JP6903567B2 - Work vehicle - Google Patents

Description

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

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

The following Patent Document 1 discloses a failure diagnosis device for a hydraulic pump of a work machine. In Patent Document 1, the discharge pressure and the discharge flow rate of the hydraulic pump are collected from the start to the stop of the engine, and the maximum discharge flow rate D1 ₂ (n) at the nth engine start number and the discharge pressure D1 at the time of the maximum discharge flow rate are collected. ₁ (n) and is obtained. Then, the target pump discharge flow rate theoretical value Q1a at the discharge pressure D1 ₁ (n) is calculated, and when the actual discharge flow rate D1 ₂ (n) is smaller than -10% of the target pump discharge flow rate theoretical value Q1a, the engine The determination result of the nth start count is set to 1. Such a process is repeated every 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 out of order.

Japanese Unexamined Patent Publication No. 2002-242849

In Patent Document 1, the discharge pressure and the discharge flow rate are continuously collected from the start to the stop of the engine, and after acquiring the maximum discharge flow rate and the corresponding discharge pressure, it is determined whether or not an abnormality has occurred in the hydraulic pump. To do. In Patent Document 1, since the failure is not determined until the determination results for a plurality of times are all 1, it is difficult to detect the abnormality at the initial stage when the abnormality of the hydraulic pump occurs. In addition, when the hydraulic pump suddenly discharges pressure oil at a flow rate close to the theoretical value even though an abnormality has occurred in the hydraulic pump, or when the symptoms of the abnormality appear intermittently, the hydraulic pump It cannot be determined that an abnormality has occurred in.

Therefore, in view of the above problems, an object of the present invention is to provide a work vehicle capable of promptly detecting an abnormality of a hydraulic pump.

The work vehicle of the present invention is a work vehicle having a work unit and has a work unit.
The hydraulic actuator that drives the work unit and
A hydraulic pump that supplies hydraulic oil to the hydraulic actuator and
A data acquisition unit that repeatedly acquires data on the discharge pressure and discharge flow rate of the hydraulic pump when the working unit is driven.
The discharge pressure and discharge flow rate data acquired by the data acquisition unit are arranged in the PQ characteristic diagram, and the data density in a predetermined region near the PQ characteristic curve indicating the maximum output of the hydraulic pump is defined as the predetermined data density. It is provided with an abnormality determination unit for determining that an abnormality has occurred in the hydraulic pump when the difference is more than a certain amount.

The working part of the work vehicle is driven by a hydraulic actuator. Hydraulic oil is supplied to this hydraulic actuator from a hydraulic pump. Generally, the performance of a hydraulic pump is represented by a PQ characteristic diagram showing the relationship between the discharge pressure and the discharge flow rate. The present invention focuses on the fact that the data densities of the discharge pressure and the discharge flow rate of the hydraulic pump change in the PQ characteristic diagram when an abnormality occurs in the hydraulic pump. More specifically, the present invention focuses on the fact that when an abnormality occurs in the hydraulic pump, the data density near the PQ characteristic curve indicating the maximum output of the hydraulic pump decreases. The present invention monitors the discharge pressure and the discharge flow rate, and determines that an abnormality has occurred in the hydraulic pump when the data density in the region near the PQ characteristic curve becomes different from the normal data density by a certain amount 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.

If an abnormality occurs in the hydraulic pump, the hydraulic cylinder driven by the hydraulic pump is also affected. Therefore, by assuming that the PQ characteristic of the hydraulic cylinder corresponds to the PQ characteristic of the hydraulic pump and monitoring the pressure and the flow rate of the hydraulic cylinder, it is possible to determine the occurrence of an abnormality in the hydraulic pump.

In the present invention, the abnormality determination unit has a predetermined load of the drive source of the hydraulic pump or more or a predetermined work amount of the hydraulic pump among the data of the discharge pressure and the discharge flow rate acquired by the data acquisition unit. The data acquired when the amount of work or more may be used for determining the occurrence of an abnormality in the hydraulic pump.

According to this configuration, noise and data other than during actual work (for example, during idling) can be removed from the discharge pressure and 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 the backhoe which concerns on 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 the data acquisition part. It is a figure which showed the PQ characteristic diagram of a hydraulic pump schematically. It is a figure which shows the distribution of the discharge pressure and the discharge flow rate at the time of normal. It is a figure which shows the distribution of the discharge pressure and the discharge flow rate at the time of abnormality. 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 the relationship between a boom cylinder length and a boom angle.

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

First, the schematic structure of the backhoe 1 as an example of the 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 working device 3, and a turning device 4.

The traveling device 2 is driven by receiving power from the engine 42 to drive the backhoe 1. The traveling device 2 includes a pair of left and right crawlers 21 and 21 and a pair of left and right traveling motors 22 and 22. The left and right traveling motors 22, 22 which are hydraulic motors drive the left and right crawlers 21 and 21, respectively, to enable 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 to perform excavation work such as earth and sand. The work device 3 includes a boom 31, an arm 32, and a bucket 33, and by driving these independently, excavation work is possible. The boom 31, arm 32, and bucket 33 correspond to working portions, respectively, and the backhoe 1 has a plurality of working portions.

One end of the boom 31 is supported by the front portion of the swivel device 4, and the boom 31 is rotated by a boom cylinder 31a that can be expanded and contracted. Further, one end of the arm 32 is supported by the other end of the boom 31, and the arm 32 is rotated by an arm cylinder 32a that can be expanded and contracted. Then, one end of the bucket 33 is supported by the other end of the arm 32, and the bucket 33 is rotated by a bucket cylinder 33a that can be expanded and contracted. The boom cylinder 31a, arm cylinder 32a, and bucket cylinder 33a correspond to a hydraulic actuator that drives a working unit.

The swivel device 4 swivels the working device 3. A control unit 41, an engine 42, a swivel base 43, a swivel motor 44, and the like are arranged in the swivel device 4. The swivel motor 44, which is a hydraulic motor, drives the swivel base 43 to swivel the work device 3. Further, the swivel device 4 is provided with a plurality of hydraulic pumps (not shown in FIG. 1) driven by the engine 42. These hydraulic pumps supply hydraulic oil to the boom cylinder 31a, the arm cylinder 32a, and the bucket cylinder 33a.

A driver's seat 411 is arranged in the control unit 41. A pair of work operation levers 421 and 412 are arranged on the left and right sides of the driver's seat 411, and a pair of traveling levers 413 and 413 are arranged in front of the cockpit 411. The operator controls the engine 42, each hydraulic motor, each hydraulic actuator, etc. by operating the work operation levers 421, 412, traveling levers 413, 413, etc. while seated in the driver's seat 411, and travels, turns, and works. Etc. can be performed.

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 a 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 shows the maximum output of the hydraulic pump. The PQ characteristic curve G is predetermined for each hydraulic pump.

When the hydraulic pump is normal, when the data of the discharge pressure P and the discharge flow rate Q while the hydraulic pump is being driven are plotted on the PQ characteristic diagram, the data are 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 normally driven and can generate a maximum output.

On the other hand, when an abnormality has occurred in the hydraulic pump, if the data of the discharge pressure P and the discharge flow rate Q while the hydraulic pump is being driven are plotted on the PQ characteristic diagram, the hydraulic pump may generate the maximum output. Therefore, as shown in FIG. 5B, the data density near the PQ characteristic curve G decreases. Therefore, when the data density near the PQ characteristic curve G differs from the predetermined data density by a certain amount or more, it can be determined that an abnormality has occurred in the hydraulic pump. 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 do not completely match (for example, f ₀ (p, q) and f (p, q, which will be described later). ) Is different by 10% or more of).

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. _{In the calculation of the abnormality degree Anom, the density distribution f 0} (p, q) of the data of the discharge pressure P and the discharge flow rate Q in the normal state and the data of the discharge pressure P and the discharge flow rate Q acquired by the data acquisition unit 51 are used. The density distribution f (p, q) is used.

The density distribution f (p, q) is estimated from the data in which PQ corresponds to a predetermined value or more. The method used for estimating the density distribution f (p, q) may be a non-parametric method such as kernel density estimation, or a parametric method such as maximum likelihood estimation. The range in which PQ is equal to or higher 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, the data acquired when the work amount (PQ) of the hydraulic pump is equal to or greater than the predetermined work amount is used for determining the occurrence of an abnormality in the hydraulic pump. As a result, the density distribution f (p, q) can be estimated based on the data near 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 anomaly degree Anom can be calculated by the following equation (1).

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

The abnormality determination unit 54 determines whether or not 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 has occurred in the hydraulic pump. Is determined. The threshold value is, for example, the probability that the value has an abnormal degree in the normal state is represented by the probability density function, and the false detection rate is set to a value ^{below a certain level (for example, 10-9).}

Next, a pump abnormality detection method using the pump abnormality detection system 5 described above 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 at the same time, the discharge flow rate Q of the hydraulic pump is measured by the flow rate sensor 512, and the data of the discharge pressure P and the discharge flow rate Q are 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 or not a certain number or more of data is stored in the data storage unit 52 (step S3). Here, the data of a certain number or more is thousands to tens of thousands of data. In step S3, among 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 equal to or more than the predetermined load, or the work load of the hydraulic pump is predetermined. The number of acquired data is counted when the amount of work is equal to or greater than the amount of work of In the present embodiment, the number of data of the discharge pressure P and the discharge flow rate Q 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, more preferably 90% or more of the maximum load of the drive source. The predetermined work amount of the hydraulic pump means 80% or more, more preferably 90% or more of the maximum work amount of the hydraulic pump.

When it is determined that a certain number or more of data are stored in the data storage unit 52, 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 arranged in the PQ characteristic diagram, and the formula is used. The anomaly degree Anom is calculated based on (1) (step S4).

On the other hand, when it is determined that a certain number or more of data are not stored in the data storage unit 52, the load of the drive source (engine 42) of the hydraulic pump is equal to or greater than the predetermined load, or the workload of the hydraulic pump is equal to or greater than the predetermined workload. (Step S7). When the load of the drive source (engine 42) of the hydraulic pump is equal to or greater than the predetermined load or the workload of the hydraulic pump is equal to or greater than the predetermined workload, the data storage unit 52 is informed of the discharge pressure P and the discharge flow rate Q acquired in step S2. Data is added (step S8). When the load of the drive source (engine 42) of the hydraulic pump is not more than the predetermined load and the work amount of the hydraulic pump is not more than the predetermined work amount, the process returns to step S2, and the data of the discharge pressure P and the discharge flow rate Q are repeated. get.

After step S4, it is then determined whether or not the calculated anomaly degree Anom exceeds the threshold (step S5). If the abnormality degree Anom exceeds the threshold value, it is determined that an abnormality has occurred 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-described 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 more than the predetermined load or the work amount of the hydraulic pump is equal to or more than the predetermined work amount are used. Although the anomaly degree Anom is calculated, the anomaly degree Anom may be calculated using all the 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 on the pressure Pc and the flow rate Qc of the hydraulic cylinder. 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, if A, B, and C are defined 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 numeral A indicates a linear distance from the rotation axis of the boom 31 with respect to the swivel device 4 (the portion where the boom 31 is supported by the swivel device 4) to the connection portion between the boom 31 and the boom cylinder 31a. Reference numerals B and C indicate a linear distance in the vertical direction and a linear distance in the front-rear direction from the connection portion between the boom cylinder 31a and the swivel device 4 to the rotation axis, respectively.

That is, the length x of the boom cylinder 31a is determined by the boom angle θ of the boom 31. Therefore, the boom angle θ of the boom 31 can be 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 flow rate Qc of the hydraulic cylinder 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 generally unnecessary to provide an expensive flow rate sensor in order to measure the flow rate Qc of the hydraulic cylinder. Therefore, the cost can be reduced.

Although the embodiments of the present invention have been described above with reference to the drawings, it should be considered that the specific configuration is not limited to these embodiments. The scope of the present invention is shown not only by the description of the above-described embodiment but also by the scope of claims, and further includes all modifications within the meaning and scope equivalent to the scope of claims.

1 Back ho 3 Work equipment 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 calculation unit 54 Abnormality judgment unit 511 Pressure sensor 512 Flow sensor 513 Pressure sensor 514 Flow calculation unit

Claims (4)

A work vehicle that has a work unit
The hydraulic actuator that drives the work unit and
A hydraulic pump that supplies hydraulic oil to the hydraulic actuator and
A data acquisition unit that repeatedly acquires data on the discharge pressure and discharge flow rate of the hydraulic pump when the working unit is driven.
A storage unit that stores data on the discharge pressure and discharge flow rate when the hydraulic pump is normally driven, and a storage unit.
The degree of concentration of data in a predetermined region near the PQ characteristic curve indicating the maximum output of the hydraulic pump, which is obtained by arranging the discharge pressure and discharge flow rate data acquired by the data acquisition unit on the PQ characteristic diagram, is determined. When it is determined that the indicated data density is different from the data density in the region obtained from the data of the discharge pressure and the discharge flow rate at the normal time by a certain amount or more, it is determined that an abnormality has occurred in the hydraulic pump. A work vehicle including a judgment unit. Whether or not the two data densities differ by a certain amount or more can be obtained from the density distribution obtained from the data of the discharge pressure and the discharge flow rate at the normal time and the data of the discharge pressure and the discharge flow rate acquired by the data acquisition unit. The work vehicle according to claim 1, wherein the work vehicle is determined by comparing the degree of anomaly obtained using the density distribution with a predetermined threshold value. The hydraulic actuator includes a hydraulic cylinder.
The work vehicle according to claim 1 or 2 , 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. .. In the abnormality determination unit, among the data of the discharge pressure and the discharge flow rate acquired by the data acquisition unit, the load of the drive source of the hydraulic pump is equal to or more than a predetermined load, or the work amount of the hydraulic pump is equal to or more than a predetermined work amount. The work vehicle according to any one of claims 1 to 3 , wherein the data acquired in the case is used for determining the occurrence of an abnormality in the hydraulic pump.

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