JP6383676B2 - Work machine - Google Patents

Description

  The present invention relates to a work machine, and more particularly to a work machine including a hydraulic drive control device such as a hydraulic excavator.

  In recent years, in working machines such as excavators, the number of throttle elements in the hydraulic circuit that drives hydraulic actuators such as hydraulic cylinders has been reduced, and hydraulic oil is directly fed from the hydraulic pump, which is a hydraulic drive source, to the hydraulic actuator to drive the hydraulic actuator. Development of a hydraulic circuit called a closed circuit in which hydraulic oil after work is performed so as to return the hydraulic oil to the hydraulic pump without returning it to the tank is underway.

  An object of the present invention is to provide a work vehicle capable of suppressing an increase in size of a vehicle while maintaining a drive speed of a hydraulic actuator, and a power source and a first main pump connected to each other in series and driven by the power source. And a second main pump, a first hydraulic actuator driven by hydraulic oil from the main pump unit, and a first pump for connecting the main pump unit and the first hydraulic actuator. A hydraulic circuit, a work machine pump unit having a first work machine pump and a second work machine pump connected to each other in series and driven by the power source; and driven by hydraulic oil from the work machine pump unit. Second hydraulic actuator, the work machine pump unit, and the second hydraulic actuator Connecting the second hydraulic circuit constituting the closed circuit, the main pump unit and the work implement pump unit to the power source in parallel with each other, and increasing the rotation from the power source to increase the rotation speed. There is a work vehicle including a power take-out device that transmits to a work machine pump unit (see, for example, Patent Document 1).

JP 2014-84558 A

  Generally, when a hydraulic actuator constituting a closed circuit performs a regenerative operation, the pressure on the suction port side of the closed circuit pump becomes higher than the pressure on the discharge port side, and the closed circuit pump is driven as a hydraulic motor. As a result, regenerative torque is obtained from the drive shaft of the closed circuit pump.

  The work vehicle described in Patent Document 1 is provided with a first hydraulic circuit that constitutes an open circuit and a second hydraulic circuit that constitutes a closed circuit, and a power take-out device is provided between the closed circuit pump and the open circuit pump. Connected through. For this reason, when the hydraulic actuator which comprises a closed circuit performs regenerative operation, the regenerative torque output to the drive shaft of a closed circuit pump can be transmitted to the drive shaft of an open circuit pump via a power extraction device. As a result, the load on the engine is reduced and fuel consumption can be reduced. However, there is a problem that the regenerative torque output from the closed circuit pump is reduced by the efficiency of the power take-off device before it is transmitted to the drive shaft of the open circuit pump.

  The present invention has been made based on the above-described matters, and an object of the present invention is to provide a work machine including a hydraulic drive control device that can regenerate energy with high efficiency.

  In order to solve the above problems, for example, the configuration described in the claims is adopted. The present application includes a plurality of means for solving the above-mentioned problem. To give an example, the application source, a plurality of hydraulic pumps having flow rate adjusting means for controlling the flow rate of the discharged hydraulic fluid, and the operation A plurality of hydraulic actuators driven by liquid, and a flow path of one hydraulic pump of the plurality of hydraulic pumps with respect to a flow path of one of the plurality of hydraulic actuators. Closed circuit switching means for hydraulic actuators selectively connected in a closed circuit form, and a plurality of closed circuit switching means for hydraulic actuators connected from the one hydraulic actuator to the plurality of closed circuit switching means for hydraulic actuators A connection flow path, a drive shaft to which at least two hydraulic pumps are connected, a power transmission device that distributes the power of the drive source to the plurality of drive shafts, and a plurality of the hydraulic actuators. A power running / regeneration determining means for determining whether the motor is in a power running operation or a regenerative operation; and the power running / regeneration determining means for determining the operating states of the plurality of hydraulic actuators, and one of the ones connected to the drive shaft. The closed circuit for the hydraulic actuator is connected to the hydraulic pump that is being powered by the hydraulic pump, and the hydraulic actuator that is being regenerated is connected to the other hydraulic pump that is coupled to the drive shaft. A control device for controlling the switching means is provided.

  According to the present invention, hydraulic oil from a plurality of hydraulic pumps can be selectively joined to a plurality of drive shafts in which at least two hydraulic pumps are coupled to one shaft and one hydraulic actuator. The regenerative torque is increased by controlling the hydraulic pump connected to the same drive shaft as the hydraulic pump connected to the hydraulic actuator during regeneration to be connected to the hydraulic actuator during power running. It can be used as drive torque for efficiency.

1 is a side view showing a hydraulic excavator that is an embodiment of a working machine of the present invention. 1 is a hydraulic circuit diagram showing a hydraulic pressure drive control device constituting an embodiment of a work machine of the present invention. It is a flowchart figure which shows the processing content of the hydraulic drive control apparatus which comprises one Embodiment of the working machine of this invention.

Embodiments of a working machine of the present invention will be described below with reference to the drawings.
FIG. 1 is a side view showing a hydraulic excavator which is an embodiment of the working machine of the present invention, and FIG. 2 is a hydraulic circuit diagram showing a hydraulic drive control device constituting the embodiment of the working machine of the present invention. .

  In this embodiment, four closed circuit pumps and four open circuit pumps and at least two closed circuit pumps or open circuit pumps are provided for three types of hydraulic piece rod cylinders and three types of hydraulic motors. A plurality of drive shafts connected to one shaft are provided, and when the hydraulic piece rod cylinder is driven, flow control is performed by combining one closed circuit pump and one open circuit pump. In addition, by providing a switching valve in each closed circuit pump and each open circuit pump, a plurality of closed circuit pumps and a plurality of open circuit pumps can selectively merge with respect to one hydraulic piece rod cylinder. ing. At the time of merging to one hydraulic rod cylinder, the switching valve is controlled so that merging is performed by combining one closed circuit pump and one open circuit pump, and whether or not the hydraulic actuator is being regenerated is determined. If the regenerative operation is determined, the switching valve is connected so that the closed circuit pump supplying hydraulic fluid to the other hydraulic actuators in power running or the closed circuit pump connected to the same drive shaft as the open circuit pump is connected. It has a controller to control.

  In FIG. 1, a hydraulic excavator 100 includes a lower traveling body 101 having a crawler type traveling device 8, and an upper revolving body 102 provided on the lower traveling body 101 via a swiveling device 7 so as to be rotatable. Yes. A cabin 103 on which an operator is boarded is disposed on the upper swing body 102. In addition, a base end portion of the front working device 104 is rotatably attached to the front side of the upper swing body 102.

  The front working device 104 has an articulated structure having a boom 2, an arm 4, and a bucket 6. The boom 2 is rotated up and down with respect to the upper swing body 102 by the expansion and contraction of the boom cylinder 1, and the arm 4 is an arm cylinder. 3 is rotated up and down and front and rear with respect to the boom 2. The bucket 6 is rotated up and down and front and rear with respect to the arm 4 by expansion and contraction of the bucket cylinder 5.

  As shown in FIG. 2, the hydraulic drive control device 105 is a boom cylinder 1 that is a hydraulic actuator in accordance with the operation direction and the operation amount of each operation lever 56 a to 56 d of the operation lever device arranged in the cabin 103. The arm cylinder 3, the bucket cylinder 5, and the turning device 7 are driven. Although not shown, the traveling devices 8a and 8b are driven according to the amount of pedal operation.

  As shown in FIG. 2, the hydraulic drive control device 105 includes an engine 9 as a drive source and a power transmission device 10 that distributes the power of the engine 9 to five drive shafts. The first drive shaft 68 of the power transmission device 10 is connected to the first hydraulic pump 12 and the third hydraulic pump 14, which are variable capacity closed circuit hydraulic pumps, and the second drive shaft 69 is connected to the first drive shaft 68. A fifth hydraulic pump 16 and a seventh hydraulic pump 18 which are variable capacity closed circuit hydraulic pumps are connected.

  The third drive shaft 70 of the power transmission device 10 is connected to the second hydraulic pressure pump 13 and the fourth hydraulic pressure pump 15, which are variable capacity open circuit hydraulic pumps. Are connected to a sixth hydraulic pump 17 and an eighth hydraulic pump 19 which are variable capacity open circuit hydraulic pumps. Further, the fifth drive shaft 71 of the power transmission device 10 is connected to a charge pump 11 that replenishes hydraulic oil when the closed-circuit hydraulic pressure decreases.

  The first, third, fifth and seventh hydraulic pumps 12, 14, 16, and 18 which are closed circuit hydraulic pumps are both tilted swash plate mechanisms capable of discharging hydraulic oil in both directions, and the tilts of both tilted swash plates. Regulators 12 a, 14 a, 16 a, and 18 a that adjust the angle are provided, and the regulators 12 a, 14 a, 16 a, and 18 a are controlled by command signals from the controller 57.

  The second, fourth, sixth, eighth hydraulic pumps 13, 15, 17, 19 which are open circuit hydraulic pumps are composed of a unidirectional swash plate mechanism capable of discharging hydraulic oil in one direction, and a unidirectional swash plate. Regulators 13 a, 15 a, 17 a, and 19 a that adjust the tilt angle are provided, and the regulators 13 a, 15 a, 17 a, and 19 a are controlled by command signals from the controller 57.

  The first hydraulic pump 12 has a flow path 200 connected to one input / output port and a flow path 201 connected to the other input / output port. The flow paths 200 and 201 are provided with four switching valves 43a to 43d as closed circuit switching means for a hydraulic actuator that switches the supply destination of hydraulic oil from the first hydraulic pump 12. The switching valves 43a to 43d are for switching between communication and blocking of the flow path by a command signal from the controller 57. When there is no command signal from the controller 57, the switching valves 43a to 43d are cut off. The controller 57 controls so that any two or more of the switching valves 43a to 43d are not simultaneously communicated.

  The switching valve 43a is connected to the boom cylinder 1 via flow paths 212 and 213 which are closed circuit switching means connecting flow paths for hydraulic actuators. When the switching valve 43a is in communication with the command signal from the controller 57, the first hydraulic pump 12 is connected to the boom cylinder 1 via the flow paths 200 and 201, the switching valve 43a, and the flow paths 212 and 213. This constitutes a closed circuit. The switching valve 43b is connected to the arm cylinder 3 via flow paths 214 and 215 which are closed circuit switching means connecting flow paths for hydraulic actuators. When the switching valve 43b is in communication with the command signal from the controller 57, the first hydraulic pump 12 is connected to the arm cylinder 3 via the flow paths 200 and 201, the switching valve 43b, and the flow paths 214 and 215. This constitutes a closed circuit.

  The switching valve 43c is connected to the bucket cylinder 5 via flow paths 216 and 217 which are closed circuit switching means connecting flow paths for hydraulic actuators. When the switching valve 43c is in communication with the command signal from the controller 57, the first hydraulic pump 12 is connected to the bucket cylinder 5 via the flow paths 200 and 201, the switching valve 43c, and the flow paths 216 and 217. This constitutes a closed circuit. The switching valve 43d is connected to the turning device 7 via the flow paths 218 and 219 which are closed circuit switching means connection flow paths for the hydraulic actuator. When the switching valve 43d is brought into a communication state by a command signal from the controller 57, the first hydraulic pump 12 is connected to the turning device 7 via the flow paths 200, 201, the switching valve 43d, and the flow paths 218, 219. This constitutes a closed circuit.

  The third hydraulic pump 14 has a flow path 203 connected to one input / output port and a flow path 204 connected to the other input / output port. The flow paths 203 and 204 are provided with four switching valves 45a to 45d as closed circuit switching means for a hydraulic actuator that switches the supply destination of hydraulic oil from the third hydraulic pump 14. The switching valves 45a to 45d are used to switch between communication and blocking of the flow path according to a command signal from the controller 57. When there is no command signal from the controller 57, the switching valves 45a to 45d are cut off. The controller 57 performs control so that any two or more of the switching valves 45a to 45d are not simultaneously communicated.

  The switching valve 45 a is connected to the boom cylinder 1 via the flow paths 212 and 213. When the switching valve 45a is in communication with the command signal from the controller 57, the third hydraulic pump 14 is connected to the boom cylinder 1 via the flow paths 203, 204, the switching valve 45a, and the flow paths 212, 213. This constitutes a closed circuit. The switching valve 45 b is connected to the arm cylinder 3 via the flow paths 214 and 215. When the switching valve 45b is in communication with the command signal from the controller 57, the third hydraulic pump 14 is connected to the arm cylinder 3 via the flow paths 203 and 204, the switching valve 45b, and the flow paths 214 and 215. This constitutes a closed circuit.

  The switching valve 45 c is connected to the bucket cylinder 5 via flow paths 216 and 217. When the switching valve 45c is in communication with the command signal from the controller 57, the third hydraulic pump 14 is connected to the bucket cylinder 5 via the flow paths 203 and 204, the switching valve 45c, and the flow paths 216 and 217. This constitutes a closed circuit. The switching valve 45d is connected to the turning device 7 via the flow paths 218 and 219. When the switching valve 45d is brought into a communication state by a command signal from the controller 57, the third hydraulic pump 14 is connected to the turning device 7 via the flow paths 203 and 204, the switching valve 45d, and the flow paths 218 and 219. This constitutes a closed circuit.

  The fifth hydraulic pump 16 has a flow path 206 connected to one input / output port and a flow path 207 connected to the other input / output port. The flow paths 206 and 207 are provided with four switching valves 47a to 47d as closed circuit switching means for a hydraulic actuator that switches the supply destination of hydraulic oil from the fifth hydraulic pump 16. The switching valves 47a to 47d are for switching between communication and blocking of the flow path by a command signal from the controller 57. When there is no command signal from the controller 57, the switching valves 47a to 47d are cut off. The controller 57 controls so that any two or more of the switching valves 47a to 47d are not simultaneously communicated.

  The switching valve 47 a is connected to the boom cylinder 1 via the flow paths 212 and 213. When the switching valve 47a is in communication with the command signal from the controller 57, the fifth hydraulic pump 16 is connected to the boom cylinder 1 via the flow paths 206 and 207, the switching valve 47a, and the flow paths 212 and 213. This constitutes a closed circuit. The switching valve 47 b is connected to the arm cylinder 3 via the flow paths 214 and 215. When the switching valve 47b is in communication with the command signal from the controller 57, the fifth hydraulic pump 16 is connected to the arm cylinder 3 via the flow paths 206 and 207, the switching valve 47b, and the flow paths 214 and 215. This constitutes a closed circuit.

  The switching valve 47 c is connected to the bucket cylinder 5 via the flow paths 216 and 217. When the switching valve 47c is in communication with the command signal from the controller 57, the fifth hydraulic pump 16 is connected to the bucket cylinder 5 via the flow paths 206 and 207, the switching valve 47c, and the flow paths 216 and 217. This constitutes a closed circuit. The switching valve 47d is connected to the turning device 7 via the flow paths 218 and 219. When the switching valve 47d is in communication with the command signal from the controller 57, the fifth hydraulic pump 16 is connected to the swivel device 7 via the flow paths 206, 207, the switching valve 47d, and the flow paths 218, 219. This constitutes a closed circuit.

  The seventh hydraulic pump 18 has a flow path 209 connected to one input / output port and a flow path 210 connected to the other input / output port. The flow paths 209 and 210 are provided with four switching valves 49a to 49d serving as hydraulic circuit closed circuit switching means for switching the supply destination of hydraulic oil from the seventh hydraulic pump 18. The switching valves 49a to 49d are for switching between communication and blocking of the flow path by a command signal from the controller 57. When there is no command signal from the controller 57, the switching valves 49a to 49d are cut off. The controller 57 controls so that any two or more of the switching valves 49a to 49d are not simultaneously communicated.

  The switching valve 49 a is connected to the boom cylinder 1 via the flow paths 212 and 213. When the switching valve 49a is in communication with the command signal from the controller 57, the seventh hydraulic pump 18 is connected to the boom cylinder 1 via the flow paths 209 and 210, the switching valve 49a, and the flow paths 212 and 213. This constitutes a closed circuit. The switching valve 49 b is connected to the arm cylinder 3 via the flow paths 214 and 215. When the switching valve 49b is in communication with the command signal from the controller 57, the seventh hydraulic pump 18 is connected to the arm cylinder 3 via the flow paths 209 and 210, the switching valve 49b, and the flow paths 214 and 215. This constitutes a closed circuit.

  The switching valve 49 c is connected to the bucket cylinder 5 via the flow paths 216 and 217. When the switching valve 49c is in communication with the command signal from the controller 57, the seventh hydraulic pump 18 is connected to the bucket cylinder 5 via the flow paths 209 and 210, the switching valve 49c, and the flow paths 216 and 217. This constitutes a closed circuit. The switching valve 49d is connected to the turning device 7 via the flow paths 218 and 219. When the switching valve 49d is in communication with the command signal from the controller 57, the seventh hydraulic pump 18 is connected to the swivel device 7 via the flow paths 209 and 210, the switching valve 49d, and the flow paths 218 and 219. This constitutes a closed circuit.

  The second hydraulic pump 13 which is an open circuit hydraulic pump has a flow path 202 connected to the output port and a flow path communicating with the hydraulic oil tank 25 connected to the input port. The flow path 202 is provided with four switching valves 44 a to 44 d and a relief valve 21 for switching the supply destination of the hydraulic oil from the second hydraulic pump 13. The switching valves 44a to 44d are for switching communication and blocking of the flow path 202 by a command signal from the controller 57. When there is no command signal from the controller 57, the switching valves 44a to 44d are switched off. The controller 57 controls so that any two or more of the switching valves 44a to 44d are not simultaneously communicated.

  The switching valve 44 a is connected to the boom cylinder 1 via the flow path 212. The switching valve 44 b is connected to the arm cylinder 3 via the flow path 214. The switching valve 44 c is connected to the bucket cylinder 5 via the flow path 216. The switching valve 44d is connected to the proportional switching valves 54 and 55 that control the supply and discharge of the hydraulic oil to and from the traveling devices 8a and 8b via the flow path 220. The relief valve 21 releases the hydraulic oil in the flow path to the hydraulic oil tank 25 and protects the hydraulic circuit when the hydraulic oil pressure in the flow path 202 exceeds a predetermined pressure.

  A flow rate control valve 73 is provided in a pipe that branches from the flow path 202 and leads to the hydraulic oil tank 25. The flow rate control valve 73 is a flow rate control valve with pressure compensation, and controls the flow rate of the hydraulic oil flowing from the flow path 202 to the hydraulic oil tank 25 by a command signal from the controller 57. When there is no command signal from the controller 57, a shut-off state is established.

  The fourth hydraulic pump 15 that is an open circuit hydraulic pump has a flow path 205 connected to the output port and a flow path communicating with the hydraulic oil tank 25 connected to the input port. The flow path 205 is provided with four switching valves 46 a to 46 d and a relief valve 22 for switching the supply destination of the hydraulic oil from the fourth hydraulic pump 15. The switching valves 46a to 46d are for switching communication and blocking of the flow path 205 according to a command signal from the controller 57. When there is no command signal from the controller 57, the switching valves 46a to 46d are cut off. The controller 57 controls so that any two or more of the switching valves 46a to 46d are not simultaneously communicated.

  The switching valve 46 a is connected to the boom cylinder 1 via the flow path 212. The switching valve 46 b is connected to the arm cylinder 3 via the flow path 214. The switching valve 46 c is connected to the bucket cylinder 5 via the flow path 216. The switching valve 46d is connected to the proportional switching valves 54 and 55 that control the supply and discharge of the hydraulic oil to and from the traveling devices 8a and 8b via the flow path 220. The relief valve 22 protects the hydraulic circuit by allowing the hydraulic oil in the flow path to escape to the hydraulic oil tank 25 when the hydraulic oil pressure in the flow path 205 exceeds a predetermined pressure.

  A flow rate control valve 74 is provided in a pipe that branches from the flow path 205 and leads to the hydraulic oil tank 25. The flow rate control valve 74 is a control valve with pressure compensation, and controls the flow rate of the hydraulic oil flowing from the flow path 205 to the hydraulic oil tank 25 by a command signal from the controller 57. When there is no command signal from the controller 57, a shut-off state is established.

  The sixth hydraulic pump 17 that is an open circuit hydraulic pump has a flow path 208 connected to the output port, and a flow path communicating with the hydraulic oil tank 25 connected to the input port. The flow path 208 is provided with four switching valves 48 a to 48 d and a relief valve 23 for switching the supply destination of the hydraulic oil from the sixth hydraulic pump 17. The switching valves 48a to 48d are for switching communication and blocking of the flow path 208 by a command signal from the controller 57. When there is no command signal from the controller 57, the switching valves 48a to 48d are in a blocking state. The controller 57 controls so that any two or more of the switching valves 48a to 48d are not simultaneously communicated.

  The switching valve 48 a is connected to the boom cylinder 1 via the flow path 212. The switching valve 48 b is connected to the arm cylinder 3 via the flow path 214. The switching valve 48 c is connected to the bucket cylinder 5 via the flow path 216. The switching valve 48d is connected to the proportional switching valves 54 and 55 that control the supply and discharge of the hydraulic oil to and from the traveling devices 8a and 8b via the flow path 220. The relief valve 23 protects the hydraulic circuit by allowing the hydraulic oil in the flow path to escape to the hydraulic oil tank 25 when the hydraulic oil pressure in the flow path 208 exceeds a predetermined pressure.

  A flow control valve 75 is provided in a pipe that branches from the flow path 208 and leads to the hydraulic oil tank 25. The flow control valve 75 is a control valve with pressure compensation, and controls the flow rate of the hydraulic oil flowing from the flow path 208 to the hydraulic oil tank 25 by a command signal from the controller 57. When there is no command signal from the controller 57, a shut-off state is established.

  The eighth hydraulic pump 19 that is an open circuit hydraulic pump has a flow path 211 connected to the output port, and a flow path communicating with the hydraulic oil tank 25 connected to the input port. The flow path 211 is provided with four switching valves 50 a to 50 d and a relief valve 24 for switching the supply destination of the hydraulic oil from the eighth hydraulic pump 19. The switching valves 50a to 50d are for switching communication and blocking of the flow path 211 by a command signal from the controller 57. When there is no command signal from the controller 57, the switching valves 50a to 50d are in a blocking state. The controller 57 performs control so that any two or more of the switching valves 50a to 50d are not simultaneously communicated.

  The switching valve 50 a is connected to the boom cylinder 1 via the flow path 212. The switching valve 50 b is connected to the arm cylinder 3 through the flow path 214. The switching valve 50 c is connected to the bucket cylinder 5 via the flow path 216. The switching valve 50d is connected to the proportional switching valves 54 and 55 that control the supply and discharge of the hydraulic oil to and from the traveling devices 8a and 8b via the flow path 220. The relief valve 24 protects the hydraulic circuit by allowing the hydraulic oil in the flow path to escape to the hydraulic oil tank 25 when the hydraulic oil pressure in the flow path 211 exceeds a predetermined pressure.

  A flow rate control valve 76 is provided in a pipeline that branches from the flow path 211 and connects to the hydraulic oil tank 25. The flow rate control valve 76 is a control valve with pressure compensation, and controls the flow rate of hydraulic oil flowing from the flow path 211 to the hydraulic oil tank 25 by a command signal from the controller 57. When there is no command signal from the controller 57, a shut-off state is established.

  In the charge pump 11, a flow path 229 is connected to the discharge port, and a flow path communicating with the hydraulic oil tank 25 is connected to the suction port. The flow path 229 is provided with a charge relief valve 20 and charge check valves 26 to 29, 40a, 40b, 41a, 41b, 42a, and 42b. The charge relief valve 20 adjusts the charge pressure of the charge check valves 26 to 29, 40a, 40b, 41a, 41b, 42a, and 42b.

  The charge check valve 26 supplies the pressure oil of the charge pump 11 to the flow paths 200 and 201 when the pressure of the flow paths 200 and 201 falls below the pressure set by the charge relief valve 20. The charge check valve 27 supplies the pressure oil of the charge pump 11 to the flow paths 203 and 204 when the pressure of the flow paths 203 and 204 is lower than the pressure set by the charge relief valve 20. The charge check valve 28 supplies the pressure oil of the charge pump 11 to the flow paths 206 and 207 when the pressure in the flow paths 206 and 207 falls below the pressure set by the charge relief valve 20. The charge check valve 29 supplies the pressure oil of the charge pump 11 to the flow paths 209 and 210 when the pressure of the flow paths 209 and 210 is lower than the pressure set by the charge relief valve 20.

  The charge check valves 40a and 40b supply the pressure oil of the charge pump 11 to the flow paths 212 and 213 when the pressure in the flow paths 212 and 213 falls below the pressure set by the charge relief valve 20. The charge check valves 41a and 41b supply the pressure oil of the charge pump 11 to the flow paths 214 and 215 when the pressure in the flow paths 214 and 215 falls below the pressure set by the charge relief valve 20. The charge check valves 42a and 42b supply the pressure oil of the charge pump 11 to the flow paths 216 and 217 when the pressure in the flow paths 216 and 217 falls below the pressure set by the charge relief valve 20.

  Relief valves 30a and 30b provided between the flow paths 200 and 201 allow the hydraulic oil to flow from the flow path 229 to the relief valve 20 when the pressure of the hydraulic oil in the flow path exceeds a predetermined pressure. Through the hydraulic oil tank 25 to protect the hydraulic circuit. The relief valves 31a and 31b provided between the flow paths 203 and 204 allow the hydraulic oil to flow from the flow path 229 to the relief valve 20 when the pressure of the hydraulic oil in the flow path exceeds a predetermined pressure. Through the hydraulic oil tank 25 to protect the hydraulic circuit.

  The relief valves 32a and 32b provided between the flow paths 206 and 207 allow the hydraulic oil to flow from the flow path 229 to the relief valve 20 when the pressure of the hydraulic oil in the flow path exceeds a predetermined pressure. Through the hydraulic oil tank 25 to protect the hydraulic circuit. Relief valves 33a and 33b provided between the flow paths 209 and 210 allow the hydraulic oil to flow from the flow path 229 to the relief valve 20 when the pressure of the hydraulic oil in the flow path exceeds a predetermined pressure. Through the hydraulic oil tank 25 to protect the hydraulic circuit.

  The flow path 212 is connected to the head side oil chamber 1 a of the boom cylinder 1. The flow path 213 is connected to the rod side oil chamber 1 b of the boom cylinder 1. The boom cylinder 1 is a hydraulic piece rod cylinder that receives a supply of hydraulic oil and expands and contracts the cylinder rod. Relief valves 37a and 37b provided between the flow paths 212 and 213 allow the hydraulic oil to flow from the flow path 229 to the relief valve 20 when the pressure of the hydraulic oil in the flow path exceeds a predetermined pressure. Through the hydraulic oil tank 25 to protect the hydraulic circuit. The flushing valve 34 provided between the flow paths 212 and 213 discharges excess oil in the flow path from the flow path 229 to the hydraulic oil tank 25 through the charge relief valve 20. The flow paths 212 and 213 are provided with pressure sensors 64 a and 64 b for detecting the pressure in the flow path, and signals detected by these pressure sensors are input to the controller 57.

  The flow path 214 is connected to the head side oil chamber 3 a of the arm cylinder 3. The flow path 215 is connected to the rod side oil chamber 3 b of the arm cylinder 3. The arm cylinder 3 is a hydraulic rod cylinder that is supplied with hydraulic oil and expands and contracts the cylinder rod. The relief valves 38a and 38b provided between the flow paths 214 and 215 allow the hydraulic oil to flow from the flow path 229 to the relief valve 20 when the pressure of the hydraulic oil in the flow path exceeds a predetermined pressure. Through the hydraulic oil tank 25 to protect the hydraulic circuit. The flushing valve 35 provided between the flow paths 214 and 215 discharges excess oil in the flow path from the flow path 229 to the hydraulic oil tank 25 through the charge relief valve 20. The flow paths 214 and 215 are provided with pressure sensors 65 a and 65 b that detect pressure in the flow path, and signals detected by these pressure sensors are input to the controller 57.

  The flow path 216 is connected to the head side oil chamber 5 a of the bucket cylinder 5. The flow path 217 is connected to the rod side oil chamber 5 b of the bucket cylinder 5. The bucket cylinder 5 is a hydraulic piece rod cylinder that receives the supply of hydraulic oil and expands and contracts the cylinder rod. The relief valves 39a and 39b provided between the flow paths 216 and 217 allow the hydraulic oil to flow from the flow path 229 to the relief valve 20 when the pressure of the hydraulic oil in the flow path exceeds a predetermined pressure. Through the hydraulic oil tank 25 to protect the hydraulic circuit. The flushing valve 36 provided between the flow paths 216 and 217 discharges excess oil in the flow path from the flow path 229 to the hydraulic oil tank 25 through the charge relief valve 20. The flow paths 216 and 217 are provided with pressure sensors 66 a and 66 b for detecting the pressure in the flow path, and signals detected by these pressure sensors are input to the controller 57.

  The flow paths 218 and 219 are connected to the turning device 7. The swivel device 7 is a hydraulic motor that rotates upon receiving hydraulic oil. Relief valves 51a and 51b provided in the flow paths 218 and 219 operate from the high-pressure side flow path to the low-pressure side flow path when the flow pressure difference between the flow paths 218 and 219 exceeds a predetermined pressure. Let the oil escape and protect the hydraulic circuit. The flow paths 218 and 219 are provided with pressure sensors 67 a and 67 b for detecting the pressure in the flow path, and signals detected by these pressure sensors are input to the controller 57.

  The flow paths 221 and 222 have one end connected to the traveling device 8a and the other end connected to the proportional switching valve 54. The traveling device 8a is a hydraulic motor that rotates upon receiving hydraulic oil. Relief valves 52a and 52b provided in the flow paths 221 and 222 operate from the high-pressure side flow path to the low-pressure side flow path when the flow path pressure difference between the flow paths 221 and 222 exceeds a predetermined pressure. Let the oil escape and protect the hydraulic circuit. The proportional switching valve 54 can switch the connection destination of the flow path 220 and the hydraulic oil tank 25 to the flow path 221 or the flow path 222 by a command signal from the controller 57, and can also adjust the flow rate. .

  The flow paths 223 and 224 are connected at one end side to the traveling device 8 b and connected at the other end side to the proportional switching valve 55. The traveling device 8b is a hydraulic motor that rotates upon receiving hydraulic oil. Relief valves 53a and 53b provided in the flow paths 223 and 224 operate from the high-pressure side flow path to the low-pressure side flow path when the flow path pressure difference between the flow paths 223 and 224 exceeds a predetermined pressure. Let the oil escape and protect the hydraulic circuit. The proportional switching valve 55 can switch the connection destination of the flow path 220 and the hydraulic oil tank 25 to the flow path 223 or the flow path 224 according to a command signal from the controller 57, and can also adjust the flow rate. .

  The controller 57 includes command values for the expansion and contraction directions and speeds of the boom cylinder 1, the arm cylinder 3, and the bucket cylinder 5 from the operation levers 56 a to 56 d, and command values for the rotation direction and the rotation speed of the swivel device 7. The regulators 12a to 19a of the first to eighth hydraulic pumps 12 to 19 are based on the command values of the rotational direction and rotational speed of the travel devices 8a and 8b from the pedal and the pressure sensor information in the hydraulic circuit. The switching valves 43a to 50a, 43b to 50b, 43c to 50c, 43d to 50d, the proportional switching valves 54 and 55, and the flow control valves 73 to 76 are controlled. Specifically, the flow rate control unit that controls the regulators 12a to 19a and the flow rate control valves 73 to 76 of the first hydraulic pressure pump 12 to the eighth hydraulic pressure pump 19, and the switching valves 43a to 50a, 43b to 50b, 43c to And a switching control unit for controlling 50c, 43d to 50d.

  For example, the flow rate control unit of the controller 57 is the flow rate of the closed circuit side pump (any one of the first, third, fifth, and seventh hydraulic pumps) on the flow path 212 side connected to the head side oil chamber 1a of the boom cylinder 1. Is the first flow rate, and the flow rate of the open circuit side pump (any one of the second, fourth, sixth and eighth hydraulic pumps) connected via any one of the switching valves 44a, 46a, 48a, 50a is the second flow rate. As described above, the pump flow rate control is performed such that the ratio between the first flow rate and the second flow rate becomes a predetermined value set in advance according to the pressure receiving area of the head side oil chamber 1a and the rod side oil chamber 1b of the boom cylinder 1. . The controller 57 also performs similar pump flow rate control for the arm cylinder 3 and the bucket cylinder 5.

  Further, the switching control unit of the controller 57 switches the switching valves 43a to 50a, 43b so that when one fluid pressure rod cylinder joins, one closed circuit pump and one open circuit pump join together. -50b, 43c to 50c, 43d to 50d are controlled, and it is determined whether the hydraulic actuator is regenerative, and when it is determined to be regenerative, the hydraulic fluid is supplied to other hydraulic actuators in power running Pump switching control is performed to control the switching valve so as to connect a closed circuit pump connected to the same drive shaft as the circuit pump.

  The operation lever 56 a of the operation lever device gives the controller 57 a command value for the expansion and contraction direction and speed of the boom cylinder 1. The operation lever 56 b gives the controller 57 a command value for the expansion and contraction direction and speed of the arm cylinder 3. The operation lever 56 c gives the controller 57 a command value for the expansion / contraction direction and speed of the bucket cylinder 5. The operation lever 56 d gives the rotation direction and rotation speed command values of the turning device 7 to the controller 57. Although not shown, an operation pedal is also provided that gives the controller 57 command values for the rotation direction and the rotation speed of the traveling devices 8a and 8b.

  Next, control of the switching control unit described above will be described with reference to FIG. FIG. 3 is a flowchart showing the processing contents of the hydraulic drive control device constituting one embodiment of the working machine of the present invention. This processing flow is processed for each hydraulic actuator. For example, the processing flow in the boom cylinder 1 and the processing flow in the arm cylinder 3 are performed in parallel. Here, a description will be given based on the hydraulic actuator.

  The controller 57 inputs an operator operation signal (step S1). Specifically, command values for the operation direction and speed of the hydraulic actuator are input from the operation lever.

  The controller 57 determines the operation direction of the hydraulic actuator based on the input operation signal (step S2). Specifically, it is determined whether the cylinder rod of the hydraulic actuator is in the extending direction or the reducing direction.

The controller 57 determines the input pressure _PAin and the output pressure _PAout with respect to the signal from the pressure sensor according to the operation direction of the hydraulic actuator (step S3). Specifically, for example, when the piston rod of the boom cylinder 1 is extended, the pressure signal detected by the pressure sensor 64a that is the pressure of the head side oil chamber 1a of the boom cylinder 1 is determined as the input pressure _PAin, and the rod side The pressure signal detected by the pressure sensor 64b, which is the pressure in the oil chamber 1b, is determined as the output pressure _PAout . Conversely, when the piston rod is contracted, the pressure signal detected by the pressure sensor 64b, which is the pressure in the rod-side oil chamber 1b of the boom cylinder 1, is determined as the input pressure _PAin, and the pressure, which is the pressure in the head-side oil chamber 1a. The pressure signal detected by the sensor 64a is determined as the output pressure _PAout .

The controller 57 determines whether the hydraulic actuator is in a regenerative state or a power running state from the magnitude relationship between the input pressure _PAin and the output pressure _PAout of the hydraulic actuator (step S4). Specifically, for example, when the input pressure P _Ain is larger than the output pressure _PAout , in the closed circuit pump connected to the hydraulic actuator, the discharge pressure becomes larger than the suction pressure, so the determination is power running. On the other hand, when the input pressure P _Ain is smaller than the output pressure _PAout , in the closed circuit pump connected to the hydraulic actuator, the suction pressure is larger than the discharge pressure, so the determination is regeneration. When the input pressure P _Ain is larger than the output pressure _PAout , the process proceeds to (Step S10), and otherwise, the process proceeds to (Step S5).

At (step S4), and when the output pressure _{P Aout} is larger than the input pressure _{P Ain,} the controller 57 determines that the fluid pressure actuator is a regeneration state (step S5). For example, when extending the piston rod of the boom cylinder 1, when the pressure of the head-side oil chamber 1a which was determined input pressure P _Ain is, it becomes smaller than the pressure of the determined output pressure P _Aout rod-side oil chamber 1b, _{Alternatively} , when the piston rod of the boom cylinder 1 is contracted, the pressure in the rod-side oil chamber 1b determined as the input pressure _PAin becomes smaller than the pressure in the head-side oil chamber 1a determined as the output pressure _PAout. Applicable.

  The controller 57 determines whether there is a hydraulic pump during power running (step S6). Specifically, the presence or absence of a hydraulic pump connected to a hydraulic actuator other than the hydraulic actuator that has been determined to be in powering is searched. If there is a hydraulic pump during power running, the process proceeds to (Step S7), otherwise the process proceeds to (Step S9).

  The controller 57 determines whether or not the hydraulic pump on the same drive shaft as that of the power running hydraulic pump is empty (step S7). Here, the vacant hydraulic pump is a hydraulic pump that is not connected to any hydraulic actuator, and specifically, a hydraulic pump in which all the switching valves of the hydraulic pump are in a shut-off state. A pressure pump. For example, assuming that the fifth hydraulic pump 16 supplies hydraulic fluid to the swivel device 7 by communicating the switching valve 47d, the second drive shaft 69 is the same as the fifth hydraulic pump. It is determined whether the connected seventh hydraulic pump 18 is not connected to any hydraulic actuator. If the hydraulic pump on the same drive shaft as the hydraulic pump in power running is empty, the process proceeds to (Step S8), and otherwise proceeds to (Step S9).

  The controller 57 connects a hydraulic pump on the same drive shaft as the hydraulic pump during power running to the actuator (step S8). Specifically, the switching valve 49a is connected to connect the seventh hydraulic pump 18 connected to the second drive shaft 69, which is the same as the fifth hydraulic pump 16 described above, to the boom cylinder 1. As a result, the hydraulic oil having regenerative energy from the boom cylinder 1 flows into the seventh hydraulic pump 18, so that the seventh hydraulic pump 18 operates as a hydraulic motor and passes through the second drive shaft 69. Assist the drive of the fifth hydraulic pump 16.

  When there is no hydraulic pump during power running in (Step S6), and when the hydraulic pump on the same drive shaft as the hydraulic pump during power running is not empty in (Step S7), The controller 57 connects a vacant hydraulic pump to the actuator (step S9). For example, the seventh hydraulic pump 18 is connected to any hydraulic actuator even when the above-described fifth hydraulic pump 16 is not powering or the fifth hydraulic pump 16 is powering. This is the case. This case corresponds to the case where there is no hydraulic pump that can effectively use the regenerative energy from the hydraulic actuator, and is connected to a suitable free hydraulic pump. Connect to any available hydraulic pump. Here, for any vacant hydraulic pump to be connected, a priority may be set in advance in order to realize smooth switching.

If the input pressure P _Ain is greater than the output pressure _{PAout in} (Step S4), the controller 57 determines that the hydraulic actuator is in a power running state (Step S10). For example, when extending the piston rod of the boom cylinder 1, when the pressure of the head-side oil chamber 1a which was determined input pressure P _Ain is, it becomes greater than the pressure of the determined output pressure P _Aout rod-side oil chamber 1b, or, in the case of reducing the piston rod of the boom cylinder 1, is when the pressure is determined as the input pressure P _Ain rod-side oil chamber 1b is, becomes greater than the pressure of the head-side oil chamber 1a determining the output pressure P _Aout Applicable.

  The controller 57 determines whether or not there is a hydraulic pump other than the hydraulic pump connected to the hydraulic actuator that is being regenerated (step S11). Specifically, the presence or absence of a hydraulic pump connected to a hydraulic actuator other than the hydraulic actuator that has been determined to be regenerating is searched. If there is a regenerating hydraulic pump, the process proceeds to (Step S12), and otherwise the process proceeds to (Step S14).

  The controller 57 determines whether or not a hydraulic pump on the same drive shaft as the hydraulic pump being regenerated is empty (step S12). Here, the vacant hydraulic pump is a hydraulic pump that is not connected to any hydraulic actuator, and specifically, a hydraulic pump in which all the switching valves of the hydraulic pump are in a shut-off state. A pressure pump. For example, if it is assumed that hydraulic oil is supplied to the fifth hydraulic pump 16 from the swivel device 7 through the switching valve 47d and is being regenerated, it is connected to the same second drive shaft 69 as the fifth hydraulic pump. It is determined whether the seventh hydraulic pump 18 is not connected to any hydraulic actuator. When the hydraulic pump on the same drive shaft as the hydraulic pump being regenerated is empty, the process proceeds to (Step S13), and otherwise the process proceeds to (Step S14).

  The controller 57 connects a hydraulic pump on the same drive shaft as the hydraulic pump being regenerated to the actuator (step S13). Specifically, the switching valve 49a is connected to connect the seventh hydraulic pump 18 connected to the second drive shaft 69, which is the same as the fifth hydraulic pump 16 described above, to the boom cylinder 1. As a result, the hydraulic oil having regenerative energy from the swivel device 7 flows into the fifth hydraulic pump 16, so that the fifth hydraulic pump 16 operates as a hydraulic motor and passes through the second drive shaft 69. The drive of the seventh hydraulic pump 18 is assisted. The hydraulic fluid is supplied from the seventh hydraulic pump 18 that is assisted and driven by regenerative energy to the boom cylinder 1 that is running.

  When there is no hydraulic pump during regeneration in (Step S11), and when the hydraulic pump on the same drive shaft as the hydraulic pump during regeneration is not empty in (Step S12), The controller 57 connects a vacant hydraulic pump to the actuator (step S14). For example, even if the fifth hydraulic pump 16 is not being regenerated or the fifth hydraulic pump 16 is being regenerated, the seventh hydraulic pump 18 is being connected to any hydraulic actuator. This is the case. This case corresponds to the case where there is no hydraulic pump that can effectively use the regenerative energy to the hydraulic actuator, and is connected to a suitable free hydraulic pump. Here, for any vacant hydraulic pump to be connected, a priority may be set in advance in order to realize smooth switching.

  The controller 57 performs an end process after executing the process of (Step S8) or (Step S9) or (Step S13) or (Step S14).

Next, operation | movement of one Embodiment of the working machine of this invention is demonstrated.
First, when none of the operation levers 56a to 56d is operated (when not operated),
The controller 57 outputs a minimum tilt angle control command signal to the regulators 12a to 19a of the first hydraulic pump 12 to the eighth hydraulic pump 19, and the switching valves 43a to 50a, 43b to 50b, 43c to 50c, 43d to 50d, proportional switching valves 54 and 55, and flow control valves 73 to 76 are output with shutoff / close command signals. As a result, the boom cylinder 1, the arm cylinder 3, the bucket cylinder 5, the turning device 7, and the traveling devices 8a and 8b are held in a stopped (non-operating) state.

A single raising operation of the boom 2 will be described. In FIG. 2, when an operation to instruct to raise the boom is performed by the operation lever 56a, the control switching unit of the controller 57 determines the input side pressure _PAin when the piston rod of the boom cylinder 1 is extended. Since the pressure of 1a becomes larger than the pressure of the rod side oil chamber 1b determined to be the output pressure _PAout, it is determined that the power is running (step S10), and there is no hydraulic pump during regeneration (step S11). Then, the switching valve is controlled so that the boom cylinder 1 is connected to the vacant hydraulic pump (step S14). Here, the first hydraulic pressure pump 12 and the second hydraulic pressure pump 13 are selected from preset priorities, and the switching valves 43a and 44a are controlled to communicate.

  The flow rate controller of the controller 57 controls the regulator 12 a of the first hydraulic pump 12 to drive the swash plate of the first hydraulic pump 12 so that the discharge port of the first hydraulic pump 12 becomes the flow path 201. To do. At the same time, the flow rate control unit of the controller 57 controls the regulator 13 a of the second hydraulic pump 13 to drive the swash plate so that hydraulic oil is discharged from the second hydraulic pump 13 to the flow path 202.

  The flow control unit of the controller 57 includes an area ratio (Aa1: Aa2) between the pressure receiving area (Aa1) of the head side oil chamber 1a of the boom cylinder 1 and the pressure receiving area (Aa2) of the rod side oil chamber 1b, and the first and first The discharge flow rates (Qcp1, Qop1) of the first and second hydraulic pumps 12, 13 are determined and controlled so that the flow rate ratio [(Qcp1 + Qop1): Qcp1) of the two hydraulic pumps 12, 13 is equal. The pressure receiving area ratio control is executed. Further, the flow rate controller of the controller 57 controls the ratio of the discharge flow rate of the first hydraulic pump 12 and the discharge flow rate of the second hydraulic pump 13 to change while maintaining the relationship of Qcp1: Qop1.

Next, the independent lowering operation of the boom 2 will be described. In FIG. 2, when an operation to instruct boom lowering is performed by the operation lever 56 a, the control switching unit of the controller 57 determines the input side pressure _PAin when the piston rod of the boom cylinder 1 is contracted. Since the pressure of 1b is smaller than the pressure of the head side oil chamber 1a determined to be the output pressure _PAout , it is determined that regeneration is occurring (step S5), and at this time there is no hydraulic pump during power running (step S6). Then, the switching valve is controlled so that the boom cylinder 1 is connected to the vacant hydraulic pump (step S9). Here, the first hydraulic pressure pump 12 and the second hydraulic pressure pump 13 are selected from preset priorities, and the switching valves 43a and 44a are controlled to communicate.

  The flow rate controller of the controller 57 controls the regulator 12 a of the first hydraulic pump 12 to drive the swash plate of the first hydraulic pump 12 so that the discharge port of the first hydraulic pump 12 becomes the flow path 201. To do. At the same time, the flow rate control unit of the controller 57 controls the regulator 13 a of the second hydraulic pump 13 to drive the swash plate so that hydraulic oil is discharged from the second hydraulic pump 13 to the flow path 202.

  The flow rate control unit of the controller 57 controls the regulator 12a of the first hydraulic pump 12 to set the discharge flow rate to -Qcp1 in the direction opposite to that when the boom is raised, and the discharge discharged from the flow control valve 73 to the hydraulic oil tank 25. The flow rate is set to -Qop1 in the direction opposite to that when the boom is raised, and the pressure receiving area ratio control similar to that when the boom is raised is executed between the discharge flow rate of the first hydraulic pump 12 and the discharge flow rate of the flow rate control valve 73. Furthermore, the flow rate control unit of the controller 57 controls the ratio of the discharge flow rate of the first hydraulic pump 12 and the discharge flow rate of the flow rate control valve to change while maintaining the relationship of Qcp1: Qop1.

  Next, the combined operation of the hydraulic actuator will be described. Here, the boom cylinder 1 and the turning device 7 will be described as examples of the hydraulic actuator. An example will be described in which the first hydraulic pump 12 and the second hydraulic pump 13 are connected to the boom cylinder 1, and the seventh hydraulic pump 18 is connected to the turning device 7.

  First, the operator performs a single raising operation of the boom 2 and the above-described operation is executed. After the lifting operation of the boom 2 is completed, the switching valves 43a and 44a that connect the boom cylinder 1 to the first hydraulic pump 12 and the second hydraulic pump 13 are shut off. Thereafter, in FIG. 2, when an operation for instructing the left or right turn is performed by the operation lever 56 d, the controller 57 controls the regulator 18 a of the seventh hydraulic pump 18 to control the seventh hydraulic pump, for example. The swash plate of the seventh hydraulic pump 18 is driven so that the 18 outlets become the flow path 209, and the switching valve 49d is controlled to communicate. At this time, the turning device 7 which is a hydraulic actuator is in a power running state.

Next, when the operator performs a lowering operation of the boom 2, the control switching unit of the controller 57 reduces the piston rod of the boom cylinder 1 to reduce the pressure in the rod-side oil chamber 1 b determined as the input pressure _PAin . Since it is smaller than the pressure of the head side oil chamber 1a determined to be the output pressure _PAout , it is determined that regeneration is in progress (step S5), and it is determined whether there is a hydraulic pump during power running (step S6). At this time, since the seventh hydraulic pump 18 connected to the turning device 7 is in power running, it is determined whether or not the hydraulic pump on the same drive shaft as the hydraulic pump in power running is empty (step S7). Specifically, it is determined whether or not the fifth hydraulic pump 16 of the second drive shaft 69 connected to the seventh hydraulic pump 18 is free. Here, since the fifth hydraulic pump 16 is empty, the process proceeds to (Step S8).

  The control switching unit of the controller 57 causes the switching valve 47a to communicate with the boom cylinder 1 in order to connect the fifth hydraulic pump 16 connected to the same second drive shaft 69 as the seventh hydraulic pump 18 in power running ( Step S8). As a result, hydraulic oil having regenerative energy from the boom cylinder 1 flows into the fifth hydraulic pump 16, so that the fifth hydraulic pump 16 operates as a hydraulic motor and is connected via the second drive shaft 69. The driving of the seventh hydraulic pump 18 can be assisted.

  The flow rate controller of the controller 57 controls the regulator 16 a of the fifth hydraulic pump 16 to drive the swash plate of the fifth hydraulic pump 16 so that the discharge port of the fifth hydraulic pump 16 becomes the flow path 207. To do. At the same time, the flow controller of the controller 57 outputs a flow command to the flow control valve 73.

  The flow rate controller of the controller 57 controls the regulator 16a of the fifth hydraulic pump 16 to set the discharge flow rate to -Qcp1 in the direction opposite to that when the boom is raised, and the discharge discharged from the flow control valve 73 to the hydraulic oil tank 25. The flow rate is set to -Qop1 in the opposite direction to that when the boom is raised, and the same pressure receiving area ratio control as that when the boom is raised is executed between the discharge flow rate of the fifth hydraulic pump 16 and the discharge flow rate of the flow rate control valve 73. Furthermore, the flow rate control unit of the controller 57 controls the ratio of the discharge flow rate of the fifth hydraulic pump 16 and the discharge flow rate of the flow rate control valve 73 to change while maintaining the relationship of Qcp1: Qop1.

  In the present embodiment, the boom cylinder 1 at the time of lowering the boom is determined to be regenerated, and the turning device 7 at the time of turning is determined to perform powering, whereby the boom cylinder 1 is connected to the fifth hydraulic pump 16 and the turning device 7 is Connect to the seventh hydraulic pump 18. Since the fifth hydraulic pump 16 is regeneratively driven, a regenerative torque is generated on the drive shaft of the fifth hydraulic pump 16. The regenerative torque is transmitted to the seventh hydraulic pump 17 via the second drive shaft 69. Therefore, the regenerative torque can be directly applied to the seventh hydraulic pump 18 during power running without using the power transmission device 10. Highly efficient regeneration without using the power transmission device 10 can be realized.

  According to the embodiment of the work machine of the present invention described above, a plurality of drive shafts in which at least two hydraulic pumps are connected to one shaft, and a plurality of hydraulic pumps for one hydraulic actuator. The hydraulic pump connected to the same drive shaft as the hydraulic pump connected to the hydraulic actuator during regeneration is connected to the hydraulic actuator during power running. Thus, the regenerative torque can be used as the drive torque with high efficiency.

  In the present embodiment, the case where the hydraulic pumps connected to the boom cylinder 1, the arm cylinder 3, the bucket cylinder 5, and the swivel device 7 are switchable using the switching valves 43 to 50 is taken as an example. Although demonstrated, it is good also as a structure which fixes to the hydraulic pump on the same drive shaft the hydraulic pump connected to the boom cylinder 1 and the turning apparatus 7 with high frequency of regenerative operation.

  In the present embodiment, the case where the closed circuit hydraulic pumps are provided on the first and second drive shafts and the open circuit pump is provided on the third and fourth drive shafts has been described as an example. It is not a thing. A closed circuit hydraulic pump and an open circuit hydraulic pump may be provided on one drive shaft.

  The present invention is not limited to the above-described embodiments, and includes various modifications within the scope not departing from the gist thereof. For example, in the above-described embodiment, the case where the present invention is applied to a hydraulic excavator has been described. However, the present invention is not limited to this, and any other work such as a hydraulic crane, a wheel loader, or the like can be used as long as the working machine includes a hydraulic actuator. It can also be applied to machines.

1: Boom cylinder (hydraulic actuator), 3: Arm cylinder (hydraulic actuator), 5: Bucket cylinder (hydraulic actuator), 7: Swivel device (hydraulic actuator), 9: Engine (drive source), 10: Power transmission device, 12: first hydraulic pump (hydraulic pump), 12a: regulator (flow rate adjusting means), 13: second hydraulic pump (hydraulic pump), 13a: regulator (flow rate adjusting means), 25: Hydraulic oil tanks, 43a to d: switching valve (hydraulic actuator closed circuit switching means), 44a to d: switching valve (hydraulic actuator closed circuit switching means), 45a to d: switching valve (hydraulic actuator closing) Circuit switching means), 56a: operating lever, 56b: operating lever, 57: controller (control device), 64a, b: pressure sensor, 65a, b: pressure sensor , 68: first driving shaft, 69: second drive shaft, 70: third driving shaft, 71: fourth drive shaft, 73: flow control valve, 74: flow control valve, 105: hydraulic drive control device

Claims (5)

A driving source;
A plurality of hydraulic pumps having flow rate adjusting means for controlling the flow rate of the discharged hydraulic fluid;
A plurality of hydraulic actuators driven by the hydraulic fluid;
A hydraulic pressure for selectively connecting the flow path of one hydraulic pump of the plurality of hydraulic pumps in a closed circuit to the flow path of one hydraulic actuator of the plurality of hydraulic actuators Actuator closed circuit switching means;
A plurality of hydraulic actuator closed circuit switching means connecting flow paths connecting from the one hydraulic actuator to the plurality of hydraulic actuator closed circuit switching means;
A drive shaft to which at least two hydraulic pumps are connected;
A power transmission device that distributes the power of the drive source to the plurality of drive shafts;
Power running / regeneration determining means for determining whether the plurality of hydraulic actuators are in a power running operation or a regenerative operation;
The power running / regeneration determining means determines the operating states of a plurality of the hydraulic actuators, connects the hydraulic actuator in power running to one of the hydraulic pumps connected to the drive shaft, and connects the drive shaft to the drive shaft. A work machine comprising: a control device that controls the closed circuit switching means for the hydraulic actuator so that the hydraulic actuator being regenerated is connected to the other connected hydraulic pump. The work machine according to claim 1,
The control device includes: the other hydraulic pressure coupled to the same drive shaft as the one hydraulic pump having a flow path connected to the hydraulic actuator determined to be in regeneration by the power running / regenerative determination unit. A working machine that controls the hydraulic actuator closed circuit switching means so that a pump connects a flow path to the hydraulic actuator determined to be in power running by the power running / regeneration determining means. The work machine according to claim 1,
The control device includes: the other hydraulic pressure coupled to the same drive shaft as the one hydraulic pump having a flow path connected to the hydraulic actuator determined to be in power running by the power running / regeneration determining means. A working machine that controls the hydraulic actuator closed circuit switching means so that a pump connects a flow path to the hydraulic actuator that is determined to be regenerating by the power running / regeneration determining means. The work machine according to any one of claims 1 to 3,
One pressure sensor for detecting the pressure of the outlet port of the hydraulic actuator, another pressure sensor for detecting the pressure of the inlet port of the hydraulic actuator, and an operating device for commanding the operating direction and speed of the hydraulic actuator; Further comprising
The power running / regeneration determining means includes a signal for commanding an operation direction and speed of the hydraulic actuator from the operating device, a pressure at the outlet port of the hydraulic actuator detected by the one pressure sensor, and the other pressure sensor. The pressure actuator detects the pressure of the inlet port of the hydraulic actuator, and the hydraulic actuator performs a power running operation according to the operation direction of the hydraulic actuator, the pressure of the outlet port of the hydraulic actuator, and the pressure of the inlet port. A work machine characterized by determining whether it is in medium or regenerative operation. The work machine according to claim 4,
The plurality of hydraulic actuators include a plurality of single rod hydraulic cylinders and a plurality of hydraulic motors.

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