control state is always located at the neutral point, the stool 5 is in this position.
The position detection signal is monitored.

First, when the movable terminal C of the changeover switch 8 is switched to the fixed terminal 1 side, the stool position detection output signal after completing the neutral point (zero point) adjustment is transferred from the displacement meter antenna f1 to the fixed terminal C of the switch 8 and the movable terminal 1. The signal is then input to the φ converter 9, where it is converted into a digital signal and stored in the initial value memory IOK.

Next, switch the movable terminal C of the switch 8 to the fixed terminal side, and input the stool position detection output signal from the displacement meter Angua to the A/D converter 11, where it is converted into a digital signal, and then the time constant It passes through a circuit 12 to an arithmetic circuit 13 where the initial value is compared with the value stored in the initial value memo 910, the deviation is detected, and the deviation is converted into analog by the D/A converter 14. After that, a signal is given to the matching amplifier 2 to continuously correct the zero point. Therefore, the present invention can be applied to equipment controlled using servo valves.

〔Effect of the invention〕

As described above, according to the automatic zero point adjustment device for a servo valve of the present invention, the movement of the neutral point is detected by comparing the detection signal obtained by detecting the stool position of the servo valve with the normal value at the time of initial adjustment, and detects the movement of the neutral point. Since the neutral point correction is automatically performed by feeding back the detection signal, adjustment work can be reduced, deterioration of control accuracy can be prevented, normal control can be performed, and an uncontrollable state can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the structure of an embodiment of the automatic zero point adjustment device for a servo valve according to the present invention, and FIG. 2 is a block diagram of a conventional automatic zero point adjustment device for Chiza pulp. 2... Matching amplifier, 4... Search coil, 5
...stool, 6...displacement meter, 7...an for displacement meter! , 8... Changeover switch, 9, 11... ~ controller, 10... memory for initial value, 12... time constant circuit, 13... arithmetic circuit, 14... D/A converter. Applicant Sub-Agent Patent Attorney Takehiko Suzue Figure 1 Figure 2

Claims (1)

[Claims] A servo coil that is driven by a setting signal to operate the spool of the servo valve, a feedback system that matches the detection signal that detects the position of the spool with the setting signal and controls the deviation to zero, and adjusts the neutral point of the spool. A storage means for storing the spool position detection signal after completion and a value stored in the storage means for comparing the spool position detection signal passed through a time constant circuit during the initial adjustment with the value stored in the storage means, and the deviation thereof is provided to the feedback system. An automatic zero point adjustment device for a servo valve, comprising means for automatically correcting a neutral point.