JP7096178B2 - Construction machinery - Google Patents

Description

The present invention relates to construction machinery such as hydraulic excavators.

Due to the growing environmental awareness in recent years, energy saving of construction machinery is required. In construction machines such as hydraulic excavators and wheel loaders, it is important to save energy in the hydraulic system for driving the machine, and various systems have been proposed so far.

As a system applicable to a hydraulic excavator, the application of a system in which a hydraulic pump and an actuator are connected without a throttle valve and the actuator is directly controlled by the discharge flow rate of the hydraulic pump is being studied. In this system, since the pump discharges only the flow rate required by the actuator, there is no loss due to shunt flow, and energy saving can be expected.

The system described in Patent Document 1 has been proposed by the inventors as an example of application to a hydraulic excavator. This is a hydraulic circuit in which a plurality of hydraulic pumps and a plurality of actuators can be connected via a valve, and it is possible to continue the work even if one of the hydraulic pumps fails.

Japanese Unexamined Patent Publication No. 2014-205977

The inventors examined the system when the pump failed as in the above-mentioned known example, but further researched the system which enables the continuation of work while suppressing the deterioration of operability even when the valve fails. Invented this time.

Explain the possible inconveniences when a valve fails. Now, the hydraulic valve Vij on the flow path connecting a certain pump Pi (i = 1,2, ..., number of pumps) and a certain actuator Aj (j = 1,2, ..., number of actuators) keeps opening due to a failure ( If the pump Pi is connected to another actuator Ak (k ≠ j) by opening the valve Vik, the actuator Aj and the actuator Ak will be connected via the valve Vij and the valve Vik. Control of the two actuators is lost.

Further, when the valve Vij on the flow path connecting a certain pump Pi and a certain actuator Aj is kept closed (closed and fixed) due to a failure, oil cannot be supplied from the pump Pi to the actuator Aj. As a result, the actuator Aj may not operate as intended by the operator, and the operability may be significantly impaired.

The present invention has been made in view of the above problems, and an object thereof is to be able to continue the work even if any of the plurality of valves connecting the plurality of closed circuit pumps and the plurality of actuators fails. It is to provide construction machinery.

In order to achieve the above object, the present invention comprises a plurality of closed circuit pumps, a plurality of actuators connected to the plurality of closed circuit pumps, and communication between the plurality of closed circuit pumps and the plurality of actuators. It is provided with a plurality of valves for switching between shutoff, an operation lever for operating the plurality of actuators, and a controller for outputting an open / close command for the plurality of valves in response to an operation signal input from the operation lever. In a construction machine, the controller determines the failure state of the plurality of valves and connects one of the plurality of closed circuit pumps to the closed circuit pump and one of the plurality of actuators. When it is determined that one of the plurality of valves is in a failed state, the open command is not output to the valves other than the one valve connected to the one closed circuit pump. The opening / closing commands of multiple valves shall be corrected.

According to the present invention configured as described above, even if one of a plurality of valves fails, two or more actuators among the plurality of actuators are simultaneously connected to one closed circuit pump. Since there is no such thing, it is possible to prevent each of the plurality of actuators from operating against the intention of the operator. This makes it possible to continue the work even if any of the plurality of valves fails.

According to the construction machine according to the present invention, it is possible to continue the work even if any of the plurality of valves connecting the plurality of closed circuit pumps and the plurality of actuators fails.

It is a side view of the hydraulic excavator which concerns on 1st Embodiment of this invention. It is a schematic block diagram of the hydraulic drive system in 1st Embodiment of this invention. It is a figure which shows the relationship between the lever operation amount and the actuator required flow rate in 1st Embodiment of this invention. It is a figure which shows an example of the priority connection table in 1st Embodiment of this invention. It is a functional block diagram of the controller shown in FIG. It is a flowchart which shows the process of 1 control cycle of the valve failure determination part shown in FIG. It is a flowchart which shows the process of 1 control cycle of the valve pump command correction part shown in FIG. It is a figure which shows an example of the priority connection table when a valve is open-fixed in the 1st Embodiment of this invention. It is a figure which shows an example of the priority connection table when a valve is closed and fixed in the 1st Embodiment of this invention. It is a schematic block diagram of the hydraulic drive system in 2nd Embodiment of this invention. It is a figure which shows the relationship between the lever operation amount and the actuator required flow rate in the 2nd Embodiment of this invention. It is a figure which shows an example of the priority connection table in the 2nd Embodiment of this invention. It is a figure which shows an example of the priority connection table when a valve is open-fixed in the 2nd Embodiment of this invention. It is a figure which shows an example of the priority connection table when a valve is closed and fixed in the 2nd Embodiment of this invention.

Hereinafter, a hydraulic excavator will be taken as an example as a construction machine according to an embodiment of the present invention, and will be described with reference to the drawings. In each figure, the same members are designated by the same reference numerals, and duplicated description will be omitted as appropriate.

FIG. 1 is a side view of a hydraulic excavator according to the first embodiment of the present invention.

As shown in FIG. 1, the hydraulic excavator 100 includes a lower traveling body 101 equipped with a crawler-type traveling device 101a and an upper rotating body 102 rotatably mounted on the lower traveling body 101 via a turning device 102a. A front device 103 that is rotatably attached to the front portion of the upper swing body 102 in the vertical direction is provided. The traveling device 101a is driven by the traveling motor 8, and the swivel device 102a is driven by the swivel motor 7. On the left side of the front part of the upper swivel body 102, a cab 104 on which the operator is boarded is provided.

The front device 103 includes a boom 2 rotatably attached to the front portion of the upper swing body 102 in the vertical direction, an arm 4 rotatably attached to the tip portion of the boom 2 in the vertical direction or a front-rear direction, and an arm. A bucket 6 rotatably attached to the tip of 4 in the up-down or front-back direction, a boom cylinder 1 for driving the boom 2, an arm cylinder 3 for driving the arm 4, and a bucket cylinder 5 for driving the bucket 6. Has.

FIG. 2 is a schematic configuration diagram of a hydraulic drive system mounted on the hydraulic excavator 100 shown in FIG.

The closed circuit pumps P1 and P2, which are bi-tilt variable capacity pumps, and the charge pump 21, which is a one-side tilt fixed capacity pump, are driven by a prime mover (not shown).

The closed circuit pumps P1 and P2 are connected via valves V11, V12, V21, and V22 so as to suck oil from one of the head chambers or rod chambers of the hydraulic cylinders A1 and A2 and discharge the oil to the other, and connect each cylinder and the closed circuit. Configure. In FIG. 2, the actuator A1 is, for example, a boom cylinder 1, the actuator A2 is, for example, an arm cylinder 3, and other parts related to driving the actuator are omitted.

The charge pump 21 sucks oil from the tank 22 and replenishes each closed circuit with oil via the make-up valves 23a to 23d. The flushing valves 24a and 24b discharge excess oil in the closed circuit generated by the difference in pressure receiving area between the head chamber and the rod chamber of the cylinder to the charge circuit 40. The main relief valves 25a to 25d set the maximum pressure of the closed circuit, and the charge relief valve 26 sets the maximum pressure of the charge circuit 40.

The controller 50 is based on the pressure information of the pressure sensors 27a to 27d and 28a to 28d and the operation amount information of the operation lever 31 installed in the cab 104, and discharge flow rate commands of the closed circuit pumps P1 and P2, valves V11 and V12. , V21, V22 open / close command.

Next, an operation example will be described. The valve / pump command calculation unit 51 of the controller 50 calculates an open / close command to the valve and a discharge flow rate command to the pump with respect to the operation amount of the operation lever 31.

The valve / pump command calculation unit 51 first calculates the required flow rate of each actuator by using the correspondence between the lever operation amount and the required flow rate shown in FIG. For example, when only the operation lever 31 corresponding to the actuator A1 is operated by 80% of the maximum operation amount, the required flow rate of the actuator A1 is calculated as 1.6 due to the relationship determined from the graph 41. This means that the actuator A1 requires the flow rate of 1.6 pumps having the maximum flow rate.

For the required flow rate determined in this way, commands to valves and pumps are specifically calculated using, for example, the rules shown in Table 60 of FIG. Table 60 is a priority connection table that defines the priority order when connecting the closed circuit pumps P1 and P2 to the actuators A1 and A2, and the connection with the smaller number is given higher priority. In the previous example, the required flow rate of the actuator A1 was 1.6, so two pumps are required. Therefore, the controller issues a valve opening command to the valves V11 and V12, and a discharge flow rate command of 1.0 to the pump P1 and 0.6 to the pump P2, respectively.

Here, it is assumed that the operating lever 31 corresponding to the actuator A2 is operated by 20% while maintaining the operating amount of the actuator A1 by 80%. At this time, the required flow rate of the actuator A1 is 1.6 from the graph 41 of FIG. 3, and the required flow rate of the actuator A2 is 0.4 from the graph 42. Therefore, the actuator A1 requires two pumps and the actuator A2 requires one. do. Therefore, from Table 60 , the actuator A1 requests the use of the pump P1 (rank 1) and the pump P2 (rank 2), and the actuator A2 requests the use of the pump P2 (rank 1). Here, since the pump P2 is required for two or more actuators, adjustment is performed according to the order. That is, since the rank of the actuator A2 is 1 from the viewpoint of the pump P2 and is smaller than the rank 2 of the actuator A1, the pump P2 is preferentially connected to the actuator A2. Therefore, the controller issues a valve opening command to the valves V11 and V22, and a discharge flow rate command of 1.0 to the pump P1 and 0.4 to the pump P2, respectively.

FIG. 5 is a functional block diagram of the controller 50.

In parallel with the processing of the valve / pump command calculation unit 51 described above, the controller 50 determines the failure of each valve and classifies the failure state by the valve failure determination unit 52. In the judgment, the information on the opening / closing command to the valve and the information on the pressure sensor are used. For example, if there is no pressure difference between the front and rear of a valve even though the valve has not been commanded to open, that is, the valve is closed, it is determined that the valve is a failure that remains open (open sticking failure). .. Further, if there is a pressure difference before and after the valve even though the valve opening command is issued, it is determined that the valve is a failure of keeping it closed (closed and stuck failure).

FIG. 6 is a flowchart showing the processing of one control cycle of the valve failure determination unit 52.

The valve failure determination unit 52, first, in step S11, determines whether or not the pump Pi and the actuator Aj are connected via the valve Vij. If YES is determined in step S21, the process proceeds to step S22, and if NO is determined, the flow ends.

In step S12, it is determined whether or not an open command is output to the valve Vij. If YES is determined in step S12, the process proceeds to step S13, and if NO is determined, the process proceeds to step S16.

In step S13, it is determined whether or not the pump Pi is discharging. If YES is determined in step S13, the process proceeds to step S14, and if NO is determined, the flow is terminated.

In step S14, it is determined whether or not the discharge pressure of the pump Pi is equal to the relief pressure (there is a pressure difference before and after the valve Vij). If YES is determined in step S14, the process proceeds to step S15, and if NO is determined, the flow is terminated.

In step S15, it is determined that the valve Vij is closed and stuck, and the flow is terminated.

In step S16, it is determined whether or not the discharge pressure of the pump Pi is equal to the pressure of the actuator Aj (there is no pressure difference before and after the valve Vij). If YES is determined in step S16, the process proceeds to step S17, and if NO is determined, the flow is terminated.

In step S17, it is determined that the valve Vij is open and stuck, and the flow is terminated.

Returning to FIG. 5, the valve / pump command correction unit 53 uses the valve / pump command information calculated by the valve / pump command calculation unit 51 based on the valve failure information determined and classified by the valve failure determination unit 52. to correct.

FIG. 7 is a flowchart showing the processing of the valve / pump command correction unit 53. The flow shown in FIG. 7 is executed every control cycle for all combinations of the pump Pi (i = 1, 2, ..., M) and the actuator Aj (j = 1, 2, ..., N). Here, M is the number of pumps and N is the number of actuators.

First, in step S21, the valve / pump command correction unit 53 determines whether or not the pump Pi and the actuator Aj are connected via the valve Vij. If YES is determined in step S21, the process proceeds to step S22, and if NO is determined, the flow ends.

In step S22, it is determined whether or not the valve Vij is out of order. If YES is determined in step S22, the process proceeds to step S23, and if NO is determined, the flow ends.

In step S23, it is determined whether or not there is an instruction to shift to the degenerate operation mode. The instruction to shift to the degenerate operation mode is given by operating the input means (for example, the switch 32) in the cab 104. If YES is determined in step S23, the process proceeds to step S24, and if NO is determined, the flow is terminated.

In step S24, it is determined whether or not the valve Vij has an open sticking failure. If YES is determined in step S4, the process proceeds to step S25, and if NO is determined, the process proceeds to step S26.

In step S25, the correction process at the time of open sticking is executed. Specifically, the command to the valve and the pump is corrected so that the pump Pi is connected only to the actuator Aj. The details of the correction process at the time of open sticking will be described later.

In step S26, it is determined whether or not the valve Vij is closed and stuck. If YES is determined in step S26, the process proceeds to step S27, and if NO is determined, the flow is terminated.

In step S27, the correction process at the time of closing and sticking is executed. Specifically, the command to the valve and the pump is corrected so that the pump Pi is connected only to the actuator other than the actuator Aj. The details of the correction process at the time of closing failure will be described later.

The valve failure determination unit 52 may be any as long as it classifies the failure information as an open sticking failure or a closed sticking failure and outputs the failure information, and the valve failure determination unit 52 is not limited to the one using the above-mentioned pressure information. For example, the displacement of the displacement sensor valve may be directly measured and determined, or the passing flow rate of the valve may be measured and determined by the flow rate sensor.

<Operation example 1-1>
In FIG. 2, the operation when the valve V12 connecting the pump P1 and the actuator A2 is open-fixed will be described.

The processing flow of the valve / pump command correction unit 53 in this case will be described with reference to FIG. 7 . After it is determined in step S21 that the pump P1 and the actuator A2 are connected via the valve V12 (YES), the valve Vij is determined to be faulty (YES) in step S22. After it is determined in step S23 that there is a degenerate operation transition instruction (YES), it is determined in step S24 that the valve Vij is open-fixed (YES). In the following step S25, the command to the valve and the pump is corrected so that the pump P1 is connected only to the actuator A2.

The correction of this command is performed, for example, by changing the priority connection table, and in this embodiment, the table 60 shown in FIG. 4 is changed to the table 61 shown in FIG. The table in Table 61 shows that the pump P1 is not connected to the actuator A1. Therefore, the valve V11 on the flow path connecting the pump P1 and the actuator A1 does not open. Therefore, since the pump P1 is not connected to both the actuators A1 and A2 at the same time, the actuator A1 and the actuator A2 are not connected via the valve V11 and the valve V12. Therefore, the work can be continued even after the open sticking failure.

<Operation example 1-2>
In FIG. 2, the operation when the valve V12 connecting the pump P1 and the actuator A2 is open-fixed will be described.

The processing flow of the valve / pump command correction unit 53 in this case will be described with reference to FIG. After it is determined in step S21 that the pump P1 and the actuator A2 are connected via the valve V12 (YES), the valve Vij is determined to be faulty (YES) in step S22. After it is determined in step S23 that there is a degenerate operation transition instruction (YES), it is determined in step S24 that the valve Vij is not open-fixed (NO), and in step S26 it is determined that Vij is a closed failure (YES). In the subsequent step S27, the command to the valve and the pump is corrected so that the pump P1 is connected only to the actuator A1 other than the actuator A2.

The correction of this command is performed, for example, by changing the priority connection table. Specifically, the priority connection table is changed from Table 60 shown in FIG. 4 to Table 62 shown in FIG. The table in Table 62 shows that the pump P1 is not connected to the actuator A2. As a result, the valve V12 on the flow path connecting the pump P1 and the actuator A2 does not open. Therefore, since the discharge flow rate of the pump P1 is not unintentionally closed by the valve V12, the flow rate according to the lever operation amount can be continuously supplied to the actuator A2 even after the valve V12 is closed and fixed, and the operation can be performed. It is possible to suppress the deterioration of sex.

In this embodiment, a plurality of closed circuit pumps P1 and P2, a plurality of actuators A1 and A2 connected to the plurality of closed circuit pumps P1 and P2, and a plurality of closed circuit pumps P1 and P2 and a plurality of actuators A1 and 1. A plurality of valves V11, V12, V21, V22 for switching between communication and disconnection with A2, an operation lever 31 for operating a plurality of actuators A1 and A2, and an operation signal input from the operation lever 31. In the construction machine 100 including the controller 50 that outputs the open / close command of the plurality of valves V11, V12, V21, V22, the controller 50 determines the failure state of the plurality of valves V11, V12, V21, V22, and a plurality of valves V11, V12, V21, and V22. One of a plurality of valves V11, V12, V21, V22 connecting the closed circuit pump Pi of the closed circuit pumps P1 and P2 and the actuator Aj of the plurality of actuators A1 and A2. When it is determined that the Pij is in a failed state, a plurality of valves V11, V12, so that an open command is not output to a valve Vij (j ≠ k) other than the valve Vij connected to the closed circuit pump Pi. Correct the open / close command of V21 and V22.

According to the present embodiment configured as described above, even if one of the plurality of valves V11, V12, V21, and V22 fails, two or more actuators among the plurality of actuators A1 and A2 are used. Since Aj and Ak (j ≠ k) are not connected to one closed circuit pump Pi at the same time, it is possible to prevent each of the plurality of actuators A1 and A2 from operating against the intention of the operator. This makes it possible to continue the work even if any of the plurality of valves V11, V12, V21, and V22 fails.

Further, the controller 50 has a plurality of valves V11, V12, V21, so that the controller 50 does not output an open command to the one valve Vij when the failure state of the one valve Vij is closed and fixed. Correct the open / close command of V22. As a result, when the valve Vij is open-fixed, the closed circuit pump Pk (k ≠ i) other than the closed circuit pump Pi is connected to the actuator Aj, so that the actuator Aj is operated as intended by the operator. Is possible.

Further, the controller 50 has a priority connection table 60 that defines the connection order of the plurality of closed circuit pumps P1 and P2 for the plurality of actuators A1 and A2, and by changing the priority connection table 60, the plurality of valves V11 and V12. , V21, V22 open / close command is corrected. As a result, when one of the plurality of valves V11, V12, V21, V22 fails, the plurality of valves V11, V12, V21, can be changed by changing the priority connection table 60 which has been widely used conventionally. It is possible to correct the open / close command of V22.

The hydraulic excavator 100 according to the second embodiment of the present invention will be described focusing on the differences from the first embodiment.

FIG. 10 is a schematic configuration diagram of the hydraulic drive system in this embodiment. In the first embodiment, the hydraulic circuit configuration has been described as a 2-pump-2 actuator, but in this embodiment, the hydraulic circuit configuration will be extended to a 4-pump-4 actuator.

In FIG. 10, the closed circuit pumps P1 to P4, which are bi-tilt variable capacity pumps, and the charge pump 21, which is a one-side tilt fixed capacity pump, are driven by a prime mover (not shown).

The closed circuit pumps P1 to P4 are connected to suck oil from one of the actuators A1 to A4 and discharge it to the other via valves V11 to V14, V21 to V24, V31 to 34, and V41 to 44, and are connected to each actuator and a closed circuit. To configure. In FIG. 10, the actuator A1 is, for example, a boom cylinder 1, the actuator A2 is, for example, an arm cylinder 3, the actuator A3 is, for example, a bucket cylinder 5, the actuator A4 is, for example, a swivel motor 7, and other actuators. The part related to driving is omitted.

The charge pump 21 sucks oil from the tank 22 and replenishes each closed circuit with oil via the make-up valves 23a to 23h. The flushing valves 24a to 24d discharge excess oil on the low pressure side of the closed circuit to the charge circuit 40. The main relief valves 25a to 25h set the maximum pressure of each closed circuit.

The controller 50 is based on the pressure information of the pressure sensors 27a to 27h and 28a to 28h and the operation amount information of the operation lever 31, the discharge flow rate command of the closed circuit pumps P1 to P4, the valves V11 to V14, V21 to V24, V31 to. 34, V41 to 44 are commanded to open and close.

In this hydraulic circuit configuration, the valve / pump command calculation unit 51 of the controller 50 performs calculations using, for example, the relationships shown in FIGS. 11 and 12. Graphs 71 to 74 of FIG. 11 are graphs showing the correspondence between the operation amount and the required flow rate, and each actuator requires four pumps having a maximum discharge flow rate with a lever operation amount of 100%. Table 80 of FIG. 12 is a priority connection table in this configuration, and has the same function as Table 60 of FIG.

<Operation example 2-1>
In FIG. 10, the operation when the valve V12 connecting the pump P1 and the actuator A2 is open-fixed will be described.

In this case, the valve / pump command correction unit 53 corrects the command to the valve and the pump so that the pump P1 is not connected to the actuator A1 other than the actuator A2 in step S25 of FIG. 6, as in the first embodiment. ..

The correction of this command is performed, for example, by changing the priority connection table. Specifically, the priority connection table is changed from Table 80 shown in FIG. 12 to Table 81 shown in FIG. The table in Table 81 shows that the pump P1 is connected only to the actuator A2 and not to any of the actuators A1, A3 and A4. As a result, the pump P1 is always connected only to the actuator A2, so that it is not connected to two or more actuators at the same time. Therefore, the actuator A2 and the other actuator A1 are not connected, and the work can be continued even after the open sticking failure.

<Operation example 2-2>
In FIG. 10, the operation when the valve V12 connecting the pump P1 and the actuator A2 is closed and fixed will be described.

In this case, the valve / pump command correction unit 53 corrects the command to the valve and the pump so that the pump P1 is connected only to the actuator A2 in step S27 of FIG. 6, as in the second embodiment. Specifically, the priority connection table is changed from Table 80 shown in FIG. 12 to Table 82 shown in FIG. The table in Table 82 shows that the pump P1 is connected only to any of the actuators A1, A3, A4 and not to the actuator A2. Therefore, since the discharge flow rate of the pump P1 is not unintentionally closed by the valve V12, the flow rate according to the lever operation amount can be continuously supplied to the actuator A2 even after the valve V12 is closed and fixed, and the operation can be performed. It is possible to suppress the deterioration of sex.

Although the examples of the present invention have been described in detail above, the present invention is not limited to the above-mentioned examples, and includes, for example, the following modifications.

The valve / pump command calculation unit 51 may calculate the valve open / close command and the pump discharge flow rate command from the operation amount input of the operation lever 31, and is not limited to the method using the priority connection table. For example, it is possible to perform an operation such that the pumps that are vacant each time are randomly used without using the priority connection table.

Further, in the above-described embodiment, the actuator is driven by using only the closed circuit pump, but the present invention is not limited to this, and all of them are configured as an open circuit pump configuration or a configuration in which a closed circuit pump and an open circuit pump are mixed. May be good. In that case, a directional control valve for switching the direction of the discharge flow rate of the open circuit pump is required separately.

Further, the number of pumps and the number of actuators are not limited to those of the above-described embodiment. For example, the number of pumps may be 3 and the number of actuators may be 4, or the number of pumps may be 4 and the number of actuators may be 2.

1 ... Boom cylinder, 2 ... Boom, 3 ... Arm cylinder, 4 ... Arm, 5 ... Bucket cylinder, 6 ... Bucket, 7 ... Swing motor, 8 ... Travel motor, 21 ... Charge pump, 22 ... Tank, 23a-23h ... Makeup valve, 24a to 24d ... Flushing valve, 25a to 25h ... Main relief valve, 26 ... Charge relief valve, 27a to 27h, 28a to 28h ... Pressure sensor, 30 ... Charge circuit, 31 ... Operation lever, 32 ... Switch, 41, 42 ... Graph, 50 ... Controller, 51 ... Valve / pump command calculation unit, 52 ... Valve failure determination unit, 53 ... Valve / pump command correction unit, 60-62 ... Priority connection table, 71-74 ... Graph, 80 ~ 82 ... Priority connection table, 100 ... hydraulic excavator (construction machine), 101 ... lower traveling body, 102 ... upper swivel body, 103 ... front device, 104 ... cab, A1 to A4 ... actuator, P1 to P4 ... closed circuit pump , V11 to V14, V21 to V24, V31 to V34, V41 to V44 ... Valve, W1 to W8, X1 to X8 ... Pressure signal, Y11 to Y14, Y21 to Y24, Y31 to Y34, Y41 to Y44 ... Open / close command signal, Z1 to Z4 ... Discharge flow command signal.

Claims (3)

With multiple closed circuit pumps,
A plurality of actuators connected to the plurality of closed circuit pumps, respectively,
A plurality of valves for switching communication and disconnection between the plurality of closed circuit pumps and the plurality of actuators,
An operation lever for operating the plurality of actuators and
In a construction machine provided with a controller that outputs an open / close command for a plurality of valves in response to an operation signal input from the operation lever.
The controller
The failure state of the plurality of valves is determined, and the failure state is determined.
When one of the plurality of valves connecting the closed circuit pump of the plurality of closed circuit pumps and one of the plurality of actuators is determined to be in a failed state. A construction machine characterized in that an opening / closing command of a plurality of valves is corrected so that an open command is not output to a valve other than the one valve connected to the one closed circuit pump. In the construction machine according to claim 1,
The controller is a construction machine characterized in that when the failure state of the one valve is closed and fixed, the opening / closing command of the plurality of valves is corrected so that an open command is not output to the one valve. .. In the construction machine according to claim 1,
The controller has a priority connection table that defines the connection order of the plurality of closed circuit pumps to the plurality of actuators, and is characterized in that the opening / closing command of the plurality of valves is corrected by changing the priority connection table. Construction machinery.

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