JP5859279B2 - Hydraulic closed circuit system - Google Patents

Description

  The present invention relates to a hydraulic closed circuit system capable of driving a hydraulic cylinder or a hydraulic motor, and more particularly to a hydraulic closed circuit system including a hydraulic pump driven by an electric motor.

  2. Description of the Related Art Conventionally, there is known a pump failure diagnosis device that diagnoses the presence or absence of a failure of a hydraulic pump mounted on a hydraulic excavator (see, for example, Patent Document 1).

  This pump failure diagnosis device includes a wear metal amount in a failure diagnosis mode in which a pump tilt angle, pump horsepower, engine speed, and pump load are controlled to preset values, and a threshold value registered in advance. Is compared to determine whether or not a failure has occurred in the engine-driven hydraulic pump in the hydraulic open circuit system.

JP 2000-241306 A

  However, the pump failure diagnosis device described in Patent Document 1 only determines whether there is a failure in the hydraulic pump based on a value detected in a failure diagnosis mode in which a predetermined operation environment is guaranteed, and the operation environment changes. In the meantime, it is impossible to determine whether or not the hydraulic pump has failed based on a value (for example, pump discharge flow rate) that fluctuates according to changes in the operating environment.

  In view of the above, an object of the present invention is to provide a closed hydraulic circuit system that can determine the state of a hydraulic pump even when the operating environment of the hydraulic pump changes.

  In order to achieve the above object, a hydraulic closed circuit system according to an embodiment of the present invention is a hydraulic closed circuit system capable of driving a hydraulic cylinder or a hydraulic motor having a first port and a second port. A hydraulic pump having a first pump port in fluid communication with the first port through a conduit and a second pump port in fluid communication with the second port through a second conduit; An electric motor that controls rotation, an electric motor control unit that feedback-controls a value related to the input of the electric motor based on a value related to the output of the electric motor, a value related to the input of the electric motor, and a value related to the output of the electric motor And a pump state determination unit that determines the state of the hydraulic pump based on the above.

  By the means described above, the present invention can provide a hydraulic closed circuit system that can determine the state of the hydraulic pump even when the operating environment of the hydraulic pump changes.

It is the schematic which shows the structural example of the hydraulic closed circuit system which concerns on the Example of this invention. It is a functional block diagram which shows the structural example of a control apparatus. It is a flowchart which shows the flow of an electric motor control process. It is a flowchart which shows the flow of a pump state determination process. It is FIG. (1) which shows the relationship between the electric current command value applied to an electric motor, and the measured value of the moving speed of a piston. It is a flowchart which shows the flow of a 2nd pump state determination process. It is FIG. (2) which shows the relationship between the electric current command value applied to an electric motor, and the measured value of the moving speed of a piston.

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

  FIG. 1 is a schematic diagram illustrating a configuration example of a hydraulic closed circuit system 100 according to an embodiment of the present invention.

  The hydraulic closed circuit system 100 is a system in which the hydraulic cylinder 3 is driven by a hydraulic pump 1 whose rotation is controlled by the electric motor 2. The hydraulic cylinder 3 is used, for example, to move a table of a large load capacity hydraulically driven large surface grinder as a controlled portion.

  In this embodiment, the hydraulic closed circuit system 100 mainly includes a hydraulic pump 1, an electric motor 2, a hydraulic cylinder 3, safety valves 4L and 4R, a shuttle valve 7, an output detection sensor 9, a control device 10, an input device 15, A display device 16 and an audio output device 17 are included.

  The hydraulic pump 1 is a device that drives the hydraulic cylinder 3, and is, for example, a fixed displacement bidirectional hydraulic pump. The hydraulic pump 1 may be a variable displacement pump.

  The electric motor 2 is a device that controls the rotation of the hydraulic pump 1, and is, for example, a variable speed AC servo motor.

  The hydraulic cylinder 3 is a hydraulic actuator having a first oil chamber 3L and a second oil chamber 3R separated by a piston 3a. The first oil chamber 3L is fluidly communicated with the first pump port 1a of the hydraulic pump 1 through the first port 3b and the conduit C1, and the second oil chamber 3R is communicated with the second port 3c and the conduit C2. The hydraulic pump 1 is in fluid communication with the second pump port 1b. In this embodiment, the hydraulic cylinder 3 is a double rod cylinder having two rods extending on both sides of the piston 3a, and one or both of the two rods are coupled to a surface grinder table (not shown). Is done. The hydraulic cylinder 3 may be a single rod cylinder having one rod extending on one side of the piston 3a, and has a rod-free configuration in which a surface grinder table is directly coupled to the piston 3a. There may be.

  The safety valve 4L is a valve for releasing the hydraulic oil in the pipeline C1 to the hydraulic oil tank T1 when the pressure in the pipeline C1 becomes equal to or higher than a predetermined pressure. The safety valve 4R is a valve for releasing the hydraulic oil in the pipe C2 to the hydraulic oil tank T1 when the pressure in the pipe C2 becomes equal to or higher than a predetermined pressure.

  The safety valve 4L is disposed on a pipe line C4 that connects the pipe line C3 and the pipe line C1 in fluid communication with the hydraulic oil tank T1, and the safety valve 4R is a pipe line C5 that connects the pipe line C3 and the pipe line C2. Placed on top.

  The shuttle valve 7 is a valve that controls the flow of hydraulic oil between the pipe C1 or the pipe C2 and the hydraulic oil tank T1, and includes one primary port 7a and two secondary ports 7b and 7c. Have.

  The primary side port 7a is fluidly communicated with the hydraulic oil tank T1 via the conduit C11, and one of the secondary ports 7b is fluidly communicated with the conduit C1 via the conduit C7. The other secondary port 7c is in fluid communication with the conduit C2 via the conduit C8.

  Specifically, the shuttle valve 7 introduces the hydraulic oil in the hydraulic oil tank T1 into the pipe C1 through the secondary port 7b when the pressure in the pipe C1 is lower than the pressure in the hydraulic oil tank T1. To do. Further, when the pressure in the pipe C2 is lower than the pressure in the hydraulic oil tank T1, the shuttle valve 7 introduces the hydraulic oil in the hydraulic oil tank T1 into the pipe C2 through the secondary port 7c. This is to compensate for the lack of hydraulic oil in the pipe line C1 or the pipe line C2 caused by the rotation of the hydraulic pump 1 or the like.

  The output detection sensor 9 is a sensor that detects a value related to the output of the electric motor 2. For example, the position sensor 9 a that detects the position of the piston 3 a, the rotation sensor 9 b that detects the rotation of the hydraulic pump 1, and the hydraulic pump 1. A first discharge amount sensor 9c1 that detects a discharge amount from the first pump port 1a, a first discharge amount sensor 9c2 that detects a discharge amount from the second pump port 1b of the hydraulic pump 1, and the like are included. The output detection sensor 9 outputs the detected value to the control device 10.

  The control device 10 is a device for controlling the hydraulic closed circuit system 100 and is, for example, a computer including a CPU, a RAM, a ROM, an input / output interface, and the like.

  Further, the control device 10 determines the required moving distance (the distance from the current position to the target position) of the surface grinder table, that is, the required moving distance of the piston 3a, in accordance with an input from the operator via the input device 15. To do. Further, the control device 10 determines and determines the target moving speed of the piston 3a (the moving direction of the piston 3a is expressed by the sign of the target moving speed) according to the determined required moving distance of the piston 3a. A control command corresponding to the target movement speed is output to the electric motor 2. Specifically, the control device 10 increases the target moving speed as the required moving distance of the piston 3a increases. Further, the control device 10 decreases the target moving speed as the required moving distance of the piston 3a decreases, that is, as the target position is approached.

  Further, the control device 10 determines whether or not the surface grinder table has reached the target position while monitoring the position of the piston 3a, that is, the position of the surface grinder table, based on the output of the position sensor 9a.

  When it is determined that the surface grinder table has reached the target position, the control device 10 outputs a control command for stopping the rotation of the hydraulic pump 1 to the electric motor 2.

  The input device 15 is a device that allows an operator to input various types of information to the control device 10, and is, for example, a hardware button, a keyboard, a mouse, a touch panel, or the like.

  The display device 16 is a device that displays various types of information output from the control device 10, and is, for example, a liquid crystal display, an LED lamp, or the like.

  The audio output device 17 is a device that outputs various information output by the control device 10 as audio, and is, for example, a speaker, a buzzer, or the like.

  Next, various functional elements of the control device 10 will be described with reference to FIG. FIG. 2 is a functional block diagram illustrating a configuration example of the control device 10.

  The control device 10 reads a program corresponding to each functional element of the electric motor control unit 11, the pump efficiency calculation unit 12, and the pump state determination unit 13 from the ROM, expands the program in the RAM, and performs processing corresponding to each program on the CPU. To run.

  The electric motor control unit 11 is a functional element that controls the electric motor 2. For example, the electric motor control unit 11 generates a control command for controlling the electric motor 2 based on various types of information, and sends the generated control command to the electric motor 2. Output.

  Here, with reference to FIG. 3, a flow of processing in which the electric motor control unit 11 controls the electric motor 2 (hereinafter referred to as “electric motor control processing”) will be described. FIG. 3 is a flowchart showing the flow of the electric motor control process, and the electric motor control unit 11 repeatedly executes the electric motor control process at a predetermined cycle.

  First, the electric motor control unit 11 determines a control target value for the electric motor 2 based on the target moving speed of the piston 3a (step S1). In the present embodiment, the control device 10 determines a required moving distance of the piston 3a as a control target value based on, for example, an operator's numerical input via the input device 15. And the control apparatus 10 determines the target moving speed of piston 3a based on the required moving distance of piston 3a.

  Thereafter, the electric motor control unit 11 acquires an actual measurement value corresponding to the control target value output from the output detection sensor 9 (step S2). In the present embodiment, the electric motor control unit 11 acquires the actual moving speed of the piston 3a based on the output of the position sensor 9a.

  Thereafter, the electric motor control unit 11 generates a control command value by feedback control so as to cancel the difference between the control target value and the actually measured value corresponding to the control target value (step S3), and uses the generated control command value. It outputs with respect to the electric motor 2 (step S4). In this embodiment, the electric motor control unit 11 generates and generates a speed command value so as to cancel out the difference between the target movement speed and the actual movement speed (movement distance per unit time) based on the output of the position sensor 9a. The speed command value is output to the electric motor 2.

  In this way, the electric motor control unit 11 controls the rotational speed of the electric motor 2 by feedback of the moving speed of the piston 3a. The electric motor control unit 11 calculates a torque command value (current command value) based on the speed command value, and feeds back the output of an ammeter (not shown) that measures the current flowing through the electric motor 2. The torque of the electric motor 2 may be controlled so as to cancel the difference between the current command value and the measured current value.

  As a result, the electric motor control unit 11 controls the electric motor 2 by controlling the electric motor 2 regardless of the state of the components interposed between the piston 3a and the electric motor 2, that is, whether the state of the hydraulic pump 1 is good or bad. The desired moving speed can be realized. Therefore, for example, even when the actual discharge amount of the hydraulic pump 1 corresponding to a given rotational speed of the electric motor 2 is smaller than the expected discharge amount, the electric motor control unit 11 determines the state of the operator. The piston 3a can be moved at a desired moving speed without noticing. This is for automatically compensating for the shortage of the discharge amount of the hydraulic pump 1 by increasing the rotation speed of the electric motor 2 in order to achieve control stability.

  In this embodiment, the electric motor control unit 11 employs the target moving speed of the piston 3a as the control target value. However, the target rotational speed of the hydraulic pump 1 or the target discharge amount of the hydraulic pump 1 is set as the control target value. May be adopted. In this case, the electric motor control unit 11 controls the rotational speed of the hydraulic pump 1 output by the rotation sensor 9b or the discharge amount of the hydraulic pump 1 output by the first discharge amount sensor 9c1 or the second discharge amount sensor 9c2. Acquired as an actual measurement value corresponding to the value.

  The pump efficiency calculation unit 12 is a functional element that calculates the pump efficiency of the hydraulic pump 1.

  “Pump efficiency” means the discharge efficiency of the hydraulic pump 1 and is calculated based on, for example, a value related to the input of the electric motor 2 and a value related to the output of the electric motor 2. The pump efficiency is basically a value that decreases with time, that is, due to aging deterioration of the hydraulic pump 1, and when the pump efficiency falls below a predetermined value, replacement or maintenance of the hydraulic pump 1 (hereinafter referred to as “replacement etc.”). ")") Is necessary.

  In this embodiment, the pump efficiency is a value obtained by dividing the moving speed of the piston 3a realized by the actual rotation of the electric motor 2 in accordance with the control command value input to the electric motor 2 by the control command value. Is adopted.

  The pump state determination unit 13 is a functional element that determines the state of the hydraulic pump 1. For example, the pump state determination unit 13 determines whether or not the current state of the hydraulic pump 1 is suitable for continuous use.

  Here, the flow of the process in which the pump state determination unit 13 determines the state of the hydraulic pump 1 (hereinafter referred to as “pump state determination process”) will be described with reference to FIGS. 4 and 5. FIG. 4 is a flowchart showing the flow of the pump state determination process, and the pump state determination unit 13 repeatedly executes this pump state determination process at a predetermined cycle. FIG. 5 is a diagram showing the relationship between the current command value applied to the electric motor 2 and the actual measured value of the moving speed of the piston 3a. The horizontal axis represents the current command value, and the vertical axis represents the movement of the piston 3a. Represents the measured speed value.

  Initially, the pump state determination part 13 acquires the control command value which the electric motor control part 11 output with respect to the electric motor 2 as a value regarding the input of the electric motor 2 (step S11). In the present embodiment, the pump state determination unit 13 acquires a current command value D1 as a control command value.

  Thereafter, the pump state determination unit 13 acquires a value related to the output of the electric motor 2 realized because the control command value is applied to the electric motor 2 (step S12). In this embodiment, the pump state determination unit 13 uses the position sensor 9a to calculate the actual moving speed V1 of the piston 3a that is realized because the current command value D1 is applied to the electric motor 2 and the rotational speed of the electric motor 2 changes. Get based on output.

  Thereafter, the pump state determination unit 13 acquires a reference command value based on an actual measurement value resulting from a control command value applied to the electric motor 2 (step S13). In the present embodiment, the pump state determination unit 13 acquires the reference command value Ds based on the actual moving speed V1 of the piston 3a caused by the current command value D1 applied to the electric motor 2.

  The “reference command value” means a control command value that serves as a reference required to realize a predetermined actual measurement value related to the output of the electric motor 2. In the present embodiment, the reference command value corresponds to, for example, a current command value required for realizing a predetermined moving speed of the piston 3a when the hydraulic closed circuit system 100 is initially used. The reference command value is stored in advance in the ROM of the control device 10 in the form of a correspondence table in association with each value of the moving speed of the piston 3a, for example. The broken line in FIG. 5 is a line segment representing the reference pump efficiency determined by the reference command value and the moving speed of the piston 3a. The line segment representing the reference pump efficiency in FIG. 5 indicates that the moving speed V2 of the piston 3a can be realized if the current command value D1 is the reference command value. On the other hand, the solid line in FIG. 5 is a line segment representing the current pump efficiency estimated by the current current command value D1 and the actual moving speed V1 of the piston 3a. 5 is a line segment representing the allowable lower limit pump efficiency determined by the allowable maximum command value and the moving speed of the piston 3a when the allowable maximum command value is applied.

  The “allowable maximum command value” means the maximum control command value that can be applied to realize a predetermined actual measurement value related to the output of the electric motor 2. In the present embodiment, the allowable maximum command value corresponds to, for example, the maximum current command value applicable for realizing a predetermined moving speed of the piston 3a. When the current command value exceeding the allowable maximum command value is required to realize the predetermined moving speed of the piston 3a, that is, when the pump efficiency is lower than the allowable lower limit pump efficiency, it is estimated that the hydraulic pump 1 is abnormal. it can. The hatched area in FIG. 5 represents an area where the pump efficiency is below the allowable lower limit pump efficiency.

  Specifically, the pump state determination unit 13 refers to the correspondence table stored in the ROM of the control device 10 and stores the relationship between the moving speed of the piston 3a and the reference command value, and the moving speed V1 of the histone 3a. The reference command value Ds required for realizing is acquired.

  Thereafter, the pump state determination unit 13 calculates a difference ΔD between the acquired reference command value Ds and the current current command value D1 (step S14), and compares the calculated difference ΔD with a predetermined threshold value ΔDmax (step S15). ). The predetermined threshold ΔDmax is, for example, a value stored in advance in the ROM of the control device 10 in association with the reference command value Ds as the allowable maximum value of the difference with respect to the reference command value Ds. Corresponding values are provided.

  Further, the value of the difference ΔD to be compared may be an instantaneous value, and a statistical value (for example, an average value, a median value, a value based on a plurality of difference ΔD values continuously calculated over a predetermined period of time). Minimum value, maximum value, mode value, etc.).

  When it is determined that the value of the difference ΔD exceeds the predetermined threshold value ΔDmax (YES in step S15), the pump state determination unit 13 determines that the current state of the hydraulic pump 1 is not suitable for continuous use. .

  In this case, the pump state determination unit 13 outputs a control signal to at least one of the display device 16 and the sound output device 17, and the current state of the hydraulic pump 1 is not suitable for continuous use. After notifying the operator (step S16), the current pump state determination process is terminated.

  On the other hand, when it is determined that the value of the difference ΔD is equal to or smaller than the predetermined threshold ΔDmax (NO in step S15), the pump state determination unit 13 is suitable for continuous use of the current state of the hydraulic pump 1. Judge that there is.

  In this case, the pump state determination unit 13 ends the current pump state determination process without outputting a control signal to the display device 16 and the sound output device 17.

  The pump state determination unit 13 may determine the state of the hydraulic pump 1 separately for each of the rotation directions of the hydraulic pump 1. This is because the state of the hydraulic pump 1 may become abnormal only in a specific rotational direction, so that such an abnormal state can be detected earlier.

  As described above, the hydraulic closed circuit system 100 is configured to calculate the current command value D1 as a value related to the input of the electric motor 2 and the reference command value Ds derived from the moving speed V1 of the piston 3a as a value related to the output of the electric motor 2. The state of the hydraulic pump 1 is determined based on the difference. As a result, the hydraulic closed circuit system 100 can determine the state of the hydraulic pump 1 even when the operating environment of the hydraulic pump 1 changes. Moreover, the hydraulic closed circuit system 100 can detect an increase in energy loss accompanying a decrease in pump efficiency of the hydraulic pump 1 due to deterioration over time or the like at an earlier stage. Moreover, the hydraulic closed circuit system 100 can notify the operator of the necessity of replacement of the hydraulic pump 1 at an early stage, and can realize energy saving, running cost reduction, and the like.

  In addition, the hydraulic closed circuit system 100 includes only the hydraulic pump 1 as a main component interposed between the electric motor 2 and the hydraulic cylinder 3, and the electric pump 1 and the hydraulic cylinder 3 are associated with each other in a one-to-one correspondence. The moving speed of the piston 3a is adopted as a value related to the output of the motor 2. As a result, the hydraulic closed circuit system 100 can easily detect a value related to the output of the electric motor 2.

  Next, another embodiment of the pump state determination process (hereinafter referred to as “second pump state determination process”) will be described with reference to FIGS. 6 and 7. FIG. 6 is a flowchart showing the flow of the second pump state determination process, and the pump state determination unit 13 repeatedly executes the second pump state determination process at a predetermined cycle. FIG. 7 is a diagram showing the relationship between the current command value applied to the electric motor 2 and the actual measured value of the moving speed of the piston 3a, and corresponds to FIG.

  Initially, the pump state determination part 13 acquires the control command value which the electric motor control part 11 output with respect to the electric motor 2 as a value regarding the input of the electric motor 2 (step S21). In the present embodiment, the pump state determination unit 13 acquires a current command value as a control command value.

  Thereafter, the pump state determination unit 13 acquires a value related to the output of the electric motor 2 realized because the control command value is applied to the electric motor 2 (step S22). In this embodiment, the pump state determination unit 13 uses the position sensor 9a to calculate the actual moving speed V1 of the piston 3a that is realized because the current command value D1 is applied to the electric motor 2 and the rotational speed of the electric motor 2 changes. Get based on output.

  Thereafter, the pump state determination unit 13 acquires the pump efficiency calculated by the pump efficiency calculation unit 12 based on the control command value applied to the electric motor 2 and the actual measurement value resulting from the control command value (step S23). . In the present embodiment, the pump state determination unit 13 calculates the pump efficiency θ (= movement) calculated by the pump efficiency calculation unit 12 based on the current command value D1 applied to the electric motor 2 and the actual moving speed V1 of the piston 3a. Speed V1 ÷ current command value D1) is acquired.

  Thereafter, the pump state determination unit 13 compares the acquired pump efficiency θ with a predetermined allowable lower limit pump efficiency θmin (step S24). The predetermined allowable lower limit pump efficiency θmin is a value determined by, for example, the maximum allowable command value and the moving speed of the piston 3a when the maximum allowable command value is applied, and is stored in advance in the ROM of the control device 10. Yes. Further, the pump efficiency θ to be compared may be an instantaneous value, and a statistical value (for example, an average value, a median value, a minimum value) based on a plurality of pump efficiency values continuously calculated over a predetermined period. Value, maximum value, mode value, etc.).

  When it is determined that the acquired pump efficiency θ is lower than the predetermined allowable lower limit pump efficiency θmin (YES in step S24), the pump state determination unit 13 does not indicate that the current state of the hydraulic pump 1 is suitable for continuous use. Judge that there is no.

  In this case, the pump state determination unit 13 outputs a control signal to at least one of the display device 16 and the sound output device 17, and the current state of the hydraulic pump 1 is not suitable for continuous use. After notifying the operator (step S25), the current pump state determination process is terminated.

  On the other hand, when it is determined that the acquired pump efficiency θ is equal to or greater than the predetermined allowable lower limit pump efficiency θmin (NO in step S24), the pump state determination unit 13 determines that the current state of the hydraulic pump 1 is continuously used. Judge that it is suitable.

  In this case, the pump state determination unit 13 ends the current pump state determination process without outputting a control signal to the display device 16 and the sound output device 17.

  The pump state determination unit 13 may determine the state of the hydraulic pump 1 separately for each of the rotation directions of the hydraulic pump 1. This is because the state of the hydraulic pump 1 may become abnormal only in a specific rotational direction, so that such an abnormal state can be detected earlier.

  As described above, the hydraulic closed circuit system 100 has the pump efficiency θ derived from the current command value D1 as the value related to the input of the electric motor 2 and the moving speed V1 of the piston 3a as the value related to the output of the electric motor 2. The state of the hydraulic pump 1 is determined based on the comparison with the lower limit pump efficiency θmin. As a result, the hydraulic closed circuit system 100 can determine the state of the hydraulic pump 1 even when the operating environment of the hydraulic pump 1 changes. Moreover, the hydraulic closed circuit system 100 can detect an increase in energy loss accompanying a decrease in pump efficiency of the hydraulic pump 1 due to deterioration over time or the like at an earlier stage. Moreover, the hydraulic closed circuit system 100 can notify the operator of the necessity of replacement of the hydraulic pump 1 at an early stage, and can realize energy saving, running cost reduction, and the like.

  In addition, the hydraulic closed circuit system 100 includes only the hydraulic pump 1 as a main component interposed between the electric motor 2 and the hydraulic cylinder 3, and the electric pump 1 and the hydraulic cylinder 3 are associated with each other in a one-to-one correspondence. The moving speed of the piston 3a is adopted as a value related to the output of the motor 2. As a result, the hydraulic closed circuit system 100 can easily detect a value related to the output of the electric motor 2.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, in the above-described embodiment, the hydraulic closed circuit system 100 is configured to drive the hydraulic cylinder 3 with the hydraulic pump 1, but may be configured to drive the hydraulic motor with the hydraulic pump 1.

  In the above-described embodiment, the hydraulic closed circuit system 100 is used to move a table of a large load capacity hydraulically driven large surface grinder as a controlled portion. However, the injection cylinder and the movable platen of the injection molding machine are used. It may be used to move as a controlled part, or may be used to move components of other machine tools as controlled parts.

  DESCRIPTION OF SYMBOLS 1 ... Hydraulic pump 1a ... 1st pump port 1b ... 2nd pump port 2 ... Electric motor 3 ... Hydraulic cylinder 3a ... Piston 3b ... 1st port 3c ... 2nd port 3L ... 1st oil chamber 3R ... 2nd oil chamber 4L, 4R ... Safety valve 7 ... Shuttle valve 7a ... Primary side port 7b, 7c ... Secondary side port 9 ... Output detection sensor 9a ... Position sensor 9b ... Rotation sensor 9c1 ... First discharge amount sensor 9c2 ... Second discharge amount sensor 10 ... Control device 11 ... Electric motor control Unit 12: Pump efficiency calculation unit 13 ... Pump state determination unit 15 ... Input device 16 ... Display device 17 ... Audio output device 100 ... Hydraulic closed circuit system T1 ... Hydraulic oil tank

Claims (2)

A hydraulic closed circuit system capable of driving a hydraulic cylinder or hydraulic motor having a first port and a second port,
A hydraulic pump having a first pump port in fluid communication with the first port through a first conduit and a second pump port in fluid communication with the second port through a second conduit;
An electric motor for controlling the rotation of the hydraulic pump;
Electric motor control for controlling the electric motor by feedback-controlling a control command value corresponding to a target moving speed of the controlled part based on an actually measured moving speed of the controlled part moved by the hydraulic cylinder or the hydraulic motor And
Bei obtain a pump state determination unit determines the state of the hydraulic pump on the basis of said actual moving speed and the control command value,
Hydraulic closed circuit system characterized by that. The pump state determination unit determines the state of the hydraulic pump with respect to each of the rotation directions of the hydraulic pump;
The hydraulic closed circuit system according to claim 1.

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