JP2016031086A - Fault diagnosis device for hydraulic equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fault diagnosis device for hydraulic equipment for setting a drain amount at a hydraulic circuit to a suitable normal value to reduce loss of entire device under application of a spool valve having a spool position sensor.SOLUTION: A hydraulic cylinder 61 is operated to cause an upper die 62 to descend to depress a work-piece 64 installed at a lower die 63, and a spool valve 65 having a spool position sensor is connected to a hydraulic supply passage (oil passage) of the hydraulic cylinder 61. A reference number 66 denotes a relief valve for determining maximum pressure of the entire circuit, a reference number 67 denotes a change-over valve for on-load un-load states, a reference number 68 denotes a change-over valve for pressurizing and descending and rapid descending of the hydraulic cylinder 61, and a reference number 69 denotes a safety valve to avoid abnormal pressure in the hydraulic cylinder 61. A reference number 70 denotes a counter-balance valve to assure a back-pressure occurred at the time of descending of the hydraulic cylinder 61 and prevent its dead weight dropping. A reference number 71 denotes a hydraulic source.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hydraulic apparatus used in industrial machines and construction machines, and more particularly to a hydraulic apparatus failure diagnosis apparatus that drives an actuator such as a cylinder or a hydraulic motor with a solenoid valve.

  Conventionally, as this type of hydraulic failure diagnosis method, it is known to detect whether there is an abnormality in a hydraulic device by comparing a normal drain flow rate from a hydraulic device including a drain circuit with an abnormal drain flow rate (for example, , See Patent Document 1).

  In addition, there is a device that detects the presence or absence of abnormality by comparing the normal value of the spool movement amount with respect to the input command value and the actual value of actual movement in the servo valve (see, for example, Patent Document 2).

JP 59-03811 A JP-A-5-106613

  However, in the failure diagnosis apparatus shown in Patent Document 1, the drain amount of the hydraulic circuit varies depending on the magnitude of the acting pressure and the length of time, and is affected by the oil temperature. Therefore, an appropriate normal value should be set. Is difficult.

  Furthermore, the failure diagnosis method disclosed in Patent Document 2 can only be implemented by a hydraulic circuit using a servo valve. Further, including the servo valve and the control device is expensive, and generally the pressure loss of the servo valve is high, so that the loss of the entire apparatus increases.

  The present invention relates to a fault diagnosis apparatus for hydraulic equipment that reduces the loss of the entire apparatus without being affected by variations in the drain amount in the hydraulic circuit by using the spool valve with a spool position detector researched and developed by the present applicant in the hydraulic circuit. I will provide a.

To achieve the above object, the present invention provides:
In a hydraulic control apparatus comprising: a hydraulic drive source; an electromagnetic switching valve connected to the hydraulic drive source; and an actuator that communicates with the electromagnetic switching valve and is displaced by a switching operation of the electromagnetic switching valve.
A spool valve with a spool position detector is provided in the hydraulic circuit in place of the electromagnetic switching valve,
The time difference until the energization signal of the solenoid of the spool valve with the spool position detector and the monitoring signal change is constantly monitored, and when the time difference exceeds a threshold value, it is determined that the hydraulic device or hydraulic fluid is abnormal. It is characterized by.

  According to the present invention, it is possible to easily set a failure determination criterion by performing a failure diagnosis of a hydraulic device based on a change in response time of a spool valve with a spool position detector.

  Since a solenoid valve is used instead of a servo valve, the cost of the apparatus can be minimized. Also, the loss of the device is not changed at all.

  A device for detecting the response time is required, but a fault diagnosis function can be easily added by replacing the existing solenoid valve with a spool valve with a spool position detector.

It is a hydraulic circuit which concerns on the failure diagnosis apparatus of the hydraulic equipment which concerns on embodiment of this invention. It is a fragmentary sectional view of the spool valve with a spool position detector used for the diagnostic apparatus of FIG. It is operation | movement explanatory drawing of a spool valve with a spool position detector. It is the simplified diagram which copied and showed the solenoid non-energized state of the spool valve with a spool position detector. It is the simplification which showed the solenoid energization state of the spool valve with a spool position detector in a copying manner. It is a wave form diagram which shows the response of a switch and a cylinder.

Preferred embodiments of a failure diagnosis apparatus for hydraulic equipment according to embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic configuration diagram of a general hydraulic circuit 60 of an NC machine tool, for example, a press machine.

  In FIG. 1, reference numeral 61 is a hydraulic cylinder, which lowers the upper die 62 and presses a work 64 mounted on the lower die 63. Four ports (A, A, B, P, R) A three-position control valve, for example, a spool position detector spool valve 65 is connected.

  In FIG. 1, reference numeral 66 is a relief valve for determining the maximum pressure of the entire circuit, reference numeral 67 is an on-load / unload switching valve, reference numeral 68 is a switching valve for pressurizing and lowering the hydraulic cylinder 61, Reference numeral 69 denotes a safety valve that avoids abnormal pressure in the hydraulic cylinder 61.

  Reference numeral 70 denotes a counter balance valve, which ensures a back pressure when the hydraulic cylinder 61 is lowered, and prevents its own weight from falling. Reference numeral 71 indicates a hydraulic pressure source.

  The structure of the spool valve 65 with spool position detector used in the hydraulic circuit 60 is the same as that of the spool valve 31 with spool position detector shown in FIG. 1 shown in Japanese Patent Laid-Open No. 2005-180646. Although a schematic longitudinal sectional view replaced with is shown, detailed description thereof is omitted.

  Next, the operation of the spool valve 65 with a spool position detector will be described with reference to FIG. FIG. 3 is a partial cross-sectional view showing a state in which the electromagnetic coil 30b on the right side of the spool valve 65 with a spool position detector of FIG. 1 is energized. Note that the same components as those in FIG. 2 are denoted by the same reference numerals.

  In the neutral state shown in FIG. 2 where both the electromagnetic coils 30a and 30b are not excited, the rings 3a and 3b and the retainers 4a and 4b on both sides are in contact with the contact surfaces 13a and 13b, and the electric terminals 20a and 20b. The detection electrical terminals 21a and 21b are electrically connected to each other. As shown in FIG. 3, when the right electromagnetic coil 30b is energized in the drawing, the spool 2 moves in the left direction. Then, the right retainer 4b and the ring 3b remain in contact with each other at the contact surface 13b, but the left retainer 4a moves to the left along with the movement of the spool 2, so that the left retainer 4a and the ring 3a Contactless.

  That is, the right electrical terminal 20b and the detection electrical terminal 21b are electrically connected, but the left electrical terminal 20a and the detection electrical terminal 21a are not electrically connected. When the left electromagnetic coil 30a is excited by the same principle, the left electrical terminal 20a and the detection electrical terminal 21a are electrically connected, but the right electrical terminal 20b and the detection electrical terminal 21b are not electrically connected.

  Thus, the contact states of the left and right retainers 4a and 4b and the rings 3a and 3b are all different in the non-excitation state, the excitation state of the right electromagnetic coil 30b, and the excitation state of the left electromagnetic coil 30a. The contact state between the retainer and the ring varies depending on each state, which means that the conduction state between the electrical terminals connected to each retainer and the ring also changes, and this is used to determine the position of the spool 2. Can be detected directly.

  4 and 5 are simplified views schematically showing the operation principle and the switch mechanism of the spool valve 65 with a spool position detector shown in FIGS. 2 and 3, and FIG. 2 and FIG. These components are given the same reference numerals and detailed description thereof is omitted. The spool valve 65 with a spool position detector includes the electromagnetic coils 30a and 30b in FIGS. 2 and 3, but the operation principle of one electromagnetic coil, for example, the electromagnetic coil 30b, will be described. Since the operation principle is the same as that of the electromagnetic coil 30b, description thereof is omitted.

  FIG. 4 shows a state in which the electromagnetic coil 30b is not excited. In this state, the spool 2 is in a neutral position (see FIG. 2). For this reason, since the ring 3b (fixed contact) and the retainer 4b (movable contact) constituting the monitoring switch mechanism 65b are in contact, the monitoring switch mechanism 65b is in a conductive state, that is, a switch ON state.

When the electromagnetic coil 30b is energized in the state shown in FIG. 4, the spool 2 moves to the right as shown in FIG. 5, and the retainer 4b (movable contact) moves accordingly, and is detached from the ring 3b (fixed contact). Therefore, the monitoring switch mechanism 65b is in a non-conductive state, that is, a switch OFF state.

  FIG. 6 shows that the hydraulic cylinder 61 is “stopped (maintained at a high pressure) by a spool valve 65 with a spool position detector → forwardly moved by a solenoid, for example, an electromagnetic coil 30b-ON (lowered in FIG. 1) → stopped by an electromagnetic coil 30b-OFF”. As shown, the response waveform when driven is shown.

  In FIG. 6, response times T1, T2, T3, and T4 represent the following, respectively.

  T1: Time from the solenoid (electromagnetic coil 30b) voltage -ON (energization of the electromagnetic coil 30b) until the hydraulic cylinder 61 starts to move.

T2: Time from the solenoid (electromagnetic coil 30b) voltage -OFF (electromagnetic coil 30b energization stop) until the hydraulic cylinder 61 stops.
T3: Time from the solenoid (electromagnetic coil 30b) voltage -ON (energization of the electromagnetic coil 30b) until the monitoring switch mechanism 52b is turned off.
T4: Time from the solenoid (electromagnetic coil 30b) voltage -OFF (electromagnetic coil 30b energization stop) until the monitoring switch mechanism 52b is turned on.

  Thus, for example, if T1> T3 and T4> T2 are set, when the monitoring switch mechanism 52b is ON, the hydraulic cylinder 61 is always in a stopped state, and safety can be confirmed.

  Furthermore, the present invention uses a spool valve 65 with a spool position detector as a failure diagnosis device of the hydraulic circuit 60, and “a time difference” until the solenoid energization signal (see FIG. 6) and the monitoring signal (see FIG. 6) change. (See FIG. 6) is constantly monitored, and when the “time difference” exceeds the “threshold value”, it can be determined that the press machine has an abnormality in the hydraulic circuit 60, for example, an abnormality in hydraulic equipment or hydraulic fluid.

  Further, by using a spool valve 65 with a spool position detector in the hydraulic circuit 60 (see FIG. 1), whether the spool 2 (see FIGS. 2 to 5) is in a neutral position is determined by a signal from the monitoring switch mechanism 65b. It can be used as a condition for permitting operation of the pump. Therefore, for example, a safety confirmation type system for a machine including a press machine can be constructed.

  As described above, the spool valve with a spool position detector used in the present invention is provided with a monitoring switch mechanism that can detect the position externally to the spool valve that switches the flow of oil.

  Thereby, in an actual machine, it is possible to externally detect the time (response time) from when the coil is excited / de-energized until the switch signal changes.

  A “limit value (threshold value) indicating failure” of the response time is set, and an “abnormal” signal can be issued when the response time becomes longer.

  Furthermore, the reason why the present invention can be implemented as a failure diagnosis apparatus for hydraulic equipment is as follows.

  In general, many troubles of hydraulic equipment are affected by foreign matter in oil (hydraulic hydraulic fluid).

  Foreign matter may intrude from the outside, but may also occur from the inside of the hydraulic system (including hydraulic equipment), and damage the spool valve sliding part or entering the clearance of the sliding part. Since the response time is delayed, by detecting a “delay” in the response time, it is possible to know the possibility of a hydraulic equipment failure and the timing for performing maintenance.

  In the present invention, the “limit value indicating failure” that can be easily determined depends on only the response time of the valve alone, and thus is easy to determine.

In this case, the “limit value indicating failure” may be determined by referring to the actual measured values at the pressure, flow rate, and hydraulic oil viscosity (oil temperature) at which the response time is the slowest. You may decide with reference to.

1, 1 'body 1a axial hole 2, 2' spool 2a, 2, b2 'step 3a, 3b ring 4a, 4b, 4' retainer 5a, 5b first spacer 5c, 5d spigot 6a, 6b second Spacer 7a, 7b Conductive rod 8 Bush
11a, 11b, 11 'guide (solenoid guide)
12a, 12b Spring 13a, 13b Outer end face (contact surface)
14 communication path 60 hydraulic circuit 61 hydraulic cylinder 63 upper mold 64 lower mold 65 spool valve with spool position detector 65b monitoring switch mechanism 66 relief valve 67 on-load / unload switching valve 68 switching valve 69 safety valve 70 counter balance valve 71 hydraulic source

Claims (1)

In a hydraulic control apparatus comprising: a hydraulic drive source; an electromagnetic switching valve connected to the hydraulic drive source; and an actuator that communicates with the electromagnetic switching valve and is displaced by a switching operation of the electromagnetic switching valve.
A spool valve with a spool position detector is provided in the hydraulic circuit in place of the electromagnetic switching valve,
The time difference until the energization signal of the solenoid of the spool valve with the spool position detector and the monitoring signal change is constantly monitored, and when the time difference exceeds a threshold value, it is determined that the hydraulic device or hydraulic fluid is abnormal. Hydraulic equipment failure diagnosis device characterized by

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