JP2023103829A - Construction machine - Google Patents

Abstract

To provide a construction machine which can improve responsiveness of another actuator in the state where single-rod type hydraulic cylinders are driven by closed circuit pumps and opened circuit pumps.SOLUTION: A controller 57 performs control of stopping discharge of hydraulic oil of closed circuit pumps 12, 14, 16 and 18, and opened circuit pumps 13, 15, 17 and 19, and controls closed circuit switching valves 43a to 43d, 45a to 45d, 47a to 47d, and 49a to 49d so that connection destinations of the closed circuit pumps 12, 14, 16 and 18 are switched to the other actuator from first single-rod type hydraulic cylinders 1, 3 and 5, at such a timing after signals corresponding to the state where the discharge of the hydraulic oil of the closed circuit pumps 12, 14, 16 and 18 is stopped have been acquired from sensors 12b, 13b, ... and 19b, and before signals corresponding to the state where the discharge of the hydraulic oil of the opened circuit pumps 13, 15, 17 and 19 is stopped are acquired from the sensors 12b, 13b, ... and 19b.SELECTED DRAWING: Figure 2

Description

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

In recent years, in construction machinery such as hydraulic excavators, hydraulic oil is directly sent from a hydraulic pump, which is a source of pressure, to a single-rod hydraulic cylinder, which is a hydraulic actuator, and the single-rod hydraulic cylinder is driven to perform a predetermined work. A so-called closed-circuit hydraulic circuit is known in which the hydraulic oil after being discharged is directly returned to the single-rod hydraulic cylinder in a closed-circuit manner.

Patent Document 1 discloses a conventional technique that combines this type of closed circuit. Patent Document 1 discloses a closed circuit hydraulic fluid inflow/outflow control unit having two inflow/outflow ports that allow hydraulic fluid to flow in and out in both directions, and a single rod having a first hydraulic fluid chamber and a second hydraulic fluid chamber. and a plurality of closed circuits in which two inflow/outflow ports of the closed-circuit hydraulic fluid inflow/outflow control unit are connected to the first hydraulic fluid chamber and the second hydraulic fluid chamber in a closed circuit fashion. an open circuit hydraulic fluid inflow/outflow control unit having an inflow port for inflowing hydraulic fluid from a hydraulic fluid tank and an outflow port for outflowing hydraulic fluid; and an open circuit switching section for switching a supply destination of the hydraulic oil flowing out from the open circuit hydraulic oil inflow/outflow control section to one of the plurality of closed circuits, wherein: A plurality of the open circuit hydraulic fluid inflow/outflow control units and the open circuit switching units are provided corresponding to the plurality of the closed circuits, respectively, and the plurality of the closed circuit hydraulic fluid inflow/outflow control units and the plurality of the open circuits are provided. and a controller for controlling each of the hydraulic fluid inflow/outflow control section and the plurality of open circuit switching sections, wherein the controller is connected to one of the plurality of open circuits for each of the plurality of closed circuits. A driving device for a work machine is described, which is characterized by controlling each of the plurality of open circuit switching units so as to be connected.

Patent No. 6134614

In the prior art disclosed in the above-mentioned Patent Document 1, it is assumed that the response characteristics of the closed circuit pump and the open circuit pump are the same, and a method of determining the supply flow rate based on the pressure receiving area ratio of the single-rod hydraulic cylinder is described. ing. However, when a general swash plate type or oblique shaft type variable displacement axial piston is used for a pump, a closed circuit pump that can switch the discharge direction between two directions is more suitable for the maximum tilt of the swash plate mechanism or oblique shaft mechanism. Responsiveness is high in the direction of minimum tilt. This is because the open circuit pump has a unidirectional driving force generating mechanism that tilts the swash plate mechanism or the tilt shaft mechanism from the minimum tilt position to the maximum tilt position, and the return to the minimum tilt can use a spring. This is because closed circuit pumps are equipped with a drive force generating mechanism for changing tilting in both directions, as opposed to many. In this way, although the closed circuit pump has higher responsiveness from maximum tilting to minimum tilting than the open circuit pump, the high responsiveness of the closed circuit pump has not been utilized for operability in the prior art.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and its object is to improve the responsiveness of other actuators in a state in which a single-rod hydraulic cylinder is driven by a closed-circuit pump and an open-circuit pump. To provide a construction machine capable of

In order to achieve the above object, the present invention provides a closed circuit pump having two inflow/outflow ports through which hydraulic fluid can flow in and out, an open circuit pump having hydraulic fluid inflow and outflow ports, and a first single-rod hydraulic cylinder and other actuators, a first single-rod hydraulic cylinder and other actuators for each of said closed-circuit pump and said open-circuit pump; a plurality of actuators connected to the closed circuit pump and the open circuit pump so that hydraulic fluid can be supplied from the a closed circuit switching valve for switching between conduction and interruption of a flow path of hydraulic fluid between the closed circuit pump and the plurality of actuators so as to be connected in a circuit; an open circuit switching valve for switching between conduction and interruption of flow paths of hydraulic oil between the open circuit pump and the plurality of actuators so as to be selectively supplied to any one of the plurality of actuators; and the closed circuit. In a construction machine comprising a pump, said open circuit pump, said closed circuit switching valve, and a controller for controlling said open circuit switching valve, said controller controls said closed circuit pump to be connected to said first single rod hydraulic cylinder. and the open circuit pump is supplying hydraulic oil to the first single rod hydraulic cylinder, when performing control to switch the connection destination of the closed circuit pump to the other actuator, the closed circuit After performing control to stop the discharge of hydraulic oil from the pump and the open circuit pump, and after acquiring from the sensor a signal corresponding to the state in which the discharge of hydraulic oil from the closed circuit pump is stopped, and from the open circuit pump The connection destination of the closed circuit pump is switched from the first single-rod hydraulic cylinder to the other actuator at a timing before acquiring from the sensor a signal corresponding to a state in which the discharge of hydraulic oil is stopped. Secondly, the closed circuit switching valve is controlled.

According to the present invention configured as described above, when changing the connection destination of the closed circuit pump to another actuator while the closed circuit pump and the open circuit pump are driving the first single-rod hydraulic cylinder, By causing the closed circuit pump to stop discharging hydraulic oil earlier than the open circuit pump to stop discharging, it is possible to advance the timing of connecting the closed circuit pump to another actuator. As a result, the timing of starting to drive the other actuators can be made earlier than when the discharge of the closed circuit pump is stopped in synchronization with the open circuit pump, so that the responsiveness of the other actuators to the operation input can be improved. becomes possible.

According to the construction machine of the present invention, it is possible to improve the responsiveness of other actuators while the single-rod hydraulic cylinder is being driven by the closed-circuit pump and the open-circuit pump.

It is a schematic diagram showing a hydraulic excavator in an embodiment of the present invention. 1 is a hydraulic circuit diagram of a hydraulic drive system mounted on a hydraulic excavator according to an embodiment of the present invention; FIG. 3 is a functional block diagram of a controller in an embodiment of the invention; FIG. 4 is a time chart showing behavior of a hydraulic drive system to which the present invention is applied; 4 is an enlarged time chart showing part of the behavior of the hydraulic drive system to which the present invention is applied (at the start of a combined operation of boom raising, swinging, and arm dumping); 4 is a time chart showing the behavior of a hydraulic drive system to which the present invention is not applied; 4 is a flow chart showing connection destination switching processing of the closed circuit pump by the controller in the embodiment of the present invention.

Hereinafter, a hydraulic excavator will be described as an example of a construction machine according to an embodiment of the present invention with reference to the drawings. In addition, in each figure, the same code|symbol is attached|subjected to the same member, and the overlapping description is abbreviate|omitted suitably.

FIG. 1 is a schematic diagram showing a hydraulic excavator according to this embodiment. FIG. 2 is a hydraulic circuit diagram of a hydraulic drive system mounted on the hydraulic excavator 100. As shown in FIG.

As shown in FIG. 1, a hydraulic excavator 100 includes a lower traveling body 102 having crawler-type traveling devices 101a and 101b on both sides in the left-right direction, and an upper body as a main body mounted on the lower traveling body 102 so as to be able to turn. and a revolving body 103 . A cab 104 on which an operator rides is provided on the upper revolving body 103 . The lower traveling body 102 and the upper revolving body 103 are attached so as to be able to revolve via a revolving device 105 . Traveling devices 101 a and 101 b are driven by travel motors 8 a and 8 b, and turning device 105 is driven by turning motor 7 .

On the front side of the upper revolving body 103, a base end portion of a front work machine 106, which is a work device for performing excavation work or the like, is rotatably attached. Here, the front side refers to the direction in which the operator riding in the cab 104 faces (the left direction in FIG. 1). The front work machine 106 includes a boom 2 whose base end is connected to the front side of the upper revolving body 103 so as to be able to be raised and lowered. The boom 2 operates via a boom cylinder 1, which is a single-rod hydraulic cylinder driven by working oil (pressure oil) as a supplied fluid. The boom cylinder 1 has a rod 1c whose distal end is connected to the upper rotating body 103, and a cylinder tube 1d whose proximal end is connected to the boom 2. As shown in FIG.

Further, as shown in FIG. 2, the boom cylinder 1 is located on the proximal end side of the cylinder tube 1d and is supplied with hydraulic oil to press the piston 1e attached to the proximal end of the rod 1c to increase the hydraulic pressure. The cap chamber 1a, which is the first hydraulic oil chamber on the cap side, is provided to extend and move the rod 1c by applying a load of . Further, the boom cylinder 1 is positioned on the tip side of the cylinder tube 1d and is supplied with hydraulic oil to press the piston 1e and apply a load due to the hydraulic pressure to move the rod 1c retractingly. A rod chamber 1b is provided as an oil chamber.

Returning to FIG. 1, the base end of an arm 4 is connected to the tip of the boom 2 so as to be vertically movable. Arm 4 operates via arm cylinder 3, which is a single-rod hydraulic cylinder. The arm cylinder 3 has a rod 3 c whose tip end is connected to the arm 4 , and a cylinder tube 3 d of the arm cylinder 3 is connected to the boom 2 .

Further, as shown in FIG. 2, the arm cylinder 3 is positioned on the proximal end side of the cylinder tube 3d and is supplied with hydraulic oil to press the piston 3e attached to the proximal end portion of the rod 3c, thereby It has a cap chamber 3a for extending and moving 3c. The arm cylinder 3 is provided with a rod chamber 3b which is located on the tip end side of the cylinder tube 3d and presses the piston 3e by being supplied with hydraulic oil to retract and move the rod 3c.

Returning to FIG. 1, the base end of the bucket 6 is connected to the tip of the arm 4 so as to be vertically movable. The bucket 6 operates via a bucket cylinder 5, which is a single-rod hydraulic cylinder as a hydraulic actuator driven by supplied hydraulic oil. The bucket cylinder 5 has a rod 5 c with a distal end connected to the bucket 6 , and a cylinder tube 5 d of the bucket cylinder 5 with a base end connected to the arm 4 .

Further, as shown in FIG. 2, the bucket cylinder 5 is positioned on the proximal end side of the cylinder tube 5d and is supplied with hydraulic oil to press the piston 5e attached to the proximal end portion of the rod 5c, thereby It has a cap chamber 5a for extending and moving 5c. The bucket cylinder 5 is provided with a rod chamber 5b which is positioned on the tip end side of the cylinder tube 5d and presses the piston 5e by being supplied with hydraulic oil to retract and move the rod 5c.

The boom cylinder 1, the arm cylinder 3, and the bucket cylinder 5 are each telescopically operated by the supplied hydraulic fluid, and are driven to extend and retract depending on the direction in which the supplied hydraulic fluid is supplied.

As shown in FIG. 2, the hydraulic drive device 107 forms a closed circuit to supply hydraulic oil to three types of single-rod hydraulic cylinders and one type of hydraulic motor (swing motor 7 in this embodiment). It has four closed circuit pumps configured to be able to discharge and four open circuit pumps configured to be able to supply and discharge working oil by configuring an open circuit. Further, the hydraulic drive device 107 has a configuration capable of controlling the flow rate by combining one closed-circuit pump and one open-circuit pump when driving the single-rod hydraulic cylinder.

More specifically, the hydraulic drive device 107 is provided in each hydraulic oil flow path between the port of each hydraulic pump and each cylinder and motor, and independently switches between conduction and interruption of the flow path. It has a plurality of switching valves that can Each of the switching valves can be controlled, for example, so that a plurality of closed-circuit pumps and a plurality of open-circuit pumps can merge with one single-rod hydraulic cylinder. Further, for example, at the time of merging into one single-rod hydraulic cylinder, the controller controls the switching valve so that one closed circuit pump and one open circuit pump are combined and merged.

The hydraulic drive device 107 is a drive device for driving the hydraulic excavator 100 and is mounted on the upper revolving body 103 . Hydraulic drive device 107 is used to drive not only boom cylinder 1, arm cylinder 3, and bucket cylinder 5, which constitute front working machine 106, but also swing motor 7 and traveling motors 8a and 8b. The turning motor 7 and the traveling motors 8a and 8b are hydraulic motors that are driven to rotate by being supplied with hydraulic oil.

In addition, the hydraulic drive device 107 operates in accordance with the operation of an operation lever device 56 as an operation unit installed in the cab 104, which is a boom cylinder 1, an arm cylinder 3, a bucket cylinder 5, a swing motor 7, and a swing motor 7, which are hydraulic actuators. The travel motors 8a and 8b are driven. Here, the telescopic motion of the boom cylinder 1, the arm cylinder 3, and the bucket cylinder 5, that is, the motion direction and motion speed, are indicated by the operation direction and the operation amount of each operation lever 56a, 56b, 56c, 56d of the operation lever device 56. be done.

Further, the hydraulic drive device 107 has an engine 9 as a power source. The engine 9 is connected to a power transmission device 10 configured with, for example, predetermined gears and the like for distributing power. Connected to the power transmission device 10 are hydraulic pumps 12, 13, .

The hydraulic pumps 12, 14, 16, and 18 each have a double-tilt swash plate mechanism (not shown) having two input/output ports, i.e., a pair of input/output ports, which can flow hydraulic oil in both directions. and regulators 12a, 14a, 16a, and 18a as flow control units for adjusting the tilt angle (tilt angle) of the double-tilt type swash plate that constitutes the double-tilt swash plate mechanism. 1 to 4 closed circuit pumps. The regulators 12a, 14a, 16a, 18a adjust the tilt angles of the swash plates of the corresponding first to fourth closed circuit pumps 12, 14, 16, 18 according to the operation signal output from the controller 57 as a control unit. , to control the flow rate of hydraulic oil discharged from the first to fourth closed circuit pumps 12, 14, 16, 18.

Therefore, the first to fourth closed circuit pumps 12, 14, 16, 18 can control the discharge flow rate and discharge direction of hydraulic oil from the input/output ports by adjusting the tilt angle of the swash plate. there is Also, the first to fourth closed circuit pumps 12, 14, 16, 18 function as hydraulic motors when supplied with hydraulic oil.

Hydraulic pumps 13, 15, 17, and 19 comprise a single-tilt swash plate mechanism (not shown) having an outflow port that allows hydraulic oil to flow in and out in one direction, and this single-tilt swash plate mechanism. The first to fourth open circuit pumps are provided with regulators 13a, 15a, 17a, and 19a as flow rate adjusting units for adjusting the tilting angle (tilt angle) of the single-tilting swash plate. The regulators 13a, 15a, 17a, 19a adjust the tilt angles of the swash plates of the corresponding first to fourth open circuit pumps 13, 15, 17, 19 according to the operation signal output from the controller 57 as a control unit. is adjusted to control the flow rate of hydraulic oil discharged from the first to fourth open circuit pumps 13, 15, 17, 19.

Therefore, the first to fourth open circuit pumps 13, 15, 17, 19 can control the discharge flow rate of hydraulic oil from the outflow port by adjusting the tilt angle of the swash plate.

Further, the tilting swash plate mechanisms of the hydraulic pumps 12, 13, . . . , 19 are provided with tilting angle sensors 12b, 13b, . The time chart shown in 4 can be used when the discharge flow rate is used as a trigger for the switching timing of the switching valve. Alternatively, means for measuring the control pressure of the regulators of the hydraulic pumps 12, 13, .

In addition, the first to fourth closed circuit pumps 12, 14, 16, 18 control the tilting angle of the swash plate in two directions. The first to fourth open circuit pumps 13, 15, 17, 19 control the tilting angle of the swash plate in one direction. Therefore, the driving force by the regulator acts only in the direction of maximizing the tilt angle, and the return to the minimum angle depends on the restoring force of the spring. Therefore, the first to fourth closed circuit pumps 12, 14, 16, 18 have higher responsiveness when controlling the tilt angle in the direction of decreasing the discharge amount.

Specifically, a channel 200 is connected to one input/output port of the first closed circuit pump 12, and a channel 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, respectively. The switching valves 43a, 43b, and 43c 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 which are connected to the first closed circuit pump 12 in a closed circuit. is. The switching valve 43d is a hydraulic motor closed circuit switching valve for switching the supply of hydraulic oil to the swing motor 7 connected to the first closed circuit pump 12 in a closed circuit. The switching valves 43a, 43b, 43c, and 43d are configured to switch between conduction and interruption of the flow paths 200 and 201 in response to an operation signal output from the controller 57. When the operation signal output from the controller 57 is If not, it is cut off. The controller 57 controls the switching valves 43a, 43b, 43c, and 43d so that they are not conductive at the same time.

Further, the switching valve 43a is connected to the boom cylinder 1 via flow paths 212,213. Therefore, when the switching valve 43a is turned on in response to the operation signal output from the controller 57, the first closed circuit pump 12 closes the flow paths 200 and 201, the switching valve 43a, and the flow paths 212 and 213. A closed circuit A that is connected to the boom cylinder 1 in a closed circuit fashion is constructed.

A pressure sensor 70 a connected to the flow path 212 measures the pressure of the flow path 212 and inputs it to the controller 57 . A pressure sensor 70 b connected to the flow path 213 measures the pressure of the flow path 213 and inputs it to the controller 57 .

Further, the switching valve 43b is connected to the arm cylinder 3 via flow paths 214 and 215. As shown in FIG. Therefore, the first closed circuit pump 12 closes the flow paths 200 and 201, the switching valve 43b, and the flow paths 214 and 215 when the switching valve 43b is brought into the conductive state in response to the operation signal output from the controller 57. A closed circuit B connected to the arm cylinder 3 via the closed circuit is constructed.

A pressure sensor 71 a connected to the flow path 214 measures the pressure of the flow path 214 and inputs it to the controller 57 . A pressure sensor 71 b connected to the flow path 215 measures the pressure of the flow path 215 and inputs it to the controller 57 .

Further, the switching valve 43c is connected to the bucket cylinder 5 via flow paths 216,217. Therefore, when the operation signal from the controller 57 causes the switching valve 43c to be in a conductive state, the first closed circuit pump 12 is driven through the flow paths 200 and 201, the switching valve 43c, and the flow paths 216 and 217 to the bucket cylinder. A closed circuit C connected to 5 is configured in a closed circuit fashion.

A pressure sensor 72 a connected to the flow path 216 measures the pressure of the flow path 216 and inputs it to the controller 57 . A pressure sensor 72 b connected to the flow path 217 measures the pressure of the flow path 217 and inputs it to the controller 57 .

Also, the switching valve 43d is connected to the swing motor 7 via flow paths 218 and 219. As shown in FIG. Therefore, when the switching valve 43 d is brought into a conductive state by an operation signal from the controller 57 , the first closed circuit pump 12 is connected to the turning motor through the flow paths 200 and 201 , the switching valve 43 d, and the flow paths 218 and 219 . A closed circuit D connected to 7 is configured in a closed circuit fashion.

Here, the flow path 212 is a hydraulic cylinder connection flow path for independently connecting the boom cylinder 1 to a plurality of switching valves 44a, 46a, 48a, 50a of open circuits E, F, G, H, which will be described later. But also. 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 open circuits E, F, G, and H, which will be described later. be. Further, the flow path 216 is a connection flow path for hydraulic cylinders for independently connecting the bucket cylinder 5 to a plurality of switching valves 44c, 46c, 48c, 50c of open circuits E, F, G, H, which will be described later. But also.

Further, the channel 203 is connected to one input/output port of the second closed circuit pump 14, and the channel 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, respectively. The switching valves 45a, 45b, and 45c are closed circuit switching for switching the supply of hydraulic oil to the boom cylinder 1, the arm cylinder 3, and the bucket cylinder 5, which are connected to the second closed circuit pump 14 in a closed circuit fashion. valve. The switching valve 45d is a hydraulic motor closed circuit switching valve for switching the supply of hydraulic oil to the swing motor 7 connected to the second closed circuit pump 14 in a closed circuit. The switching valves 45a, 45b, 45c, and 45d are configured to switch between conduction and interruption of the flow paths 203 and 204 in accordance with an operation signal output from the controller 57. When the operation signal output from the controller 57 is If not, it will be in a cut-off state. The controller 57 controls the switching valves 45a, 45b, 45c, and 45d so that they are not conductive at the same time.

Further, the switching valve 45a is connected to the boom cylinder 1 via flow paths 212,213. Therefore, when the operation signal from the controller 57 causes the switch valve 45a to be in a conducting state, the second closed circuit pump 14 is driven through the flow paths 203, 204, the switch valve 45a, and the flow paths 212, 213 to the boom cylinder. 1 constitutes a closed circuit A connected in a closed circuit fashion. Further, the switching valve 45b is connected to the arm cylinder 3 via flow paths 214 and 215. As shown in FIG. Therefore, when the operation signal from the controller 57 causes the switching valve 45b to be in a conductive state, the second closed circuit pump 14 is operated through the flow paths 203 and 204, the switching valve 45b, and the flow paths 214 and 215 to the arm cylinder. 3 constitutes a closed circuit B connected in a closed circuit fashion.

Further, the switching valve 45c is connected to the bucket cylinder 5 via flow paths 216,217. Therefore, when the operation signal from the controller 57 causes the switching valve 45c to be in a conductive state, the second closed circuit pump 14 is driven through the flow paths 203 and 204, the switching valve 45c, and the flow paths 216 and 217 to the bucket cylinder. A closed circuit C connected to 5 is configured in a closed circuit fashion. Further, the switching valve 45d is connected to the swing motor 7 via flow paths 218 and 219. As shown in FIG. Therefore, when the operation signal from the controller 57 causes the switching valve 45d to be in a conductive state, the second closed circuit pump 14 is driven by the turning motor through the flow paths 203 and 204, the switching valve 45d, and the flow paths 218 and 219. A closed circuit D connected to 7 is configured in a closed circuit fashion.

Next, the channel 206 is connected to one input/output port of the third closed circuit pump 16, and the channel 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, respectively. The switching valves 47a, 47b, and 47c are closed circuit switching for switching the supply of hydraulic oil to the boom cylinder 1, the arm cylinder 3, and the bucket cylinder 5, which are connected to the third closed circuit pump 16 in a closed circuit fashion. valve. The switching valve 47d is a hydraulic motor closed circuit switching valve for switching the supply of hydraulic oil to the swing motor 7 connected to the third closed circuit pump 16 in a closed circuit. The switching valves 47a, 47b, 47c, and 47d are configured to switch between conduction and interruption of the flow path in response to an operation signal output from the controller 57, and when there is no operation signal output from the controller 57, It becomes a cutoff state. The controller 57 controls the switching valves 47a, 47b, 47c, and 47d so that they are not conductive at the same time.

Further, the switching valve 47a is connected to the boom cylinder 1 via flow paths 212,213. Therefore, when the operation signal from the controller 57 causes the switching valve 47a to be in a conductive state, the third closed circuit pump 16 is driven through the flow paths 206, 207, the switching valve 47a, and the flow paths 212, 213 to the boom cylinder. 1 constitutes a closed circuit A connected in a closed circuit fashion. Also, the switching valve 47b is connected to the arm cylinder 3 via flow paths 214 and 215. As shown in FIG. Therefore, when the operation signal from the controller 57 causes the switch valve 47b to be in a conductive state, the third closed circuit pump 16 is operated through the flow paths 206, 207, the switch valve 47b, and the flow paths 214, 215 to the arm cylinder. 3 constitutes a closed circuit B connected in a closed circuit fashion.

Also, the switching valve 47 c is connected to the bucket cylinder 5 via flow paths 216 and 217 . Therefore, when the operation signal from the controller 57 causes the switching valve 47c to be in a conductive state, the third closed circuit pump 16 is driven through the flow paths 206, 207, the switching valve 47c, and the flow paths 216, 217 to the bucket cylinder. A closed circuit C connected to 5 is configured in a closed circuit fashion. Further, the switching valve 47d is connected to the swing motor 7 via flow paths 218 and 219. As shown in FIG. Therefore, when the operation signal from the controller 57 causes the switching valve 47d to be in a conducting state, the third closed circuit pump 16 is driven by the turning motor through the flow paths 206 and 207, the switching valve 47d, and the flow paths 218 and 219. 7 and a closed circuit D connected in a closed circuit configuration.

Next, the channel 209 is connected to one input/output port of the fourth closed circuit pump 18, and the channel 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, respectively. The switching valves 49a, 49b, and 49c are closed circuit switching for switching the supply of hydraulic oil to the boom cylinder 1, the arm cylinder 3, and the bucket cylinder 5, which are connected to the fourth closed circuit pump 18 in a closed circuit fashion. valve. Further, the switching valve 49d is a closed circuit switching valve for the hydraulic motor for switching the supply of hydraulic oil to the turning motor 7 connected to the fourth closed circuit pump 18 in a closed circuit. The switching valves 49a, 49b, 49c, and 49d are configured to switch between conduction and blocking of the flow path according to an operation signal output from the controller 57. When the operation signal is not output from the controller 57, It is cut off. The controller 57 controls the switching valves 49a, 49b, 49c, and 49d so that they are not conductive at the same time.

The switching valve 49a is connected to the boom cylinder 1 through passages 212 and 213. As shown in FIG. Therefore, when the operation signal from the controller 57 causes the switching valve 49a to be in a conductive state, the fourth closed circuit pump 18 is driven through the flow paths 209 and 210, the switching valve 49a, and the flow paths 212 and 213 to the boom cylinder. 1 and a closed circuit A that is connected in a closed circuit configuration. Also, the switching valve 49b is connected to the arm cylinder 3 via flow paths 214 and 215. As shown in FIG. Therefore, when the operation signal from the controller 57 causes the switching valve 49b to be in a conductive state, the fourth closed circuit pump 18 is operated through the flow paths 209 and 210, the switching valve 49b, and the flow paths 214 and 215 to the arm cylinder. 3 constitutes a closed circuit B connected in a closed circuit fashion.

Further, the switching valve 49c is connected to the bucket cylinder 5 via flow paths 216,217. Therefore, when the operation signal from the controller 57 causes the switching valve 49c to be in a conducting state, the fourth closed circuit pump 18 is driven through the flow paths 209 and 210, the switching valve 49c, and the flow paths 216 and 217 to the bucket cylinder. A closed circuit C connected to 5 is configured in a closed circuit fashion. In addition, the switching valve 49d is connected to the swing motor 7 via flow paths 218 and 219. As shown in FIG. Therefore, when the operation signal from the controller 57 causes the switch valve 49d to be in a conducting state, the fourth closed circuit pump 18 is operated by the turning motor through the flow paths 209 and 210, the switch valve 49d, and the flow paths 218 and 219. A closed circuit D connected to 7 is configured in a closed circuit fashion.

Further, one input/output port of the first open circuit pump 13 is connected via a flow path 202 to a plurality of switching valves 44a, 44b, 44c, 44d and a relief valve 21, for example four. 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, and 44d switch between conduction and interruption of the flow path 202 according to an operation signal output from the controller 57, and the supply destination of the hydraulic oil flowing out from the first open circuit pump 13 is It is an open circuit switching valve that switches to connecting flow paths 301, 302, 303, and 304, which will be described later, and is closed when there is no output of an operation signal from the controller 57. FIG. The controller 57 controls the switching valves 44a, 44b, 44c, and 44d so that they are not conductive at the same time.

Also, the switching valve 44 a is connected to the boom cylinder 1 via the connecting flow path 301 and the flow path 212 . The connecting channel 301 is a connecting pipeline branched from the channel 212 . Also, the switching valve 44 b is connected to the arm cylinder 3 via the connecting flow path 302 and the flow path 214 . The connecting channel 302 is a connecting pipeline branched from the channel 214 . Furthermore, the switching valve 44 c is connected to the bucket cylinder 5 via the connecting flow path 303 and the flow path 216 . The connecting channel 303 is a connecting pipeline branched from the channel 216 . Also, the switching valve 44d is connected via a connecting flow path 304 and a flow path 220 to proportional switching valves 54 and 55, which are control valves for controlling the supply and discharge of working oil to the traveling motors 8a and 8b. On the other hand, the relief valve 21 releases the hydraulic oil in the flow path 202 to the hydraulic oil tank 25 when the working oil pressure in the flow path 202 exceeds a predetermined pressure, thereby hydraulic circuit).

A proportional valve 64 as a flow control 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 a flow path 202, which is a pipeline connecting the switching valves 44a, 44b, 44c, 44d and the first open circuit pump 13, and which is connected to the hydraulic oil tank 25. It is connected to the. Therefore, the proportional valve 64 controls the flow rate of the hydraulic fluid that flows from the flow path 202 to the hydraulic fluid tank 25 according to the operation signal output from the controller 57 . Further, the proportional valve 64 is closed when there is no operation signal output from the controller 57 .

Furthermore, one input/output port of the second open circuit pump 15 is connected to a plurality of, for example, four switching valves 46a, 46b, 46c, and 46d and a relief valve 22 via a flow path 205. As shown in FIG. 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, and 46d switch between conduction and interruption of the flow path 205 according to an operation signal output from the controller 57, and the supply destination of the hydraulic oil flowing out from the second open circuit pump 15 is selected from It is an open-circuit switching valve that switches to the connecting flow paths 301, 302, 303, and 304, and is closed when there is no operation signal output from the controller 57. FIG. The controller 57 controls the switching valves 46a, 46b, 46c, and 46d so that they are not conductive at the same time.

Also, the switching valve 46 a is connected to the boom cylinder 1 via the connecting flow path 301 and the flow path 212 . The switching valve 46 b is connected to the arm cylinder 3 via the connecting flow path 302 and the flow path 214 . Also, the switching valve 46 c is connected to the bucket cylinder 5 via the connecting flow path 303 and the flow path 216 . Switching valve 46 d is connected to proportional switching valves 54 and 55 via connecting channel 304 and channel 220 . On the other hand, the relief valve 22 releases the hydraulic oil in the flow path 205 to the hydraulic oil tank 25 to protect the flow path 205 when the hydraulic pressure in the flow path 205 exceeds a predetermined pressure.

A proportional valve 65 as a flow control 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 a flow path 205, which is a pipeline connecting the switching valves 46a, 46b, 46c, 46d and the second open circuit pump 15, and which is connected to the hydraulic oil tank 25. It is connected to the. Therefore, the proportional valve 65 controls the flow rate of the hydraulic fluid flowing from the flow path 205 to the hydraulic fluid tank 25 according to the operation signal output from the controller 57 . Also, the proportional valve 65 is closed when there is no operation signal output from the controller 57 .

Further, one input/output port of the third open circuit pump 17 is connected via a flow path 208 to a plurality of switching valves 48a, 48b, 48c, 48d and a relief valve 23, for example four. 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, and 48d switch between conduction and interruption of the flow path 208 according to an operation signal output from the controller 57, and the supply destination of the hydraulic oil flowing out from the third open circuit pump 17 is It is an open-circuit switching valve that switches to the connecting flow paths 301, 302, 303, and 304, and is closed when there is no operation signal output from the controller 57. FIG. The controller 57 controls the switching valves 48a, 48b, 48c, and 48d so that they are not conductive at the same time.

Also, the switching valve 48 a is connected to the boom cylinder 1 via the connecting flow path 301 and the flow path 212 . The switching valve 48 b is connected to the arm cylinder 3 via the connecting flow path 302 and the flow path 214 . Also, the switching valve 48 c is connected to the bucket cylinder 5 via the connecting flow path 303 and the flow path 216 . Switching valve 48 d is connected to proportional switching valves 54 and 55 via connecting channel 304 and channel 220 . On the other hand, the relief valve 23 protects the flow path 208 by releasing the hydraulic oil in the flow path 208 to the hydraulic oil tank 25 when the working oil pressure in the flow path 208 exceeds a predetermined pressure.

A proportional valve 66 as a flow control 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 a flow path 208 which is a pipeline connecting the switching valves 48a, 48b, 48c and 48d and the third open circuit pump 17 and which is connected to the hydraulic oil tank 25. It is connected to the. Therefore, the proportional valve 66 controls the flow rate of the hydraulic fluid flowing from the flow path 208 to the hydraulic fluid tank 25 according to the operation signal output from the controller 57 . Further, the proportional valve 66 is closed when there is no operation signal output from the controller 57 .

Further, one input/output port of the fourth open circuit pump 19 is connected to a plurality of, for example, four switching valves 50a, 50b, 50c, and 50d and a relief valve 24 via a flow path 211. As shown in FIG. 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 switch between conduction and interruption of the flow path 211 according to an operation signal output from the controller 57, and the supply destination of the hydraulic oil flowing out from the fourth open circuit pump 19 is set to It is an open-circuit switching valve that switches to the connecting flow paths 301, 302, 303, and 304, and is shut off when there is no operation signal output from the controller 57. FIG. The controller 57 controls the switching valves 50a, 50b, 50c and 50d so as not to be conductive at the same time.

Also, the switching valve 50 a is connected to the boom cylinder 1 via the connecting flow path 301 and the flow path 212 . The switching valve 50 b is connected to the arm cylinder 3 via the connecting flow path 302 and the flow path 214 . Also, the switching valve 50 c is connected to the bucket cylinder 5 via the connecting flow path 303 and the flow path 216 . Switching valve 50 d is connected to proportional switching valves 54 and 55 via connecting channel 304 and channel 220 . On the other hand, the relief valve 24 protects the flow path 211 by releasing the hydraulic oil in the flow path 211 to the hydraulic oil tank 25 when the working oil pressure in the flow path 211 exceeds a predetermined pressure.

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 located on a branched flow path 211a that is a pipeline that branches off from a flow path 211 that is a pipeline that connects the switching valves 50a, 50b, 50c, and 50d and the fourth open circuit pump 19 and that is connected to the hydraulic oil tank 25. It is connected to the. 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 . Further, the proportional valve 67 is closed when there is no operation signal output from the controller 57 .

Here, the connecting flow path 301 is connected to the discharge side of at least one of the switching valves 44a, 46a, 48a, 50a of the plurality of open circuits E, F, G, H, from which hydraulic oil flows out. 305a, 306a, 307a, and 308a, and a closed circuit connection flow path 309a connected to the flow path 212 forming the closed circuit A. The connecting flow path 302 is an open circuit connected to the discharge side of at least one of the switching valves 44b, 46b, 48b, 50b out of the plurality of open circuits E, F, G, H, from which hydraulic oil flows out. connection flow paths 305b, 306b, 307b, and 308b, and a closed circuit connection flow path 309b connected to the flow path 214 constituting the closed circuit B. The connecting flow path 303 is an open circuit connected to the discharge side of at least one of the switching valves 44c, 46c, 48c, 50c of the plurality of open circuits E, F, G, H, from which hydraulic oil flows out. connection flow paths 305c, 306c, 307c, and 308c, and a closed circuit connection flow path 309c connected to the flow path 216 forming the closed circuit C. The connecting flow path 304 is connected to the discharge side of at least one switching valve 44d, 46d, 48d, 50d of the plurality of open circuits E, F, G, H, from which hydraulic oil flows out. It is composed of circuit connecting channels 305 d , 306 d , 307 d and 308 d and a connecting channel 309 d connected to the channel 220 .

Hydraulic drive device 107 includes first to fourth closed circuit pumps 12, 14, 16, 18, boom cylinder 1, arm cylinder 3, bucket cylinder 5, and swing motor 7, which are connected from one input/output port of the hydraulic pump. It is composed of closed circuits A, B, C, and D which are connected to the other input/output port via actuators in a closed circuit fashion, and further includes first to fourth 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, 50d connect switching valves to one input/output port of the hydraulic pump, and the other open circuits E, F, G, and H to which the hydraulic oil tank 25 is connected. Further, the closed circuits A, B, C, D and the open circuits E, F, G, H are provided in pairs, for example, four circuits each.

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

Also, the charge check valve 26 supplies hydraulic oil from the charge pump 11 to the flow paths 200 and 201 when the hydraulic pressure in the flow paths 200 and 201 falls below the pressure set by the charge relief valve 20. . Similarly, the charge check valve 27 supplies hydraulic oil from the charge pump 11 to the flow paths 203 and 204 when the hydraulic pressure in the flow paths 203 and 204 falls below the pressure set by the charge relief valve 20. do. Also, the charge check valve 28 supplies hydraulic oil from the charge pump 11 to the flow paths 206 and 207 when the working oil pressure in the flow paths 206 and 207 falls below the pressure set by the charge relief valve 20. . Similarly, the charge check valve 29 supplies hydraulic oil from the charge pump 11 to the flow paths 209 and 210 when the hydraulic pressure in the flow paths 209 and 210 falls below the pressure set by the charge relief valve 20. do.

Further, the charging check valves 40a and 40b allow hydraulic fluid to flow from the charge pump 11 to the flow paths 212 and 213 when the working oil pressure in the flow paths 212 and 213 falls below the pressure set by the charging relief valve 20. supply. Similarly, charging check valves 41 a and 41 b allow hydraulic fluid from charge pump 11 to flow through flow paths 214 and 215 when the hydraulic pressure in flow paths 214 and 215 falls below the pressure set by charge relief valve 20 . supply. Also, the charge check valves 42a and 42b supply hydraulic oil from the charge pump 11 to the flow paths 216 and 217 when the working oil pressure in the flow paths 216 and 217 falls below the pressure set by the charge relief valve 20. supply.

A pair of relief valves 30 a and 30 b are connected between the flow paths 200 and 201 . Relief valves 30a and 30b release the hydraulic oil in flow paths 200 and 201 to hydraulic oil tank 25 via charge relief valve 20 when the hydraulic pressure in flow paths 200 and 201 exceeds a predetermined pressure. to protect the channels 200 and 201. Similarly, a pair of relief valves 31a and 31b are connected between the flow paths 203 and 204, respectively. The relief valves 31a and 31b release the hydraulic oil in the flow paths 203 and 204 to the hydraulic oil tank 25 via the charge relief valve 20 when the working oil pressure in the flow paths 203 and 204 exceeds a predetermined pressure. to protect the channels 203 and 204.

Furthermore, relief valves 32a and 32b are also connected between the flow paths 206 and 207, respectively. The relief valves 32a and 32b release the hydraulic oil in the flow paths 206 and 207 to the hydraulic oil tank 25 via the relief valve 20 for charging when the working oil pressure in the flow paths 206 and 207 exceeds a predetermined pressure. to protect the channels 206 and 207. Relief valves 33 a and 33 b are also connected between the flow paths 209 and 210 . Relief valves 33a and 33b release the hydraulic oil in flow paths 209 and 210 to hydraulic oil tank 25 via charge relief valve 20 when the working oil pressure in flow paths 209 and 210 exceeds a predetermined pressure. to protect the channels 209 and 210.

The flow path 212 is then connected to the cap chamber 1 a of the boom cylinder 1 . The flow path 213 is connected to the rod chamber 1b of the boom cylinder 1. As shown in FIG. Relief valves 37 a and 37 b are connected between the flow paths 212 and 213 . The relief valves 37a and 37b release the hydraulic oil in the flow paths 212 and 213 to the hydraulic oil tank 25 via the charge relief valve 20 when the working oil pressure in the flow paths 212 and 213 exceeds a predetermined pressure. to protect the channels 212 and 213. Furthermore, a flushing valve 34 is connected between the flow paths 212 and 213 . The flushing valve 34 discharges excess hydraulic oil (surplus oil) in the flow paths 212 and 213 to the hydraulic oil tank 25 via the charge relief valve 20 .

Also, the flow path 214 is connected to the cap chamber 3 a of the arm cylinder 3 . The flow path 215 is connected to the rod chamber 3b of the arm cylinder 3. Furthermore, relief valves 38a and 38b are connected between the flow paths 214 and 215, respectively. The relief valves 38a, 38b release the hydraulic oil in the flow paths 214, 215 to the hydraulic oil tank 25 via the charge relief valve 20 when the working oil pressure in the flow paths 214, 215 exceeds a predetermined pressure. to protect the channels 214 and 215. Furthermore, a flushing valve 35 is connected between the flow paths 214 and 215 . The flushing valve 35 discharges excess hydraulic fluid in the flow paths 214 and 215 to the hydraulic fluid tank 25 via the charge relief valve 20 .

Also, the flow path 216 is connected to the cap chamber 5 a of the bucket cylinder 5 . The flow path 217 is connected to the rod chamber 5b of the bucket cylinder 5. As shown in FIG. Furthermore, relief valves 39a and 39b are connected between the flow paths 216 and 217, respectively. The relief valves 39a and 39b release the hydraulic oil in the flow paths 216 and 217 to the hydraulic oil tank 25 via the charge relief valve 20 when the working oil pressure in the flow paths 216 and 217 exceeds a predetermined pressure. to protect the channels 216 and 217. Further, a flushing valve 36 is connected between the flow paths 216,217. The flushing valve 36 discharges excess hydraulic fluid in the flow paths 216 and 217 to the hydraulic fluid tank 25 via the charge relief valve 20 .

Furthermore, the channels 218 and 219 are connected to the turning motor 7 respectively. Relief valves 51a and 51b are connected between the flow paths 218 and 219, respectively. The relief valves 51a and 51b reduce the hydraulic oil in the high pressure side flow paths 218 and 219 to a low pressure when the pressure difference (flow path pressure difference) of the hydraulic fluid between the flow paths 218 and 219 exceeds a predetermined pressure. It escapes to the channels 219 and 218 on the side to protect the channels 218 and 219 .

Further, the proportional switching valve 54 and the traveling motor 8a are connected by flow paths 221 and 222. As shown in FIG. Relief valves 52 a and 52 b are connected between the flow paths 221 and 222 . The relief valves 52a and 52b allow the hydraulic oil in the high-pressure side flow paths 221 and 222 to flow through the low-pressure side flow paths 222 and 222 when the pressure difference of the hydraulic fluid between the flow paths 221 and 222 reaches or exceeds a predetermined pressure. 221 to protect the channels 221 and 222. The proportional switching valve 54 is configured to switch the connection destination of the flow path 220 and the hydraulic oil tank 25 to either the flow path 221 or the flow path 222 in accordance with an operation signal output from the controller 57. It is possible.

Furthermore, the proportional switching valve 55 and the traveling motor 8b are connected by flow paths 223 and 224. As shown in FIG. Relief valves 53 a and 53 b are connected between the flow paths 223 and 224 . The relief valves 53a, 53b allow the hydraulic oil in the high-pressure side flow paths 223, 224 to flow through the low-pressure side flow paths 224, 224 when the pressure difference of the hydraulic fluid between the flow paths 223, 224 exceeds a predetermined pressure. 223 to protect the channels 223 and 224. The proportional switching valve 55 is configured to switch the connection destination of the flow path 220 and the hydraulic oil tank 25 to either the flow path 223 or the flow path 224 in accordance with an operation signal output from the controller 57. It is possible.

The controller 57 receives command values for the telescopic direction and telescopic speed of the boom cylinder 1, the arm cylinder 3 and the bucket cylinder 5 from the operating lever device 56, and command values for the rotational direction and rotational speed of the swing motor 7 and the travel motors 8a and 8b. , 19a, switching valves 43a, 44a, . . . , 50a, 43b, 44b, . , 50c, 43d, 44d, .

Specifically, the controller 57 controls, for example, the first flow rate, which is the flow rate of the first closed circuit pump 12 on the flow path 212 side connected to the cap chamber 1a and the rod chamber 1b of the boom cylinder 1, and the connection flow path 301. A ratio of the second flow rate, which is the flow rate of the first open circuit pump 13 connected via the switching valve 44a, is set in advance according to the pressure receiving areas of the cap chamber 1a and the rod chamber 1b of the boom cylinder 1. Pressure-receiving area control is performed to control the first flow rate and the second flow rate so that the values are obtained. Similarly, the controller 57 performs the pressure receiving area control for the arm cylinder 3 and the bucket cylinder 5 other than the boom cylinder 1 as well.

Further, the controller 57 operates the switching valves 43a, 44a, . . . , 50a, 43b, 44b, . , 50b, 43c, 44c, . . . , 50c, 43d, 44d, . Hydraulic oil discharged from the first to fourth open circuit pumps 13, 15, 17, 19 is supplied to at least one of boom cylinder 1, arm cylinder 3, and bucket cylinder 5 to be operated.

Further, the operating lever 56a of the operating lever device 56 gives command values for the telescopic direction and telescopic speed of the boom cylinder 1 to the controller 57 . The operating lever 56b gives the controller 57 command values for the telescopic direction and the telescopic speed of the arm cylinder 3, and the operating lever 56c gives the command values for the telescopic direction and the telescopic speed of the bucket cylinder 5 to the controller 57. Further, the operating lever 56 d provides the controller 57 with command values for the rotation direction and rotation speed of the turning motor 7 . An operation lever (not shown) is also provided for giving command values for the rotation direction and rotation speed of the travel motors 8a and 8b to the controller 57. FIG.

As described above, the hydraulic drive device 107 includes closed circuit pumps (for example, the first to fourth closed circuit pumps 12, 14, 16, 18) and open circuit pumps (for example, the first to fourth open circuit pumps 13, 15, 17, 19) and hydraulically to the closed and open circuit pumps so that each can be supplied with hydraulic fluid from the closed and open circuit pumps. and a plurality of connected actuators (eg, boom cylinder 1, arm cylinder 3, bucket cylinder 5, swing motor 7).

Further, the hydraulic drive device 107 is configured such that, for example, the closed circuit pump is selectively connected to any one of the plurality of actuators in the form of a closed circuit (constituting closed circuits A to D). Closed circuit switching valves (for example, switching valves 43a to 43d, 45a to 45d, 47a to 47d, 49a to 49d) for switching between conduction and interruption of hydraulic oil flow paths between the pump and the plurality of actuators, and the open circuit The open circuit pump and the hydraulic fluid discharged from the pump are selectively supplied to any one of the plurality of actuators (for example, supplied to any one of the connecting flow paths 301 to 304). and open circuit switching valves (eg switching valves 44a to 44d, 46a to 46d, 48a to 48d, 50a to 50d) for switching between conduction and interruption of flow paths of hydraulic oil between a plurality of actuators.

In addition, the controller 57 receives an operation input via the operation lever device 56, and controls the closed circuit pump, the open circuit pump, the closed circuit switching valve, and the open circuit switching so as to perform the operations described above, for example. It provides control of each component within the hydraulic drive 107, including the valves.

FIG. 3 shows a functional block diagram of the controller 57. As shown in FIG. The controller 57 is composed of a lever operation amount calculator 57a, an actuator pressure calculator 57b, and an actuator allocated flow rate calculator 57c.

The lever operation amount calculation unit 57a calculates the operation direction and the target operation speed of each actuator in response to the operator's lever input, and inputs them to the actuator allocation flow calculation unit 57c.

The actuator pressure calculation unit 57b calculates the pressure of each actuator from the values of the pressure sensors 70a, 70b, 71a, 71b, 72a, and 72b provided in the boom cylinder 1, the arm cylinder 3, and the bucket cylinder 5, and calculates the actuator allocation flow rate. Input to the calculation unit 57c.

Based on the inputs from the lever operation amount calculation unit F11 and the actuator pressure calculation unit 57b, the actuator allocation flow rate calculation unit 57c operates the switching valve, the proportional valve, and the Calculates the command value for the regulator. The actuator allocation flow rate calculator 57c calculates the discharge flow rate from a signal indicating the pump state from the regulator, such as the tilt angle and the regulator pressure. Further, the actuator allocation flow rate calculation unit 57c of the controller 57 controls the switching valve based on the discharge flow rate, and performs switching control between the actuator and the pump.

In this embodiment, the discharge flow rate is calculated based on the signals from the tilt angle sensors 12b to 19b. It is also possible to calculate the discharge flow rate based on the command value.

Further, the actuator allocation flow rate calculation unit 57c of the controller 57, when changing the connection destination of the pump and the actuator by the switching valve, first performs control to stop the discharge of the working oil of the pump. When the actuator allocation flow rate calculation unit 57c detects that the calculated discharge flow rate of each pump has reached a predetermined value, it determines that the discharge of hydraulic oil to the connection destination before the change has been stopped. Then, at the timing after that, control is performed to switch the connection destination of the pump to the actuator to be the change destination. Then, after detecting that the pump is connected to the changed actuator based on the operation state of the switching valve, the actuator allocation flow rate calculation unit 57c controls the pump to start discharging hydraulic oil.

In the following embodiment, a case will be described in which the discharge flow rate of the pump is set to be substantially zero as the completion condition of the discharge stop of the pump, which is the switching condition by the controller 57 . More specifically, in this embodiment, for each pump, the detected value of the tilt angle sensor (that is, the actual tilt angle of the pump) corresponds to a discharge flow rate of a predetermined amount or less (for example, several cc or less). If it is a value (angle), the actuator allocation flow rate calculator 57c determines that the pump is in a state where the discharge of hydraulic oil is stopped. In other words, the actuator allocation flow rate calculation unit 57c determines whether the pump is in a state of discharging hydraulic oil or in a state of stopping discharge based on the signal acquired from the tilt angle sensor. judge. For example, when the acquired signal value (sensor value) is within a range corresponding to a predetermined tilt angle or less (a signal value threshold value or less), the actuator allocation flow rate calculation unit 57c causes the pump to discharge hydraulic oil. It is determined that the pump is in a stopped state, and if it is within the range corresponding to the tilt angle exceeding the predetermined tilt angle, it is determined that the pump is in a state of discharging hydraulic oil.

Next, regarding the driving method of the hydraulic drive device 107 according to the above-described embodiment, there are two types of operation: when the boom cylinder 1 is operated alone, and when the swing motor 7, the arm cylinder 3, and the bucket cylinder 5 are operated in addition to the boom cylinder 1. 4, 5, and 6 show the behavior of the combined operation of the hydraulic pumps 12, 13, . 6 for explanation. In the following explanation, it is assumed that the first to fourth closed circuit pumps 12, 14, 16, 18 connected to the closed circuits A, B, C, D have the same capacity. Furthermore, it is assumed that the boom cylinder 1, the arm cylinder 3, and the bucket cylinder 5 have the same pressure receiving area ratio (rod chamber pressure receiving area/cap chamber pressure receiving area).

4, 5, and 6 are time charts showing states during operation of the hydraulic drive device 107. FIG. In the figure, (a) is the amount of operation of the operation lever 56a, (b) is the amount of operation of the operation lever 56b, (c) is the amount of operation of the operation lever 56c, (d) is the amount of operation of the operation lever 56d, and (e) is the state of the switching valves 43a and 44a. (f) is the flow rate of the first closed circuit pump 12, (g) is the flow rate of the first open circuit pump 13, (h) is the state of the switching valves 45a and 46a, (i) is the state of the switching valve 45d, (j ) is the flow rate of the second closed circuit pump 14 . (k) is the flow rate of the second open circuit pump 15, (l) is the state of the switching valves 47a and 48a, (m) is the state of the switching valves 47b and 48b, (n) is the flow rate of the third closed circuit pump 16, (o) is the flow rate of the third open circuit pump 17; (p) is the flow rate of the proportional valve 66, (q) the state of the switching valves 49a and 50a, (r) is the state of the switching valves 49c and 50c, (s) is the flow rate of the fourth closed circuit pump 18, and (t) is The flow rate of the fourth open circuit pump 19, and (u) the pressure of the arm cylinder 3 (cap chamber 3a, rod chamber 3b). 4 shows behavior when the present invention is applied, and FIG. 6 shows behavior when the present invention is not applied. Furthermore, FIG. 5 is an enlarged view of the behavior at the start of a combined operation of boom raising, swinging, and arm dumping.

<During stop: t0 to t11>
In FIG. 4, each of the hydraulic pumps 12, 13, . . . Drive control is performed so that the tilting angle of the plate becomes the minimum tilting angle, and the discharge flow rate of the hydraulic pumps 12, 13, . . . control is maintained to stop the ejection of At this time, all of the switching valves 43a, . 8b are held in a stopped state.

<When raising the boom alone: t11 to t21>
In FIG. 4, when the operating lever 56a of the operating lever device 56 is operated (t11), the controller 57 controls the regulator 12a of the first closed circuit pump 12 to cause the first closed circuit pump 12 to discharge. The swash plate of the first closed circuit pump 12 is driven so that the outlet becomes the flow path 200 . At the same time, the controller 57 controls the regulator 13 a of the first open circuit pump 13 to drive the swash plate so that the first open circuit pump 13 discharges hydraulic oil to the flow path 202 . At this time, the controller 57 controls the switching valves 43a and 44a.

Then, at time t12, the discharge flow rate of the first closed circuit pump 12 becomes Qcp1, and the discharge flow rate of the first open circuit pump 13 becomes Qop1. At this time, the pressure receiving area control is performed by the controller 57, and the area ratio (Aa1:Aa2) between the pressure receiving area (Aa1) of the cap chamber 1a of the boom cylinder 1 and the pressure receiving area (Aa2) of the rod chamber 1b is The discharge flow rates (Qcp1, Qop1) of the first closed circuit pump 12 and the first open circuit pump 13 are adjusted so that the flow rate ratio {(Qcp1+Qop1):Qcp1} of the first closed circuit pump 12 and the first open circuit pump 13 becomes equal. is determined. Further, the first closed circuit pump 12 is controlled by the controller 57 such that the ratio of the discharge flow rate of the first closed circuit pump 12 and the discharge flow rate of the first open circuit pump 13 is changed while maintaining the relationship of Qcp1:Qop1. and the discharge flow rate of the first open circuit pump 13 is controlled.

Further, when the operation amount of the operating lever 56a further increases (t12), the controller 57 controls the regulator 14a of the second closed circuit pump 14 so that the discharge port of the second closed circuit pump 14 becomes the flow path 203. The swash plate of the second closed circuit pump 14 is driven. At the same time, the controller 57 controls the regulator 15 a of the second open circuit pump 15 to drive the swash plate so that hydraulic oil is discharged from the second open circuit pump 15 to the flow path 205 . At this time, the controller 57 controls the switching valves 45a and 46a.

Then, when the operation value of the operating lever 56a further increases (t13), the discharge flow rate of the second closed circuit pump 14 becomes Qcp1, and the discharge flow rate of the second open circuit pump 15 becomes Qop1. At this time as well, the pressure receiving area control is performed by the controller 57, and the ratio of the discharge flow rate of the second closed circuit pump 14 and the discharge flow rate of the second open circuit pump 15 changes while maintaining the relationship of Qcp1:Qop1. Thus, the discharge flow rates of the second closed circuit pump 14 and the second open circuit pump 15 are controlled.

Further, when the operation amount of the operating lever 56a further increases (t13), the controller 57 controls the regulator 16a of the third closed circuit pump 16 so that the discharge port of the third closed circuit pump 16 becomes the flow path 206. The swash plate of the third closed circuit pump 16 is driven. At the same time, the controller 57 controls the regulator 17 a of the third open circuit pump 17 to drive the swash plate so that hydraulic oil is discharged from the third open circuit pump 17 to the flow path 208 . At this time, the controller 57 controls the switching valves 47a and 48a.

Then, when the operation amount of the operating lever 56a further increases (t14), the discharge flow rate of the third closed circuit pump 16 reaches Qcp1, and the discharge flow rate of the third open circuit pump 17 reaches Qop1. At this time also, the pressure receiving area control is performed by the controller 57, and the ratio between the discharge flow rate of the third closed circuit pump 16 and the discharge flow rate of the third open circuit pump 17 maintains the relationship of Qcp1:Qop1. The discharge flow rates of the third closed circuit pump 16 and the third open circuit pump 17 are controlled to change.

Further, when the operation amount of the operating lever 56a further increases (t14), the controller 57 controls the regulator 18a of the fourth closed circuit pump 18 so that the discharge port of the fourth closed circuit pump 18 becomes the flow path 209. The swash plate of the fourth closed circuit pump 18 is driven. At the same time, the controller 57 controls the regulator 19 a of the fourth open circuit pump 19 to drive the swash plate so that the fourth open circuit pump 19 discharges hydraulic oil to the flow path 211 . At this time, the controller 57 controls the switching valves 49a and 50a.

Then, when the operation amount of the operating lever 56a reaches +X (t15), the discharge flow rate of the fourth closed circuit pump 18 becomes Qcp1, and the discharge flow rate of the fourth open circuit pump 19 becomes Qop1. At this time as well, the pressure receiving area control is performed by the controller 57, and the ratio between the discharge flow rate of the fourth closed circuit pump 18 and the discharge flow rate of the fourth open circuit pump 19 maintains the relationship of Qcp1:Qop1. The discharge flow rates of the fourth closed circuit pump 18 and the fourth open circuit pump 19 are controlled so as to change while the

<Boom raising + turning combined: t21 to t31>
In FIG. 4, when the operation lever 56d is operated from the state where the operation amount of the operation lever 56a is X and the boom cylinder 1 is independently operated (t21), the controller 57 connects the second closed circuit pump 14. Control is performed to switch the former actuator from the boom cylinder 1 to the swing motor 7 .

More specifically, first, the controller 57 performs (starts) control to stop the second closed circuit pump 14 from discharging hydraulic oil. As a result, the regulator 14a is controlled so that the tilting angle of the swash plate of the second closed circuit pump 14 becomes the minimum tilting angle. Then, the controller 57 operates the second closed circuit pump 14 by calculating from the signal obtained from the tilt angle sensor that the tilt angle of the second closed circuit pump 14 has actually reached the minimum tilt angle. It is determined that the oil discharge stop has been completed (time t22).

Further, in this embodiment, the controller 57 performs control to stop the discharge of hydraulic oil from the second open circuit pump 15 at the same time as controlling the discharge of hydraulic oil from the second closed circuit pump 14 (at time t21). (Start). As a result, the regulator 15a of the second open circuit pump 15 is controlled to drive the swash plate of the second open circuit pump 15 to the minimum tilt angle. Then, the controller 57 operates the second open circuit pump 15 by calculating from the signal obtained from the tilt angle sensor that the tilt angle of the second open circuit pump 15 has actually reached the minimum tilt angle. It is determined that the oil discharge stop has been completed (time t24).

Here, in the conventional technique shown in FIG. 6, the swash plate of the second closed circuit pump 14 and the swash plate of the second open circuit pump 15 are at the minimum tilt angle at the same time. On the other hand, in the present invention, the control for returning the tilting of the closed circuit pump is switched according to the next connection destination of the closed circuit pump according to the flowchart shown in FIG. At t21, the turning motor 7 is connected next because the operation lever 56d is pressed.

First, in step S1, it is determined whether or not the connection destination after the change is the single-rod hydraulic cylinder and the requested operation is the cylinder extension operation. Since the turning motor 7 is connected this time, the process proceeds to step S4. By step S4, the closed circuit pump is brought into the discharge stop state at the fastest. Therefore, as shown in FIG. 4, according to the present invention, the discharge flow rate of the second closed circuit pump 14 becomes substantially zero from t21 to t22. On the other hand, the second open circuit pump 15 with low response takes from t21 to t24 until the discharge flow rate becomes almost zero.

On the other hand, in the present embodiment, as shown in FIG. 4, when the discharge stop of the second closed circuit pump 14 is completed (t22), the controller 57 closes the switching valve 45a and then closes the switching valve 45a. 45d is turned on. As a result, the second closed circuit pump 14 and the swing motor 7 are connected in a closed circuit. In this embodiment, at the same time (time t22), according to the flowchart shown in FIG. 7, the controller 57 follows the flow chart shown in FIG. The second closed circuit pump 14 is controlled to start discharging hydraulic oil, and the inflow flow rate of the swing motor 7 is controlled by the second closed circuit pump 14 . As a result, the regulator 14 a of the second closed circuit pump 14 is controlled, and the swash plate of the second closed circuit pump 14 is driven so that the discharge port of the second closed circuit pump 14 becomes the flow path 203 .

Further, at the timing (t24) after the second closed circuit pump 14 is connected to the swing motor 7 (after time t22), when the second open circuit pump 15 stops discharging hydraulic oil, the controller 57 performs control to shut off the switching valve 46a.

Note that the timing before the second open circuit pump 15 stops discharging the hydraulic oil (before time t24), that is, when the second open circuit pump 15 supplies hydraulic oil to the boom cylinder 1, which is the actuator before switching, is performed. At time t23, which is the discharge timing, the second closed circuit pump 14 has started to discharge hydraulic oil to the swing motor 7, and the discharge flow rate is Qcp1. That is, when the operation lever 56d is operated, the boom cylinder 1 is supplied with the discharge flow rate (Qcp1) of the second closed circuit pump 14 and the discharge flow rate (Qop1) of the second open circuit pump 15 at t24. Since the working oil is reduced, the operating speed of the boom cylinder 1 is reduced. In this state, when the operation amount of the control lever 56d is set to zero (0), the original state (t21) is restored, and the operating speed of the boom cylinder 1 also returns (not shown).

As described above, when the present invention shown in FIG. 6 is not applied, the timing at which the discharge of the second closed circuit pump 14 is stopped is t24, which is the same as the timing at which the discharge of the second open circuit pump 15 is stopped. On the other hand, when the present invention is applied, the supply of the flow rate to the turning motor 7 can be started at t22, whereas when the present invention is not applied, it is delayed until t24.

Therefore, by applying the present invention, it is possible to shorten the time from turning lever input to supplying the flow rate to the turning motor 7 at the time of a compound operation. Save time.

<Boom raising + turning + arm dump combined: t31 to t41>
In FIG. 4, when the operation lever 56b is operated (t31) from a state in which the operation amounts of the operation levers 56a and 56d are X and the boom cylinder 1 and swing motor 7 are operating in combination, the controller 57 3 Control is performed to switch the actuator to which the closed circuit pump 16 is connected from the boom cylinder 1 to the arm cylinder 3 .

More specifically, first, the controller 57 starts control to stop discharging hydraulic oil from the third closed circuit pump 16 and the third open circuit pump 17 . As a result, the regulator 16a of the third closed circuit pump 16 is controlled so that the tilt angle of the swash plate of the third closed circuit pump 16 becomes the minimum tilt angle. When the angle actually reaches the minimum tilting angle, the third closed circuit pump 16 completes stopping the discharge of hydraulic oil (time t32).

Further, the regulator 17a of the third open circuit pump 17 is controlled so that the tilting angle of the swash plate of the third open circuit pump 17 becomes the minimum tilting angle. When the tilting angle of the third open circuit pump 17 actually reaches the minimum tilting angle, the third open circuit pump 17 stops discharging hydraulic oil (time t34).

Here, in the conventional technique shown in FIG. 6, the swash plate of the third closed circuit pump 16 and the swash plate of the third open circuit pump 17 are at the minimum tilt angle at the same time. On the other hand, in the present invention, the control for returning the tilting of the closed circuit pump is switched according to the next connection destination of the closed circuit pump according to the flowchart shown in FIG. At t31, the next connection destination is the arm cylinder 3 by inputting the operation lever 56b.

First, in step S1, it is determined whether or not the connection destination after the change is the single-rod hydraulic cylinder and the requested operation is the cylinder extension operation. Since the contraction operation of the arm cylinder 3 (arm dump operation) is performed this time, the process proceeds to step S4. By step S4, the closed circuit pump is brought into the discharge stop state at the fastest. Therefore, as shown in FIG. 4, according to the present invention, the discharge flow rate of the third closed circuit pump 16 is substantially zero from t31 to t32. On the other hand, the third open circuit pump 17 with low response takes from t31 to t34 until the discharge flow rate becomes almost zero.

On the other hand, in the case of FIG. 4 to which the present invention is applied, when the discharge flow rate of the third closed circuit pump 16 becomes almost zero (t32), the switching valve 47a is controlled to be closed by the controller 57, and then switched. The valve 47b is conductively controlled. At the same time, according to the flowchart shown in FIG. 7, the controller 57 proceeds to step S7 because the connection destination after the change is the arm cylinder 3 in step S5. As shown in FIG. 5, the pressure in the arm cylinder 3 from t32 to t33.5 is higher in the cap chamber 3a than in the rod chamber 3b. A third closed circuit pump 16 controls the outflow flow rate from the cap chamber 3a of the arm cylinder 3 for the required speed of . At this time, the maximum flow rate of the third closed circuit pump 16 becomes -Qcp1 at t33. Further, as shown in FIG. 5, the pressure in the arm cylinder 3 after t33.5 is lower than the pressure in the rod chamber 3b in the cap chamber 3a, so as shown in FIG. A third closed circuit pump 16 controls the inflow flow rate to the rod chamber 3b of the arm cylinder 3 for the required speed of . At this time, the maximum flow rate of the third closed circuit pump 16 is Qcp2. To achieve the same cylinder speed, -Qcp1<-Qcp2.

The regulator 16 a of the third closed circuit pump 16 is controlled by the controller 57 , and the swash plate of the third closed circuit pump 16 is driven so that the discharge port of the third closed circuit pump 16 becomes the flow path 207 .

When the discharge flow rate of the third open circuit pump 17 becomes substantially zero (t34), the switching valve 48a is controlled by the controller 57 to be closed. That is, when the operating lever 56b is operated, the boom cylinder 1 is supplied with an amount corresponding to the discharge flow rate (Qcp1) of the third closed circuit pump 16 and the discharge flow rate (Qop1) of the third open circuit pump 17 at t34. Since the working oil is reduced, the operating speed of the boom cylinder 1 is reduced. In this state, when the operation amount of the operating lever 56b is set to zero (0), the original state (t31) is restored, and the operating speed of the boom cylinder 1 also returns (not shown).

As shown in FIG. 5, at t34, the switching valve 48a is controlled to be closed by the controller 57, and then the switching valve 48b is controlled to be conductive. At the same time, the controller 57 controls the flow rate through the proportional valve 66 so that it becomes Qpv1. The second 3 A discharge flow rate Qcp2 of the closed circuit pump 16 and a flow rate Qpv1 through the proportional valve 66 are determined. Furthermore, the discharge flow rate of the third closed circuit pump 16 is controlled by the controller 57 so that the ratio between the discharge flow rate of the third closed circuit pump 16 and the flow rate through the proportional valve 66 changes while maintaining the relationship of Qcp2:Qpv1. and the flow rate through the proportional valve 66 is controlled.

As described above, when the present invention shown in FIG. 6 is not applied, the timing when the discharge flow rate of the third closed circuit pump 16 becomes substantially zero is the same as the timing when the discharge flow rate of the third open circuit pump 17 becomes substantially zero. t34. If the present invention is applied, the flow rate supply to the arm cylinder 3 can be started at t32, whereas if the present invention is not applied, it will be delayed until t34.

Therefore, by applying the present invention, it is possible to shorten the time from the arm lever input to the supply of the flow rate to the arm cylinder 3 during a compound operation. Save time.

<Boom raising + turning + arm dumping + bucket cloud combination: t41 to t52>
In FIG. 4, when the operation lever 56c is operated (t41) from the state where the operation amounts of the operation levers 56a, 56b, and 56d are respectively X and the boom cylinder 1, the arm cylinder 3, and the turning motor 7 are operating in combination. , the controller 57 performs control to switch the actuator to which the fourth closed circuit pump 18 and the fourth open circuit pump 19 are connected from the boom cylinder 1 to the bucket cylinder 5 .

More specifically, the regulator 18a of the fourth closed circuit pump 18 is controlled to drive the swash plate of the fourth closed circuit pump 18 to the minimum tilt angle. is stopped (time t42). At the same time, the controller 57 controls the regulator 19a of the fourth open circuit pump 19 to drive the fourth open circuit pump 19 so that the tilting angle of the swash plate of the fourth open circuit pump 19 becomes the minimum tilting angle. is stopped (time t42).

In the present invention, control for returning the tilting of the closed circuit pump is switched according to the next connection destination of the closed circuit pump according to the flowchart shown in FIG. At t41, the next connection destination is the bucket cylinder 5 by inputting the operation lever 56c.

First, in step S1, it is determined whether the connection destination after the change is the single-rod hydraulic cylinder and the requested operation is the cylinder extension operation. Since the bucket cylinder 5 is extended (bucket cloud operation) this time, the process proceeds to step S2. By step S2, the discharge of the closed circuit pump is stopped in synchronization with the open circuit pump. Therefore, as shown in FIG. 4, the discharge of the fourth closed circuit pump 18 is stopped from t41 to t42 in accordance with the fourth open circuit pump 19 with low response.

When the discharge flow rates of the fourth closed circuit pump 18 and the fourth open circuit pump 19 become substantially zero (t42), the switching valves 49a and 50a are controlled to be closed by the controller 57, and then the switching valves 49c and 50c are closed. Continuity controlled. At the same time, the controller 57 advances to step S3 according to the flowchart shown in FIG. At this time, the maximum flow rate of the fourth closed circuit pump 18 becomes Qcp1 at t43. The regulator 18 a of the fourth closed circuit pump 18 is controlled by the controller 57 , and the swash plate of the fourth closed circuit pump 18 is driven so that the discharge port of the fourth closed circuit pump 18 becomes the flow path 209 .

When the operation lever 56b is operated, the hydraulic oil supplied to the boom cylinder 1 is equal to the discharge flow rate (Qcp1) of the fourth closed circuit pump 18 and the discharge flow rate (Qop1) of the fourth open circuit pump 19 at t42. is reduced, the operating speed of the boom cylinder 1 is reduced. In this state, when the operation amount of the operating lever 56c is set to zero (0), the original state (t41) is restored, and the operating speed of the boom cylinder 1 also returns (not shown).

As shown in FIG. 4, after switching valves 49a and 50a are controlled to be closed by controller 57 at t43, switching valves 49c and 50c are controlled to be conductive. At this time, pressure-receiving area control is performed by the controller 57, and the area ratio (Aa5:Ab5) of the pressure-receiving area (Aa5) of the cap chamber 5a of the bucket cylinder 5 and the pressure-receiving area (Ab5) of the rod chamber 5b and the fourth The discharge flow rates Qcp1 and Qop1 of the fourth closed circuit pump 18 and the fourth open circuit pump 19 are adjusted so that the flow rate ratio {(Qcp1+Qop1):Qcp1} of the passing flow rates of the closed circuit pump 18 and the fourth open circuit pump 19 becomes equal. is determined. Furthermore, the fourth closed circuit pump 18 and the fourth open circuit pump 18 are controlled by the controller 57 so that the ratio of the discharge flow rates of the fourth closed circuit pump 18 and the fourth open circuit pump 19 is changed while maintaining the relationship of Qcp1:Qop1. The discharge flow rate of the circuit pump 19 is controlled.

As described above, even when the present invention is applied, the closed-circuit pumps 12, 14, 16, and 18 are synchronized with the open-circuit pumps 13, 15, 17, and 19 when the operation after changing the connection destination is the cylinder extension operation. Therefore, the responsiveness is the same as that of the prior art shown in FIG. This is because when the closed circuit pumps 12, 14, 16, and 18 perform the cylinder extension operation alone, the closed circuit pumps 12 and 14 may not operate properly, especially when the cylinder cap chamber pressure is higher than the cylinder rod chamber pressure. , 16 and 18, the return flow rate from the cylinder rod chamber side is small compared to the discharge flow rate of the closed circuit pumps 12, 14, 16 and 18. This causes negative pressure on the suction sides of the closed circuit pumps 12, 14, 16 and 18, which may cause equipment failure. . This problem can be solved by increasing the size of the charge pump 11, but there arises a problem that a mounting space is required and energy consumption during standby increases. Therefore, it is most effective to apply this patent when the change destination of the pump connection is other than the cylinder extension operation.

(summary)
In this embodiment, closed circuit pumps 12, 14, 16, 18 each having two inflow and outflow ports through which hydraulic fluid can flow in and out, and open circuit pumps 13, 15 having hydraulic fluid inflow and outflow ports. , 17, 19, and sensors 12b, 13b, . , first single-rod hydraulic cylinders 1, 3, 5 and other actuators, each supplied with hydraulic fluid from closed circuit pumps 12, 14, 16, 18 and open circuit pumps 13, 15, 17, 19. a plurality of actuators 1, 3, 5, 7 connected to closed circuit pumps 12, 14, 16, 18 and open circuit pumps 13, 15, 17, 19 so that the closed circuit pumps 12, Closed circuit pumps 12, 14, 16, 18 and a plurality of actuators 1, 14, 16, 18 are selectively connected in a closed circuit to any one of the plurality of actuators 1, 3, 5, 7 Closed circuit switching valves 43a to 43d, 45a to 45d, 47a to 47d, 49a to 49d for switching between conduction and interruption of hydraulic oil flow paths between 3, 5 and 7, open circuit pumps 13, 15, 17, The open circuit pumps 13, 15, 17, 19 and the actuators 1, 3, 19 are arranged so that the hydraulic fluid discharged from the pump 19 is selectively supplied to any one of the actuators 1, 3, 5, 7. Open circuit switching valves 44a to 44d, 46a to 46d, 48a to 48d, 50a to 50d for switching between conduction and interruption of hydraulic oil flow paths between 5 and 7, closed circuit pumps 12, 14, 16, 18, Open circuit pumps 13, 15, 17, 19, closed circuit switching valves 43a-43d, 45a-45d, 47a-47d, 49a-49d, and open circuit switching valves 44a-44d, 46a-46d, 48a-48d, 50a- 50d, the controller 57 determines that the closed circuit pumps 12, 14, 16, 18 are connected to the first single rod hydraulic cylinders 1, 3, 5 and open circuit From the state in which the pumps 13, 15, 17, 19 are supplying hydraulic oil to the first single-rod hydraulic cylinders 1, 3, 5, the closed circuit pumps 12, 14, 16, 18 are connected to the other actuators. When performing switching control, control is performed to stop discharge of hydraulic oil from the closed circuit pumps 12, 14, 16, 18 and the open circuit pumps 13, 15, 17, 19. , 19b, and after the discharge of hydraulic oil from the open circuit pumps 13, 15, 17, 19 is stopped. , 19b, the closed circuit pumps 12, 14, 16, 18 are connected to the first single-rod hydraulic cylinders 1, 3, . The closed circuit switching valves 43a to 43d, 45a to 45d, 47a to 47d, and 49a to 49d are controlled so as to switch from 5 to the other actuators.

According to the present embodiment constructed as described above, the closed circuit pumps 12, 14, 16, 18 and the open circuit pumps 13, 15, 17, 19 drive the first single-rod hydraulic cylinders 1, 3, 5. When changing the connection destination of the closed circuit pumps 12, 14, 16, 18 to other actuators in the state where the open circuit pumps 13, 15 , 17 and 19 earlier than the discharge stop of the closed circuit pumps 12, 14, 16 and 18 can be advanced to connect the other actuators. As a result, compared to the case where the discharge of the closed circuit pumps 12, 14, 16, and 18 is stopped in synchronization with the open circuit pumps 13, 15, 17, and 19, the timing of starting to drive the other actuators can be made earlier. , it is possible to improve the responsiveness of the other actuators to the operation input.

Further, in the present embodiment, the other actuators are the second single-rod hydraulic cylinders 1, 3, and 5 that have received an operation input for contraction operation, and the construction machine 100 is configured such that the second single-rod hydraulic cylinder 1 , 3, 5, and pressure sensors 70a, 70b, 71a, 71b, 72a, 72b for detecting cap chamber pressures and rod chamber pressures of the closed circuit pumps 12, 14, 16, 18 and the open circuit pump 13. , 15, 17, 19 to contract the second single-rod hydraulic cylinders 1, 3, 5, a signal corresponding to the state in which the open circuit pumps 13, 15, 17, 19 stop discharging hydraulic oil is generated. At the timing after the sensors 12b, 13b, . The open circuit switching valve is controlled to switch to the two-single-rod hydraulic cylinders 1, 3, 5, and the closed-circuit pumps 12, 14, 16, 18 are switched to the second single-rod hydraulic cylinders 1, 3, 5. , until the open circuit pumps 13, 15, 17, 19 start supplying hydraulic fluid to the second single-rod hydraulic cylinders 1, 3, 5, the cap chamber pressure and the rod chamber pressure The discharge flow rates of the closed circuit pumps 12, 14, 16, 18 are controlled so that the drive speeds of the second single-rod hydraulic cylinders 1, 3, 5 do not change according to the magnitude relationship of . As a result, immediately after switching the connections of the closed circuit pumps 12, 14, 16, 18 from the first single-rod hydraulic cylinders 1, 3, 5 to the second single-rod hydraulic cylinders 1, 3, 5, the second The driving speed of the second single-rod hydraulic cylinders 1, 3, 5 can be made the same regardless of the pressure state of the single-rod hydraulic cylinders 1, 3, 5.

Moreover, in this embodiment, the other actuator is the hydraulic motor 7 . As a result, the response of the hydraulic motor 7 when the first single-rod hydraulic cylinders 1, 3, 5 are driven by the closed circuit pumps 12, 14, 16, 18 and the open circuit pumps 13, 15, 17, 19 It is possible to improve the performance.

Further, the construction machine 100 in this embodiment includes operation levers 56a to 56d capable of setting the driving direction and driving speed of the first single-rod hydraulic cylinder and the hydraulic motor 7, and the controller 57 includes the operation levers 56a to 56d. , the connection destinations of the closed circuit pumps 12, 14, 16, 18 and the open circuit pumps 13, 15, 17, 19 are determined. This improves the responsiveness of the other actuators to the input of the operating levers 56a to 56d while the single-rod hydraulic cylinder is being driven by the closed circuit pump and the open circuit pump. becomes possible.

Also, the plurality of actuators 1, 3, 5, 7 in this embodiment includes second single-rod hydraulic cylinders 1, 3, 5, and the controller 57 controls the closed circuit pumps 12, 14, 16, 18 and the open circuit pumps 12, 14, 16, 18. When switching the connection destinations of the pumps 13, 15, 17, 19 from the first single-rod hydraulic cylinders 1, 3, 5 to the second single-rod hydraulic cylinders 1, 3, 5 that have received an operation input to perform an extension operation In addition, the discharge flow rate of the closed circuit pumps 12, 14, 16, 18 is controlled so that the discharge of the closed circuit pumps 12, 14, 16, 18 is stopped in synchronization with the open circuit pumps 13, 15, 17, 19. , the closed circuit pumps 12, 14, 16, 18 and the open circuit pumps 13, 15, 13, 15, 18, 13, 15, 18 at the timing after the discharge of the closed circuit pumps 12, 14, 16, 18 and the open circuit pumps 13, 15, 17, 19 is stopped. 17, 19 are connected to the second single-rod hydraulic cylinders 1, 3, 5. 46a-46d, 48a-48d and 50a-50d are controlled. As a result, the suction of the closed circuit pumps 12, 14, 16, 18 immediately before switching the connections of the closed circuit pumps 12, 14, 16, 18 from the first single-rod hydraulic cylinders 1, 3, 5 to the other actuators. side can be prevented from becoming negative pressure.

(others)
It should be noted that the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the above-described embodiments are described for easy understanding of the present invention, and the present invention is not necessarily limited to those having all the described configurations.

In each of the above-described embodiments, the case where the hydraulic drive device 107 is mounted on the hydraulic excavator 100 has been described as an example. The hydraulic drive system 107 according to the present invention can also be used in construction machines other than the hydraulic excavator 1 as long as the construction machines have at least one or more drivable single-rod hydraulic cylinders.

In addition, in each of the above-described embodiments, hydraulic pumps equipped with double tilting swash plate mechanisms capable of controlling the discharge/inlet direction and flow rate are used as the first to fourth open circuit pumps 13, 15, 17, and 19. , Hydraulic oil can be discharged from the hydraulic oil tank 25 only in one direction toward the switching valves 44a, 44b, 44c, 44d, 46a, 46b, 46c, 46d, 48a, 48b, 48c, 48d, 50a, 50b, 50c, 50d. A hydraulic pump having a single tilting swash plate mechanism may also be used.

Furthermore, in each of the above-described embodiments, each of the plurality of hydraulic pumps 12, 13, . A plurality of fixed displacement hydraulic pumps are prepared as the hydraulic pumps 12, 13, . A controller 57 may be used to control these electric motors to control the discharge/intake direction and discharge flow rate of hydraulic oil according to the rotation direction and rotation speed of each fixed displacement hydraulic pump.

DESCRIPTION OF SYMBOLS 1... Boom cylinder (1st single rod type hydraulic cylinder, 2nd single rod type hydraulic cylinder), 1a... Cap chamber, 1b... Rod chamber, 1c... Rod, 1d... Cylinder tube, 1e... Piston, 2... Boom, 3 ... arm cylinder (first single-rod hydraulic cylinder, second single-rod hydraulic cylinder), 3a ... cap chamber, 3b ... rod chamber, 3c ... rod, 3d ... cylinder tube, 3e ... piston, 4 ... arm, 5 ... Bucket cylinder (first single-rod hydraulic cylinder, second single-rod hydraulic cylinder), 5a: cap chamber, 5b: rod chamber, 5c: rod, 5d: cylinder tube, 5e: piston, 6: bucket, 7: turning Motor (hydraulic motor) 8a, 8b Traveling motor 9 Engine 10 Power transmission device 11 Charge pump 12 First closed circuit pump 12a Regulator 12b Tilt angle sensor 13 Third 1 open circuit pump 13a regulator 13b tilt angle sensor 14 second closed circuit pump 14a regulator 14b tilt angle sensor 15 second open circuit pump 15a regulator 15b tilt Rotation angle sensor 16 Third closed circuit pump 16a Regulator 16b Tilt angle sensor 17 Third open circuit pump 17a Regulator 17b Tilt angle sensor 18 Fourth closed circuit pump Reference numeral 18a Regulator 18b Tilt angle sensor 19 Fourth open circuit pump 19a Regulator 19b Tilt angle sensor 20 Charge relief valve 21 to 24 Relief valve 25 Hydraulic oil tank 26 to 29... charging check valves, 30a, 30b, 31a, 31b, 32a, 32b, 33a, 33b... relief valves 34 to 36... flushing valves, 37a, 37b, 38a, 38b, 39a, 39b... relief valves, 40a, 40b, 41a, 41b, 42a, 42b... charge check valves, 43a-43d, 45a-45d, 47a-47d, 49a-49d... switching valves (closed circuit switching valves), 44a-44d, 46a-46d, 48a to 48d, 50a to 50d... Switching valve (open circuit switching valve) 51a, 51b, 52a, 52b, 53a, 53b... Relief valve 54, 55... Proportional switching valve 56... Operation lever device 56a to 56d... Operation lever 57 Controller 57a Lever operation amount calculation unit 57b Actuator pressure calculation unit 57c Actuator allocation flow calculation unit 64 to 67 Proportional valve 70a, 70b, 71a, 71b, 72a, 72b Pressure Sensor 100 Hydraulic excavator (construction machine) 101a, 101b Travel device 102 Lower travel body 103 Upper revolving body 104 Cab 105 Revolving device 106 Front work machine 107 Hydraulic drive device , 200 to 202... channel, 202a... branch channel, 203 to 205... channel, 205a... branch channel, 206 to 208... channel, 208a... branch channel, 209 to 211... channel, 211a... branch Channels 212 to 224, 229... Channels 301 to 304... Connection channels 305a to 305d, 306a to 306d, 307a to 307d, 308a to 308d... For open circuit Connection channels, 309a to 309c... For closed circuit Connection channel 309d... Connection channel, A, B, C, D... Closed circuit, E, F, G, H... Open circuit.

Claims (5)

a closed circuit pump having two inflow and outflow ports through which hydraulic fluid can flow in and out;
an open circuit pump having hydraulic fluid inlet and outlet ports;
a sensor that detects a signal that changes according to the discharge flow rate of the closed circuit pump and the open circuit pump;
a first single rod hydraulic cylinder and other actuators to the closed circuit pump and the open circuit pump such that hydraulic fluid can be supplied from the closed circuit pump and the open circuit pump to each; a plurality of connected actuators;
connecting and disconnecting hydraulic oil flow paths between the closed circuit pump and the plurality of actuators so that the closed circuit pump is selectively connected to any one of the plurality of actuators in a closed circuit configuration; a switching closed circuit switching valve;
connecting a hydraulic fluid flow path between the open circuit pump and the plurality of actuators so that the hydraulic fluid discharged from the open circuit pump is selectively supplied to any one of the plurality of actuators; an open circuit switching valve that switches between shutoff;
A construction machine comprising the closed circuit pump, the open circuit pump, the closed circuit switching valve, and a controller that controls the open circuit switching valve,
The controller controls the closed-circuit pump from a state in which the closed-circuit pump is connected to the first single-rod hydraulic cylinder and the open-circuit pump is supplying hydraulic oil to the first single-rod hydraulic cylinder. When performing control to switch the connection destination of to the other actuator,
After performing control to stop the discharge of hydraulic oil from the closed circuit pump and the open circuit pump, and after acquiring from the sensor a signal corresponding to the state in which the discharge of hydraulic oil from the closed circuit pump is stopped, and The connection destination of the closed-circuit pump is changed from the first single-rod hydraulic cylinder to the other actuator at a timing before a signal corresponding to a state in which the open-circuit pump stops discharging hydraulic oil is acquired from the sensor. A construction machine characterized by controlling the closed circuit switching valve so as to switch. In the construction machine according to claim 1,
the other actuator is a second single-rod hydraulic cylinder that receives an operation input that performs a contraction operation;
A pressure sensor for detecting cap chamber pressure and rod chamber pressure of the second single-rod hydraulic cylinder,
The controller is
When contracting the second single-rod hydraulic cylinder by the closed-circuit pump and the open-circuit pump, after acquiring from the sensor a signal corresponding to a state in which the discharge of the hydraulic oil of the open-circuit pump is stopped controlling the open circuit switching valve so that the supply destination of hydraulic oil from the open circuit pump is switched from the first single rod hydraulic cylinder to the second single rod hydraulic cylinder at the timing;
The cap chamber pressure and the A construction machine, wherein the discharge flow rate of the closed circuit pump is controlled so that the driving speed of the second single-rod hydraulic cylinder does not change according to the magnitude relationship of the rod chamber pressure. In the construction machine according to claim 1,
The construction machine, wherein the other actuator is a hydraulic motor. In the construction machine according to claim 3,
An operation lever capable of setting the driving direction and driving speed of the first single-rod hydraulic cylinder and the hydraulic motor,
The construction machine, wherein the controller determines connection destinations of the closed circuit pump and the open circuit pump in accordance with an input from the operation lever. In the construction machine according to claim 1,
the plurality of actuators includes a second single-rod hydraulic cylinder;
When switching the connection destination of the closed circuit pump and the open circuit pump from the first single-rod hydraulic cylinder to the second single-rod hydraulic cylinder that receives an operation input for performing an extension operation,
controlling the discharge flow rate of the closed circuit pump so that the discharge of the closed circuit pump is stopped in synchronization with the open circuit pump;
The closed-circuit switching valve and the closed-circuit switching valve are connected to the second single-rod hydraulic cylinder at a timing after the discharge of the closed-circuit pump and the open-circuit pump is stopped. A construction machine characterized by controlling an open circuit switching valve.

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