JP2004337668A - Automatic examination method for clogging of filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic examination method for the clogging of a filter capable of accurately detecting the clogging of a filter element even if a special correction mechanism is not added. <P>SOLUTION: A control unit 36 for sensing the fear of the clogging of the filter element 22a is constituted so as to confirm whether the operator of a work machine carries out the automatic examination method for the clogging of a filter to perform the automatic examination method for the clogging of a filter on the basis of the affirmation operation of the operator. In this automatic examination method for the clogging of the filter, the difference pressure before and after the filter element 22a is measured in such a state that the temperature of oil passed through the filter element 22a is controlled so as to enter a reference range, and the flow rate of the oil is controlled to a prescribed flow rate and compared with a reference value to automatically detect the presence of the clogging of the filter element 22a. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a filter clogging automatic examination method for detecting the presence / absence of clogging of a filter element.
[0002]
[Prior art]
FIG. 4 shows a hydraulic circuit of the hydraulic shovel. Hydraulic oil discharged from a variable displacement main pump 1 is controlled by a control valve 2 to control various hydraulic actuators of a traveling system, a swing system, and a working machine system (not shown). ), And is returned from these various hydraulic actuators to the tank 3 via the control valve 2. The return oil is cooled by the oil cooler 4 and filtered by the filter element 5 a of the working oil filter 5. .
[0003]
The filter element 5a has a function of removing contamination in oil, but if left as it is, clogging occurs due to contamination. Therefore, when the clogging is detected, the filter element 5a needs to be replaced. .
[0004]
In order to detect the clogging of the filter element 5a, an indicator 6 for monitoring the differential pressure across the filter element 5a is installed. When the differential pressure across the filter element 5a exceeds a certain reference value, the indicator 6 A signal is transmitted to the control device (ECM) 7 to warn the operator through the monitor 8 or the like to replace the filter element 5a.
[0005]
The method of measuring only the differential pressure across the filter element 5a using the indicator 6 has the following problems.
[0006]
(1) During actual work, the flow rate passing through the filter element 5a changes every moment, so that the differential pressure across the filter element 5a changes according to the flow rate. Therefore, even though the degree of clogging has not reached the allowable limit, the indicator 6 operates and there is a risk of misdiagnosis.
[0007]
(2) Even if the same operation is performed, the oil temperature differs and the kinematic viscosity changes depending on the ambient temperature of the machine body, so that the differential pressure across the filter element 5a also changes with respect to the oil temperature. Therefore, there is a risk of misdiagnosis as in (1).
[0008]
(3) For the above reasons, it is necessary to flow a hydraulic oil at a constant oil temperature and a constant flow rate through the hydraulic oil filter 5 to measure the differential pressure across the filter element 5a. Regarding the flow of the constant flow rate, the clogging is finally diagnosed by a traveling operation capable of flowing the constant flow rate.
[0009]
However, traveling operations cannot be performed on all the aircraft because there are many cases where traveling operations cannot be performed depending on the site. Regarding setting the oil temperature within a certain range, an oil temperature management system has not been established, and there is still a risk of misdiagnosis.
[0010]
On the other hand, in addition to the hydraulic oil filter that filters hydraulic oil, a fixed throttle (not shown) is interposed in series with the hydraulic oil filter in the hydraulic oil passage upstream of the hydraulic oil filter, and the front-back difference The pressure difference is detected by the filter differential pressure detecting means, the differential pressure across the fixed throttle is detected by the fixed throttle differential pressure detecting means, and the hydraulic oil filter differential pressure information detected by the filter differential pressure detecting means is detected by the fixed throttle differential. A predetermined value is compared with a division value obtained by dividing the fixed throttle differential pressure information detected by the pressure detection means, and when the division value exceeds the predetermined value, it is detected that the hydraulic oil filter is clogged. There is an operating oil filter clogging state detecting device that performs the operation (for example, see Patent Document 1).
[0011]
The hydraulic oil filter clogging state detection device, which corrects the hydraulic oil filter differential pressure information with the fixed throttle differential pressure information, detects the clogged state of the hydraulic oil filter without being affected by changes in the viscosity or flow rate of the hydraulic oil. Although it is possible, it is necessary to newly provide a fixed throttle, a fixed throttle differential pressure detecting means, and the like, and waste energy due to generation of heat in the fixed throttle.
[0012]
[Patent Document 1]
JP-A-10-5511 (page 3-4, FIG. 1-3)
[0013]
[Problems to be solved by the invention]
As described above, the method of measuring only the differential pressure across the filter element 5a using the indicator 6 may cause a misdiagnosis when the flow rate or the oil temperature changes, and the information of the hydraulic oil filter differential pressure may be fixed fixed differential pressure differential. The method of correcting with information needs to be equipped with a facility for that, and has a problem that it involves energy loss due to generation of unnecessary heat.
[0014]
The present invention has been made in view of such a point, and an object of the present invention is to provide a filter clogging automatic examination method capable of accurately detecting clogging of a filter element without adding a special correction mechanism. Things.
[0015]
[Means for Solving the Problems]
The invention described in claim 1 measures the differential pressure across the filter element while controlling the flow rate of the oil passing through the filter element to a specified flow rate, compares the differential pressure across the filter element with a reference value, and compares the differential pressure with the reference value. This is a filter clogging automatic inspection method that automatically detects the presence or absence of clogging of the filter element. By controlling the flow rate of hydraulic oil that affects the differential pressure across the filter element to an appropriate specified flow rate, Correct diagnosis of clogging can be made from the pressure. Moreover, clogging of the filter element can be accurately detected without adding a special correction mechanism, energy loss due to generation of heat in the fixed throttle as in the conventional example can be prevented, and the life of the filter element can be reduced. Since it can be used to the maximum extent, running costs can be reduced.
[0016]
According to a second aspect of the present invention, there is provided the automatic filter clogging inspection method according to the first aspect, wherein the temperature of the oil passing through the filter element is controlled within a reference range. By controlling the flow rate and the flow rate to a predetermined state, it is possible to appropriately control the kinematic viscosity and the flow rate of the hydraulic oil which affect the differential pressure across the filter element. Diagnosis can be performed with higher accuracy.
[0017]
According to a third aspect of the present invention, a control device that senses a possibility of clogging of a filter element in a hydraulic circuit of a work machine implements the filter clogging automatic inspection method according to the first or second aspect to an operator of the work machine. A filter clogging automatic inspection method for performing the filter clogging automatic inspection method according to claim 1 or 2 by confirming whether or not to perform the filter clogging automatic inspection method, wherein the hydraulic circuit of the working machine requires a sufficient oil amount. In the case where the control device detects the risk of clogging of the filter element, the operator does not perform an affirmative operation, so that the filter clogging automatic inspection method according to claim 1 or 2 is performed. Since it is possible to select not to perform the operation, it is possible to prevent a decrease in work efficiency of the work machine.
[0018]
According to a fourth aspect of the present invention, in the automatic filter clogging inspection method according to the third aspect, even if the operator selects not to perform the filter clogging automatic inspection method, the operation device for operating the work machine is not operated. When the operation state continues for a reference time or more, the filter clogging automatic examination method for reconfirming whether or not to perform the filter clogging automatic examination method according to claim 1 or 2, and does not operate the work machine. If the non-operation state continues for more than the reference time, the operator can be alerted by re-confirming whether or not to perform the above-mentioned filter clogging automatic inspection method, and the filter element may be clogged. Can be prevented from continuing for a long time.
[0019]
According to a fifth aspect of the present invention, in the automatic filter clogging inspection method according to the third or fourth aspect, the control device is provided when the work machine is operated without replacing the element even after detecting the filter element clogging. Is a filter clogging automatic inspection method in which the function of the work machine is forcibly reduced when the work machine has been working for a certain period of time, and the work machine is operated for a long time with the filter element clogged. If this occurs, contamination that has clogged the filter element may enter the hydraulic circuit and damage the hydraulic circuit components.Forcibly lowering the function of the work machine and replacing the filter element By forcing, the damage of the hydraulic circuit components can be prevented.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to one embodiment shown in FIGS.
[0021]
FIG. 1 shows a hydraulic circuit of a hydraulic shovel as a working machine. Hydraulic oil as oil discharged from a plurality of variable displacement main pumps 11 is controlled by a control valve 12 and various hydraulic actuators of the hydraulic shovel. (Not shown), ie, a hydraulic motor for traveling of the lower traveling body, a hydraulic motor for rotating the upper rotating body with respect to the lower traveling body, and a hydraulic cylinder of a working device mounted on the upper rotating body. It is returned from various hydraulic actuators to the tank 13 via the control valve 12.
[0022]
A plurality of electric relief valves 14 capable of variably adjusting a set pressure by an electric signal from the outside are built in the control valve 12, and a return oil line 15 passing through these electric relief valves 14 is connected to an oil cooler 16 and an external An electric bypass valve 17 that changes a set pressure according to an electric signal is connected in parallel.
[0023]
A return oil line 21 that has passed through the oil cooler 16 or the electric bypass valve 17 has a hydraulic oil filter 22 that filters and removes contamination in hydraulic oil by a filter element 22a, and a differential pressure across the filter element 22a of the hydraulic oil filter 22. And the indicator 23 that transmits a clogging detection signal when the filter element 22a is clogged due to contamination in the hydraulic oil and the differential pressure across the hydraulic oil filter 22 exceeds a reference value, and the differential pressure between the hydraulic oil filter 22 A bypass check valve 24 that opens when the limit value is exceeded and prevents the filter element 22a from being damaged is connected in parallel.
[0024]
The tank 13 and the like are provided with an oil temperature sensor 25 for measuring the temperature of the hydraulic oil, that is, the oil temperature. The oil cooler 16 is provided with a cooling fan 27 driven by a motor 26 whose rotation speed can be controlled.
[0025]
A hydraulic shovel equipped with an oil temperature sensor 25 for measuring the oil temperature, a cooling fan 27 capable of controlling the rotation speed, and the like uses these existing facilities as they are.
[0026]
Each of the plurality of variable displacement main pumps 11 includes a displacement variable means 31 such as a swash plate. Each of the displacement variable means 31 is tilted and driven by a regulator 32, and the displacement amount of the regulator 32 is a displacement sensor. 33. Further, the displacement of these regulators 32 is controlled by the operating pressure controlled by an electric pressure reducing valve 35 of the pilot oil pressure discharged from the pilot pump 34.
[0027]
The indicator 23, the oil temperature sensor 25, and the displacement sensor 33 are connected to inputs of a control device (ECM) 36, and outputs of the control device 36 include the electric relief valve 14, the electric bypass valve 17, the motor 26, The electric pressure reducing valve 35 and the monitor 37 are connected. The monitor 37 displays a warning such as "replace the filter element" to the operator.
[0028]
The control device 36 controls the electric bypass valve 17 to control the amount of oil to the oil cooler 16, and also controls the rotation speed of the motor 26 to control the rotation speed of the cooling fan 27, thereby controlling the filter element. By controlling the temperature of the oil passing through 22a within the reference range and controlling the electric pressure reducing valve 35 to control the capacity variable means 31 by the regulator 32, the hydraulic oil discharge flow rate from the main pump 11 is set to the specified flow rate. And further controls the electric relief valve 14 to flow all the oil discharged from the main pump 11 to the return oil line 15 side. The indicator 23 monitors the differential pressure across the filter element 22a, and this differential pressure is used as a reference. The presence / absence of clogging of the filter element 22a is automatically detected in comparison with the value.
[0029]
At this time, the control device 36 that has detected the clogging of the filter element 22a urges the operator of the excavator to issue a warning via the monitor 37 to replace the filter element 22a.
[0030]
Next, a control method of the control device 36 will be described with reference to flowcharts shown in FIGS.
[0031]
(Step 1)
By automatically controlling the set pressure of the electric relief valve 14, the set pressure of the electric bypass valve 17, and the rotation speed of the cooling fan 27, the oil temperature management function for keeping the oil temperature of the working oil within a certain range allows the oil temperature during operation to be controlled. Manage.
[0032]
For example, when lowering the oil temperature, the electric relief valve 14 is set to the lowest pressure, the electric bypass valve 17 is throttled, and the set pressure on the upstream side is increased to increase the oil amount ratio to the oil cooler 16; The rotation speed of the cooling fan 27 is increased.
[0033]
On the other hand, when raising the oil temperature, the electric relief valve 14 is set at a certain pressure to generate heat, the electric bypass valve 17 is opened, and the set pressure on the upstream side is reduced, so that the oil amount to the oil cooler 16 is reduced. The ratio is reduced, and the rotation speed of the cooling fan 27 is reduced.
[0034]
(Step 2)
The control device 36 determines whether or not the filter clogging signal from the indicator 23 has been detected for a predetermined time or more.
[0035]
(Step 3)
The control device 36, which has sensed the filter clogging signal from the indicator 23 for a certain period of time or more, confirms with the operator whether or not to perform the filter clogging automatic examination method through display on the monitor 37 or the like.
[0036]
(Step 4)
Control device 36 waits for the operator to select YES or NO. At this time, if the operator is in the midst of the work and the operator determines that it is dangerous, and selects NO, the filter clogging automatic examination function does not operate.
[0037]
(Step 5)
Even if the operator chooses not to perform the filter clogging automatic examination method, the operating device for operating the hydraulic excavator (the operating lever for the working machine, the operating lever for traveling, the operating lever for turning, the switch, etc.) is in the non-operating state, If the state at the neutral position has continued for a certain reference time or more, the operator is again asked whether or not to perform the automatic filter clogging inspection method, and if NO, this is repeated.
[0038]
(Step 6)
If the operator selects YES in step 4, the filter clogging automatic examination function is activated, and the controller 36 first checks the oil temperature of the operating oil by the oil temperature sensor 25.
[0039]
(Step 7)
The control device 36 determines whether or not the oil temperature detected by the oil temperature sensor 25 is within a certain reference range.
[0040]
(Step 8)
If the oil temperature is out of the reference range, the controller 36 activates an oil temperature correction function for controlling the set pressure of the electric relief valve 14, the set pressure of the electric bypass valve 17, and the rotation speed of the cooling fan 27, thereby reducing the oil temperature. Automatic correction within the reference range. For example, when lowering the oil temperature, the electric relief valve 14 is set to the lowest pressure, the electric bypass valve 17 is throttled, and the set pressure on the upstream side is increased to increase the oil amount ratio to the oil cooler 16; The rotation speed of the cooling fan 27 is increased. On the other hand, when raising the oil temperature, the electric relief valve 14 is set at a certain pressure to generate heat, the electric bypass valve 17 is opened, and the set pressure on the upstream side is reduced, so that the oil amount to the oil cooler 16 is reduced. The ratio is reduced, and the rotation speed of the cooling fan 27 is reduced. In this way, the correction is made so that the oil temperature of the working oil falls within a certain range.
[0041]
(Step 9)
When the controller 36 determines that the oil temperature is within a certain reference range, it sends a control signal to the electric relief valve 14 to set the relief set value to the minimum pressure.
[0042]
(Step 10)
The control device 36 sends a control signal to the electric pressure reducing valve 35 and issues a command to the main pump 11 via the regulator 32 to discharge a specified flow rate.
[0043]
(Step 11)
The control device 36 waits for a certain time whether or not the indicator 23 installed on the hydraulic oil filter 22 is operated.
[0044]
(Step 12)
After a certain period of time, the control device 36 determines whether or not the indicator 23 has been activated due to an increase in the differential pressure across the filter element 22a.
[0045]
(Step 13)
When the indicator 23 is activated, the control device 36 notifies the user of “replacement of the filter element” through the monitor 37 or the like.
[0046]
(Step 14)
When the indicator 23 does not operate, the control device 36 notifies “no abnormality” through the monitor 37 or the like.
[0047]
(Step 15)
The control device 36 that has notified the "replacement of the filter element" monitors whether or not the replacement of the filter element 22a has actually been performed. When the filter element 22a is replaced, the controller 37 is notified through the monitor 37 that the filter element has been replaced.
[0048]
(Step 16)
The control device 36 determines whether or not the operation time for operating the hydraulic excavator has passed a certain time while the operator ignores the warning from the monitor 37 without replacing the filter element 22a.
[0049]
(Step 17)
When the excavator is operated without replacing the element even after detecting the clogging of the filter element 22a, the control device 36 forcibly resets the function of the excavator when the operation time of the excavator has passed a certain time. To lower.
[0050]
That is, if the element is not replaced even after the clogging of the filter element 22a is detected, the bypass check valve 24 of the filter unit opens, the contamination enters the tank 13, and the hydraulic equipment such as the main pump 11 and various valves is operated. Since there is a possibility that the main pump 11 and the pilot pump 34 may be damaged, the control device 36 may reduce the rotation speed of the engine (not shown) that drives the main pump 11 and the pilot pump 34 or reduce the discharge flow rate of the main pump 11 to continue the work. And protect the aircraft.
[0051]
If a day jam is diagnosed by the above function, the machine down time is minimized by immediately contacting the machine management department such as a sales company through the remote information communication system.
[0052]
Next, the effects of this embodiment will be described.
[0053]
As shown in steps 6 to 10, by using a hydraulic shovel equipped with a system function capable of keeping the oil temperature within a reference range and supplying a constant flow rate, the oil temperature and flow rate are controlled to predetermined states. Therefore, the kinematic viscosity and flow rate of the hydraulic oil that affects the differential pressure across the filter element 22a can be appropriately controlled, and as shown in step 12, the clogging of the filter element 22a is reduced from the differential pressure across the filter element 22a. A correct diagnosis can be made.
[0054]
Moreover, the clogging of the filter element 22a can be accurately detected by using the existing equipment for controlling the temperature and the flow rate of the oil without adding a special correction mechanism as described in Patent Document 1. Energy loss due to the generation of heat in the fixed throttle as in the example can be prevented, and the life of the filter element 22a can be maximized, so that the running cost can be reduced.
[0055]
Further, as shown in Steps 2 to 4, when the hydraulic circuit of the hydraulic shovel is under operation requiring a sufficient amount of oil, the control device 36 detects the possibility of clogging of the filter element 22a. Even if the operator does not perform an affirmative operation, it is possible to select not to perform the above-described automatic filter clogging inspection method accompanied by a decrease in flow rate, so that it is possible to prevent a decrease in work efficiency of the excavator.
[0056]
Further, as shown in Steps 3 to 5, when the non-operation state in which the hydraulic excavator is not operated continues for a reference time or more, the operator is asked again to confirm whether or not to perform the above-mentioned filter clogging automatic inspection method. This can draw the operator's attention, and can prevent a state in which the filter element 22a may be clogged for a long time.
[0057]
In addition, as shown in steps 13 to 17, when the excavator is operated for a long time while the filter element 22a is clogged, contamination clogged in the filter element 22a enters the hydraulic circuit. Since the hydraulic circuit components may be damaged, the function of the hydraulic shovel is forcibly reduced, thereby forcing the replacement of the filter element 22a and preventing the hydraulic circuit components from being damaged.
[0058]
The present invention is not limited to the hydraulic oil of a hydraulic shovel, but may be applied to hydraulic oil, lubricating oil, and the like of working machines other than the hydraulic shovel.
[0059]
【The invention's effect】
According to the first aspect of the present invention, clogging can be correctly diagnosed based on the differential pressure across the filter element by controlling the flow rate of hydraulic oil that affects the differential pressure across the filter element to an appropriate prescribed flow rate. Moreover, clogging of the filter element can be accurately detected without adding a special correction mechanism, energy loss due to generation of heat in the fixed throttle as in the conventional example can be prevented, and the life of the filter element can be reduced. Since it can be used to the maximum extent, running costs can be reduced.
[0060]
According to the second aspect of the invention, by controlling the temperature and the flow rate of the oil to a predetermined state, it is possible to appropriately control the kinematic viscosity and the flow rate of the hydraulic oil which affect the differential pressure across the filter element. Thus, correct diagnosis of clogging can be performed with higher accuracy from the differential pressure across the filter element.
[0061]
According to the third aspect of the present invention, when the hydraulic circuit of the work machine is performing a work requiring a sufficient amount of oil, even if the control device senses the possibility of clogging of the filter element, the operator is not required to perform the operation. By not performing the affirmative operation, it is possible to select not to carry out the automatic filter clogging inspection method according to claim 1 or 2, so that it is possible to prevent a decrease in work efficiency of the work machine.
[0062]
According to the fourth aspect of the present invention, when the non-operation state in which the work machine is not operated continues for the reference time or more, the operator is asked again to confirm whether or not to perform the automatic filter clogging inspection method, and the operator To prevent the filter element from being clogged for a long time.
[0063]
According to the invention as set forth in claim 5, when the work machine is operated for a long time with the filter element clogged, contamination clogged in the filter element is mixed into the hydraulic circuit, and the hydraulic circuit component is removed. Since there is a possibility of damage, the function of the work machine is forcibly reduced, thereby forcibly exchanging the filter element and preventing damage to the hydraulic circuit components.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an embodiment of a hydraulic circuit and a control circuit for performing an automatic examination method for filter clogging according to the present invention.
FIG. 2 is a flowchart showing a control procedure in a preliminary stage of the automatic filter clogging automatic examination method.
FIG. 3 is a flowchart showing a control procedure of an automatic inspection function of the automatic filter clogging automatic inspection method.
FIG. 4 is a circuit diagram showing an example of a conventional hydraulic circuit and a control circuit having a filter clogging detection function.
[Explanation of symbols]
22a Filter element 36 Control device

Claims (5)

With the flow rate of oil passing through the filter element controlled to the specified flow rate,
Measure the differential pressure across the filter element,
A filter clogging automatic examination method characterized in that the difference between the front and rear pressures is compared with a reference value to automatically detect whether or not the filter element is clogged. 2. The method according to claim 1, wherein the temperature of the oil passing through the filter element is controlled within a reference range. The control device that has detected the risk of clogging of the filter element in the hydraulic circuit of the work machine,
Confirming with the operator of the work machine whether or not to perform the filter clogging automatic inspection method according to claim 1 or 2;
3. An automatic filter clogging medical examination method according to claim 1 or 2, wherein the filter clogging automatic examination method is performed by an affirmative operation of an operator. Even if the operator chooses not to implement the filter clogging automatic screening method,
If the non-operation state of the operating device that operates the work machine has continued for the reference time or longer,
4. The automatic filter clogging inspection method according to claim 3, wherein the operator is again asked whether or not to perform the filter clogging automatic inspection method according to claim 1 or 2. If the work machine is started without replacing the element even after detecting the clogging of the filter element,
The method according to claim 3, wherein the control device forcibly reduces the function of the work machine when the work time of the work machine has passed a predetermined time.

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