JPH0633775B2 - Fault diagnosis device for hydraulic pump - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hydraulic pump failure diagnosis device for performing a failure diagnosis of a hydraulic pump that is a hydraulic power source in a hydraulic system provided in a machine tool, a construction machine, or the like. Regarding

[Prior Art] If a hydraulic pump has a failure and continues to operate without knowing it, the failure will eventually spread and cause a sudden stop of operation. There is a risk that the hydraulic system that was being driven will become inoperable, creating a dangerous condition, and that all work related to that hydraulic system will have to be stopped, which will significantly reduce work efficiency. is there. In order to avoid such a state, it is necessary to find out a failure of the hydraulic pump while it is mild and take appropriate measures.

2. Description of the Related Art Conventionally, as a device for detecting a failure of a hydraulic pump, that is, a failure diagnosis device for a hydraulic pump, there has been proposed a means for detecting a vibration frequency generated from the hydraulic pump and determining whether or not there is a failure based on the vibration frequency.

[Problems to be Solved by the Invention] However, with this means, it is necessary to conduct an experiment or the like in advance for each hydraulic pump and to grasp the vibration frequency characteristics when a failure occurs in the hydraulic pump. Had to spend a lot of time and effort, was extremely uneconomical and troublesome.

The present invention has been made in view of such circumstances, and its purpose is. Excluding the conventional drawbacks described above, it is an object of the present invention to provide a failure diagnosis device for a hydraulic pump that can very easily determine whether or not there is a failure in the hydraulic pump.

[Means for Solving the Problems] In order to achieve the above object, the present invention relates to a hydraulic pump for driving a hydraulic actuator, a rotational speed detecting device for detecting the rotational speed of the hydraulic pump, and the rotational speed detecting device. A first calculating means for obtaining a theoretical discharge amount of the hydraulic pump based on the rotation speed detected by the second calculating means; and a second calculating means for obtaining an actual discharge amount supplied from the hydraulic pump to the hydraulic actuator. Second calculation means for calculating the deviation between the theoretical discharge quantity and the actual discharge quantity, comparison means for comparing the deviation calculated by the third calculation means with a predetermined set value, and this comparison Means for outputting an abnormal signal when the deviation is equal to or more than the set value as a result of comparison by the means.

[Operation] The first calculating means obtains the theoretical discharge amount of the hydraulic pump obtained from the rotational speed of the hydraulic pump, and the second calculating means obtains the actual discharge amount supplied from the hydraulic pump to the hydraulic actuator. , Compares whether or not the deviation between the theoretical discharge amount and the actual discharge amount is equal to or greater than a set value, and when the deviation is equal to or greater than the set value, outputs an abnormality signal indicating an abnormality of the hydraulic pump.

[Examples] Hereinafter, the present invention will be described based on illustrated examples.

FIG. 1 is a system diagram of a failure diagnosis device according to a first embodiment of the present invention. In the figure, 1 is a hydraulic pump, 2 is a hydraulic pump 1
A drive source such as an internal combustion engine for rotationally driving the engine 3 is a hydraulic pump 1
The hydraulic cylinders 4 driven by means of a switching valve are interposed between the hydraulic pump 1 and the hydraulic cylinder 3 to control the driving of the hydraulic cylinder 3. Reference numeral 5 is a displacement gauge that detects the displacement amount of the hydraulic cylinder 3 and outputs a displacement amount signal x corresponding thereto, and 6 is a limit switch that detects the stroke of the switching valve 4 and outputs an operation signal e. The operation signal e of the limit switch 6 has a predetermined value only when the stroke of the switching valve 4 is the maximum stroke, and is 0 in other strokes. Reference numeral 7 denotes a tachometer that detects the number of revolutions of the hydraulic pump 1, and outputs a number-of-revolutions signal n corresponding to the number of revolutions.
Reference numeral 8 is a control device using a microcomputer for inputting signals x, e, and n to perform required arithmetic operations and control, and 9 is a display device operated by an output signal of the control device 8.

Next, the operation of this embodiment will be described with reference to the flowchart shown in FIG. Generally, when a failure occurs in the hydraulic pump, the failure not only appears as a change in the above-mentioned vibration frequency but also appears as a decrease in efficiency. In the present embodiment, the phenomenon of this efficiency decrease is captured, and this phenomenon is calculated based on the theoretical discharge amount of the hydraulic pump based on the rotation speed signal n.
It is intended to perform a failure diagnosis by observing by obtaining a difference from the actual discharge amount of the hydraulic pump based on the displacement amount signal x.

First, the microcomputer constituting the control device 8 reads the operation signal e (procedure S ₁ ) and judges whether or not the signal e is 0 (procedure S ₂ ). If the signal e is 0,
Since the switching valve 4 is not in full stroke, steps S ₁ , S ₂
Is repeated. Here, the reason for detecting the full stroke will be described. As shown in FIG. 1, the failure diagnosis device of this embodiment is applied to a hydraulic open circuit. Therefore, in the case other than the full stroke, the pressure oil from the hydraulic pump 1 is
A part of the oil is discarded and all the pressure oil does not enter the hydraulic cylinder 3, resulting in inaccurate calculation of the actual discharge amount (described later). Therefore, it is necessary to detect the full stroke.

Procedure not 0 the signal e at S _2, the switching valve 4 is determined to have been full-stroke operation, then the rotational speed signal n is read in (Step S _3), theoretical discharge amount based on the signal n Q
₀ is calculated (procedure S ₄ ). This calculation is executed by the following equation.

Q ₀ = D · n However, the value D is the displacement volume of the hydraulic pump 1, and is given as a constant when the hydraulic pump 1 is a gear pump.

Next, the actual discharge amount of the hydraulic pump 1 is calculated. This operation is performed as follows. First, the displacement amount signal x is read (procedure S ₅ ). Then, after a predetermined short time by the timer routine procedures S _6, again displacement signal x after the time 'is read (Step S _7). Next, the difference Δx (Δx = x′−x) between the signal x ′ read this time and the signal x read earlier is calculated (procedure S ₈ ), and the difference Δ
The displacement speed Δ of the hydraulic cylinder 3 is obtained based on x and the minute time in the timer routine (step S ₉ ). Based on this speed Δ, the actual discharge amount Q ₁ of the hydraulic pump 1 is calculated by the following equation (step S ₁₀ ).

Q ₁ = A · Δ However, the value A is the pressure receiving area on the bottom side of the hydraulic cylinder 2.

The theoretical discharge amount Q ₀ of the hydraulic pump 1 thus obtained
In step S ₁₁ , the degree ΔQ (ΔQ = Q ₀ −Q ₁ ) of the efficiency decrease of the hydraulic pump 1 is calculated based on the actual discharge amount Q ₁ and the actual discharge amount Q ₁ . The smaller the value ΔQ is, the higher the efficiency is. On the contrary, the larger the value ΔQ is, the more the efficiency is significantly reduced.
Next, the value ΔQ is compared with a predetermined set value ΔQ ₅ (step S ₁₂ ). The set value ΔQ ₅ is determined according to various conditions such as the structure of the body of the hydraulic pump 1 and the usage of the hydraulic system. When the value ΔQ is less than the set value ΔQ _s in step S ₁₂ , it is determined that the hydraulic pump 1 is normal,
And it outputs the normality determination signal to the display device 9 (S _13). When the value ΔQ is equal to or greater than the set value ΔQ _s , it is determined that the hydraulic pump 1 has a failure, and the abnormality determination signal is output to the display device 9. When the processing in step S ₁₃ or step S ₁₄ is completed, the procedure returns to S ₁ again, and the same procedure is repeated. As a result, the clerk can know whether the hydraulic pump 1 is out of order by looking at the display device 9, and can take necessary measures to prevent the accident.

As described above, in this embodiment, when the switching valve reaches the maximum stroke, the theoretical discharge amount is obtained from the rotation speed of the hydraulic pump, and the actual discharge amount is obtained from the displacement amount of the hydraulic cylinder. Since the normality is displayed when the value is less than the set value and the failure is displayed when the value is equal to or more than the set value, the failure determination of the hydraulic pump can be performed extremely easily. Further, since the displacement gauge, the tachometer, and the display device are often provided in the hydraulic system, it is possible to configure them at low cost by using them together, and in a hydraulic system provided with a microcomputer. Can also take advantage of this. Furthermore, if the set value is reduced, it can be predicted that a failure will occur soon.

FIG. 3 is a system diagram of a failure diagnosis device for a hydraulic pump in a hydraulic excavator according to a second embodiment of the present invention. In the figure,
10 is a variable displacement hydraulic pump mounted on a hydraulic excavator,
11 is a lower traveling body of the hydraulic excavator, 11M is a traveling hydraulic motor, 12 is an upper revolving body, 12M is a revolving hydraulic motor, 13 is a boom rotatably supported by the upper revolving body 12, and 14 is a rotatable body on the boom 13. The arm 15 is movably supported, 15 is a bucket rotatably supported by the arm 14, 16 is a boom cylinder, 17 is an arm cylinder, and 18 is a bucket cylinder. 19L ₀ is an arm lever that drives the arm cylinder 17 to operate the arm 14. 19L ₁ is a swing hydraulic motor 12M that drives the upper swing body 12.
The pivoting lever pivoting operation, 19L ₂ is a traveling lever for traveling operation of the lower traveling body 11 by driving the traveling motor 11M. The illustration and description of the other operating levers are omitted. 20L ₀ , 20L ₁ and 20L ₂ are lever stroke meters, which output operation signals l ₀ , l ₁ and l ₂ corresponding to the operation amounts of the arm lever 19L ₀ , the swing lever 19L ₁ and the traveling lever 19L ₂ , respectively. Reference numeral 21 is a tachometer that detects the rotation speed of the hydraulic pump 10 and outputs a rotation speed signal n corresponding thereto, and 22 is a tilt angle that detects the tilt angle of the hydraulic pump 10 and outputs a tilt angle signal α corresponding thereto. Reference numeral 23 is a front angle meter that detects the relative angle between the boom 13 and the arm 14 and outputs an angle signal θ corresponding thereto.
Reference numeral 24 is a control device for inputting each signal l ₀ , l ₁ , l ₂ , n, α, θ to perform a failure diagnosis, which is configured by using a microcomputer. Reference numeral 25 is a display device which is operated by an output signal of the control device 24.

Next, the operation of this embodiment will be described with reference to the flow chart shown in FIG. 4 and the displacement diagram of the arm cylinder shown in FIG. Now, suppose that the actuators for supplying the hydraulic oil of the hydraulic pump 10 are the traveling motor 11M, the swing motor 12M, and the arm cylinder 17. As described above, when there are a plurality of actuators to which the hydraulic oil of the hydraulic pump 10 is supplied, in order to obtain the actual discharge amount of the hydraulic pump 10, only one of the actuators is used and the displacement of that actuator is used. Need to detect. In this embodiment, the arm cylinder 17 is selected as this one actuator.

First, the operation signals l ₁ of the swivel lever 19L ₁ is read in (Step S
₂₁ ), it is judged whether or not the signal l ₁ is 0 (step S ₂₂ ). When the pressure oil of the hydraulic pump 10 is being supplied to the swing motor 12M, the signal l ₁ does not become 0, and the arm cylinder
Since it is impossible to calculate the actual discharge amount by 17, the process returns to the first step S ₂₁ . Pressure oil is not supplied to the swing motor 12M, when the signal l ₁ is 0, travel lever 19L ₂ of the operation signal l ₂ is read rare (Step S _23), signal l ₂
There is judged whether or not 0 (Step S _24). Traveling motor
When the pressure oil is supplied to 11M, the process steps S ₂₁
Returning to, when the pressure oil is not supplied, the operation signal l ₀ of the arm lever 19L ₀ is read (Step S _25). The read signal l ₀ is compared with a preset maximum operation signal of the arm lever 19L ₀ (step S ₂₆ ). This maximum operation signal is set for the same reason as the full stroke signal e of the switching valve 4 in the previous embodiment. Signal l ₀
When but does not reach the maximum operation amount signal, the process returns to step S _21. On the other hand, when the signal l ₀ has reached the maximum operation amount signal, the process proceeds to step S ₂₇ , and the rotation speed signal n and the tilt angle signal α are read. Next, the theoretical discharge amount Q ₀ of the hydraulic pump 10 is calculated based on the signals n and α (step S ₂₃ ). This calculation is performed by Q ₀ = D · n as in the process in step S ₄ in the previous embodiment, but in the case of the variable displacement hydraulic pump, the agate volume D is as follows.

Axial oblique axis type Axial swash plate type However, D ₁ …… Sloping shaft type connecting rod mounting end pitch circle diameter D ₂ …… Cylinder hole pitch circle diameter of swash plate type cylinder block d …… Cylinder block diameter on cylinder block z …… Cylinder block Number of installed cylinders α ₁ , α ₂ ... Oblique axis, tilt angle of swash plate When the theoretical discharge amount Q ₀ is calculated in step S ₂₃ , the angle signal θ is read next. (Procedure S ₂₀ ), after a predetermined minute time by the timer routine (Procedure S ₃₀ ),
The angle signal (the angle signal at this time is designated as θ ') is read again. In step S ₃₂ , the displacement amount Δx is calculated based on these two angle signals θ and θ ′. The calculation of the displacement amount Δx will be described with reference to the diagram shown in FIG. In FIG. 3, the connecting point of the arm cylinder 17 in the boom 13 is B,
The connection point of the arm cylinder 17 in the arm 14 is C, the connection point of the boom 13 and the arm 14 is D, the distance between the connection points B and D is c, and the distance between the connection points C and D is b. And A line segment connecting the connecting points B, C and D is shown in FIG. Now, it is assumed that the rod of the arm cylinder 17 extends and the connecting point C moves to the position C'during the passage of time by the timer routine. Since the angle signal read at this time is the signal θ ′, the displacement angle Δθ becomes the angle (θ′−θ). If the distance between the connecting points B and C before displacement is x, then x
Is expressed by the following equation.

When the extension of the arm cylinder 17 is Δx, the distance between the connecting point B and the position C ′ is expressed by the following equation.

Therefore, the displacement amount Δx of the arm cylinder 17 is Becomes

When the displacement amount Δx is obtained in step S ₃₂ , the processing of the subsequent steps S _{33 to} S ₃₃ is exactly the same as the processing of steps S _{9 to} S _{14 in} the embodiment, the calculation of the speed Δ and the actual discharge. The quantity Q ₁ is calculated, the deviation ΔQ is calculated, the deviation ΔQ is compared with the set value ΔQ _s, and output to the display device 25. The details of these processes follow the description in the previous embodiment.

As described above, in the present embodiment, only when the arm cylinder is operated and the operation amount is the maximum operation amount, the theoretical discharge amount from the rotational speed of the hydraulic pump, and
The actual discharge amount is calculated from the displacement amount of the arm cylinder, and when the difference between the two is less than the set value, normal is displayed, and when the difference is more than the set value, the failure is displayed. Total,
If a tachometer, a tilt angle meter, and a front angle meter are installed, the same effect can be obtained by using them.

In the description of the above embodiment, the failure diagnosis device for the hydraulic pump used in the hydraulic open circuit has been described, but it is naturally applicable to the hydraulic closed circuit. Further, although the hydraulic cylinder is exemplified as the actuator used for obtaining the actual discharge amount, the calculation becomes easier if the hydraulic motor is used. Further, the control device can be configured by an analog circuit instead of the microcomputer. Furthermore, the failure diagnosis does not have to be executed all the time, and can be executed only at any time by installing an appropriate switch or the like. Further, if the set value ΔQ _s is not a constant but a variable having the discharge pressure and the rotational speed of the hydraulic pump as parameters, the accuracy can be further improved.

〔The invention's effect〕

As described above, in the present invention, the theoretical discharge amount is obtained based on the rotational speed of the hydraulic pump, the actual discharge amount is obtained based on the displacement amount of the actuator, and the deviation between the two is compared with the set value to determine the failure. Therefore, it is possible to very easily determine whether or not there is a failure in the hydraulic pump.

[Brief description of drawings]

FIG. 1 is a system diagram of a failure diagnosis device according to a first embodiment of the present invention, FIG. 2 is a flow chart for explaining the operation of the control device shown in FIG. 1, and FIG. 3 is a second embodiment of the present invention. Failure diagnosis device for hydraulic pump in hydraulic excavator according to example 4,
FIG. 5 is a flow chart for explaining the operation of the control device shown in FIG. 3, and FIG. 5 is a diagram for explaining the calculation of the arm cylinder displacement amount shown in FIG. 1, 10 ... hydraulic pump, 3 ... hydraulic cylinder, 4 ... switching valve, 5 ... displacement meter, 6 ... limit switch, 7,21
...... Tachometer, 8,24 …… Control device, 9,25 …… Display device, 17 …… Arm cylinder, 19L ₀ …… Arm lever, 19
L ₁ …… Swing lever, 19L ₂ …… Travel lever, 20L ₀ , 20L ₁ ,
20L ₂ …… Lever stroke meter, 22 …… Tilting angle meter, 23…
… Front angle meter.

Front page continuation (72) Inventor Masaki Kanehara 650 Kintatemachi, Tsuchiura, Ibaraki Prefecture Tsuchiura Plant, Hitachi Construction Machinery Co., Ltd. Tsuchiura Factory (56) References JP-A-59-162395 (JP, A)

Claims (1)

[Claims] 1. In a hydraulic pump for driving a hydraulic actuator, a rotation speed detection device for detecting the rotation speed of the hydraulic pump, and a theoretical discharge amount of the hydraulic pump based on the rotation speed detected by the rotation speed detection device. A first calculation means for calculating the actual discharge amount supplied from the hydraulic pump to the hydraulic actuator, a second calculation means for calculating the actual discharge amount supplied from the hydraulic pump to the hydraulic actuator, and a second calculation device for calculating a deviation between the theoretical discharge amount and the actual discharge amount. No. 3 calculation means, comparison means for comparing the deviation calculated by the third calculation means with a preset value, and an abnormal signal when the deviation is greater than the set value as a result of comparison by the comparison means. A fault diagnosis device for a hydraulic pump, comprising: