JP2019116721A - Working vehicle - Google Patents

Abstract

An object of the present invention is to provide a work vehicle capable of promptly detecting an abnormality of a hydraulic pump.
A working vehicle having a working unit, comprising: a hydraulic actuator for driving the working unit; a hydraulic pump for supplying hydraulic fluid to the hydraulic actuator; and discharge of the hydraulic pump when the working unit is driven Data acquisition unit 51 repeatedly acquiring data of pressure P1 and discharge flow rate Q1 and data of discharge pressure P1 and discharge flow rate Q1 acquired by data acquisition unit 51 are arranged in a PQ characteristic diagram, and the maximum output of the hydraulic pump is An abnormality determination unit that determines that an abnormality occurs in the hydraulic pump when the data density of a predetermined region in the vicinity of the PQ characteristic curve shown is different from a predetermined data density by a certain amount or more.
[Selected figure] Figure 6

Description

  The present invention relates to a work vehicle having a work unit.

  In working vehicles such as backhoes and wheel loaders, a plurality of working units are operated by driving a plurality of hydraulic actuators by hydraulic oil supplied by a plurality of hydraulic pumps.

Patent Document 1 below discloses a failure diagnosis device for a hydraulic pump of a working machine. In Patent Document 1, the discharge pressure and the discharge flow rate of the hydraulic pump are collected from the engine start to the stop, and the maximum discharge flow rate D1 ₂ (n) at the engine start number n and the discharge pressure D1 at the maximum discharge flow time You get ₁ (n). Then, the target pump discharge flow theoretical value Q1a at the discharge pressure D1 ₁ (n) is calculated, and when the actual discharge flow D1 ₂ (n) is smaller than -10% of the target pump discharge flow theoretical value Q1a, the engine The judgment result of the nth start is set to 1. Such processing is repeated each time the engine is started, and when the determination results for a plurality of times are all 1, it is determined that the hydraulic pump is broken.

JP 2002-242849 A

  In Patent Document 1, discharge pressure and discharge flow rate are continuously collected from engine start to stop, and after determining the maximum discharge flow rate and the discharge pressure corresponding thereto, it is determined whether or not an abnormality occurs in the hydraulic pump. Do. In Patent Document 1, it is not determined as a failure until all of the determination results for a plurality of times become 1. Therefore, when an abnormality occurs in the hydraulic pump, it is difficult to detect the abnormality at the initial stage. Also, in the case where pressure oil is suddenly discharged at a flow rate close to the theoretical value despite occurrence of an abnormality in the hydraulic pump, or when an abnormal symptom appears intermittently, the hydraulic pump It can not be determined that an abnormality has occurred in

  Then, in view of the said subject, an object of this invention is to provide the working vehicle which can detect abnormality of a hydraulic pump promptly.

The work vehicle of the present invention is a work vehicle having a work unit, and
A hydraulic actuator for driving the working unit;
A hydraulic pump for supplying hydraulic fluid to the hydraulic actuator;
A data acquisition unit that repeatedly acquires data of discharge pressure and discharge flow rate of the hydraulic pump when the working unit is driven;
The data of the discharge pressure and the discharge flow rate acquired by the data acquisition unit are arranged in a PQ characteristic diagram, and the data density of a predetermined area near the PQ characteristic curve indicating the maximum output of the hydraulic pump is a predetermined data density And an abnormality determination unit that determines that an abnormality has occurred in the hydraulic pump when they differ by a predetermined amount or more.

  The work unit of the work vehicle is driven by a hydraulic actuator. Hydraulic oil is supplied to the hydraulic actuator from a hydraulic pump. Generally, the performance of a hydraulic pump is represented by a PQ characteristic diagram showing the relationship between discharge pressure and discharge flow rate. The present invention focuses on the fact that the data density of the discharge pressure and discharge flow rate of the hydraulic pump changes in the PQ characteristic diagram when an abnormality occurs in the hydraulic pump. More specifically, the present invention focuses on the fact that the data density in the vicinity of the PQ characteristic curve indicating the maximum output of the hydraulic pump decreases when an abnormality occurs in the hydraulic pump. The present invention monitors the discharge pressure and the discharge flow rate, and determines that an abnormality has occurred in the hydraulic pump at a stage where the data density in the region near the PQ characteristic curve becomes different from the data density at the time of normality or more. . Therefore, the abnormality of the hydraulic pump can be detected promptly.

In the present invention, the hydraulic actuator includes a hydraulic cylinder,
The data acquisition unit may use the pressure of the hydraulic cylinder as a value corresponding to the discharge pressure, and use the flow rate of the hydraulic cylinder as a value corresponding to the discharge flow rate.

  When a failure occurs in the hydraulic pump, the hydraulic cylinder driven by the hydraulic pump is also affected. Therefore, the occurrence of an abnormality in the hydraulic pump can be determined by monitoring the pressure and flow rate of the hydraulic cylinder with the PQ characteristic of the hydraulic cylinder as that corresponding to the PQ characteristic of the hydraulic pump.

  In the present invention, the abnormality determination unit determines that the load of the drive source of the hydraulic pump is equal to or greater than a predetermined load or the workload of the hydraulic pump is predetermined among the discharge pressure and discharge flow rate data acquired by the data acquisition unit. Data acquired in the case of work load or more may be used for determination of abnormality occurrence of the hydraulic pump.

  According to this configuration, it is possible to remove noise and data other than actual work (for example, during idling) from the discharge pressure and the discharge flow rate data acquired by the data acquisition unit. Therefore, it is possible to more reliably determine whether or not an abnormality has occurred in the hydraulic pump.

It is a left side view of a backhoe concerning this embodiment. It is a functional block diagram which shows the structure of a pump abnormality detection system. It is a functional block diagram which shows the structure of a data acquisition part. It is the figure which showed the PQ characteristic figure of the hydraulic pump typically. It is a figure which shows distribution of the discharge pressure at the time of normal, and discharge flow volume. It is a figure which shows distribution of the discharge pressure at the time of abnormality, and discharge flow volume. It is a flowchart which shows the procedure of the pump abnormality detection method. It is a functional block diagram which shows the structure of the data acquisition part which concerns on other embodiment. It is a figure which shows boom cylinder length and the relationship of a boom angle.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, a schematic structure of a backhoe 1 as an example of a work vehicle will be described with reference to FIG. However, the work vehicle is not limited to the backhoe 1, and may be another vehicle such as a wheel loader. The backhoe 1 includes a traveling device 2, a work device 3, and a turning device 4.

  The traveling device 2 is driven by receiving power from the engine 42 and causes the backhoe 1 to travel. The traveling device 2 includes a pair of left and right crawlers 21 and a pair of left and right traveling motors 22 and 22. The left and right traveling motors 22, 22 as hydraulic motors drive the left and right crawlers 21, 21, respectively, to allow the backhoe 1 to move forward and backward. Further, the traveling device 2 is provided with a blade 23 and a blade cylinder 24 which is a hydraulic actuator for rotating the blade 23 in the vertical direction.

  The work device 3 is driven by receiving power from the engine 42, and performs digging work of soil and the like. The working device 3 includes a boom 31, an arm 32 and a bucket 33, and can independently perform drilling operations by driving them independently. The boom 31, the arm 32, and the bucket 33 correspond to working units, respectively, and the backhoe 1 has a plurality of working units.

  One end of the boom 31 is supported at the front of the pivoting device 4 and is pivoted by a telescopically movable boom cylinder 31 a. Further, the arm 32 is supported by the other end of the boom 31 at one end, and is rotated by the telescopically movable arm cylinder 32 a. One end of the bucket 33 is supported by the other end of the arm 32, and the bucket 33 is pivoted by a telescopically movable bucket cylinder 33a. The boom cylinder 31a, the arm cylinder 32a, and the bucket cylinder 33a correspond to hydraulic actuators that drive the working unit.

  The turning device 4 turns the work device 3. In the turning device 4, a control unit 41, an engine 42, a turning stand 43, a turning motor 44, and the like are disposed. The swing motor 44, which is a hydraulic motor, drives the swing base 43 to cause the working device 3 to swing. Further, in the turning device 4, a plurality of hydraulic pumps (not shown in FIG. 1) driven by the engine 42 are disposed. These hydraulic pumps supply hydraulic oil to the boom cylinder 31a, the arm cylinder 32a, and the bucket cylinder 33a.

  In the control unit 41, a control seat 411 is disposed. A pair of work operation levers 412 and 412 are disposed on the left and right of the pilot seat 411, and a pair of travel levers 413 and 413 are disposed on the front. The operator controls the engine 42, each hydraulic motor, each hydraulic actuator, etc. by sitting on the cockpit 411 and operating the work operation levers 412, 412, the travel levers 413, 413, etc., and travels, turns, works Etc. can be done.

  The pump abnormality detection system 5 of the present embodiment is provided in the work vehicle as described above, and FIG. 2 is a block diagram showing the configuration of the pump abnormality detection system 5. The pump abnormality detection system 5 includes a data acquisition unit 51, a data storage unit 52, an abnormality degree calculation unit 53, and an abnormality determination unit 54.

  The data acquisition unit 51 repeatedly acquires data of the discharge pressure P and the discharge flow rate Q of the hydraulic pump when the working unit is driven. As shown in FIG. 3, the data acquisition unit 51 includes a pressure sensor 511 that measures the discharge pressure P of the hydraulic pump, and a flow rate sensor 512 that measures the discharge flow rate Q.

  Generally, the performance of a hydraulic pump is represented by a PQ characteristic diagram as shown in FIG. The horizontal axis is the discharge pressure P, and the vertical axis is the discharge flow rate Q. In the PQ characteristic diagram, the PQ characteristic curve G indicates the maximum output of the hydraulic pump. The PQ characteristic curve G is previously determined for each hydraulic pump.

  When the hydraulic pump is normal, the data of the discharge pressure P and the discharge flow rate Q during the operation of the hydraulic pump are plotted on the PQ characteristic chart, and the data is concentrated in the vicinity of the PQ characteristic curve G as shown in FIG. 5A. That is, in the state shown in FIG. 5A, the hydraulic pump is operating normally and can generate the maximum output.

On the other hand, if there is an abnormality in the hydraulic pump, plotting the data of the discharge pressure P and the discharge flow rate Q in the PQ characteristic diagram while the hydraulic pump is being driven, the hydraulic pump can generate the maximum output. Because this can not be done, the data density in the vicinity of the PQ characteristic curve G decreases as shown in FIG. 5B. Therefore, when the data density in the vicinity of the PQ characteristic curve G differs from the predetermined data density by a certain amount or more, it can be determined that an abnormality occurs in the hydraulic pump. If the data density near the PQ characteristic curve G differs from the predetermined data density by a certain amount or more, for example, when both data density distributions completely disagree (for example, f ₀ (p, q) and f (p, q described later) When the difference with 2) is 10% or more of the difference.

  The data storage unit 52 can store the data acquired by the data acquisition unit 51. The data storage unit 52 also stores data of the discharge pressure P and the discharge flow rate Q when the hydraulic pump is normally driven (normal time).

The abnormality degree calculation unit 53 calculates the abnormality degree Anom using the data stored in the data storage unit 52. For calculation of the degree of abnormality Anom, density distribution f ₀ (p, q) of data of discharge pressure P and discharge flow rate Q at normal time and data of discharge pressure P and discharge flow rate Q acquired by data acquisition unit 51 The density distribution f (p, q) is used.

  The density distribution f (p, q) is estimated from data in which PQ falls within a predetermined value range or more. The method used to estimate the density distribution f (p, q) may be a nonparametric method such as kernel density estimation or a parametric method such as maximum likelihood estimation. The range where the PQ is equal to or more than a predetermined value is a range in which the discharge pressure P and the discharge flow rate Q are larger than the curve T in FIG. 5B. That is, among the data acquired by the data acquisition unit 51, data acquired when the amount of work (PQ) of the hydraulic pump is equal to or more than a predetermined amount of work is used for determination of abnormality occurrence of the hydraulic pump. Thus, the density distribution f (p, q) can be estimated based on data in the vicinity of the PQ characteristic curve G.

なお、式（１）において、油圧ポンプの高負荷部分の密度変化を敏感に捉えたいため、活性化関数としてｐ×ｑを掛けている。ただし、このような計算を簡便にすべく、例えば異常の検出精度は下がるものの、ＰＱ特性曲線Ｇ付近のデータから計算されるＰＱの平均値や中央値でもって異常度とすることも可能である。 The abnormality degree Anom can be calculated by the following equation (1).

In the equation (1), in order to sensitively capture the density change of the high load portion of the hydraulic pump, it is multiplied by p × q as an activation function. However, in order to simplify such calculation, for example, although the detection accuracy of the abnormality is lowered, it is possible to make the abnormality degree by the average value or the median value of PQ calculated from the data near the PQ characteristic curve G. .

The abnormality determination unit 54 determines whether the abnormality degree Anom calculated by the abnormality degree calculation unit 53 exceeds the threshold value, and if the abnormality degree Anom exceeds the threshold value, an abnormality occurs in the hydraulic pump It is determined that The threshold value is, for example, a probability density function representing the probability of becoming a certain value of the degree of abnormality in a normal state, and is a value such that the false alarm rate is less than or equal to a predetermined value (e.g. ^10-9 ).

  Next, a pump abnormality detection method using the above-described pump abnormality detection system 5 will be described. FIG. 6 is a flowchart showing the procedure of the pump abnormality detection method.

  First, when the engine is turned on (step S1), the hydraulic pump is also turned on. When the hydraulic pump is turned on, the discharge pressure P of the hydraulic pump is measured by the pressure sensor 511, and simultaneously the discharge flow rate Q of the hydraulic pump is measured by the flow rate sensor 512, and data of the discharge pressure P and the discharge flow rate Q is repeatedly acquired. (Step S2). The data of the discharge pressure P and the discharge flow rate Q acquired by the pressure sensor 511 and the flow rate sensor 512 are stored in the data storage unit 52 (memory).

  Next, it is determined whether a predetermined number or more of data is stored in the data storage unit 52 (step S3). Here, the predetermined number or more of data means several thousands to several tens of thousands of data. In step S3, of the data of the discharge pressure P and the discharge flow rate Q acquired by the pressure sensor 511 and the flow rate sensor 512, the load of the drive source (engine 42) of the hydraulic pump is a predetermined load or more or the workload of the hydraulic pump is predetermined. The number of data acquired when the amount of work is equal to or more is counted, and it is determined whether the number of data is equal to or more than a predetermined number. In the present embodiment, the number of data of the discharge pressure P and the discharge flow rate Q which are larger than the curve T of FIG. 5B is counted. That is, the curve T is a curve showing a predetermined work amount (PQ) of the hydraulic pump. Here, the predetermined load of the drive source (engine 42) of the hydraulic pump means, for example, 80% or more of the maximum load of the drive source, and more preferably 90% or more. The predetermined work amount of the hydraulic pump means 80% or more of the maximum work amount of the hydraulic pump, more preferably 90% or more.

  If it is determined that a predetermined number or more of data is stored in the data storage unit 52, the discharge pressure P and discharge flow rate Q data acquired by the pressure sensor 511 and the flow rate sensor 512 are arranged in the PQ characteristic diagram, Based on (1), the abnormality degree Anom is calculated (step S4).

  On the other hand, when it is determined that the data storage unit 52 does not store a predetermined number or more of data, the load of the drive source (engine 42) of the hydraulic pump is a predetermined load or more or the workload of the hydraulic pump is a predetermined workload or more It is determined whether or not (step S7). If the load of the drive source (engine 42) of the hydraulic pump is equal to or greater than a predetermined load or the workload of the hydraulic pump is equal to or greater than a predetermined workload, the data storage unit 52 stores the discharge pressure P and the discharge flow rate Q obtained in step S2. Data is added (step S8). If the load of the drive source (engine 42) of the hydraulic pump is not more than the predetermined load and the workload of the hydraulic pump is not more than the predetermined workload, the process returns to step S2 and the data of discharge pressure P and discharge flow rate Q are repeated. get.

  After step S4, it is then determined whether the calculated abnormality degree Anom exceeds a threshold (step S5). If the abnormality degree Anom exceeds the threshold value, it is determined that an abnormality occurs in the hydraulic pump (step S6). If the abnormality degree Anom does not exceed the threshold value, the data in the data storage unit 52 is reset (step S9).

  In the above embodiment, only the data of the discharge pressure P and the discharge flow rate Q acquired when the load of the drive source of the hydraulic pump is equal to or higher than a predetermined load or the workload of the hydraulic pump is equal to or higher than a predetermined workload Although the abnormality degree Anom is calculated, the abnormality degree Anom may be calculated using all data. At this time, the determination in step S3 is unnecessary, and steps S7 and S8 are also unnecessary.

[Other embodiments]
The data acquisition unit 51 may use the pressure Pc of the hydraulic cylinder as a value corresponding to the discharge pressure P, and may use the flow rate Qc of the hydraulic cylinder as a value corresponding to the discharge flow rate Q. The data acquisition unit 51 repeatedly acquires data of the pressure Pc of the hydraulic cylinder and the flow rate Qc. In this case, as shown in FIG. 7, the data acquisition unit 51 includes a pressure sensor 513 that measures the pressure Pc of the hydraulic cylinder, and a flow rate calculation unit 514 that calculates the flow rate Qc of the hydraulic cylinder.

すなわち、ブームシリンダ３１ａの長さｘは、ブーム３１のブーム角θによって定まる。よって、ブーム３１の一端部に設けられた不図示の角度センサによりブーム３１のブーム角θを計測し、式（２）を用いることでブームシリンダ３１ａの長さｘを計算できる。ブームシリンダ３１ａの長さｘから得られる伸長速度Δｘをシリンダ断面積ｓに掛けることで油圧シリンダの流量Ｑｃを計算できる。 The flow rate calculation unit 514 calculates the flow rate Qc of the hydraulic cylinder from the cylinder cross-sectional area s of the hydraulic cylinder and the cylinder extension speed Δx. For example, when A, B and C are determined as shown in FIG. 8, the length x of the boom cylinder 31a and the boom angle θ of the boom 31 satisfy the following equation (2). In FIG. 8, reference symbol A indicates a linear distance from the rotation axis of the boom 31 with respect to the turning device 4 (a portion where the boom 31 is supported by the turning device 4) to a connection portion between the boom 31 and the boom cylinder 31 a. The symbols B and C respectively indicate the linear distance in the vertical direction from the connecting portion of the boom cylinder 31a and the turning device 4 to the rotation shaft and the linear distance in the longitudinal direction.

That is, the length x of the boom cylinder 31 a is determined by the boom angle θ of the boom 31. Therefore, the boom angle θ of the boom 31 is measured by an angle sensor (not shown) provided at one end of the boom 31, and the length x of the boom cylinder 31a can be calculated by using the equation (2). The hydraulic cylinder flow rate Qc can be calculated by multiplying the cylinder cross-sectional area s by the extension speed Δx obtained from the length x of the boom cylinder 31a.

  According to this configuration, it is not generally necessary to provide an expensive flow rate sensor to measure the flow rate Qc of the hydraulic cylinder. Therefore, the cost can be reduced.

  As mentioned above, although embodiment of this invention was described based on drawing, it should be thought that a specific structure is not limited to these embodiment. The scope of the present invention is indicated not only by the description of the embodiments described above but also by the claims, and further includes all modifications within the meaning and scope equivalent to the claims.

DESCRIPTION OF SYMBOLS 1 backhoe 3 working device 5 pump abnormality detection system 31 boom 31a boom cylinder 32 arm 32a arm cylinder 33 bucket 33a bucket cylinder 42 engine 51 data acquisition unit 53 abnormality degree calculation unit 54 abnormality determination unit 511 pressure sensor 512 flow sensor 513 pressure sensor 514 Flow rate calculation unit

Claims (3)

A working vehicle having a working unit,
A hydraulic actuator for driving the working unit;
A hydraulic pump for supplying hydraulic fluid to the hydraulic actuator;
A data acquisition unit that repeatedly acquires data of discharge pressure and discharge flow rate of the hydraulic pump when the working unit is driven;
The data of the discharge pressure and the discharge flow rate acquired by the data acquisition unit are arranged in a PQ characteristic diagram, and the data density of a predetermined area near the PQ characteristic curve indicating the maximum output of the hydraulic pump is a predetermined data density A working vehicle comprising: an abnormality determining unit that determines that an abnormality has occurred in the hydraulic pump when they differ by a predetermined amount or more. The hydraulic actuator includes a hydraulic cylinder,
The work vehicle according to claim 1, wherein the data acquisition unit uses the pressure of the hydraulic cylinder as a value corresponding to the discharge pressure, and uses the flow rate of the hydraulic cylinder as a value corresponding to the discharge flow rate. The abnormality determination unit is configured such that, among the discharge pressure and discharge flow rate data acquired by the data acquisition unit, the load of the drive source of the hydraulic pump is a predetermined load or more or the workload of the hydraulic pump is a predetermined workload or more. The work vehicle according to claim 1, wherein data acquired in some cases is used to determine an abnormality occurrence of the hydraulic pump.

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