JPS6088883A - Fault predictor for rotary hydraulic machine - Google Patents

Abstract

PURPOSE:To predict occurrence of fault thus to prevent fault and deterioration of working efficiency by operating reduction of service life of bearing on the basis of detected levels of pressure, flow, rotation of rotary hydraulic machine then informing the service life reducing function on the basis of operated level. CONSTITUTION:Levels detected through pressure detector 5, delivery capacity detector 6 and rotation detector 7 hydraulic pump 2 are inputted to an operational controller 9 which will operate reduction of service life of bearing on the basis of said levels. The results are compared with predetermined levels to display the comparison results on a display 10. Consequently, faults originated from the rotary shaft can be predicted to prevent fatal faults, destroying of structure or deterioration of working efficiency thus to enable scheduled maintenance.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a malfunction detection system for rotary hydraulic machines for detecting malfunctions in hydraulic pumps, hydraulic motors, etc. used in hydraulic systems of construction machinery, machine tools, etc. in advance.

The components that make up the hydraulic system are subject to failures such as breakage and unusability due to fatigue, wear, deterioration, etc.

The occurrence of such a failure is extremely dangerous as it may cause personal injury or destroy other structures in the vicinity. On the hook.

The repercussions of this danger are evident in rotary hydraulic machines such as hydraulic pumps and hydraulic motors. Therefore, it is important to prevent the rotary hydraulic machine from breaking down in order to prevent the above-mentioned dangers from occurring. Furthermore, even if such personal injury or destruction could be avoided, it would take a great deal of time to replace the parts of the rotary hydraulic machine that caused the failure.
During that time, all work with and involving that hydraulic system must cease;
If the working efficiency is significantly reduced, this will cause a disadvantage, and this disadvantage will be even greater if the failed shaft raw hot water Fyr is located in a remote area or overseas.

By the way, a serious failure of a one-rotation hydraulic machine that is directly related to its rotation is due to damage or unusability of the rotating shaft and bearings. For this reason, it is extremely important to know in advance the degree of fatigue, wear, deterioration, etc. of the rotating shaft and bearings of rotary hydraulic machines.
We replace rotating shafts and bearings that are nearing the end of their service life to prevent the aforementioned personal accidents, destruction, and decreases in work efficiency.
This allows the hydraulic system to operate without any problems.

Conventionally, such a failure prediction device has not been known, and failure prediction can only be estimated by humans by visually observing the rotating shaft or bearing itself, or by measuring the usage time of the rotary hydraulic machine. there were. With this method, it is naturally impossible to accurately detect failures, so as a second best measure, the manufacturer or the user overhauls the hydraulic system at regular intervals. Incidentally, the degree of fatigue, wear, deterioration, etc. of the rotating shaft and bearings of a rotary hydraulic machine greatly differs depending on the frequency of use, manner of use, magnitude of load, etc. of the rotary hydraulic machine. In other words, if the torque and rotational speed of a rotary hydraulic machine are constant, it is easy to estimate the occurrence of a failure, but since the actual usage conditions vary extremely complexly, it is impossible to predict failure accurately. It's impossible. Special feature: For variable displacement hydraulic pumps or hydraulic motors, torque changes due to pressure and discharge capacity.
'4-ruσ] to predict failures &! -1- It is difficult. As described above, it is difficult to understand the manufacturer's actual usage of the hydraulic system including this rotary hydraulic machine.

When manufacturing rotary hydraulic machines, manufacturers design rotating shafts and bearings with high strength in order to withstand severe use. However, if the rotary hydraulic machine is used more harshly than expected by the car manufacturer, there is a risk that the rotary hydraulic machine will fail before being overhauled, resulting in the above-mentioned dangers and reduced work efficiency. (On the contrary, if the operating force of a rotary hydraulic machine is small (or continues to use a light load), the degree of fatigue, wear, deterioration, etc. of the rotating shaft and bearings will be small.
in this case.

During overhaul, it is extremely uneconomical to replace something that does not need to be done, and it also causes the inconvenience of not being able to fully demonstrate the durability of the rotating shaft and bearing. .

However, in the absence of an appropriate failure prediction device, failure prevention has had to rely on overhauling, which has the drawbacks mentioned above.

Furthermore, there are known devices that indicate the occurrence of a malfunction using a lamp or the like or sound a buzzer to issue an alarm; however, such devices are activated when a malfunction occurs; It is impossible to predict the above-mentioned conventional drawbacks (2).

The present invention was developed in view of these circumstances, and its purpose is to be able to predict the occurrence of failures, and by this prediction, prevent personal injury, destruction of nearby structures, and reduction in work efficiency. The purpose is to provide a malfunction detection system for rotary hydraulic machines that can prevent malfunctions.

To achieve this objective, the present invention detects the oil pressure, flow rate, and rotational speed of a rotary hydraulic machine, and determines the degree of life reduction of at least one of the rotating shaft and bearing of the rotary hydraulic machine based on these detected values. The present invention is characterized in that a calculation is performed, and notification related to the degree of decrease in life is performed based on the value obtained by this calculation.

The present invention will be explained below based on the embodiments shown in FIGS. 1 and 2.

FIG. 1 is a system diagram of a failure prediction device for a bearing of a hydraulic pump according to an embodiment of the present invention. In the figure, 1 is a prime mover such as an engine, 2 is a hydraulic pump that is driven by the original 311II machine IK and discharges pressure oil, 2a is a displacement displacement O3 variable mechanism that controls the discharge capacity of the hydraulic pump 2, and 3 is a hydraulic pump. 2 is a hydraulic motor driven by pressure oil, and 4 is a switching valve interposed between the hydraulic pump 2 and the hydraulic motor 3 to switch the pressure oil from the hydraulic pump 2. 5 is a pressure detector for detecting the discharge pressure of the hydraulic pump 2, 6 is a discharge capacity detector for detecting the discharge capacity of the hydraulic pump 2, and 7 is a rotation detector for detecting the number of rotations of the hydraulic pump 20. 8 is the clear switch (
), 9 is a pressure detector 5. Discharge volume detector6.
The values detected by the rotation detector 7 are input, and based on these values, the degree of fatigue, wear deterioration, etc. of the bearings of the hydraulic pump 2 is determined.
That is, the degree of decrease in lifespan (hereinafter referred to as the degree of decrease in lifespan) is calculated.

an arithmetic and control device that compares the value obtained by the arithmetic operation with a required value and outputs the result; 9a is an output terminal of the arithmetic and control device; 10 is a display device 1 that displays the results of the comparison in the arithmetic and control device 9; ．． log is an input terminal of the display device.

Figure 2 is ml! ! It is a system configuration diagram of an arithmetic and control device shown in JK. In the figure, 9b indicates the pressure p detected by the pressure detector 5 and the discharge volume q detected by the discharge volume detector 6.
9c & 1 is an A/L converter that converts the manually applied pressure p and discharge volume q into digital values, and 9d is the CPU of the microcomputer.
(Central Processing Unit), 9e & 2
(read-only memory), 9f is a RAM (random access memory) that stores input values, values obtained as a result of calculations, etc., and 9g is an output that outputs processed values, comparison results, etc. The circuit, 9h1.9h, outputs the output of the rotation detector 7 and the clear switch 8, respectively, to the CPU9 dK.
This is an interface circuit for large inputs.

Now, the hydraulic pump 2 driven by the prime mover 1 discharges an oil amount q corresponding to the amount of tilting of the variable displacement mechanism 2a, and this K generates an oil pressure p. The discharge capacity detector 6 detects the amount of tilting of the displacement variable mechanism 2a, and outputs a value corresponding to this. On the other hand, the rotation detector 7 generates one pulse every time the hydraulic pump 2 rotates once. When the hydraulic pump 2 rotates in this manner, a weight proportional to the load torque acts on the bearing supporting the rotating shaft, and the life of the bearing gradually decreases due to this K.

Here, the degree of reduction in bearing life will be explained.

In general, the lifespan of bearings such as ball bearings and roller bearings is L... Lifespan (total number of rotations until breakage) C...
...Basic dynamic load rating (constant determined by bearing type and size) F...Load applied to the bearing n...
Assuming that the constant is determined by the ffI class of the bearing, it is expressed by the following equation.

L=(C/F)" Re... °(1) Assume that the load jiF applied to the bearing changes stepwise, and the load for each stepwise change is F, , F,...k" I, and the (b) rotation number of IH during the period when that load was applied is N.
1. N,...-N+, and the lifespan L of the relevant period
L, L, fist...If we say Lt, it becomes , and then K.

L, := (C/F, ), L, = (C/Ft
)″...Lt = (C/Fsu3, so
N,・F,"+N,・l""-)-#1111+minor"
" = l * m a m a 13) C"C" c
It becomes n. Multiplying both sides of equation (3) by KC''/L yields, and since C''/L=F'', consider the value F at this time to be the equal-sided load Fm, and calculate the life as the total rotation until failure. number
When replaced with N=ΣN1, it becomes. This equal side load F
Failure of the bearing occurs when m reaches a predetermined value.

On the other hand, formula (3) can be expressed in a more easily understandable form as follows.

NH”FI” 10N2”k2”+”’
−−+I'll IIJ'I" = C"Then, if the degree of decrease in life is expressed by D, it becomes D=Σ(N+@F+"), and when this degree of decrease in life reaches a constant value of H[ Since it is determined that the service life has come to an end, instead of the load JiLPr, it is calculated as the product of the pressure p and the discharge at that time '4sagiq,
That is, the degree of decrease in life can be obtained by expressing the torque T (T=pXq).

Next, the operation of this embodiment will be explained with reference to the flowchart shown in FIG. First, when the bearing is first started to be used, when the clear switch 8 is operated, a clear command No. 46 is manually inputted to the CPU 9 dK via the interface circuit 9h. The CPU 9 d determines that the clear command signal has been input, and goes to step S,).
The value of the address where the degree of decrease in bearing life in IVI9fK is to be stored is cleared to 0 (S,). Next K, rotation detector 7
It is determined whether or not a signal (interrupt signal) is input from the interface circuit 9h through the interface circuit 9h (S3), and if no interrupt signal is input, the process returns to step S1.

Note that once the bearing has started to be used, there is no input of the clear command signal, so the determination in step S is made immediately without going through the operation in step S2.

When the hydraulic pump 2 is rotating and such an interrupt signal is input to the rotation detector 7, C1'U9d switches the multiplexer 9b to sequentially input the pressure p and the discharge capacity q, and inputs the pressure p and the discharge capacity q to the A/D converter. 9C reads these as digital clay (S4). Next, the load FI at that time is calculated by multiplying the read value p+q by a constant. Then, the calculated value is stored in a predetermined location. (ss). As mentioned above, the one-rotation detector 7 outputs one pulse every 201 rotations of the hydraulic pump, and this pulse becomes an interrupt signal, reducing the lifespan for one rotation until the next pulse is input. The degree D=IXF+ is calculated, and this calculated value is multiplied by the life reduction degree DK210$.
The degree of decrease in the life of the bearing at 19 fK is stored in a predetermined location (S6).

On the other hand, an appropriate degree of life reduction before reaching the life limit is set in advance for the bearing, and the value calculated in step S6 is read from the address to determine the predetermined life reduction. It is compared with the degree (S7). If the value DIJ' is less than the degree of life reduction, the operation returns to step S. When the value is less than a predetermined degree of decrease in life, a signal is sent to the display device 1 via the output circuit 9f.
0 (S6), and the display device IO indicates that the usage of the bearing has reached near its limit based on this issue.

With this display, it is possible to predict a failure of the hydraulic pump 2 caused by the bearing.

In addition, the display of the display device can be a lighting display of a lamp, a display of characters, or any other display form, and
This can also be replaced by a warning device such as a buzzer.

In this way, in this embodiment, the pressure, discharge capacity, and rotation speed of the hydraulic pump are detected, the degree of reduction in life of the bearing is calculated based on these detected values, and the calculated value and the limit value of the degree of reduction in life are calculated. When the life reduction rate reaches the set limit value, a signal is output and displayed or an alarm is issued.
Hydraulic pump failures caused by bearings can be predicted, preventing personal accidents, structural destruction, and reduced work efficiency.
VJ can be stopped, and planned maintenance without waste becomes possible. Furthermore, it is possible to obtain data on the actual usage conditions of the bearing, which can be used as a reference when designing the next bearing, allowing for a more rational design.

Although the bearing of the hydraulic pump has been described above, it is also possible to compensate for the reduction in the lifespan of the rotating shaft of the hydraulic pump instead of the bearing. That is, as in the case of a bearing, when an interrupt signal is received, the pressure p and the discharge capacity q are read, and the torque T is calculated.

Then, this torque 11 is temporarily stored in the H1 standard location of the AM, and the amount of torque variation and the number of times n thereof are calculated using the rainflow method or other known method.

Based on this calculated vibration component, the torsional stress of the rotating shaft is calculated from a predetermined mathematical formula. The number of repeated fractures N+ for this stress is taken into account from the given data, and the cumulative value of the cup is N life reduction. The equipment for performing such calculations is the same as the equipment shown in Figures @1 and 2, except that RCJ
There is only a difference in the CPU operating element/II K used in MK1. and.

Rotation +1; By displaying or notifying everyone that the lifespan decrease degree of +i has reached the set limit area trap, the same effect as the previous @Uke is achieved.

Although the calculation of the degree of life reduction of the bearings and rotating shafts of the hydraulic pump, the relative softness with the set value, and the display of the results have been described above, the same applies to the bearing of the hydraulic motor and the rotating shaft of one rotational shaft. Also 1. In the above example.

Although it is configured to compare the degree of decrease in lifespan with a limit value, such a comparison is not necessarily necessary, and it is also possible to configure the degree of decrease in lifespan to be directly expressed in the table. In this case, if the limit value is known in advance, then from the usage period of the component and the degree of life reduction at that time, how much longer can the component be used, and in my opinion when will a failure occur? can be predicted. In addition, the display device is carried by the person in charge of after-sales service for the hydraulic system.

The input terminal may be connected to the output terminal of the control device when necessary.

As described above, in the present invention, the pressure, flow rate, and rotation speed of a rotary hydraulic machine are detected, and based on these detected values, the degree of reduction in the life of at least one of the rotating shaft and the bearing is calculated. Since notifications related to the degree of reduction in life are made based on the values obtained by calculation, it is possible to predict failures caused by rotating shafts and bearings, preventing personal accidents, destruction of pickled objects, and reductions in work efficiency. It is possible to prevent this from happening, and it is also possible to carry out systematic maintenance without waste. moreover,
Data on the actual usage conditions of the rotating shaft and bearings can be obtained, which will serve as a reference when designing the rotating shaft and bearings, allowing for more rational designs.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a failure detection device for a hydraulic pump according to an embodiment of the present invention, Fig. 2- is a system configuration diagram of the arithmetic and control device shown in Fig. 16, and Fig. 3 is a system diagram of the system configuration of the arithmetic and control device shown in Fig. 2. It is a flow chart explaining operation of a control device. 2... Hydraulic pump, 2a... Variable displacement mechanism, 5... Pressure detector, 6...
...Discharge volume detector, 7...Rotation detector, 8
... Clear switch, 9 ... Arithmetic control device. 10...Display brass.

Claims (1)

[Claims] A pressure detection device that detects the oil pressure of a rotary hydraulic machine in a hydraulic system, a flow rate detection device that detects the flow rate of the rotary hydraulic machine, a rotation speed detection device that detects the rotation speed of the rotary hydraulic machine, and each of these devices. calculation means for calculating the degree of reduction in the life of at least one of the rotating shaft and the bearing of the rotary hydraulic machine based on the value detected by the detection device; 1. A failure prediction device for a rotary hydraulic machine, characterized in that a failure prediction device for a rotary hydraulic machine is provided.