Construction machine

Abstract

The purpose of the present invention is to provide a construction machine in which, when an actuator for driving a work device is driven by configuring a closed circuit between a plurality of hydraulic pumps and the actuator, it is possible to suppress a decrease in operability when a pressure sensor for measuring the pressure of the actuator fails. Therefore, when the controller determines that the actuator pressure sensor has failed, the controller calculates a pseudo-pressure of the actuator from a measurement value of the attitude sensor, and calculates a differential pressure before and after the closed-loop switching valve using the pseudo-pressure instead of the measurement value of the actuator pressure sensor.

Description

Technical Field

[0001] The present invention relates to a construction machine having a hydraulic circuit for driving a hydraulic actuator by pressure oil discharged from a hydraulic pump. Background Art

[0002] In recent years, in order to reduce the throttling elements in the hydraulic circuit that drives the hydraulic actuator such as the hydraulic cylinder in construction machinery such as hydraulic excavators, and thus reduce the fuel consumption rate, the development of a hydraulic circuit (defined as a closed circuit) connected in the following manner is being carried out: the hydraulic oil is delivered from the hydraulic drive source such as the hydraulic pump to the hydraulic actuator, and the hydraulic oil that has been operated by the hydraulic actuator is not returned to the oil tank but to the hydraulic pump. In addition, in the excavator using the closed circuit, a structure in which a pump is connected to the head chamber side in order to compensate for the pressure area difference of the single-rod cylinder is proposed.

[0003] In these hydraulic circuits, the following structure is proposed: a structure is set to be able to redundantly connect multiple pumps to one actuator, thereby achieving a composite operation based on multiple actuators and speed improvement during individual actions. In such a hydraulic circuit where the connection destination actuator of the pump can be changed, it is necessary to switch the connection and disconnection between the pump and the actuator. At this time, if the pressure difference between the actuator and the pump is large, an impact is generated. Patent document 1 records a hydraulic drive device that connects the pump to the actuator after reducing the pressure difference between the actuator and the pump.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2015-203453 Summary of the invention

[0007] Problems to be solved by the invention

[0008] In Patent Document 1, the actuator pressure is measured by a pressure sensor, and the pump is connected to the actuator after the pump pressure is increased to the measured actuator pressure. Therefore, when the pressure sensor fails, the pump pressure is increased to a pressure different from the actual actuator pressure before the pump is connected to the actuator, thereby generating a shock when the pump is connected to the actuator, and operability may be reduced.

[0009] The present invention has been completed in view of the above-mentioned problems, and its purpose is to provide a construction machine that can suppress the reduction in operability when a pressure sensor measuring the pressure of the actuator fails when a closed circuit is formed between an actuator for driving a working device and multiple hydraulic pumps to drive the actuator.

[0010] Means for solving problems

[0011] In order to achieve the above-mentioned purpose, the engineering machinery of the present invention comprises: a working device; an actuator, which drives the working device; a plurality of variable capacity closed-circuit pumps, which have two inlet and outlet ports; a plurality of closed-circuit switching valves, which can switch the connection or disconnection between the actuator and the plurality of closed-circuit pumps; a posture sensor, which detects the posture of the working device; a plurality of closed-circuit pump pressure sensors, which detect the pressure of the plurality of closed-circuit pumps; an actuator pressure sensor, which detects the pressure of the actuator; an operating device, which indicates the action of the actuator; and a controller, which controls the plurality of closed-circuit switching valves and the plurality of closed-circuit pumps according to an input signal from the operating device, and when starting to supply working oil from one of the plurality of closed-circuit pumps to the actuator, the controller controls the one closed-circuit pump and then opens a closed-circuit switching valve corresponding to the one closed-circuit pump, so that the pressure difference before and after the closed-circuit switching valve is a specified first threshold value or less, wherein the pressure difference across the closed-loop switching valve refers to: when one of the multiple closed-loop switching valves corresponding to the one closed-loop pump is closed, the difference between the measurement value of a closed-loop pump pressure sensor corresponding to the one closed-loop pump and the measurement value of the actuator pressure sensor, wherein, when two or more closed-loop pumps among the multiple closed-loop pumps are connected to the actuator, the controller determines whether the actuator pressure sensor is faulty based on the measurement values ​​of two or more closed-loop pump pressure sensors corresponding to the two or more closed-loop pumps among the multiple closed-loop pump pressure sensors and the measurement value of the actuator pressure sensor, and when the controller determines that the actuator pressure sensor is faulty, the controller calculates the pseudo pressure of the actuator based on the measurement value of the posture sensor, and calculates the pressure difference across the closed-loop switching valve using the pseudo pressure instead of the measurement value of the actuator pressure sensor.

[0012] According to the present invention configured as described above, the failure of the actuator pressure sensor can be correctly determined based on the comparison result of the measured value of the actuator pressure sensor and the measured values ​​of two or more closed-circuit pump pressure sensors. In addition, when the actuator pressure sensor fails, the front-rear pressure difference of the closed-circuit switching valve is calculated using the pseudo pressure of the actuator calculated based on the posture of the working device instead of the measured value of the failed pressure sensor. As a result, the impact when the closed-circuit pump is connected to the actuator is suppressed, so that the operability can be prevented from being reduced.

[0013] Effects of the Invention

[0014] According to the construction machine of the present invention, it is possible to suppress a decrease in operability when a pressure sensor that measures the pressure of an actuator driving a working device fails. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a side view of the hydraulic excavator in the embodiment of the present invention.

[0016] Figure 2 This is a hydraulic circuit diagram of a hydraulic drive system mounted on a hydraulic excavator according to an embodiment of the present invention.

[0017] Figure 3 This is a functional block diagram of a controller in an embodiment of the present invention.

[0018] Figure 4 This is a timing chart showing the state change of the hydraulic drive device when the boom cylinder in the embodiment of the present invention is extended.

[0019] Figure 5 This is a flowchart showing a part of the processing of the pressure sensor failure detection unit in the embodiment of the present invention.

[0020] Figure 6 It is a diagram showing a change in the posture of the hydraulic excavator when the arm cylinder in the embodiment of the present invention is extended.

[0021] Figure 7 It is a diagram showing the relationship between the stroke of the arm cylinder and the pressure in the head chamber in the embodiment of the present invention.

[0022] Figure 8 Detailed Description of the Invention This is a flowchart showing the processing of the pressure sensor failure diagnosis input generating unit in the embodiment of the present invention.

[0023] Fig. 9 This is a timing chart showing the state change of the hydraulic drive system corresponding to the input of the pressure sensor failure diagnosis input generating device in the embodiment of the present invention. DETAILED DESCRIPTION

[0024] Hereinafter, as the construction machine of the present invention, a hydraulic excavator is taken as an example and described with reference to the accompanying drawings. In addition, in each figure, the same reference numerals are attached to the same components, and repeated descriptions are appropriately omitted.

[0025] Figure 1 is a side view of the hydraulic excavator in this embodiment, Figure 2 This is a hydraulic circuit diagram of a hydraulic drive system mounted on the hydraulic excavator in this embodiment.

[0026] like Figure 1As shown in FIG. 1 , the hydraulic excavator 100 comprises: a lower traveling body 102 having crawler-type traveling devices 101a and 101b on both sides in the left and right directions; and an upper revolving body 103 which is mounted on the lower traveling body 102 in a revolving manner. A cab 104 for an operator to ride in is provided on the upper revolving body 103. The upper revolving body 103 is mounted on the lower traveling body 102 via a revolving device 105 in a revolving manner. The traveling devices 101a and 101b are driven by traveling motors 8a and 8b ( Figure 2 As shown), the rotary device 105 is driven by a rotary motor 7 ( Figure 2 shown) drive.

[0027] The base end of a front working machine 106, which is a working device for performing excavation work, is mounted on the front side of the upper rotating body 103 in a manner that allows it to rotate in the up-down direction. The front working machine 106 has a boom 2 whose base end is connected to the front side of the upper rotating body 103 in a manner that allows it to rotate in the up-down direction. The boom 2 is operated by a boom cylinder 1, which is a single-rod hydraulic cylinder driven by working oil (pressure oil) as a supplied fluid. The front end of the rod 1c of the boom cylinder 1 is connected to the upper rotating body 103, and the base end of the cylinder 1d is connected to the boom 2.

[0028] like Figure 2 As shown, the boom cylinder 1 has a head chamber 1a, which is a first working oil chamber on the head side, located at the base end side of the cylinder tube 1d and to which a load based on the working oil pressure is applied by pressing a piston 1e attached to the base end of a rod 1c when the working oil is supplied, thereby extending and moving the rod 1c. In addition, the boom cylinder 1 has a rod chamber 1b, which is a second working oil chamber on the rod side, located at the front end side of the cylinder tube 1d and to which a load based on the working oil pressure is applied by pressing the piston 1e when the working oil is supplied, thereby retracting and moving the rod 1c.

[0029] return Figure 1 The front end of the boom 2 is connected to the base end of the boom 4 in a manner that allows pitching motion. The boom 4 is moved by the boom cylinder 3, which is a single-rod hydraulic cylinder. The front end of the rod 3c of the boom cylinder 3 is connected to the boom 4, and the cylinder 3d of the boom cylinder 3 is connected to the boom 2.

[0030] like Figure 2 As shown, the boom cylinder 3 has a cap chamber 3a, which is located at the base end side of the cylinder tube 3d and is supplied with hydraulic oil to press the piston 3e installed at the base end of the rod 3c, so that the rod 3c is extended and moved. In addition, the boom cylinder 3 has a rod chamber 3b, which is located at the front end side of the cylinder tube 3d and is supplied with hydraulic oil to press the piston 3e, so that the rod 3c is retracted and moved.

[0031] return Figure 1The front end of the boom 4 is connected to the base end of the bucket 6 in a manner that allows pitching motion. The bucket 6 is moved by the bucket cylinder 5, which is a single-rod hydraulic cylinder of a hydraulic actuator driven by supplied hydraulic oil. The front end of the rod 5c of the bucket cylinder 5 is connected to the bucket 6, and the base end of the cylinder 5d of the bucket cylinder 5 is connected to the boom 4.

[0032] like Figure 2 As shown, the bucket cylinder 5 has a cap chamber 5a, which is located at the base end side of the cylinder tube 5d and presses the piston 5e attached to the base end of the rod 5c by supplying hydraulic oil, so that the rod 5c is extended and moved. In addition, the bucket cylinder 5 has a rod chamber 5b, which is located at the front end side of the cylinder tube 5d and presses the piston 5e by supplying hydraulic oil, so that the rod 5c is retracted and moved.

[0033] In addition, the boom cylinder 1, the arm cylinder 3 and the bucket cylinder 5 are respectively extended and retracted by the supplied working oil, and are extended and retracted according to the supply direction of the supplied working oil. The hydraulic excavator 100 in this embodiment is a backhoe excavator, which is configured to pull the bucket 6 back to the rear by extending the arm cylinder 3 or the bucket cylinder 5.

[0034] The boom 2 is provided with a posture sensor 400 capable of measuring a posture angle. The arm 4 is provided with a posture sensor 401 capable of measuring a posture angle. The bucket 6 is provided with a posture sensor 402 capable of measuring a posture angle. The upper rotating body 103 is provided with a posture sensor 403 capable of measuring a rotation angle and a posture of the upper rotating body. The posture sensor 403 can also measure the posture angle of the upper rotating body 103 when the vehicle is parked on a slope.

[0035] like Figure 2 As shown, for three types of single-rod hydraulic cylinders and three types of hydraulic motors, the hydraulic drive device 107 has four closed-loop pumps connected in a closed loop and four open-loop pumps connected in an open loop. When driving the single-rod hydraulic cylinder, one closed-loop pump and one open-loop pump are combined to control the flow rate. In addition, a switching valve is provided in each of these hydraulic pumps, so that multiple closed-loop pumps and multiple open-loop pumps can merge with respect to one single-rod hydraulic cylinder. And, when merging with one single-rod hydraulic cylinder, the controller controls the switching valve so that one closed-loop pump and one open-loop pump are combined to merge.

[0036] The hydraulic drive device 107 is a drive device for driving the hydraulic excavator 100, and is mounted on the upper swing body 103. The hydraulic drive device 107 is used to drive the swing motor 7 and the travel motors 8a and 8b in addition to the boom cylinder 1, the arm cylinder 3, and the bucket cylinder 5 that constitute the front working machine 106. The swing motor 7 and the travel motors 8a and 8b are hydraulic motors that are driven to rotate by receiving the supply of working oil.

[0037] In addition, the hydraulic drive device 107 drives the boom cylinder 1, the arm cylinder 3, the bucket cylinder 5, the swing motor 7, and the travel motors 8a and 8b as hydraulic actuators according to the operation of the operating device 56 installed in the cab 101. Here, the telescopic operation of the boom cylinder 1, the arm cylinder 3, and the bucket cylinder 5, that is, the operation direction and the operation speed, are indicated by the operation direction and the operation amount of each lever 56a to 56d of the operating device 56.

[0038] In addition, the hydraulic drive device 107 has an engine 9 as a power source. The engine 9 is composed of, for example, predetermined gears, and is connected to a power transmission device 10 for distributing power. The power transmission device 10 is connected to hydraulic pumps 12, 13, ..., 19 as variable flow hydraulic pumps and a supply pump 11 for replenishing pressure oil to a flow path 229 described later.

[0039] The hydraulic pumps 12, 14, 16, and 18 are variable capacity closed-circuit pumps, and include: a double deflection swash plate mechanism (not shown) having two input and output ports, i.e., a pair of inflow and outflow ports, that can allow the hydraulic oil to flow in and out in two directions; and regulators 12a, 14a, 16a, and 18a that adjust the deflection angle (inclination angle) of the double deflection swash plate constituting the double deflection swash plate mechanism. The regulators 12a, 14a, 16a, and 18a adjust the deflection angle of the swash plate of the corresponding closed-circuit pump 12, 14, 16, and 18 in accordance with an operation signal output from the controller 57, and control the flow rate of the hydraulic oil discharged from the closed-circuit pump 12, 14, 16, and 18. In addition, the closed-circuit pumps 12, 14, 16, and 18 function as hydraulic motors when receiving the supply of hydraulic oil.

[0040] Furthermore, the hydraulic pumps 13, 15, 17, and 19 are variable capacity open circuit pumps, and include: a single deflection swash plate mechanism (not shown) having an outflow port that allows the working oil to flow in and out in one direction; and regulators 13a, 15a, 17a, and 19a that adjust the deflection angle (inclination angle) of the single deflection swash plate constituting the single deflection swash plate mechanism. The regulators 13a, 15a, 17a, and 19a adjust the deflection angle of the swash plate of the corresponding open circuit pumps 13, 15, 17, and 19 according to an operation signal output from the controller 57, thereby controlling the flow rate of the working oil discharged from the open circuit pumps 13, 15, 17, and 19.

[0041] Furthermore, the deflection swash plate mechanism of the hydraulic pumps 12, 13, ..., 19 has a unit (not shown) for detecting a deflection angle, which will be described later. Figure 4 In the timing chart shown, the discharge flow rate can be used as the switching timing of the switching valve when triggering. Alternatively, a unit for measuring the control pressure of the regulator of the hydraulic pumps 12, 13, ..., 19 can be provided to calculate the deflection state of the swash plate and the discharge flow rate of each pump based on the regulator control pressure.

[0042] In addition, the closed-circuit pumps 12, 14, 16, and 18 are configured to generate driving forces based on the regulator in two directions, i.e., the direction in which the deflection angle is set to the maximum angle and the direction in which the deflection angle is set to the minimum angle, in order to control the deflection angle of the swash plate in two directions. In contrast, the open-circuit pumps 13, 15, 17, and 19 are configured to generate driving forces based on the regulator in two directions, i.e., the direction in which the deflection angle is set to the maximum angle, and the return to the minimum angle depends on the restoring force of the spring. Therefore, the closed-circuit pumps 12, 14, 16, and 18 have high responsiveness when controlling the deflection angle in the direction in which the discharge amount is reduced.

[0043] Specifically, the flow path 200 is connected to one input / output port of the first closed-loop pump 12, and the flow path 201 is connected to the other input / output port. A plurality of, for example, four, switching valves 43a, 43b, 43c, and 43d are connected to the flow paths 200 and 201. The switching valves 43a, 43b, and 43c are closed-loop switching valves for switching the supply of hydraulic oil to the boom cylinder 1, the arm cylinder 3, and the bucket cylinder 5 connected in a closed-loop manner to the first closed-loop pump 12. In addition, the switching valve 43d is a closed-loop switching valve for a hydraulic motor for switching the supply of hydraulic oil to the swing motor 7 connected in a closed-loop manner to the first closed-loop pump 12. Furthermore, the switching valves 43a, 43b, 43c, and 43d are configured to switch the conduction and cutoff of the flow paths 200 and 201 according to the operation signal output from the controller 57, and are in a cutoff state when there is no output of the operation signal from the controller 57. The controller 57 controls the switching valves 43a, 43b, 43c, and 43d so as not to be in the on state at the same time.

[0044] Furthermore, the switching valve 43a is connected to the boom cylinder 1 via the flow paths 212 and 213. Thus, when the switching valve 43a is turned on in accordance with an operation signal output from the controller 57, the first closed circuit pump 12 forms a closed circuit A connected to the boom cylinder 1 in a closed circuit state via the flow paths 200 and 201, the switching valve 43a, and the flow paths 212 and 213.

[0045] In addition, the switching valve 43b is connected to the boom cylinder 3 via the flow paths 214 and 215. Therefore, when the switching valve 43b is turned on according to the operation signal output from the controller 57, the first closed-loop pump 12 forms a closed loop B connected to the boom cylinder 3 in a closed-loop manner via the flow paths 200 and 201, the switching valve 43b and the flow paths 214 and 215.

[0046] Furthermore, the switching valve 43c is connected to the bucket cylinder 5 via the flow paths 216 and 217. Therefore, when the switching valve 43c is turned on by an operation signal from the controller 57, the first closed-circuit pump 12 forms a closed-circuit C connected to the bucket cylinder 5 in a closed-circuit state via the flow paths 200 and 201, the switching valve 43c, and the flow paths 216 and 217.

[0047] In addition, the switching valve 43d is connected to the rotary motor 7 via the flow paths 218 and 219. Therefore, when the switching valve 43d is turned on by an operation signal from the controller 57, the first closed-circuit pump 12 forms a closed-circuit D connected to the rotary motor 7 via the flow paths 200 and 201, the switching valve 43d, and the flow paths 218 and 219.

[0048] Here, the flow path 212 is also a hydraulic cylinder connection flow path for independently connecting the boom cylinder 1 to a plurality of switching valves 44a, 46a, 48a, and 50a of the open circuits E, F, G, and H described later. In addition, the flow path 214 is also a hydraulic cylinder connection flow path for independently connecting the arm cylinder 3 to a plurality of switching valves 44b, 46b, 48b, and 50b of the open circuits E, F, G, and H described later. Furthermore, the flow path 216 is also a hydraulic cylinder connection flow path for independently connecting the bucket cylinder 5 to a plurality of switching valves 44c, 46c, 48c, and 50c of the open circuits E, F, G, and H described later.

[0049] In addition, a flow path 203 is connected to one input / output port of the second closed-loop pump 14, and a flow path 204 is connected to the other input / output port. A plurality of, for example, four, switching valves 45a, 45b, 45c, and 45d are connected to the flow paths 203 and 204. The switching valves 45a, 45b, and 45c are closed-loop switching valves for switching the supply of hydraulic oil to the boom cylinder 1, the arm cylinder 3, and the bucket cylinder 5 connected in a closed-loop manner to the second closed-loop pump 14. In addition, the switching valve 45d is a closed-loop switching valve for a hydraulic motor for switching the supply of hydraulic oil to the swing motor 7 connected in a closed-loop manner to the second closed-loop pump 14. Furthermore, the switching valves 45a, 45b, 45c, and 45d are configured to switch the conduction and cutoff of the flow paths 203 and 204 according to the operation signal output from the controller 57, and are in a cutoff state when there is no output of the operation signal from the controller 57. The controller 57 controls the switching valves 45a, 45b, 45c, and 45d so as not to be in the on state at the same time.

[0050] Furthermore, the switching valve 45a is connected to the boom cylinder 1 via the flow paths 212 and 213. Therefore, when the switching valve 45a is turned on according to the operation signal from the controller 57, the second closed-circuit pump 14 forms a closed-circuit A connected to the boom cylinder 1 in a closed-circuit manner via the flow paths 203 and 204, the switching valve 45a, and the flow paths 212 and 213. In addition, the switching valve 45b is connected to the boom cylinder 3 via the flow paths 214 and 215. Therefore, when the switching valve 45b is turned on according to the operation signal from the controller 57, the second closed-circuit pump 14 forms a closed-circuit B connected to the boom cylinder 3 in a closed-circuit manner via the flow paths 203 and 204, the switching valve 45b, and the flow paths 214 and 215.

[0051] Furthermore, the switching valve 45c is connected to the bucket cylinder 5 via the flow paths 216 and 217. Therefore, when the switching valve 45c is turned on by the operation signal from the controller 57, the second closed-circuit pump 14 forms a closed-circuit C connected to the bucket cylinder 5 in a closed-circuit state via the flow paths 203 and 204, the switching valve 45c, and the flow paths 216 and 217. In addition, the switching valve 45d is connected to the swing motor 7 via the flow paths 218 and 219. Therefore, when the switching valve 45d is turned on by the operation signal from the controller 57, the second closed-circuit pump 14 forms a closed-circuit D connected to the swing motor 7 in a closed-circuit state via the flow paths 203 and 204, the switching valve 45d, and the flow paths 218 and 219.

[0052] Next, a flow path 206 is connected to one input / output port of the third closed-circuit pump 16, and a flow path 207 is connected to the other input / output port. A plurality of, for example, four, switching valves 47a, 47b, 47c, and 47d are connected to the flow paths 206 and 207. The switching valves 47a, 47b, and 47c are closed-circuit switching valves for switching the supply of hydraulic oil to the boom cylinder 1, the arm cylinder 3, and the bucket cylinder 5 connected in a closed-circuit manner to the third closed-circuit pump 16. In addition, the switching valve 47d is a closed-circuit switching valve for a hydraulic motor for switching the supply of hydraulic oil to the swing motor 7 connected in a closed-circuit manner to the third closed-circuit pump 16. Furthermore, the switching valves 47a, 47b, 47c, and 47d are configured to switch the conduction and cutoff of the flow paths according to an operation signal output from the controller 57, and are in a cutoff state when no operation signal is output from the controller 57. The controller 57 controls the switching valves 47a, 47b, 47c, and 47d so that they are not in a conduction state at the same time.

[0053] Furthermore, the switching valve 47a is connected to the boom cylinder 1 via the flow paths 212 and 213. Therefore, when the switching valve 47a is turned on according to the operation signal from the controller 57, the third closed-circuit pump 16 forms a closed-circuit A connected to the boom cylinder 1 in a closed-circuit manner via the flow paths 206 and 207, the switching valve 47a, and the flow paths 212 and 213. In addition, the switching valve 47b is connected to the boom cylinder 3 via the flow paths 214 and 215. Therefore, when the switching valve 47b is turned on according to the operation signal from the controller 57, the third closed-circuit pump 16 forms a closed-circuit B connected to the boom cylinder 3 in a closed-circuit manner via the flow paths 206 and 207, the switching valve 47b, and the flow paths 214 and 215.

[0054] In addition, the switching valve 47c is connected to the bucket cylinder 5 via the flow paths 216 and 217. Therefore, when the switching valve 47c is turned on by the operation signal from the controller 57, the third closed-circuit pump 16 forms a closed-circuit C connected to the bucket cylinder 5 in a closed-circuit state via the flow paths 206 and 207, the switching valve 47c, and the flow paths 216 and 217. In addition, the switching valve 47d is connected to the swing motor 7 via the flow paths 218 and 219. Therefore, when the switching valve 47d is turned on by the operation signal from the controller 57, the third closed-circuit pump 16 forms a closed-circuit D connected to the swing motor 7 in a closed-circuit state via the flow paths 206 and 207, the switching valve 47d, and the flow paths 218 and 219.

[0055] Next, a flow path 209 is connected to one input / output port of the fourth closed-loop pump 18, and a flow path 210 is connected to the other input / output port. A plurality of, for example, four, switching valves 49a, 49b, 49c, and 49d are connected to the flow paths 209 and 210. The switching valves 49a, 49b, and 49c are closed-loop switching valves for switching the supply of hydraulic oil to the boom cylinder 1, the arm cylinder 3, and the bucket cylinder 5 connected in a closed-loop manner to the fourth closed-loop pump 18. In addition, the switching valve 49d is a closed-loop switching valve for a hydraulic motor for switching the supply of hydraulic oil to the swing motor 7 connected in a closed-loop manner to the fourth closed-loop pump 18. Furthermore, the switching valves 49a, 49b, 49c, and 49d are configured to switch the conduction and cutoff of the flow path according to the operation signal output from the controller 57, and are in a cutoff state when there is no output of the operation signal from the controller 57. The controller 57 controls the switching valves 49a, 49b, 49c, and 49d so as not to be in the on state at the same time.

[0056] Furthermore, the switching valve 49a is connected to the boom cylinder 1 via the flow paths 212 and 213. Therefore, when the switching valve 49a is turned on by the operation signal from the controller 57, the fourth closed-circuit pump 18 forms a closed-circuit A connected to the boom cylinder 1 in a closed-circuit manner via the flow paths 209 and 210, the switching valve 49a, and the flow paths 212 and 213. In addition, the switching valve 49b is connected to the boom cylinder 3 via the flow paths 214 and 215. Therefore, when the switching valve 49b is turned on by the operation signal from the controller 57, the fourth closed-circuit pump 18 forms a closed-circuit B connected to the boom cylinder 3 in a closed-circuit manner via the flow paths 209 and 210, the switching valve 49b, and the flow paths 214 and 215.

[0057] Furthermore, the switching valve 49c is connected to the bucket cylinder 5 via the flow paths 216 and 217. Therefore, when the switching valve 49c is turned on by the operation signal from the controller 57, the fourth closed-circuit pump 18 forms a closed-circuit C connected to the bucket cylinder 5 in a closed-circuit state via the flow paths 209 and 210, the switching valve 49c, and the flow paths 216 and 217. In addition, the switching valve 49d is connected to the swing motor 7 via the flow paths 218 and 219. Therefore, when the switching valve 49d is turned on by the operation signal from the controller 57, the fourth closed-circuit pump 18 forms a closed-circuit D connected to the swing motor 7 in a closed-circuit state via the flow paths 209 and 210, the switching valve 49d, and the flow paths 218 and 219.

[0058] Furthermore, a plurality of, for example, four, switching valves 44a, 44b, 44c, 44d and the relief valve 21 are connected to one input / output port of the first open-circuit pump 13 via the flow path 202. The other input / output port of the first open-circuit pump 13 is connected to the hydraulic oil tank 25 to form an open circuit E. The switching valves 44a, 44b, 44c, 44d are open-circuit switching valves that switch the flow path 202 between on and off according to an operation signal output from the controller 57, and switch the supply destination of the hydraulic oil flowing out of the first open-circuit pump 13 to the later-described connecting flow paths 301, 302, 303, 304, and are set to a cut-off state when there is no output of an operation signal from the controller 57. The controller 57 controls the switching valves 44a, 44b, 44c, 44d so that they are not in an on state at the same time.

[0059] In addition, the switching valve 44a is connected to the boom cylinder 1 via the connecting flow path 301 and the flow path 212. The connecting flow path 301 is a connecting pipeline branched from the flow path 212. In addition, the switching valve 44b is connected to the boom cylinder 3 via the connecting flow path 302 and the flow path 214. The connecting flow path 302 is a connecting pipeline branched from the flow path 214. And, the switching valve 44c is connected to the bucket cylinder 5 via the connecting flow path 303 and the flow path 216. The connecting flow path 303 is a connecting pipeline branched from the flow path 216. In addition, the switching valve 44d is connected to the control valves that control the supply and discharge of the working oil to the travel motors 8a and 8b, that is, the proportional switching valves 54 and 55, via the connecting flow path 304 and the flow path 220. On the other hand, when the hydraulic oil pressure in the flow path 202 becomes equal to or higher than a predetermined pressure, the relief valve 21 releases the hydraulic oil in the flow path 202 to the hydraulic oil tank 25 to protect the flow path 202 and further protect the hydraulic drive device 107 (hydraulic circuit).

[0060] In addition, a proportional valve 64 as a flow regulating valve with pressure compensation is connected between the flow path 202 and the hydraulic oil tank 25. The proportional valve 64 is provided on a branch flow path 202a which is a pipeline branched from the flow path 202 which is a pipeline connecting the switching valves 44a, 44b, 44c, 44d and the first open circuit pump 13 and connected to the hydraulic oil tank 25. Therefore, the proportional valve 64 controls the flow rate of the hydraulic oil flowing from the flow path 202 to the hydraulic oil tank 25 according to the operation signal output from the controller 57. In addition, the proportional valve 64 is in a cut-off state when there is no output of the operation signal from the controller 57.

[0061] Furthermore, a plurality of, for example, four, switching valves 46a, 46b, 46c, 46d and the relief valve 22 are connected to one input / output port of the second open-circuit pump 15 via the flow path 205. The other input / output port of the second open-circuit pump 15 is connected to the hydraulic oil tank 25 to form an open circuit F. The switching valves 46a, 46b, 46c, 46d are open circuit switching valves that switch the flow path 205 between on and off according to an operation signal output from the controller 57, and switch the supply destination of the hydraulic oil flowing out of the second open-circuit pump 15 to the connection flow paths 301, 302, 303, 304, and are set to a cut-off state when there is no output of an operation signal from the controller 57. The controller 57 controls the switching valves 46a, 46b, 46c, 46d so that they are not in an on state at the same time.

[0062] In addition, the switching valve 46a is connected to the boom cylinder 1 via the connecting flow path 301 and the flow path 212. The switching valve 46b is connected to the arm cylinder 3 via the connecting flow path 302 and the flow path 214. In addition, the switching valve 46c is connected to the bucket cylinder 5 via the connecting flow path 303 and the flow path 216. The switching valve 46d is connected to the proportional switching valves 54 and 55 via the connecting flow path 304 and the flow path 220. On the other hand, when the working oil pressure in the flow path 205 is higher than the specified pressure, the relief valve 22 releases the working oil in the flow path 205 to the working oil tank 25 to protect the flow path 205.

[0063] In addition, a proportional valve 65 as a flow regulating valve with pressure compensation is connected between the flow path 205 and the hydraulic oil tank 25. The proportional valve 65 is provided on a branch flow path 205a which is a pipeline branched from the flow path 205 which is a pipeline connecting the switching valves 46a, 46b, 46c, 46d and the second open circuit pump 15 and connected to the hydraulic oil tank 25. Therefore, the proportional valve 65 controls the flow rate of the hydraulic oil flowing from the flow path 205 to the hydraulic oil tank 25 according to the operation signal output from the controller 57. In addition, the proportional valve 65 is in a cut-off state when there is no output of the operation signal from the controller 57.

[0064] Furthermore, a plurality of, for example, four, switching valves 48a, 48b, 48c, 48d and the relief valve 23 are connected to one input / output port of the third open-circuit pump 17 via the flow path 208. The other input / output port of the third open-circuit pump 17 is connected to the hydraulic oil tank 25 to form an open circuit G. The switching valves 48a, 48b, 48c, 48d are open-circuit switching valves that switch the flow path 208 between on and off according to an operation signal output from the controller 57, and switch the supply destination of the hydraulic oil flowing out of the third open-circuit pump 17 to the connecting flow paths 301, 302, 303, 304, and are set to a cut-off state when there is no output of an operation signal from the controller 57. The controller 57 controls the switching valves 48a, 48b, 48c, 48d so that they are not in an on state at the same time.

[0065] In addition, the switching valve 48a is connected to the boom cylinder 1 via the connecting flow path 301 and the flow path 212. The switching valve 48b is connected to the arm cylinder 3 via the connecting flow path 302 and the flow path 214. In addition, the switching valve 48c is connected to the bucket cylinder 5 via the connecting flow path 303 and the flow path 216. The switching valve 48d is connected to the proportional switching valves 54 and 55 via the connecting flow path 304 and the flow path 220. On the other hand, when the working oil pressure in the flow path 208 becomes higher than the specified pressure, the relief valve 23 releases the working oil in the flow path 208 to the working oil tank 25 to protect the flow path 208.

[0066] In addition, a proportional valve 66 as a flow regulating valve with pressure compensation is connected between the flow path 208 and the hydraulic oil tank 25. The proportional valve 66 is provided on a branch flow path 208a which is a pipeline branched from the flow path 208 which is a pipeline connecting the switching valves 48a, 48b, 48c, 48d and the third open circuit pump 17 and connected to the hydraulic oil tank 25. Therefore, the proportional valve 66 controls the flow rate flowing from the flow path 208 to the hydraulic oil tank 25 according to the operation signal output from the controller 57. In addition, the proportional valve 66 is in a cut-off state when there is no output of the operation signal from the controller 57.

[0067] Furthermore, a plurality of, for example, four, switching valves 50a, 50b, 50c, and 50d and a relief valve 24 are connected to one input / output port of the fourth open-circuit pump 19 via a flow path 211. The other input / output port of the fourth open-circuit pump 19 is connected to the hydraulic oil tank 25 to form an open circuit H. The switching valves 50a, 50b, 50c, and 50d are open-circuit switching valves that switch the flow path 211 between on and off according to an operation signal output from the controller 57, and switch the supply destination of the hydraulic oil flowing out of the fourth open-circuit pump 19 to the connection flow paths 301, 302, 303, and 304, and are set to a cut-off state when there is no output of an operation signal from the controller 57. The controller 57 controls the switching valves 50a, 50b, 50c, and 50d so that they are not in an on state at the same time.

[0068] In addition, the switching valve 50a is connected to the boom cylinder 1 via the connecting flow path 301 and the flow path 212. The switching valve 50b is connected to the arm cylinder 3 via the connecting flow path 302 and the flow path 214. In addition, the switching valve 50c is connected to the bucket cylinder 5 via the connecting flow path 303 and the flow path 216. The switching valve 50d is connected to the proportional switching valves 54 and 55 via the connecting flow path 304 and the flow path 220. On the other hand, when the working oil pressure in the flow path 211 becomes higher than the specified pressure, the relief valve 24 releases the working oil in the flow path 211 to the working oil tank 25 to protect the flow path 211.

[0069] In addition, a proportional valve 67 with pressure compensation is connected between the flow path 211 and the hydraulic oil tank 25. The proportional valve 67 is provided on a branch flow path 211a which is a pipeline branched from the flow path 211 which is a pipeline connecting the switching valves 50a, 50b, 50c, 50d and the fourth open circuit pump 19 and connected to the hydraulic oil tank 25. Therefore, the proportional valve 67 controls the flow rate of the hydraulic oil flowing from the flow path 211 to the hydraulic oil tank 25 according to the operation signal output from the controller 57. In addition, the proportional valve 67 is in a cut-off state when there is no output of the operation signal from the controller 57.

[0070] Here, the connecting flow path 301 is composed of connecting flow paths 305a, 306a, 307a, 308a for open circuits and a connecting flow path 309a for closed circuits, wherein the connecting flow paths 305a, 306a, 307a, 308a for open circuits are connected to the side, i.e., the discharge side, from which the working oil flows out of at least one switching valve 44a, 46a, 48a, 50a in the multiple open circuits E, F, G, H, and the connecting flow path 309a for closed circuits is connected to the flow path 212 constituting the closed circuit A. The connecting flow path 302 is composed of connecting flow paths 305b, 306b, 307b, 308b for open circuits and a connecting flow path 309b for closed circuits, wherein the connecting flow paths 305b, 306b, 307b, 308b for open circuits are connected to the side, i.e., the discharge side, from which the working oil flows out of at least one switching valve 44b, 46b, 48b, 50b in the multiple open circuits E, F, G, H, and the connecting flow path 309b for closed circuits is connected to the flow path 214 constituting the closed circuit B. The connecting flow path 303 is composed of connecting flow paths 305c, 306c, 307c, 308c for open circuits and a connecting flow path 309c for closed circuits, wherein the connecting flow paths 305c, 306c, 307c, 308c for open circuits are connected to the side, i.e., the discharge side, from which the working oil flows out of at least one switching valve 44c, 46c, 48c, 50c in the multiple open circuits E, F, G, H, and the connecting flow path 309c for closed circuits is connected to the flow path 216 constituting the closed circuit C. In addition, the connecting flow path 304 is composed of open circuit connecting flow paths 305d, 306d, 307d, 308d and a connecting flow path 309d, wherein the open circuit connecting flow paths 305d, 306d, 307d, 308d are connected to the side where the working oil flows out of at least one switching valve 44d, 46d, 48d, 50d in the multiple open circuits E, F, G, H, that is, the discharge side, and the connecting flow path 309d is connected to the flow path 220.

[0071] The hydraulic drive device 107 is composed of closed circuit pumps 12, 14, 16, 18 and the boom cylinder 1, the arm cylinder 3, the bucket cylinder 5 and the swing motor 7, and closed circuits A, B, C, and D connected from one input / output port of the hydraulic pump to the other input / output port via an actuator in a closed loop state, and open circuit pumps 13, 15, 17, and 19 and switching valves 44a, 44b, 44c, 44d, 46a, 46b, 46c, 46d, 48a, 48b, 48c, 48d, 50a, 50b, 50c, and 50d are composed of open circuits E, F, G, and H in which the switching valve is connected to one input / output port of the hydraulic pump and the other input / output port is connected to the hydraulic oil tank 25. In addition, the closed circuits A, B, C, and D and the open circuits E, F, G, and H are provided, for example, four each, and are provided in pairs.

[0072] On the other hand, the discharge port of the supply pump 11 is connected to the supply relief valve 20 and the supply check valves 26, 27, 28, 29, 40a, 40b, 41a, 41b, 42a, 42b via the flow path 229. The suction port of the supply pump 11 is connected to the hydraulic oil tank 25. Here, the supply relief valve 20 adjusts the supply pressure of the supply check valves 26, 27, 28, 29, 40a, 40b, 41a, 41b, 42a, 42b.

[0073] When the hydraulic oil pressure in the flow passages 200 and 201 is lower than the pressure set by the supply relief valve 20, the supply check valve 26 supplies hydraulic oil from the supply pump 11 to the flow passages 200 and 201. Similarly, when the hydraulic oil pressure in the flow passages 203 and 204 is lower than the pressure set by the supply relief valve 20, the supply check valve 27 supplies hydraulic oil from the supply pump 11 to the flow passages 203 and 204. When the hydraulic oil pressure in the flow passages 206 and 207 is lower than the pressure set by the supply relief valve 20, the supply check valve 28 supplies hydraulic oil from the supply pump 11 to the flow passages 206 and 207. Similarly, when the hydraulic oil pressure in the flow passages 209 and 210 is lower than the pressure set by the supply relief valve 20, the supply check valve 29 supplies hydraulic oil from the supply pump 11 to the flow passages 209 and 210.

[0074] Furthermore, when the hydraulic oil pressure in the flow paths 212 and 213 is lower than the pressure set by the supply relief valve 20, the supply check valves 40a and 40b supply hydraulic oil from the supply pump 11 to the flow paths 212 and 213. Similarly, when the hydraulic oil pressure in the flow paths 214 and 215 is lower than the pressure set by the supply relief valve 20, the supply check valves 41a and 41b supply hydraulic oil from the supply pump 11 to the flow paths 214 and 215. Furthermore, when the hydraulic oil pressure in the flow paths 216 and 217 is lower than the pressure set by the supply relief valve 20, the supply check valves 42a and 42b supply hydraulic oil from the supply pump 11 to the flow paths 216 and 217.

[0075] In addition, a pair of relief valves 30a and 30b are connected between the flow paths 200 and 201. When the working oil pressure in the flow paths 200 and 201 is higher than a predetermined pressure, the relief valves 30a and 30b release the working oil in the flow paths 200 and 201 to the working oil tank 25 via the supply relief valve 20, thereby protecting the flow paths 200 and 201. Similarly, a pair of relief valves 31a and 31b are connected between the flow paths 203 and 204. When the working oil pressure in the flow paths 203 and 204 is higher than a predetermined pressure, the relief valves 31a and 31b release the working oil in the flow paths 203 and 204 to the working oil tank 25 via the supply relief valve 20, thereby protecting the flow paths 203 and 204.

[0076] Furthermore, relief valves 32a and 32b are also connected between the flow paths 206 and 207. When the working oil pressure in the flow paths 206 and 207 is higher than a predetermined pressure, the relief valves 32a and 32b release the working oil in the flow paths 206 and 207 to the working oil tank 25 via the supply relief valve 20, thereby protecting the flow paths 206 and 207. Furthermore, relief valves 33a and 33b are also connected between the flow paths 209 and 210. When the working oil pressure in the flow paths 209 and 210 is higher than a predetermined pressure, the relief valves 33a and 33b release the working oil in the flow paths 209 and 210 to the working oil tank 25 via the supply relief valve 20, thereby protecting the flow paths 209 and 210.

[0077] Next, the flow path 212 is connected to the cover chamber 1a of the boom cylinder 1. The flow path 213 is connected to the rod chamber 1b of the boom cylinder 1. Furthermore, relief valves 37a and 37b are connected between the flow paths 212 and 213. When the working oil pressure in the flow paths 212 and 213 is above a predetermined pressure, the relief valves 37a and 37b release the working oil in the flow paths 212 and 213 to the working oil tank 25 via the supply relief valve 20, thereby protecting the flow paths 212 and 213. Furthermore, a flushing valve 34 is connected between the flow paths 212 and 213. The flushing valve 34 discharges the remaining working oil (residual oil) in the flow paths 212 and 213 to the working oil tank 25 via the supply relief valve 20.

[0078] In addition, the flow path 214 is connected to the cover chamber 3a of the boom cylinder 3. The flow path 215 is connected to the rod chamber 3b of the boom cylinder 3. Furthermore, relief valves 38a and 38b are connected between the flow paths 214 and 215. When the working oil pressure in the flow paths 214 and 215 is above a predetermined pressure, the relief valves 38a and 38b release the working oil in the flow paths 214 and 215 to the working oil tank 25 via the supply relief valve 20, thereby protecting the flow paths 214 and 215. Furthermore, a flushing valve 35 is connected between the flow paths 214 and 215. The flushing valve 35 discharges the remaining working oil in the flow paths 214 and 215 to the working oil tank 25 via the supply relief valve 20.

[0079] In addition, the flow path 216 is connected to the head chamber 5a of the bucket cylinder 5. The flow path 217 is connected to the rod chamber 5b of the bucket cylinder 5. Furthermore, relief valves 39a and 39b are connected between the flow paths 216 and 217. When the working oil pressure in the flow paths 216 and 217 is equal to or higher than a predetermined pressure, the relief valves 39a and 39b release the working oil in the flow paths 216 and 217 to the working oil tank 25 via the supply relief valve 20, thereby protecting the flow paths 216 and 217. Furthermore, the flushing valve 36 is connected between the flow paths 216 and 217. The flushing valve 36 discharges the remaining working oil in the flow paths 216 and 217 to the working oil tank 25 via the supply relief valve 20.

[0080] Furthermore, the flow paths 218 and 219 are connected to the rotary motor 7, respectively. In addition, relief valves 51a and 51b are connected between the flow paths 218 and 219. When the pressure difference of the working oil between the flow paths 218 and 219 (flow path pressure difference) is equal to or greater than a predetermined pressure, the relief valves 51a and 51b release the working oil in the flow paths 218 and 219 on the high-pressure side to the flow paths 219 and 218 on the low-pressure side, thereby protecting the flow paths 218 and 219.

[0081] In addition, the proportional switching valve 54 is connected to the travel motor 8a through the flow paths 221 and 222. Relief valves 52a and 52b are connected between the flow paths 221 and 222. When the pressure difference of the working oil between the flow paths 221 and 222 is equal to or higher than a predetermined pressure, the relief valves 52a and 52b release the working oil in the flow paths 221 and 222 on the high-pressure side to the flow paths 222 and 221 on the low-pressure side, thereby protecting the flow paths 221 and 222. The proportional switching valve 54 is configured to switch the connection destination of the flow path 220 and the working oil tank 25 to one of the flow path 221 and the flow path 222 according to the operation signal output from the controller 57, so that the flow rate can be adjusted.

[0082] In addition, the proportional switching valve 55 is connected to the travel motor 8b through the flow paths 223 and 224. Relief valves 53a and 53b are connected between the flow paths 223 and 224. When the pressure difference of the working oil between the flow paths 223 and 224 is equal to or higher than a predetermined pressure, the relief valves 53a and 53b release the working oil in the flow paths 223 and 224 on the high-pressure side to the flow paths 224 and 223 on the low-pressure side, thereby protecting the flow paths 223 and 224. The proportional switching valve 55 is configured to switch the connection destination of the flow path 220 and the working oil tank 25 to one of the flow path 223 and the flow path 224 according to the operation signal output from the controller 57, so that the flow rate can be adjusted.

[0083] The pressure sensor 80a connected to the flow path 200 measures the pressure of the flow path 200 and inputs it to the controller 57. The pressure sensor 80a measures the pressure of one input / output port of the first closed-loop pump 12 by measuring the pressure of the flow path 200. The pressure sensor 80b connected to the flow path 201 measures the pressure of the flow path 201 and inputs it to the controller 57. The pressure sensor 80b measures the pressure of the other input / output port of the first closed-loop pump 12 by measuring the pressure of the flow path 201. The pressure sensor 81 connected to the flow path 202 measures the pressure of the flow path 202 and inputs it to the controller 57. The pressure sensor 81 measures the pressure of the discharge port of the first open-loop pump 13 by measuring the pressure of the flow path 202.

[0084] The pressure sensor 82a connected to the flow path 203 measures the pressure of the flow path 203 and inputs it to the controller 57. The pressure sensor 82a measures the pressure of one input / output port of the second closed-loop pump 14 by measuring the pressure of the flow path 203. The pressure sensor 82b connected to the flow path 204 measures the pressure of the flow path 204 and inputs it to the controller 57. The pressure sensor 82b measures the pressure of the other input / output port of the second closed-loop pump 14 by measuring the pressure of the flow path 204. The pressure sensor 83 connected to the flow path 205 measures the pressure of the flow path 205 and inputs it to the controller 57. The pressure sensor 83 measures the pressure of the discharge port of the second open-loop pump 15 by measuring the pressure of the flow path 205.

[0085] The pressure sensor 84a connected to the flow path 206 measures the pressure of the flow path 206 and inputs it to the controller 57. The pressure sensor 84a measures the pressure of one input / output port of the third closed-loop pump 16 by measuring the pressure of the flow path 206. The pressure sensor 84b connected to the flow path 207 measures the pressure of the flow path 207 and inputs it to the controller 57. The pressure sensor 84b measures the pressure of the other input / output port of the third closed-loop pump 16 by measuring the pressure of the flow path 207.

[0086] The pressure sensor 85 connected to the flow path 208 measures the pressure of the flow path 208 and inputs the pressure to the controller 57. The pressure sensor 85 measures the pressure of the discharge port of the third open circuit pump 17 by measuring the pressure of the flow path 208.

[0087] The pressure sensor 86a connected to the flow path 209 measures the pressure of the flow path 209 and inputs it to the controller 57. The pressure sensor 86a measures the pressure of one input / output port of the fourth closed-loop pump 18 by measuring the pressure of the flow path 209. The pressure sensor 86b connected to the flow path 210 measures the pressure of the flow path 210 and inputs it to the controller 57. The pressure sensor 86b measures the pressure of the other input / output port of the fourth closed-loop pump 18 by measuring the pressure of the flow path 210. The pressure sensor 87 connected to the flow path 211 measures the pressure of the flow path 211 and inputs it to the controller 57. The pressure sensor 87 measures the pressure of the discharge port of the fourth open-loop pump 19 by measuring the pressure of the flow path 211.

[0088] The pressure sensor 70a connected to the flow path 212 measures the pressure of the flow path 212 and inputs the pressure to the controller 57. The pressure sensor 70a measures the pressure of the head chamber 1a of the boom cylinder 1 by measuring the pressure of the flow path 212. The pressure sensor 70b connected to the flow path 213 measures the pressure of the flow path 213 and inputs the pressure to the controller 57. The pressure sensor 70b measures the pressure of the rod chamber 1b of the boom cylinder 1 by measuring the pressure of the flow path 213.

[0089] The pressure sensor 71a connected to the flow path 214 measures the pressure of the flow path 214 and inputs it to the controller 57. The pressure sensor 71a measures the pressure of the head chamber 3a of the boom cylinder 3 by measuring the pressure of the flow path 214. The pressure sensor 71b connected to the flow path 215 measures the pressure of the flow path 215 and inputs it to the controller 57. The pressure sensor 71b measures the pressure of the rod chamber 3b of the boom cylinder 3 by measuring the pressure of the flow path 215.

[0090] The pressure sensor 72a connected to the flow path 216 measures the pressure of the flow path 216 and inputs the pressure to the controller 57. The pressure sensor 72a measures the pressure of the head chamber 5a of the bucket cylinder 5 by measuring the pressure of the flow path 216. The pressure sensor 72b connected to the flow path 217 measures the pressure of the flow path 217 and inputs the pressure to the controller 57. The pressure sensor 72b measures the pressure of the rod chamber 5b of the bucket cylinder 5 by measuring the pressure of the flow path 217.

[0091] The pressure sensor 73a connected to the flow path 218 measures the pressure of the flow path 218 and inputs it to the controller 57. The pressure sensor 73a measures the pressure of one input / output port of the rotary motor 7 by measuring the pressure of the flow path 218. The pressure sensor 73b connected to the flow path 219 measures the pressure of the flow path 219 and inputs it to the controller 57. The pressure sensor 73b measures the pressure of the other input / output port of the rotary motor 7 by measuring the pressure of the flow path 219.

[0092] The controller 57 controls the regulators 12a, 13a, ..., 19a, the switching valves 43a, 44a, ..., 50a, 43b, 44b, ..., 50b, 43c, 44c, ..., 50c, 43d, 44d, ..., 50d and the proportional switching valves 54, 55 according to the command values ​​of the extension and retraction direction and speed of the boom cylinder 1, the arm cylinder 3 and the bucket cylinder 5 from the operating device 56, the command values ​​of the rotation direction and speed of the slewing motor 7 and the travel motors 8a, 8b, and the various sensor information in the hydraulic drive device 107.

[0093] Specifically, the controller 57 controls the pressure area of ​​the first flow rate and the second flow rate, for example, so that the ratio of the first flow rate to the second flow rate is a predetermined value preset corresponding to the pressure area of ​​the cover chamber 1a and the rod chamber 1b of the boom cylinder 1, wherein the first flow rate is the flow rate of the first closed-circuit pump 12 on the side of the flow path 212 connected to the cover chamber 1a and the rod chamber 1b of the boom cylinder 1, and the second flow rate is the flow rate of the first open-circuit pump 13 connected to the connecting flow path 301 via the switching valve 44a. Similarly, the controller 57 also performs the above-mentioned pressure area control on the arm cylinder 3 and the bucket cylinder 5.

[0094] In addition, when the controller 57 actuates at least one of the boom cylinder 1, the arm cylinder 3 and the bucket cylinder 5, it appropriately controls the switching valves 43a~50a, 43b~50b, 43c~50c, 43d~50d to supply the working oil discharged from the same number of open circuit pumps 13, 15, 17, 19 as the corresponding closed circuit pumps 12, 14, 16, 18 to at least one of the boom cylinder 1, the arm cylinder 3 and the bucket cylinder 5 to be actuated.

[0095] Furthermore, the boom lever 56a of the operating device 56 provides the command values ​​of the extension and retraction direction and the extension and retraction speed of the boom cylinder 1 to the controller 57. The boom lever 56b provides the command values ​​of the extension and retraction direction and the extension and retraction speed of the boom cylinder 3 to the controller 57, and the bucket lever 56c provides the command values ​​of the extension and retraction direction and the extension and retraction speed of the bucket cylinder 5 to the controller 57. Furthermore, the swing lever 56d provides the command values ​​of the rotation direction and the rotation speed of the swing motor 7 to the controller 57. In addition, it is assumed that there is also a structure having an operating lever (not shown), wherein the operating lever is used to provide the command values ​​of the rotation direction and the rotation speed of the travel motors 8a, 8b to the controller 57. In addition, the controller 57 is connected to a display device 58 for notifying the operator of the vehicle body status.

[0096] Figure 3 1 is a functional block diagram of the controller 57. The controller 57 is composed of a lever operation amount calculation unit 57a, a pressure calculation unit 57b, an actuator distribution flow rate calculation unit 57c, a pressure sensor failure detection unit 57d, and a pseudo pressure calculation unit 57e.

[0097] The lever operation amount calculation unit 57 a calculates the operation direction and operation speed target of each actuator in response to the operator's lever input, and inputs the calculated operation direction and operation speed target to the actuator distribution flow rate calculation unit 57 c .

[0098] The pressure calculation unit 57 b calculates the pressure of each part based on the measurement values ​​of the pressure sensors 70 a to 73 b and 80 to 87 provided in each part, and inputs the calculated pressure to the actuator distribution flow rate calculation unit 57 c and the display device 58 .

[0099] The pressure sensor failure detection unit 57d detects the connection state between the pressure sensors determined by the measured values ​​of the pressure sensors 70a to 73b and 80 to 87 and the command values ​​to the switching valves 43a to 49d. Figure 5 The flowchart shown detects a failure of the pressure sensor and inputs the failure to the actuator distribution flow rate calculation unit 57 c and the display device 58 .

[0100] The pseudo-pressure calculation unit 57 e calculates the pseudo-pressures of the actuators 1 , 3 , and 5 based on the measurement values ​​of the posture sensors 400 to 403 , and inputs the pseudo-pressures to the actuator distribution flow rate calculation unit 57 c and the display device 58 .

[0101] The actuator distribution flow rate calculation unit 57c calculates the command values ​​for the switching valves 43a to 50d, the proportional valves 64 to 67, and the regulators 12a to 19a based on the inputs from the lever operation amount calculation unit 57a and the pressure calculation unit 57b in normal times. On the other hand, when the pressure sensor failure detection unit 57d detects a failure of the pressure sensor, the command values ​​for the switching valves 43a to 50d, the proportional valves 64 to 67, and the regulators 12a to 19a are calculated based on the inputs from the pseudo pressure calculation unit 57e and the lever operation amount calculation unit 57a.

[0102] The display device 58 displays the measurement values ​​of the pressure sensors input from the pressure calculation unit 57 b , the failure states of the pressure sensors input from the pressure sensor failure detection unit 57 d , and the pseudo pressure input from the pseudo pressure calculation unit 57 e .

[0103] The pressure sensor fault diagnosis input generation device 59 connected to the controller 57 is a device for improving the fault detection accuracy of the pressure sensor fault detection unit 57d. The pressure sensor fault diagnosis input generation device 59 outputs a lever operation signal for causing the hydraulic excavator 100 to take a prescribed posture (diagnostic posture) suitable for the diagnosis of the pressure sensor to the lever operation amount calculation unit 57a based on the measurement values ​​of the posture sensors 400 to 403, and outputs an opening instruction to the switching valves 43a to 50d when the hydraulic excavator 100 is stationary in the diagnostic posture. In this embodiment, the pressure sensor fault diagnosis input generation device 59 is constituted by a device independent of the controller 57, and can also be constituted as a part of the function of the controller 57. The details of the pressure sensor fault diagnosis input generation device 59 will be described later.

[0104] Next, Figure 2 The operation of the hydraulic drive device 107 shown will be described.

[0105] (1) Non-operating

[0106] exist Figure 2 When the levers 56a to 56d are not operated, the hydraulic pumps 12 to 19 are controlled to the minimum tilt angle, the switching valves 43a to 50d are all closed, and the boom cylinder 1, the arm cylinder 3, the bucket cylinder 5 and the swing motor 7 are kept in a stopped state.

[0107] (2) When the boom is raised

[0108] Figure 4 1 shows the state change of the hydraulic drive device 107 when the boom cylinder 1 is extended. Figure 4 , the measured values ​​of the pressure sensors 70a, 80a, 82a, 84a, and 86a are shown when the pressure sensor 70a is normal and when the pressure sensor 70a fails and the measured value drift is positive.

[0109] From time t0 to time t1, the input to the boom lever 56a is 0, and the boom cylinder 1 is stationary.

[0110] From time t1 to time t5, the input of the boom lever 56a raises the command value for extending the boom cylinder 1 to the maximum value. The number of connected pumps increases in accordance with the increase in the input of the boom lever 56a. The timing at which the switching valves 43a, 45a, 47a, and 49a are opened is the timing at which the closed-circuit pumps 12, 14, 16, and 18 are connected to the boom cylinder 1.

[0111] At time t1, the boom rod 56a is input. At this time, before the first closed-circuit pump 12 is connected to the boom cylinder 1, the switching valve 43a is opened after the discharge pressure of the first closed-circuit pump 12 is increased to the pressure of the head chamber 1a of the boom cylinder 1. The pressure increase operation is performed based on the values ​​measured by the pressure sensors 70a and 80a, and the switching valve 43a is opened after the difference between the measured value of the pressure sensor 80a and the measured value of the pressure sensor 70a is less than a threshold value (first threshold value).

[0112] When the pressure sensor 70a is normal, the discharge pressure of the first closed circuit pump 12 measured by the pressure sensor 80a is sufficiently increased before the switching valve 43a is opened by the pressure increase process. If the discharge flow rate of the first closed circuit pump 12 increases from time t1 to time t2, the measured value of the pressure sensor 80a is greater than the measured value of the pressure sensor 70a by the amount of pressure loss generated when passing through the pipeline and the switching valve 43a.

[0113] When the pressure sensor 70a fails and the measured value drifts to the positive side, the discharge pressure of the first closed circuit pump 12 measured by the pressure sensor 80a before the switching valve 43a is opened by the pressure-increasing process is higher than the pressure of the head chamber 1a of the boom cylinder 1. As a result, a shock is generated when the switching valve 43a is opened.

[0114] From time t2 to time t3, the switching valve 45a is opened after the second closed circuit pump 14 is pressurized. However, when the pressure sensor 70a fails, the pressure is over-pressurized, and a shock is generated when each switching valve is opened. During the period until time t3, three or more pressure sensors are connected to the same pipeline, so the failure of the pressure sensor 70a is detected by the processing of the pressure sensor failure detection unit 57d described later.

[0115] From time t3 to time t5, the failure of the pressure sensor 70a is detected, and therefore, the differential pressure across the switching valves 47a and 49a is calculated using the pseudo pressure calculated by the pseudo pressure calculation unit 57e instead of the measured value of the pressure sensor 70a. By using the pseudo pressure instead of the measured value of the failed pressure sensor 70a, it is possible to prevent the closed circuit pumps 16 and 18 from over-increasing the pressure, and thus it is possible to suppress the shock when the switching valves 47a and 49a are opened.

[0116] Figure 5 4 is a flowchart showing a part of the processing of the pressure sensor failure detection unit 57d. Figure 5 In FIG. 1 , only the process of detecting a failure of the pressure sensor 70a of the boom cylinder 1 is shown. The failure detection of the pressure sensor 70a of the boom cylinder 1 is performed by comparing the measured value of the pressure sensor 70a with the measured values ​​of the pressure sensors 80a, 82a, 84a, 86a of the closed-circuit pumps 12, 14, 16, 18 and the pressure sensors 81, 83, 85, 87 of the open-circuit pumps 13, 15, 17, 19 connected to the boom cylinder 1 by the same pipe. Figure 5 In the above, the process of comparing the measured values ​​of the pressure sensors 81, 83, 85, and 87 of the open circuit pumps 13, 15, 17, and 19 is omitted. Figure 5 The following describes each step.

[0117] The pressure sensor fault detection unit 57d first determines whether the boom cylinder 1 is connected to the closed-loop pump 12 (step S11). When it is determined to be yes in step S11, transfer to step S21 described later. When it is determined to be yes in step S11, calculate the absolute value (pressure difference) of the difference between the measured values ​​of the pressure sensors 70a and 80a (step S12). Following step S12, determine whether the pressure difference is smaller than a specified threshold value Plim (step S13). Here, the threshold value Plim is a value predetermined in consideration of the measurement error and flow pressure loss characteristics of the pressure sensor. In addition, in the present embodiment, the threshold value Plim is set to a fixed value, but it can also be set to a value that changes corresponding to the pump discharge flow rate. When it is determined to be no in step S13, transfer to step S21 described later. When it is determined to be no in step S13, add 1 to the fault flag of the pressure sensor 70a (step S14).

[0118] Following step S14, it is determined whether the boom cylinder 1 is connected to the closed circuit pump 14 (step S21). When it is determined to be yes in step S21, the absolute value (pressure difference) of the difference between the measured values ​​of the pressure sensors 70a and 82a is calculated (step S22). Following step S22, it is determined whether the pressure difference is smaller than the threshold value Plim (step S23). When it is determined to be no in step S23, it is transferred to step S31 described later. When it is determined to be no in step S23, the fault flag of the pressure sensor 70a is increased by 1 (step S24).

[0119] Following step S24, it is determined whether the boom cylinder 1 is connected to the closed circuit pump 16 (step S31). When it is determined to be yes in step S31, the absolute value (pressure difference) of the difference between the measured values ​​of the pressure sensors 70a and 84a is calculated (step S32). Following step S32, it is determined whether the pressure difference is smaller than the threshold value Plim (step S33). When it is determined to be no in step S33, it is transferred to step S41 described later. When it is determined to be no in step S33, the fault flag of the pressure sensor 70a is increased by 1 (step S34).

[0120] Following step S34, it is determined whether the boom cylinder 1 is connected to the closed circuit pump 18 (step S41). When it is determined to be yes in step S41, the absolute value (pressure difference) of the difference between the measured values ​​of the pressure sensors 70a and 86a is calculated (step S42). Following step S42, it is determined whether the pressure difference is smaller than the threshold value Plim (step S43). When it is determined to be no in step S43, it is transferred to step S51 described later. When it is determined to be no in step S43, the fault flag of the pressure sensor 70a is increased by 1 (step S44).

[0121] Following step S44, it is determined whether the failure flag is greater than 1 (step S51). If it is determined to be NO in step S51, the process ends. If it is determined to be YES in step S51, the pressure sensor 70a is determined to be a failure (step S52), and the process ends.

[0122] The above describes the processing related to the fault detection of the pressure sensor 70a, but the pressure sensor fault detection unit 57d can also detect faults of other actuator pressure sensors 70b, 71a, 71b, 72a, 72b, 73a, 73b and pump pressure sensors 80a, 80b, 81, 82a, 82b, 83, 84a, 84b, 85, 86a, 86b, 87 by comparing the measurement values ​​according to the combination of two pressure sensors included in more than three pressure sensors that detect the pressure of the pipeline in a connected state.

[0123] Reference Figure 4 , the fault detection operation of the pressure sensor 70a which measures the head chamber pressure of the boom cylinder 1 when it is normal and when it fails will be described.

[0124] <When the pressure sensor 70a is normal>

[0125] In the state from time t1 to time t5, when the switching valves 43a, 45a, 47a, and 49a are open, it is determined in steps S11, S21, S31, and S41 whether the boom cylinder 1 and the closed circuit pumps 12, 14, 16, and 18 are connected. When connected, the pressure difference between the pressure of the boom cylinder 1 and the pressure of the pumps 12, 14, 16, and 18 is calculated in S12, S22, S32, and S42. At this time, the pressure sensor 70a is normal, and the pressure difference with the pump pressure is smaller than the threshold value Plim, so the fault flag of the pressure sensor 70a is not counted up. That is, the fault flag is zero, so it is not determined that the pressure sensor 70a is faulty in step S51.

[0126] <When the pressure sensor 70a fails>

[0127] In the state from time t1 to time t5, when the switching valves 43a, 45a, 47a, 49a are open, it is determined in steps S11, S21, S31, and S41 whether the boom cylinder 1 is connected to the closed circuit pumps 12, 14, 16, and 18. When connected, the pressure difference between the boom cylinder 1 and the pressure of the pumps 12, 14, 16, and 18 is calculated in steps S12, S22, S32, and S42. At this time, the pressure sensor 70a is faulty and the pressure difference with the pump pressure is greater than the threshold value Plim, so the fault flag of the pressure sensor 70a is counted up in steps S14, S24, S34, and S44. After time t2, when two or more pumps are connected to the boom cylinder 1, the fault flag of the pressure sensor 70a is greater than 1, so it is determined in step S51 that the pressure sensor 70a is faulty.

[0128] Next, Figure 3 The pseudo-pressure calculation unit 57e determines the pseudo-pressure for driving the actuators 1, 3, and 5 of the working mechanism 106 according to the posture of the hydraulic excavator 100. The method of determining the pseudo-pressure will be described below using the arm cylinder 3 as an example.

[0129] Figure 6 FIG. 2 shows the change in posture of the hydraulic excavator 100 when the arm cylinder 3 is extended. Figure 7 It shows the relationship between the stroke of the boom cylinder 3 and the cover chamber 3a. Figure 6 In the postures (a) to (b), Figure 7 As shown, the pressure of the cover chamber 3a of the boom cylinder 3 is fixed. This is because the force of supporting the boom 4 and the bucket 6 relative to gravity acts on the rod chamber 3b of the boom cylinder 3, and thus the pressure of the rod chamber 3b becomes higher than the pressure of the cover chamber 3a, and the cover chamber 3a on the low-pressure side is maintained at the supply pressure by the flushing valve 34. Therefore, within the stroke range of postures (a) to (b), the pseudo pressure of the cover chamber 3a of the boom cylinder 3 can be set to the supply pressure.

[0130] exist Figure 6 In postures (b) to (c), Figure 7 As shown, the pressure in the cover chamber 3a of the boom cylinder 3 increases in accordance with the stroke. This is because the force required to support the boom 4 and the bucket 6 relative to the gravity is exerted. At this time, the pressure is different depending on whether the bucket 6 is empty or fully loaded. Taking this characteristic into consideration, the pseudo pressure is set to a value greater than the pressure in the empty state (no load state) for the cylinder stroke so that the difference between the pseudo pressure and the actual pressure is small even in the loaded state. In addition, in the present embodiment, the postures of the boom cylinder 1, the bucket cylinder 5, and the upper slewing body 103 are as follows: Figure 6 Although the case where the posture is fixed is described, a pseudo pressure gauge is also provided for the case where the posture of the actuator other than the arm cylinder 3 and the upper swing body 103 are different.

[0131] By Figure 3 The function shown is provided in the controller 57, and even when the actuator pressure sensors 70a to 73b fail, the hydraulic excavator 100 can be operated without significantly reducing the operability by calculating the front and rear pressure difference of the switching valves 43a to 50d using pseudo pressure. In addition, the operator can recognize the failure state of the pressure sensor through the information displayed on the display device 58, and can be reminded to repair the pressure sensor in advance.

[0132] Figure 3 The pressure sensor failure diagnosis input generating device 59 shown in the figure makes the hydraulic excavator 100 take a predetermined diagnosis posture (for example, Figure 6 (a) The pressure in the cover chamber 3a of the arm cylinder 3 is lowered. Figure 6 (c) The pressure in the cover chamber 3a of the boom cylinder 3 increases, and the output of the normal pressure sensor and the faulty pressure sensor at various pressure levels can be compared to improve the probability of fault detection. In addition, unlike the case where the detection is performed during operation, the accuracy of fault detection can be improved by comparing the output of the pressure sensor when the hydraulic excavator 100 is stationary in the diagnostic posture, that is, when the pressure on the pipeline is uniform without the influence of the flow pressure loss characteristics. In addition, in the present embodiment, the pressure sensor fault diagnosis input generating device 59 is configured as a device independent of the controller 57, but it can also be configured as a part of the function of the controller 57.

[0133] Figure 8 1 is a flowchart showing the processing of the pressure sensor failure diagnosis input generating device 59. The processing of this flowchart is performed in a state where the hydraulic excavator 100 is installed on a horizontal ground. Hereinafter, each step will be described in order.

[0134] The pressure sensor fault diagnosis input generating device 59 first calculates the stroke (detection stroke) of the boom cylinder 1 based on the measurement values ​​of the posture sensors 400 to 403, and determines whether the detection stroke is consistent with the stroke (diagnostic stroke) of the boom cylinder 1 in the diagnostic posture (step S101). When it is determined to be no in step S101, the input of the boom rod 56a is adjusted so that the difference between the detection stroke and the diagnostic stroke becomes smaller (step S102), and the process returns to step S101. Here, the input of the boom rod 56a is adjusted to a value obtained by multiplying the difference between the diagnostic stroke and the detection stroke by a prescribed gain, for example. In addition, the prescribed gain is set to a smaller value to the extent that two or more closed-circuit pumps are not connected to the boom cylinder 1. In this way, the posture of the boom 2 can be slowly changed toward the diagnostic posture.

[0135] When it is determined to be yes in step S101, the stroke (detection stroke) of the boom cylinder 3 is calculated based on the measurement values ​​of the posture sensors 400 to 403, and it is determined whether the detection stroke is consistent with the stroke (diagnostic stroke) of the boom cylinder 3 in the diagnostic posture (step S103). When it is determined to be no in step S103, the input of the boom rod 56b is adjusted so that the difference between the detection stroke and the diagnostic stroke becomes smaller (step S104), and the process returns to step S103. Here, the input of the boom rod 56b is adjusted to a value obtained by multiplying the difference between the diagnostic stroke and the detection stroke by a prescribed gain, for example. In addition, the prescribed gain is set to a smaller value to the extent that no more than two closed-loop pumps are connected to the boom cylinder 3. In this way, the posture of the boom 4 can be slowly changed toward the diagnostic posture.

[0136] When it is determined to be yes in step S103, the stroke (detection stroke) of the bucket cylinder 5 is calculated based on the measured values ​​of the posture sensors 400 to 403, and it is determined whether the detection stroke is consistent with the stroke (diagnosis stroke) of the bucket cylinder 5 in the diagnostic posture (step S105). When it is determined to be no in step S105, the input of the bucket lever 56c is adjusted so that the difference between the detection stroke and the diagnosis stroke becomes smaller (step S106), and the process returns to step S105. Here, the input of the bucket lever 56c is adjusted to a value obtained by multiplying the difference between the diagnosis stroke and the detection stroke by a prescribed gain, for example. In addition, the prescribed gain is set to a small value to the extent that two or more closed-circuit pumps are not connected to the bucket cylinder 5. In this way, the posture of the bucket 6 can be slowly changed toward the diagnostic posture.

[0137] If the judgment is yes in step S105, an opening command is output to the switching valves 43a, 44a, 45a, 46a, 47a, 48a, 49a, 50a (step S107). Thus, when the hydraulic excavator 100 is stationary in the diagnosis posture and the closed circuit pumps 12, 14, 16, 18 are connected to the boom cylinder 1, the fault diagnosis process of the pressure sensor fault detection unit 57d is performed (step S108).

[0138] Following step S108, a closing command is output to the switching valves 43a, 44a, 45a, 46a, 47a, 48a, 49a, 50a (step S109), and an opening command is output to the switching valves 43b, 44b, 45b, 46b, 47b, 48b, 49b, 50b (step S110). Thus, with the hydraulic excavator 100 stationary in the diagnostic posture and the closed circuit pumps 12, 14, 16, 18 connected to the arm cylinder 3, the fault diagnosis process of the pressure sensor fault detection unit 57d is performed (step S111).

[0139] Following step S111, a closing command is output to the switching valves 43b, 44b, 45b, 46b, 47b, 48b, 49b, 50b (step S112), and an opening command is output to the switching valves 43c, 44c, 45c, 46c, 47c, 48c, 49c, 50c (step S113). Thus, the fault diagnosis process of the pressure sensor fault detection unit 57d is performed in a state where the hydraulic excavator 100 is stationary in the diagnosis posture and the closed circuit pumps 12, 14, 16, 18 are connected to the bucket cylinder 5 (step S114).

[0140] Following step S114, a closing command is output to the switching valves 43c, 44c, 45c, 46c, 47c, 48c, 49c, 50c (step S115), and an opening command is output to the switching valves 43d, 44d, 45d, 46d, 47d, 48d, 49d, 50d (step S116). Thus, with the hydraulic excavator 100 stationary in the diagnostic posture and the closed circuit pumps 12, 14, 16, 18 connected to the swing motor 7, the fault diagnosis process of the pressure sensor fault detection unit 57d is performed (step S117).

[0141] Following step S117, a closing command is output to the switching valves 43d, 44d, 45d, 46d, 47d, 48d, 49d, and 50d (step S118), and the flow ends.

[0142] Fig. 9 The state change of the hydraulic drive device 107 corresponding to the input of the pressure sensor failure diagnosis input generating device 59 is shown. Fig. 9 1, only the operation during the fault diagnosis of the pressure sensor 70a on the cover side of the boom cylinder 1 is shown. In addition, it is assumed that the arm 4 and the bucket 6 have already taken the diagnosis posture.

[0143] From time t10 to time t11, the pressure sensor failure diagnosis input generating device 59 is not activated, the input of the boom lever 56a is 0, and the boom cylinder 1 is stationary.

[0144] At time t11, the pressure sensor fault diagnosis input generating device 59 is started, and the input of the boom rod 56a is adjusted until the stroke of the boom cylinder 1 reaches the diagnosis stroke at time t12. The input of the boom rod 56a starts at time t11, and soon the switching valve 43a opens, and the closed-circuit pump 12 is connected to the boom cylinder 1. The input of the boom rod 56a decreases as the stroke of the boom cylinder 1 approaches the diagnosis stroke.

[0145] When the stroke of the boom cylinder 1 reaches the diagnosis stroke at time t12, the switching valve 43a is closed, and from time t12 to time t13, the switching valves 43a, 45a, 47a, and 49a are opened.

[0146] From time t13 to time t14, the failure diagnosis of the pressure sensor 70a is performed, and from time t14 to time t15, the switching valves 43a, 45a, 47a, and 49a are closed.

[0147] (Summarize)

[0148] In the present embodiment, the construction machinery comprises: a working device 106; actuators 1, 3, 5, which drive the working device 106; a plurality of variable capacity closed-circuit pumps 12, 14, 16, 18, which have two inlet and outlet ports; a plurality of closed-circuit switching valves 43a~43d, 45a~45d, 47a~47d, which can switch the connection or disconnection between the actuators 1, 3, 5 and the plurality of closed-circuit pumps 12, 14, 16, 18; posture sensors 400~403, which detect the posture of the working device 106; a plurality of closed-circuit pump pressure sensors 80a, 80b, 82a, 82b, 84a, 84b, 86a, 86b, which detect the pressure of the plurality of closed-circuit pumps 12, 14, 16, 18; and actuators 1, 3, 5, which drive the working device 106. The actuator pressure sensors 70a, 70b, 71a, 71b, 72a, 72b detect the pressure of the actuators 1, 3, 5; the operating device 56 indicates the action of the actuators 1, 3, 5; and the controller 57 controls the multiple closed-loop switching valves 43a~43d, 45a~45d, 47a~47d and the multiple closed-loop pumps 12, 14, 16, 18 according to the input signal from the operating device 56. When the operating oil is supplied to the actuators 1, 3, 5 from one of the multiple closed-loop pumps 12, 14, 16, 18, the controller 57 controls the one closed-loop pump and then opens a closed-loop switching valve corresponding to the one closed-loop pump, so that the pressure difference before and after the closed-loop switching valve is a specified first threshold value. The pressure difference before and after the closed-loop switching valve refers to the difference between the measured value of the closed-loop pump pressure sensor corresponding to the one closed-loop pump and the measured value of the actuator pressure sensor 70a, 70b, 71a, 71b, 72a, 72b when the one closed-loop switching valve corresponding to the one closed-loop pump among the multiple closed-loop switching valves 43a~43d, 45a~45d, 47a~47d is closed, wherein the controller 57 controls the pressure of the closed-loop pump 80a, 80b, 82a, 82b, 84a, 84b, 86a, 86b according to the multiple closed-loop pump pressure sensors 80a, 80b, 82a, 82b, 84a, 84b, 86a, 86b when two or more closed-loop pumps among the multiple closed-loop pumps 12, 14, 16, 18 are connected to the actuators 1, 3, 5. The measured values ​​of the two or more closed-loop pump pressure sensors corresponding to the two or more closed-loop pumps and the measured values ​​of the actuator pressure sensors 70a, 70b, 71a, 71b, 72a, 72b are used to determine whether the actuator pressure sensors 70a, 70b, 71a, 71b, 72a, 72b are faulty. When the controller 57 determines that the actuator pressure sensors 70a, 70b, 71a, 71b, 72a, 72b are faulty, the pseudo pressure of the actuators 1, 3, 5 is calculated based on the measured values ​​of the posture sensors 400~403, and the pseudo pressure is used instead of the measured values ​​of the actuator pressure sensors 70a, 70b, 71a, 71b, 72a, 72b to calculate the pressure difference before and after the closed-loop switching valve.

[0149] According to the present embodiment configured as described above, based on the comparison result of the measured values ​​of the actuator pressure sensors 70a, 70b, 71a, 71b, 72a, 72b, 73a, 73b and the measured values ​​of two or more closed circuit pump pressure sensors, it is possible to accurately determine the failure of the actuator pressure sensors 70a, 70b, 71a, 71b, 72a, 72b, 73a, 73b. In addition, when the actuator pressure sensors 70a, 70b, 71a, 71b, 72a, 72b fail, the front-rear pressure difference of the closed circuit switching valves 43a to 43d, 45a to 45d, 47a to 47d is calculated using the pseudo pressure of the actuators 1, 3, 5 calculated corresponding to the posture of the working device 106 instead of the measured value of the failed pressure sensor. As a result, the shock when the closed circuit pumps 12 , 14 , 16 , and 18 are connected to the actuators 1 , 3 , and 5 can be suppressed, thereby preventing the operability from being deteriorated.

[0150] In addition, the hydraulic excavator 100 in the present embodiment has: a plurality of variable capacity open circuit pumps 13, 15, 17, 19, which have an inflow port and an outflow port; a plurality of open circuit switching valves 44a to 44d, 46a to 46d, 48a to 48d, 50a to 50d, which can connect the plurality of open circuit pumps 13, 15, 17, 19 to the actuators 1, 3, 5; and a plurality of open circuit pump pressure sensors 81, 83, 85, 87, which detect the pressure of the plurality of open circuit pumps 13, 15, 17, 19, and at the start When working oil is supplied from one of the multiple open-circuit pumps 13, 15, 17, 19 to the actuators 1, 3, 5, the controller 57 controls the one open-circuit pump and then opens an open-circuit switching valve corresponding to the one open-circuit pump, so that the pressure difference before and after the open-circuit switching valve is below the first threshold value, wherein the pressure difference before and after the open-circuit switching valve refers to: when one of the multiple open-circuit switching valves 44a~44d, 46a~46d, 48a~48d, 50a~50d corresponding to the one open-circuit pump is opened, the pressure difference before and after the open-circuit switching valve is below the first threshold value. In the state where the switching valve is closed, the difference between the measurement value of an open-circuit pump pressure sensor corresponding to the one open-circuit pump and the measurement value of the actuator pressure sensors 70a, 70b, 71a, 71b, 72a, 72b, when two or more open-circuit pumps among the plurality of open-circuit pumps 13, 15, 17, 19 are connected to the actuators 1, 3, 5, the controller 57 generates an output signal based on the measurement value of two or more open-circuit pump pressure sensors among the plurality of open-circuit pump pressure sensors 81, 83, 85, 87 corresponding to the two or more open-circuit pumps. The controller 57 uses the pseudo pressure to calculate the pressure difference before and after the open-loop switching valve based on the measured values ​​of the actuator pressure sensors 70a, 70b, 71a, 71b, 72a, 72b and the measured values ​​of the actuator pressure sensors 70a, 70b, 71a, 71b, 72a, 72b. When the controller 57 determines that the actuator pressure sensors 70a, 70b, 71a, 71b, 72a, 72b are faulty, the pseudo pressure is used instead of the measured values ​​of the actuator pressure sensors 70a, 70b, 71a, 71b, 72a, 72b to calculate the pressure difference before and after the open-loop switching valve. Thus, based on the comparison result of the measured values ​​of the actuator pressure sensors 70a, 70b, 71a, 71b, 72a, 72b, 73a, 73b and the measured values ​​of the two or more open circuit pump pressure sensors, it is possible to accurately determine the failure of the actuator pressure sensors 70a, 70b, 71a, 71b, 72a, 72b, 73a, 73b. In addition, when the actuator pressure sensors 70a, 70b, 71a, 71b, 72a, 72b fail, the front-rear pressure difference of the open circuit switching valves 44a to 44d, 46a to 46d, 48a to 48d is calculated using the pseudo pressure of the actuators 1, 3, 5 calculated corresponding to the posture of the working device 106 instead of the measured value of the failed pressure sensor.As a result, the shock when the open circuit pumps 13, 15, 17, 19 are connected to the actuators 1, 3, 5 can be suppressed, and thus, the operability can be prevented from being deteriorated.

[0151] In addition, the controller 57 in this embodiment calculates the difference of the measured values ​​according to the combination of the actuator pressure sensors 70a-72b, the two or more closed-circuit pump pressure sensors, and the two or more open-circuit pump pressure sensors when the two or more closed-circuit pumps and the actuators 1, 3, and 5 are connected, and determines that the pressure sensors included in the combination of two or more pressure sensors whose difference is greater than the specified second threshold value Plim are faulty. Thus, in addition to the actuator pressure sensors 70a-72b, the closed-circuit pump pressure sensors 80a, 80b, 82a, 82b, 84a, 84b, 86a, 86b and the open-circuit pump pressure sensors 81, 83, 85, 87 can also be detected.

[0152] In addition, the hydraulic excavator 100 in the present embodiment includes a display device 58 capable of displaying information output from the controller 57. When the controller 57 determines that one pressure sensor included in the actuator pressure sensors 70a, 70b, 71a, 71b, 72a, 72b, the two or more closed-circuit pump pressure sensors, and the two or more open-circuit pump pressure sensors is faulty, the controller 57 outputs identification information of the one pressure sensor to the display device 58. Thus, the time until the faulty pressure sensor is corrected or replaced can be shortened.

[0153] In addition, the controller 57 in this embodiment calculates the pseudo pressure as a value greater than the pressure of the actuators 1, 3, and 5 when the working device 106 takes the posture detected by the posture sensors 400 to 403 in the unloaded state. Therefore, even if the actuator pressure sensors 70a, 70b, 71a, 71b, 72a, 72b, 73a, and 73b fail in the state where a load is applied to the working device 106, the impact when the switching valves 43a to 49d are opened can be suppressed.

[0154] In addition, the hydraulic excavator 100 in the present embodiment includes a pressure sensor fault diagnosis input generating device 59 that can adjust the input and output of the controller 57. By adjusting the input and output by the pressure sensor fault diagnosis input generating device 59, the controller 57 controls the plurality of closed-circuit pumps 12, 14, 16, 18 and the plurality of closed-circuit switching valves so that the working device 106 takes a predetermined posture (diagnosis posture), and then maintains the plurality of closed-circuit pumps 12, 14, 16, 18 connected to the actuators 1, 3, 5 in a state where the discharge flow rates of the plurality of closed-circuit pumps 12, 14, 16, 18 are zero. Thus, the fault diagnosis process of the pressure sensor is performed in a state where the hydraulic excavator 100 is stationary in the diagnosis posture, that is, in a state where the pressure on the pipeline is uniformized without the influence of the flow pressure loss characteristic, so that the accuracy of fault detection can be improved.

[0155] The embodiments of the present invention are described in detail above, but the present invention is not limited to the above embodiments and includes various modifications. For example, the above embodiments are described in detail to explain the present invention in an easy-to-understand manner, and the present invention is not limited to having all the structures described.

[0156] Explanation of symbols

[0157] 1… boom cylinder (actuator), 1a… cover chamber, 1b… rod chamber, 1c… rod, 1d… cylinder, 1e… piston, 2… boom, 3… arm cylinder (actuator), 3a… cover chamber, 3b… rod chamber, 3c… rod, 3d… cylinder, 3e… piston, 4… arm, 5… bucket cylinder (actuator), 5a… cover chamber, 5b… rod chamber, 5c… rod, 5d… cylinder, 5e… piston, 6… bucket, 7… swing motor (actuator), 8a, 8b… travel motor, 9… engine, 10… power transmission device, 11… supply pump, 12… first closed circuit pump, 12a… regulator, 13… first open circuit pump, 13a… regulator, 14… second closed circuit pump, 14a… regulator, 15… second open circuit pump, 15a… regulator Regulator, 16…3rd closed circuit pump, 16a…regulator, 17…3rd open circuit pump, 17a…regulator, 18…4th closed circuit pump, 18a…regulator, 19…4th open circuit pump, 19a…regulator, 20…supply relief valve, 21 to 24…relief valve, 25…working oil tank, 26 to 29…supply check valve, 30a, 30b, 31a, 31b, 32a, 32b, 33a, 33b…relief valve, 34 to 36…flush valve, 37a, 37b, 38a, 38b, 39a, 39b…relief valve, 40a, 40b, 41a, 41b, 42a, 42b…supply check valve, 43a to 43d, 45a to 45d, 47a to 47d, 49a to 4 9d...switching valve (closed circuit switching valve), 44a~44d, 46a~46d, 48a~48d, 50a~50d...switching valve (open circuit switching valve), 51a, 51b, 52a, 52b, 53a, 53b...relief valve, 54, 55...proportional switching valve, 56...operating device, 56a...boom lever, 56b...arm lever, 56c...bucket lever, 56d...swing lever, 57...controller, 57a...lever operation amount calculation unit, 57b...pressure calculation unit, 57c...actuator distribution flow calculation unit, 57d...pressure sensor failure detection unit, 57e...pseudo pressure calculation unit, 58...display device, 59...pressure sensor failure diagnosis input generation device, 64~67...proportional valve, 70a, 70b, 71a, 71b, 72a, 72b, 73a, 73b...pressure sensor (actuator pressure sensor), 80a, 80b, 82a, 82b, 84a, 84b, 86a, 86b...pressure sensor (closed circuit pump pressure sensor), 81, 83, 85, 87...pressure sensor (open circuit pump pressure sensor), 100...hydraulic excavator, 101...operating cab, 101a, 101b...traveling device, 102...lower traveling body, 103...upper swing body, 104...operating cab, 105...swinging device, 106...front working machine (working device), 107...hydraulic drive device, 200-202...flow path, 202a...branch flow path, 203-205...flow path,205a... branch flow path, 206 to 208... flow path, 208a... branch flow path, 209 to 211... flow path, 211a... branch flow path, 212 to 225... flow path, 301 to 304... connection flow path, 305a to 305d, 306a to 306d, 307a to 307d, 308a to 308d... connection flow path for open circuit, 309a to 309c... connection flow path for closed circuit, 400 to 403... posture sensor, A to D... closed circuit, E to H... open circuit.

Claims

1. An engineering machine having: Operating equipment; an actuator that drives the working device; A variable capacity multiple closed circuit pump having two inlet and outlet ports; A plurality of closed-loop switching valves capable of switching the connection or disconnection between the actuator and the plurality of closed-loop pumps; a posture sensor that detects the posture of the working device; a plurality of closed-loop pump pressure sensors, which detect the pressure of the plurality of closed-loop pumps; an actuator pressure sensor that detects the pressure of the actuator; an operating device for instructing the action of the actuator; as well as a controller that controls the plurality of closed-loop switching valves and the plurality of closed-loop pumps according to an input signal from the operating device, When the operating oil starts to be supplied from one of the multiple closed-loop pumps to the actuator, the controller controls the one closed-loop pump and then opens a closed-loop switching valve corresponding to the one closed-loop pump, so that the pressure difference before and after the closed-loop switching valve is below a specified first threshold value, wherein the pressure difference before and after the closed-loop switching valve refers to: when one of the multiple closed-loop switching valves corresponding to the one closed-loop pump is closed, the difference between the measured value of the closed-loop pump pressure sensor corresponding to the one closed-loop pump and the measured value of the actuator pressure sensor, It is characterized in that In a state where two or more closed-loop pumps among the plurality of closed-loop pumps are connected to the actuator, the controller determines whether the actuator pressure sensor is faulty based on measurement values ​​of two or more closed-loop pump pressure sensors among the plurality of closed-loop pump pressure sensors corresponding to the two or more closed-loop pumps and a measurement value of the actuator pressure sensor. When the controller determines that the actuator pressure sensor is faulty, the controller calculates a pseudo pressure of the actuator based on a measurement value of the posture sensor, and calculates a pressure difference across the closed-circuit switching valve using the pseudo pressure instead of the measurement value of the actuator pressure sensor.

2. The construction machinery according to claim 1, characterized in that: The engineering machinery has: A plurality of open circuit pumps of a variable capacity type having an inflow port and an outflow port; a plurality of open-loop switching valves capable of connecting the plurality of open-loop pumps to the actuator; as well as a plurality of open-loop pump pressure sensors, which detect the pressure of the plurality of open-loop pumps, When the operating oil starts to be supplied from one of the plurality of open-circuit pumps to the actuator, the controller controls the one open-circuit pump and then opens an open-circuit switching valve corresponding to the one open-circuit pump, so that the pressure difference before and after the open-circuit switching valve is below the first threshold value, wherein the pressure difference before and after the open-circuit switching valve refers to: when one of the plurality of open-circuit switching valves corresponding to the one open-circuit pump is closed, the difference between the measured value of the open-circuit pump pressure sensor corresponding to the one open-circuit pump and the measured value of the actuator pressure sensor, In a state where two or more open-circuit pumps among the plurality of open-circuit pumps are connected to the actuator, the controller determines whether the actuator pressure sensor is faulty based on measurement values ​​of two or more open-circuit pump pressure sensors among the plurality of open-circuit pump pressure sensors corresponding to the two or more open-circuit pumps and a measurement value of the actuator pressure sensor. When the controller determines that the actuator pressure sensor is faulty, the controller calculates the differential pressure across the open circuit switching valve using the pseudo pressure instead of the measured value of the actuator pressure sensor.

3. The construction machinery according to claim 2, characterized in that: When the two or more closed-loop pumps and the two or more open-loop pumps are connected to the actuator, the controller calculates the difference in measured values ​​according to a combination of two pressure sensors included in the actuator pressure sensor, the two or more closed-loop pump pressure sensors, and the two or more open-loop pump pressure sensors, and determines that the pressure sensor included in the combination of two or more pressure sensors whose difference is larger than a specified second threshold value is faulty.

4. The construction machine according to claim 3, characterized in that: The construction machine has a display device capable of displaying information output from the controller. The controller outputs identification information of one pressure sensor to the display device when determining that one pressure sensor included in the actuator pressure sensor, the two or more closed-circuit pump pressure sensors, and the two or more open-circuit pump pressure sensors is faulty.

5. The construction machine according to claim 1, characterized in that: The controller calculates the pseudo pressure as a value equal to or greater than the pressure of the actuator when the working device takes the posture detected by the posture sensor in a no-load state.

6. The construction machine according to claim 1, characterized in that: The engineering machine comprises: a pressure sensor fault diagnosis input generating device capable of adjusting the input and output of the controller, The pressure sensor fault diagnosis input generating device is used to adjust the input and output, whereby the controller controls the multiple closed-loop pumps and the multiple closed-loop switching valves so that the working device takes a specified posture, and then maintains the multiple closed-loop pumps connected to the actuator while making the discharge flow of the multiple closed-loop pumps zero.

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