JP3857361B2 - Hydraulic pump fault diagnosis device for work machines - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic pump failure diagnosis apparatus for a work machine that determines whether each variable capacity hydraulic pump of a work machine that includes a plurality of variable capacity hydraulic pumps and operates a plurality of hydraulic actuators to perform work.
[0002]
[Prior art]
A working machine such as a hydraulic excavator rotates a hydraulic pump by an engine and drives a hydraulic actuator with pressure oil discharged from the hydraulic pump to perform a required operation. Therefore, when a malfunction occurs in the hydraulic pump, a great hindrance to the work of the work machine occurs. For this reason, it is important to determine whether the hydraulic pump is good or bad, and to repair the parts as soon as possible in the event of a malfunction to prevent work problems to a minimum. Conventionally, the determination of the quality of a hydraulic pump (failure diagnosis) has been made by measuring the flow rate discharged from the hydraulic pump by a flow meter and checking whether this flow rate is within a predetermined range.
[0003]
[Problems to be solved by the invention]
Examples of the flow meter include a turbine flow meter, an oval flow meter, a flow meter using a pitot tube, and a flow meter for detecting the displacement amount of the poppet valve described in Japanese Patent Application No. 63-113434. There is a problem that the structure is complicated and expensive, and it lacks earthquake resistance. Therefore, the flow meter can be attached to a small hydraulic pump installed in a place with little vibration, but it is virtually impossible to attach it to a hydraulic pump of a work machine that receives large vibrations such as a hydraulic excavator. is there. For this reason, for a hydraulic pump of a work machine with large vibrations, a predetermined use period is set for each component constituting the vibration pump, and the part is replaced at an appropriate time when the use period has elapsed. It is the actual situation.
[0004]
However, the period of use is usually set with a sufficient allowance, and in most cases the parts can be used for a longer period of time without replacement. This is not preferable from the viewpoints of economy and labor and time for parts replacement. Furthermore, a large hydraulic excavator has the following problems when a malfunction occurs in the hydraulic pump. That is, usually, a large hydraulic excavator is equipped with a number of hydraulic pumps, and the hydraulic actuators are driven by merging the discharge pressure oils of the two hydraulic pumps. If any of these hydraulic pumps fail, the operator can know the occurrence of the failure by changing the operating speed of the hydraulic actuator, but the hydraulic actuator is driven by merging the discharge pressure oil of the two hydraulic pumps. If the operating speed of the hydraulic actuator changes, it can not be determined which of the hydraulic pumps is defective even if it is known that the hydraulic pump has a malfunction.
[0005]
An object of the present invention is to provide a hydraulic pump fault diagnosis device for a working machine that can solve the above-described problems in the prior art and can reliably identify a hydraulic pump that is inexpensive and has a problem without using a flow meter. It is to provide.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 is driven by a plurality of variable displacement hydraulic pumps whose discharge amount is controlled by a regulator, and pressure oil discharged from one or more of these variable displacement hydraulic pumps. A plurality of hydraulic actuators, a plurality of flow control valves for controlling driving of each of the hydraulic actuators, and one or a plurality of the variable displacement hydraulic pumps via one or a plurality of the flow control valves in a neutral position A check valve with a differential pressure sensor interposed between each of the variable displacement hydraulic pumps and the flow rate control valve, and the variable displacement hydraulic pump connected to the conduit. The maximum discharge amount instructing means for instructing the regulator to the maximum discharge amount of the variable displacement hydraulic pump and the maximum flow rate by the maximum discharge amount instructing means. Storage means for storing the detected pressure of the check valve with the differential pressure sensor for the variable displacement hydraulic pump, and failure determination means for determining pass / fail of each variable displacement hydraulic pump based on the detected pressure are provided. Features.
[0007]
According to a second aspect of the present invention, in the first aspect of the invention, a pressure-flow rate converting means for converting the detected pressure into a flow rate corresponding to the detected pressure is provided instead of the means for determining based on the detected pressure. The quality of each of the variable displacement hydraulic pumps is judged based on the flow rate converted by the pressure-flow rate conversion means.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on the illustrated embodiments.
FIG. 1 is a diagram showing a hydraulic pump failure diagnosis apparatus for a large hydraulic excavator according to an embodiment of the present invention. In this figure, 1 to 6 are variable displacement hydraulic pumps (hereinafter simply referred to as hydraulic pumps), 7 is a pilot pump, 1a to 6a are displacement displacement mechanisms of the respective hydraulic pumps (hereinafter represented by swash plates), Reference numerals 11 to 16 denote regulators for controlling the tilting amounts of the swash plates 1a to 6a, that is, the discharge flow rates of the hydraulic pumps 1 to 6, T denotes a tank, CV denotes a check valve, and RV denotes a relief valve. The hydraulic pumps 1 to 3 are driven by a first prime mover (engine) not shown, and the hydraulic pumps 4 to 6 are driven by a second prime mover (engine) not shown. The hydraulic pumps 2 to 5 are hydraulic pumps having the same capacity, and the hydraulic pumps 1 and 5 are other hydraulic pumps having the same capacity.
[0009]
Reference numerals 21 and 26 denote flow control valves for controlling the turning motor, which are connected to the hydraulic pumps 1 and 6 and have a center bypass. B_{twenty three}Is the valve block where the hydraulic pumps 2 and 3 join, B₄₅Indicates a valve block where the hydraulic pumps 4 and 5 join. Valve block B_{twenty three}Consists of tandem-connected flow control valves 231 to 234 and a conduit 30, and valve block B₄₅Consists of tandem-connected flow control valves 451 to 454 and a conduit 40. Valve block B_{twenty three}The flow rate control valve 231 is for driving motor control, the flow rate control valve 232 is for boom cylinder and bucket cylinder control, the flow rate control valve 233 is for backup, the flow rate control valve 234 is for arm cylinder control, and a valve block B₄₅The flow rate control valve 451 is for arm cylinder control, the flow rate control valve 452 is for bucket cylinder control, the flow rate control valve 453 is for boom cylinder control, and the flow rate control valve 454 is for driving motor control. Each flow control valve has a center bypass circuit and valve block B_{twenty three}When the flow rate control valves 231 to 234 are all in the neutral position, the hydraulic pumps 2 and 3 pass through the center bypass circuit of the flow rate control valves 231 to 234 to the pipe line 30 and then to the tank T via the pipe line 30. Connected to. Similarly, valve block B₄₅When the flow rate control valves 451 to 454 are all in the neutral position, the hydraulic pumps 4 and 5 pass through the center bypass circuit of the flow rate control valves 451 to 454 to the pipeline 40 and further to the tank T via the pipeline 40. Connected to.
[0010]
In the above hydraulic circuit, for example, when an operator of a hydraulic excavator operates a boom operating lever (not shown) to raise the boom, a pilot pressure P proportional to the operation amount is obtained._a Is added to the command input port on the right side of the flow rate control valve 232 and the flow rate control valve 453, the flow rate control valves 232 and 453 are switched to the right side position, and the pressure oil from the hydraulic pumps 2, 3, 4, and 5 merge. Then, it flows into the bottom side of a boom cylinder (not shown), and the rod is extended to drive the boom in the raising direction. The command input port on the left side of the flow control valve 232 in the figure is for bucket tilting, and the command input port on the left side of the flow control valve 453 in the figure is a boom lowering port.
[0011]
On the other hand, command signals are input to the regulators 11 to 16 during operation of the hydraulic pumps 1 to 6 to control the tilting of the swash plates 1a to 6a and to control the discharge flow rates of the hydraulic pumps 1 to 6. This will be described with reference to the pressure-flow rate characteristic diagram shown in FIG. In FIG. 2, the horizontal axis represents the discharge pressure of the hydraulic pump, and the vertical axis represents the discharge flow rate of the hydraulic pump. The command signal to the regulator will be described taking the regulator 12 as an example, but the command signals of other regulators are the same.
[0012]
The regulator 12 has command signal input ports 12a, 12b, and 12c. Note that illustration of command signal input ports corresponding to the command signal input ports 12b and 12c in other regulators is omitted. The command signal input port 12a has a valve block B_{twenty three}The maximum pressure of the operation pilot pressure applied to each of the flow rate control valves is input, whereby the swash plate 2a is controlled in a direction in which the discharge flow rate increases (this command signal input port is referred to as an operation signal input port). ). In many cases, the discharge pressure of the hydraulic pump 12 is input to the command signal input port 12b, and when the discharge pressure exceeds a predetermined level as shown by the solid line in FIG. The swash plate 2a is controlled in the direction to be moved. As shown by the broken line in FIG. 2, a signal for translating the pressure-flow rate characteristic is input to the command signal input port 12c. The above configuration is a known hydraulic circuit as disclosed in, for example, Japanese Patent Publication No. 62-28318 and Japanese Patent Publication No. 1-25906.
[0013]
Next, in this embodiment, a configuration added to the hydraulic circuit for failure diagnosis will be described. 51 to 56 are electromagnetic switching valves, which are always set to the upper position by the illustrated spring, and the electric signal (v₁ ~ V₆ Is switched to the lower position. When each of the electromagnetic switching valves 51 to 56 is in the upper position, a command signal in normal operation is input to the operation signal input port of each of the regulators 11 to 16, and when switched to the lower position, the pilot pressure of the pilot pump 7 is increased. The discharge flow rate of the corresponding hydraulic pump that is input is maximized.
[0014]
61 is a check valve with a differential pressure sensor provided between the hydraulic pump 1 and the flow control valve 21, 62 and 63 are hydraulic pumps 2 and 3 and a valve block B, respectively._{twenty three}Check valves with differential pressure sensors provided on the upstream side of the junction between the hydraulic pumps 4 and 5 and the valve block B, respectively.₄₅A check valve with a differential pressure sensor provided on the upstream side of the junction between them, 66 is a check valve with a differential pressure sensor provided between the hydraulic pump 6 and the flow control valve 26 (details will be described later). . Reference numeral 70 denotes a processing device (details will be described later) that is configured by a computer and determines failure of the hydraulic pump, 80 is a switch that instructs the processing device 70 to start determination, and 90 is a display device that displays determination data.
[0015]
FIG. 3 is a view showing a configuration of the check valve 61 with a differential pressure sensor. Since the other check valve with a differential pressure sensor has the same configuration, the illustration is omitted. In FIG. 3, reference numeral 611 denotes a check valve connected to the hydraulic pump 1, and 612 denotes a differential pressure sensor that detects a difference in pressure generated on both sides of the check valve. Usually, the check valve has a poppet pressed against the seat surface by a spring, and the pressure oil from the hydraulic pump acts on the surface 6110 on the pump side of the poppet, and the acting force is the spring force and the surface 6111 on the outlet side. When the sum is larger than the sum of the forces acting on the poppet, the poppet moves away from the seat surface, and the pressure oil enters from the inlet port 613 and flows out from the outlet port 614 through a gap formed in the seat surface. At this time, the pressure difference (differential pressure) between the both sides (inlet port 613 and outlet port 614) of the check valve 611 changes corresponding to the flow rate passing through. The differential pressure sensor 612 has the differential pressure dP.₆₁Is detected and output. In FIG. 1, the detection signals of the check valves 61 to 66 with differential pressure sensors are denoted by dP.₆₁~ DP₆₄It is shown in
[0016]
FIG. 4 is a system configuration diagram of the processing apparatus shown in FIG. In this figure, 71 is a central processing unit (CPU) for performing required computation and control, 72 is a read only memory (ROM) in which a control program of the CPU 71 and the like are stored, 73 is temporarily stored with measurement results, determination results, and the like. Random access memory (RAM), 74 is a timer for outputting a time signal, 75 is provided with an A / D converter, and a detected pressure signal dP of check valves 61 to 66 with a differential pressure sensor₆₁~ DP₆₆And an input interface 76 for inputting the determination start signal w of the switch 80, 76 includes a D / A converter, and a signal v for each of the electromagnetic switching valves 51 to 56.₁ ~ V₆ And an output interface for outputting display data D to the display device 90. The ROM 72 has an area 721 in which a conversion map and necessary numerical values described later are stored, an area 722 in which an input / output processing program is stored, an area 723 in which a determination processing program is stored, and an area 724 in which a display processing program is stored. Have
[0017]
FIG. 5 is a diagram showing a conversion map stored in the area 721 of the ROM 72 shown in FIG. In this figure, the detected pressure of each check valve 61-66 with a differential pressure sensor shown in FIG. 1 is taken on the horizontal axis, and the flow rate corresponding to this is taken on the vertical axis. This conversion map is created as follows. That is, each flow control valve is set to the neutral position, pressure oil is passed through the check valves 61 to 66 with differential pressure sensors, the relationship between the flow rate and the differential pressure is measured, and the obtained data is created in the form of a map. When creating in this way, as will be described later, since the failure diagnosis is performed with the discharge flow rate of the hydraulic pump as the maximum flow rate, the conversion map also creates the relationship between the flow rate and the pressure in the large flow rate part. If it is enough, it is enough. Also, if each hydraulic pump shown in FIG. 1 is new, find one point with the rated flow rate and differential pressure of the hydraulic pump, and create a conversion map using the known orifice and pipe resistance. Also good.
[0018]
Next, the operation of the present embodiment will be described with reference to the flowcharts shown in FIGS. Fault diagnosis can be performed at any time by turning on the switch 80. By the way, a large excavator often performs a continuous work for about 8 hours including a break in the middle, and in such a case, the operator of the excavator can either It is desirable to operate the switch 80 when changing with the operator. At the time of this switch operation, the rotational speed of the engine as the prime mover is maximized, and the switch 80 is turned on in a state where all the operation levers are in the neutral position. As a result, the signal w from the switch 80 is read into the CPU 71 via the input interface 75 of the processing device 70, and the input / output processing program stored in the area 722 of the ROM 72 is first activated. The processing procedure of this input / output processing program will be described with reference to FIG.
[0019]
First, the CPU 71 reads the current time T (n) from the timer 74 (procedure S).₁ ). Note that n is the procedure S₁ This represents the number of times of processing. Next, the CPU 71 sends a signal v to the electromagnetic switching valve 51.₁ Is turned on, and the signals for the other electromagnetic switching valves 52 to 56 are turned off. As a result, the electromagnetic switching valve 51 is switched to the lower position, the pressure of the pilot pump 7 is introduced to the operation signal input port of the regulator 11, the swash plate 1a is tilted to the maximum, and the discharge flow rate of the hydraulic pump 1 is maximum. Flow rate. Therefore, the differential pressure on both sides of the check valve 611 of the check valve 61 with a differential pressure sensor increases, and this differential pressure is detected by the differential pressure sensor 612. The CPU 71 outputs a signal dP from the differential pressure sensor 612.₆₁, And this is the pressure data D for the maximum flow rate of the hydraulic pump 1₁ (N) is stored in the RAM 73 (procedure S₂ ).
[0020]
Next, the CPU 71 sends a signal v to the electromagnetic switching valve 52.₂ Is turned on, and the signals for the other electromagnetic switching valves 51, 53-56 are turned off. As a result, the electromagnetic switching valve 51 returns to the upper position, the electromagnetic switching valve 52 is switched to the lower position, the pressure of the pilot pump 7 is introduced into the operation signal input port of the regulator 12, and the swash plate 2a is tilted to the maximum. Thus, the discharge flow rate of the hydraulic pump 2 becomes the maximum flow rate, and the CPU 71 at this time outputs the signal dP of the differential pressure sensor of the check valve 62 with the differential pressure sensor.₆₂Pressure data D for the maximum flow rate of the hydraulic pump 2₂ (N) is stored in the RAM 73 (procedure S_Three ). Exactly the same processing is performed for the hydraulic pumps 3 to 6 (procedure S)._Four ~ S₇ ).
[0021]
Next, the CPU 71 uses the conversion map shown in FIG. 5 stored in the area 721 of the ROM 72 to generate each pressure data D_i (N) (i = 1 to 6) is the flow rate Q corresponding to these_i (N) (i = 1 to 6)₈ ), In the area A (n) of the RAM 73, the time T (n) and each flow rate Q₁ ~ Q₆ (Step S₉ ), And terminate the input / output processing program.
The above procedure S₈ In this process, the pressure was converted to the flow rate using the conversion map stored in advance, but this is not necessarily based on the conversion map, and the accuracy is somewhat reduced, but instead of the conversion map, the following calculation is performed to calculate the flow rate relative to the pressure. You may make it ask.
Q_i = K₀ ・ D_i
Where k₀ Is a predetermined coefficient.
[0022]
When the input / output processing program ends, the determination processing program stored in the area 723 of the ROM 72 is activated next. The processing procedure of this determination processing program will be described with reference to FIG. The CPU 71 determines each flow rate Q_i In contrast, k flow data Q before the previous judgment_i (N-1), Q_i (N-2), ..., Q_i (N−k) are taken out from the areas A (n−1), A (n−2),..._iA(Procedure S₁₁). That is, the average value Q of the k flow rates before the previous time of each hydraulic pump 1-6._1A, Q_2A............ Q_6AIs obtained.
[0023]
Note that the value k is selected such that, for example, about 100 hours have passed before the current determination. As described above, when the operator changes every 8 hours and the operator makes a determination each time, the value k is set to 12 or 13 (100/8).
[0024]
Next, the CPU 71_A = T (n) -T (n-k), that is, the average value Q_iACalculation period T_A (Procedure S₁₂). Furthermore, the CPU 71 determines the flow rate Q obtained this time for the hydraulic pumps 2, 3, 4, 5 having the same capacity.₂ (N), Q_Three (N), Q_Four (N), Q_Five Average value Q of (n)_B (Step S₁₃) Then, the average value Q_B Period T_B [T_B = T (n) -T (n-k)] (procedure S₁₄).
Each period T_A , T_B Is calculated based on the time of the timer 74. The time during which the engine is at a predetermined speed or higher, or the time at which the hydraulic pump is at a predetermined pressure or higher or a predetermined flow rate is electrically Measure each period T_A , T_B Obviously it is better to calculate.
[0025]
Next, the CPU 71 calculates the following formula:
E_iA= [Q_i (N) -Q_iA] × 100 / Q_iA(%)
That is, the current flow rate Q_i Is the past long-term average Q_iA% Of increase / decrease with respect to₁₅This is stored in the RAM 73.
Also, the following formula
E_iB= [Q_i (N) -Q_i (N-1)] × 100 / Q_i (N-1) (%)
That is, the current flow rate Q_i Is the flow rate Q obtained last time_i Calculate how many% increase or decrease with respect to (n-1) (procedure S₁₆This is stored in the RAM 73.
In addition, the following formula
E_jC= [Q_j (N) -Q_B ] × 100 / Q_B (%) (J = 2, 3, 4, 5)
That is, the current flow rate Q of the hydraulic pumps 2, 3, 4, 5 of the same capacity₂ (N), Q_Three (N), Q_Four (N), Q_Five Each of (n) is their average value Q_B % Difference with respect to (step S₁₇This is stored in the RAM 73. Thereby, the determination processing program is terminated.
[0026]
Above value E_iAIs the first criterion value based on the long-term flow average for each hydraulic pump, the value E_iBIs the second criterion value based on the previous flow rate for each hydraulic pump, the value E_jCIs a third criterion value based on the current average flow rate of hydraulic pumps of the same capacity. The first determination reference value is suitable for determining a gradual change in the performance of the hydraulic pump, and the second determination reference value is effective for determining a sudden change in performance that has occurred within a few hours of the hydraulic pump. The third criterion value is effective for finding hydraulic pumps that are significantly different from each other by comparing hydraulic pumps of the same capacity.
[0027]
When the determination processing program ends, the display processing program stored in the area 724 of the ROM 72 is activated next. As shown in FIG. 8, the processing procedure of this display processing program is as follows: current time T (n) obtained by the input / output processing program and determination processing program, and elapsed time T up to k times before the previous time._A , Elapsed time T from the previous time_B , First determination reference value E_iA, Second determination reference value E_iB, And the third judgment reference value E_jCIs output as data D (usually a serial signal) to the display device 90 (step S)._{twenty one}) Processing.
[0028]
FIG. 9 is a diagram showing a display example of the display device 90. Although not shown, the display device 90 includes data D output from the processing device 70 and an input interface for inputting other necessary data, a CPU, a ROM, a RAM, a character generator, an LCD driver, an LCD, and the like. When data D is input, display is performed in the format shown in FIG. 8, for example. In FIG. 8, the underlined portion is a portion that changes depending on the input data D. The data D shown in this display example shows that the current time T (n) is “April 4, 1996 14:30” and the elapsed time T until k times before._A Is "103 hours", elapsed time T from the previous time_B Is “7.6 hours”, and the first judgment reference value E of the hydraulic pump 1_1AIs “−15%”, also the second criterion E_1BIs “−3%” ………… The third criterion value E of the hydraulic pump 2_2CIs “+7%” ............. Third criterion E for hydraulic pump 5_2CIs “+ 6%”, the first judgment reference value E of the hydraulic pump 6_6AIs “−22%”, also the second criterion value E_6BIs “−6%”.
[0029]
The operator of the hydraulic excavator looks at the screen of the display device 90 installed in the cab and determines whether there is an abnormality in each of the hydraulic pumps 1 to 6. In this judgment, the variation between the hydraulic pumps is set to several percent, and the pressure loss generated when passing through the pipe line is easily affected by the temperature of the hydraulic oil. , First determination reference value E_iAAbout 20%, and the second criterion E_iBIn order to avoid misjudgment in a short time, about 25% is further added to the third judgment reference value E._jCIs a hydraulic pump of the same capacity, and since it is a comparison at the same time and the same temperature and high accuracy can be expected, about 15% is used as a judgment value for whether or not there is an abnormality.
[0030]
Thus, in this embodiment, the check valve with a differential pressure sensor is interposed between the hydraulic pump and the flow rate control valve, and the discharge start of one hydraulic pump is set to the maximum flow rate by operating the determination start switch. In addition, the discharge flow rate of all the other hydraulic pumps is set to the minimum flow rate, and the detected differential pressure of the check valve with the differential pressure sensor corresponding to the one hydraulic pump is sampled and converted to the flow rate corresponding to each. This is performed for the hydraulic pump, and each flow rate for each determination collected in this way is stored. The flow rate obtained this time is (1) the average value of the flow rate of the same hydraulic pump for the past long time, (2) the previous flow rate. Compared with the flow rate and (3) the average value of the current flow rate of a hydraulic pump of the same capacity, this is a hydraulic pump of a work machine with a large vibration, and a plurality of hydraulic pumps are used together. Even each hydraulic port The failure diagnosis of each flop can be reliably performed.
[0031]
In addition, each part can be used up to the end of its service life as compared with a method in which the part is replaced after a predetermined usage time has elapsed, so that the use efficiency of the part can be increased and it is extremely economical.
In addition, it is possible to increase the determination accuracy by repeatedly performing the failure diagnosis of the present embodiment and accumulating data, thereby predicting the failure considerably before the occurrence of the failure, This can be dealt with in advance.
[0032]
In the above embodiment, an example has been described in which the electromagnetic switching valves are sequentially switched to collect the differential pressure of each check valve with a differential pressure sensor. However, all the hydraulic pumps are switched simultaneously by one electromagnetic switching valve, A differential pressure may be collected. In this case, since the switching of the electromagnetic switching valve becomes unnecessary, the determination time can be shortened. When such a means is adopted, the pressure oil of each hydraulic pump only passes through the flow control valve and returns to the tank, the discharge pressure of each hydraulic pump is low, the absorption torque of each hydraulic pump is small, The total absorption torque becomes the engine load, and the engine speed slightly decreases, and the hydraulic pump speed also decreases and the maximum flow rate may decrease. Is possible.
[0033]
Furthermore, although the electromagnetic switching valve is used in the above embodiment, failure determination can be performed without using such an electromagnetic switching valve. That is, by selectively operating the operation lever and operating a specific hydraulic actuator in a specific posture, the discharge flow rate of the hydraulic pump can be made a flow rate close to the maximum flow rate. For example, if the boom is lifted, the arm is extended, and the bucket is dumped, the hydraulic pumps 2, 3, 4, 5 All determination processes can be performed by collecting the differential pressure signal under the same conditions as in the previous embodiment. In this case, the pressure P in FIG.₀ It is premised that operation in an uncontrolled region is possible, but the load pressure is large and the pressure P₀ Even if a larger constant torque control range is entered, the processing based on the third criterion value is still effective, and if it is always operated in the same posture with care to ensure good reproducibility, the accuracy will be slightly reduced. However, the processing based on the first and second determination reference values can be made effective by selecting a slightly larger determination value. On the other hand, the hydraulic pumps 1 and 6 are for the swing motor, and if the operating lever is operated to the maximum amount, it is surely driven in the constant torque control region shown in FIG. Processing based on the criterion value is effective.
[0034]
In the above description of the embodiment, the hydraulic excavator has been described as an example, but it is naturally applicable to failure diagnosis of a hydraulic pump of a work machine other than the hydraulic excavator. In addition, an example has been described in which the differential pressure detected by the check valve with the differential pressure sensor is converted into a flow rate, and failure determination is performed based on this flow rate. However, it is not always necessary to convert the differential pressure into a flow rate, and a differential pressure sensor is provided. The differential pressure detected by the check valve can be used as it is.
Further, by transmitting the obtained data to a department that manages the work machine, it is possible to perform a failure diagnosis in the management department, not the operator of the work machine.
In the description of the above embodiment, an example of displaying how much the current value of each hydraulic pump is deviated from the three determination reference values is shown, but the result of comparison with the determination value is displayed, It can also be displayed using a lamp or the like.
Further, the example of performing the determination every 8 hours of work change has been described. However, the present invention is not limited to this, and the engine is set to the maximum rotation speed or a rotation speed close thereto, all the operation levers are set to neutral, and the switch 90 is turned on. It can be done at any time by operating.
Alternatively, a small throttle may be inserted upstream or downstream of the check valve between two connection points of the differential pressure sensor to increase the pressure in the pipe line.
[0035]
【The invention's effect】
As described above, in the present invention, a check valve with a differential pressure sensor is interposed between the hydraulic pump and the flow rate control valve so that the discharge amount of the hydraulic pump is maximized and the differential pressure sensor corresponding to each hydraulic pump is provided. The detected differential pressure of the check valve is sampled (or converted into a flow rate corresponding to this), and each detected differential pressure (or flow rate) for each determination is stored, and based on the detected value (or flow rate) Therefore, even if the hydraulic pumps of work machines with large vibrations are used by merging multiple hydraulic pumps, failure diagnosis for each hydraulic pump is ensured. Can be done.
[0036]
In addition, each part can be used up to the end of its service life as compared with a method in which the part is replaced after a predetermined usage time has elapsed, so that the use efficiency of the part can be increased and it is extremely economical.
Furthermore, it is possible to increase the determination accuracy by repeating the failure diagnosis and accumulating data, thereby allowing the failure to be predicted at a stage substantially before the occurrence of the failure, and dealing with this in advance. Can do.
[Brief description of the drawings]
FIG. 1 is a diagram showing a hydraulic pump failure diagnosis apparatus for a large-sized hydraulic excavator according to an embodiment of the present invention.
FIG. 2 is a characteristic diagram of the relationship between the discharge pressure and the discharge flow rate of each hydraulic pump shown in FIG.
FIG. 3 is a diagram showing a configuration of a check valve with a differential pressure sensor.
4 is a system configuration diagram of the processing apparatus shown in FIG. 1; FIG.
FIG. 5 is a characteristic diagram of a conversion map between a detected pressure and a flow rate of the pressure sensor shown in FIG. 1;
6 is a flowchart for explaining the operation of the processing apparatus shown in FIG. 1;
7 is a flowchart for explaining the operation of the processing apparatus shown in FIG. 1;
FIG. 8 is a flowchart for explaining the operation of the processing apparatus shown in FIG. 1;
9 is a diagram showing a display example of the display device shown in FIG. 1. FIG.
[Explanation of symbols]
1-6 Hydraulic pump
7 Pilot pump
11-16 Regulator
51-56 Solenoid switching valve
61-66 Check valve with differential pressure sensor
70 processing equipment
80 switches
90 Display device

Claims (5)

A plurality of variable displacement hydraulic pumps whose discharge amount is controlled by a regulator, a plurality of hydraulic actuators driven by pressure oil discharged from one or more of these variable displacement hydraulic pumps, and control of driving of each of the hydraulic actuators A work machine comprising: a plurality of flow rate control valves configured to connect one or more variable displacement hydraulic pumps to a tank via the one or more flow rate control valves in a neutral position; A check valve with a differential pressure sensor interposed between the variable displacement hydraulic pump and the flow control valve, and the maximum discharge amount of the variable displacement hydraulic pump to the regulator in a state where the variable displacement hydraulic pump is connected to the conduit. With the differential pressure sensor for the maximum discharge amount indicating means for instructing and the variable displacement hydraulic pump discharging the maximum flow rate by the maximum discharge amount indicating means A hydraulic pump fault diagnosis device for a working machine, characterized by comprising storage means for storing a detected pressure of a check valve, and failure determination means for determining pass / fail of each variable displacement hydraulic pump based on the detected pressure . A plurality of variable displacement hydraulic pumps whose discharge amount is controlled by a regulator, a plurality of hydraulic actuators driven by pressure oil discharged from one or more of these variable displacement hydraulic pumps, and control of driving of each of the hydraulic actuators A work machine comprising: a plurality of flow rate control valves configured to connect one or more variable displacement hydraulic pumps to a tank via the one or more flow rate control valves in a neutral position; A check valve with a differential pressure sensor interposed between the variable displacement hydraulic pump and the flow control valve, and the maximum discharge amount of the variable displacement hydraulic pump to the regulator in a state where the variable displacement hydraulic pump is connected to the conduit. With the differential pressure sensor for the maximum discharge amount indicating means for instructing and the variable displacement hydraulic pump discharging the maximum flow rate by the maximum discharge amount indicating means Pressure-flow rate conversion means for converting the detected pressure of the check valve into a corresponding flow rate, storage means for storing the flow rate converted by the pressure-flow rate conversion means, and each variable displacement hydraulic pressure based on the detected pressure A hydraulic pump failure diagnosis device for a working machine, comprising a failure determination means for determining whether the pump is good or bad. 3. The failure determination unit according to claim 1, wherein the failure determination unit compares the past detected pressure average value with the current detected pressure for the same variable displacement hydraulic pump, or the past pressure-flow rate conversion unit. A hydraulic pump failure diagnosis device for a work machine, characterized in that the average value of the converted flow rate by the current and the current converted flow rate are compared. In Claim 1 or Claim 2, the failure determination means compares the previous detected pressure with the current detected pressure for the same variable displacement hydraulic pump, or the converted flow rate by the previous pressure-flow rate conversion means. A hydraulic pump fault diagnosis device for work machines, which is compared with the current conversion flow rate. In Claim 1 or Claim 2, the failure determination means compares the current detected pressure average value with the current detected pressure for each of the other variable displacement hydraulic pumps having the same capacity, or the current pressure- A hydraulic pump failure diagnosis device for a working machine, wherein the average value of the converted flow rate by the flow rate conversion means is compared with the current converted flow rate.

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