JP2017015132A - Energy regeneration system - Google Patents

Abstract

An energy regeneration system capable of regenerating energy of hydraulic oil more efficiently is provided. An energy regeneration system includes a main pump, actuators and 50, excess hydraulic oil and actuators from first and second supply / discharge passages 35a and 35b connecting the main pump 11 and the actuator 30. A regenerative passage 82 that guides the hydraulic oil discharged from 30 and 50, a regenerative motor 81 that operates by the hydraulic oil supplied from the regenerative passage 82 and rotates the output shaft 12 a of the engine 12, and a branch passage that branches from the regenerative passage 82. 83, an accumulator 84 connected to the regenerative passage 82 via the branch passage 83, and a switching valve 85 that allows the flow of hydraulic oil when the valve is opened. Is allowed to accumulate the hydraulic oil from the regenerative passage 82, or the hydraulic oil in the accumulator 84 is stored in the regenerative passage 82. Characterized by feeding. [Selection] Figure 2

Description

  The present invention relates to a system for regenerating energy.

  Patent Document 1 discloses an energy regeneration system that regenerates the energy of a working fluid. The energy regeneration system includes a pump that supplies a working fluid to the boom cylinder, and a regeneration motor that is rotated by the working fluid discharged from the boom cylinder.

  In the energy regeneration system described above, the pump and the regeneration motor are connected to the output shaft of the engine. When lowering the boom, the working fluid is sent to the rod side chamber of the boom cylinder by the pump, and the working fluid in the non-rod side chamber of the boom cylinder is guided to the regenerative motor. The potential energy of the boom acts in the direction of accelerating the boom and is recovered as power of the regenerative motor. Since the power recovered by the regenerative motor drives the pump through the output shaft of the engine, power loss is reduced.

JP 2013-87831 A

  The energy of the working fluid discharged from the fluid pressure actuator such as a boom cylinder varies in accordance with the operation of the fluid pressure actuator. Therefore, when the entire amount of working fluid (returning working fluid) discharged from the fluid pressure actuator is supplied to the regenerative motor, the amount of energy regenerated by the regenerative motor may exceed the amount of energy necessary for the pump operation. In such a case, the entire amount of the return working fluid cannot be regenerated.

  In the energy regeneration system disclosed in Patent Document 1, when the entire amount of the return working fluid cannot be regenerated, excess working fluid is discharged to the tank through a discharge passage that bypasses the regenerative motor. For this reason, the energy of the working fluid cannot be efficiently regenerated.

  An object of this invention is to provide the energy regeneration system which can regenerate the energy of a working fluid more efficiently.

  According to a first aspect of the present invention, there is provided a fluid pressure supply unit that operates by rotation of an output shaft of an engine, an actuator, surplus working fluid from a passage connecting the fluid pressure supply unit and the actuator, and a working fluid discharged from the actuator. A regenerative passage for guiding, a regenerative motor that operates by a working fluid supplied from the regenerative passage and rotates the output shaft of the engine, a branch passage that branches from the regenerative passage, an accumulator connected to the regenerative passage through the branch passage, A switching valve provided in the branch passage and allowing the flow of the working fluid when the valve is opened, and the accumulator accumulates the working fluid from the regeneration passage when the switching valve allows the flow of the working fluid, or The working fluid in the accumulator is supplied to the regeneration passage.

  In the first invention, when the flow of the working fluid in the branch passage is allowed by the switching valve, the accumulator and the regeneration passage communicate with each other. Therefore, when the pressure in the regeneration passage is higher than the pressure in the accumulator, a part of the working fluid guided to the regeneration passage is accumulated in the accumulator as an excess working fluid. When the pressure in the regenerative passage is lower than the pressure in the accumulator, the working fluid accumulated as surplus working fluid in the accumulator is supplied to the regenerative motor to drive the regenerative motor.

  The second invention controls the operation of the regenerative control valve that guides the working fluid from the actuator to the regenerative motor through the regenerative passage when the valve is opened, the operating state detector that detects the operating state of the actuator, and the regenerative control valve and the switching valve. A controller, and the controller opens the switching valve when performing the energy regeneration by opening the regeneration control valve based on the detection result of the operation state detector.

  In the second invention, when the regeneration control valve is opened and energy regeneration is performed, the switching valve is opened. Therefore, the surplus working fluid is accumulated in the accumulator, or the working fluid accumulated in the accumulator as the surplus working fluid is supplied to the regenerative motor. Therefore, the energy of the working fluid can be regenerated more efficiently during energy regeneration.

  The third aspect of the invention further includes an operation state detector that detects an operation state of the fluid pressure supply unit, and the controller closes the regenerative control valve based on the detection result of the operation state detector during non-energy regeneration. When it is determined that the assistance of the fluid pressure supply unit is necessary based on the detection result of the operation state detector, the switching valve is opened.

  In the third aspect of the invention, when it is determined that the fluid pressure supply unit needs assistance during non-energy regeneration, the switching valve is opened, so that the working fluid accumulated in the accumulator during energy regeneration is regenerated. The regenerative motor is supplied to the motor to assist the fluid pressure supply unit. Therefore, the fuel efficiency of the energy regeneration system can be improved even during non-energy regeneration.

  In a fourth aspect of the invention, the actuator is a cylinder, the operation state detector is an operation detector that detects the expansion / contraction direction and expansion / contraction speed of the cylinder, and the controller is based on the detection result of the expansion / contraction direction by the operation state detector. When the extension operation of the cylinder is determined, the regenerative control valve is closed, and when the contraction operation of the cylinder is determined based on the detection result of the expansion / contraction direction by the operation state detector, the detection result of the contraction speed by the operation state detector is displayed. Based on this, the regeneration control valve is opened to perform energy regeneration.

  In the fourth invention, the regenerative control valve is opened according to the contraction speed detected by the operation state detector during the contraction operation of the cylinder. Therefore, even during the contraction operation of the cylinder, energy regeneration is not performed if the contraction speed does not satisfy a predetermined condition. Therefore, for example, when the contraction speed required by the operator is particularly high, it is possible to prevent a situation where the contraction operation required by the energy regeneration is not realized.

  According to a fifth aspect of the invention, the actuator is a turning motor, the operation state detector is a pressure detector that detects a turning pressure during a turning operation of the turning motor or a brake pressure during a braking operation, and the controller is a pressure detector. The regenerative control valve is opened based on the detection result of the turning pressure or the brake pressure by means of performing energy regeneration.

  In the fifth invention, the regeneration control valve is opened based on the detection result of the turning pressure or the brake pressure, and energy regeneration is performed. Therefore, even during the turning operation or the braking operation, energy regeneration is not performed if the turning pressure or the brake pressure does not satisfy a predetermined condition. Therefore, for example, when the turning pressure or the brake pressure is not sufficiently high, it is possible to prevent a situation in which the turning operation required by energy regeneration cannot be realized.

  The sixth invention is characterized in that the branch passage is connected to the regenerative passage through a restriction.

  In the sixth aspect of the invention, since the accumulator is connected to the regenerative passage through the throttle, fluctuations in the pressure of the working fluid in the regenerative passage are reduced. Therefore, load fluctuations and impacts in the regenerative motor, the fluid pressure supply unit, and the engine can be reduced.

  According to the present invention, the energy of the working fluid can be regenerated more efficiently.

1 is a schematic diagram of a hydraulic excavator to which an energy regeneration system according to an embodiment of the present invention is applied. It is a hydraulic circuit diagram which shows the energy regeneration system which concerns on embodiment of this invention, and shows the state which each control valve exists in a neutral position. 1 is a hydraulic circuit diagram showing an energy regeneration system according to an embodiment of the present invention, showing a state in which a control valve for a swing motor is in an operating position. 1 is a hydraulic circuit diagram showing an energy regeneration system according to an embodiment of the present invention, showing a state where a control valve for a swing motor is switched from an operating position to a neutral position. It is a hydraulic circuit diagram which shows the energy regeneration system which concerns on embodiment of this invention, and the control valve for boom cylinders exists in an expansion | extension position, and shows the state which needs the assistance of a main pump. It is a hydraulic circuit diagram which shows the energy regeneration system which concerns on embodiment of this invention, and shows the state which the control valve for boom cylinders exists in an expansion | extension position, and does not require the assistance of a main pump. 1 is a hydraulic circuit diagram showing an energy regeneration system according to an embodiment of the present invention, showing a state in which a control valve for a boom cylinder is in a contracted position and a required contraction speed is particularly high. It is a hydraulic circuit diagram which shows the energy regeneration system which concerns on embodiment of this invention, and the control valve for boom cylinders exists in a retracted position, and shows the state where a request | requirement contraction speed is low. It is a hydraulic circuit diagram which shows the energy regeneration system which concerns on embodiment of this invention, and the state which the control valve for arm cylinders and bucket cylinders exists in an expansion | extension position, and requires the assistance of a main pump. It is a hydraulic circuit diagram which shows the energy regeneration system which concerns on embodiment of this invention, and shows the state which the control valve for arm cylinders and bucket cylinders exists in an expansion | extension position, and does not require the assistance of a main pump.

  Embodiments of the present invention will be described below with reference to the drawings. Here, an energy regeneration system applied to a hydraulic excavator will be described, but the present embodiment can also be applied to devices other than hydraulic excavators. In hydraulic excavators, working oil is used as the working fluid, but other fluids such as working water may be used as the working fluid.

  As shown in FIG. 1, the excavator 1 includes a crawler-type traveling unit 2, a turning unit 3 provided at an upper portion of the traveling unit 2, and an excavation unit 4 provided at a front center portion of the turning unit 3. .

  The traveling unit 2 includes a pair of left and right crawlers 20. When the traveling motor (not shown) drives the pair of left and right crawlers 20, the excavator 1 travels. The turning unit 3 turns about the vertical axis with respect to the traveling unit 2 by operation of a turning motor 30 (see FIG. 2 and the like) described later.

  The excavation unit 4 includes a boom 5, an arm 6, and a bucket 7. The boom 5 is supported by the turning unit 3 so as to be rotatable about a horizontal axis. The arm 6 is rotatably supported at the tip of the boom 5. The bucket 7 is rotatably supported at the tip of the arm 6 to excavate earth and sand.

  Further, the excavation unit 4 rotates a boom cylinder 50 with respect to the swing unit 3, an arm cylinder 60 with which the arm 6 rotates with respect to the boom 5, and a bucket 7 with respect to the arm 6. A bucket cylinder 70 to be operated.

  In the description of the present specification, the swing motor 30, the boom cylinder 50, the arm cylinder 60, and the bucket cylinder 70 are also simply referred to as “actuators”, and the boom 5, the arm 6, and the bucket 7 are also referred to as “loads”.

  As shown in FIG. 2, the energy regeneration system 100 according to the present embodiment includes a main pump 11 as a fluid pressure supply unit. The main pump 11 is a variable displacement pump capable of adjusting the tilt angle of the swash plate. An output shaft 12 a of the engine 12 is connected to the main pump 11. The main pump 11 is operated by the rotation of the output shaft 12a, and discharges hydraulic oil stored in the tank 13 as a liquid storage unit.

  The energy regeneration system 100 includes a control valve 34 that controls the operation of the swing motor 30, a control valve 54 that controls the operation of the boom cylinder 50, a control valve 64 that controls the operation of the arm cylinder 60, and a bucket cylinder 70. And a control valve 74 for controlling the operation of The control valves 34, 54, 64, and 74 are operated by a pilot pressure that is supplied as the operator operates the operation lever.

  The control valves 34, 54, 64 and 74 are connected to the main pump 11 through the supply passage 21 and are connected to the tank 13 through the discharge passage 22. A neutral passage 23 communicates with the supply passage 21 upstream of the control valves 34, 54, 64 and 74. The neutral passage 23 communicates with the discharge passage 22 through the control valves 34, 54, 64 and 74.

  The control valve 34 is a 6-port three-position switching valve having a neutral position 34 a for stopping the operation of the turning motor 30 and first and second operating positions 34 b and 34 c for operating the turning motor 30. The control valve 54 is a 6-port three-position switching valve having a neutral position 54a for stopping the operation of the boom cylinder 50, an extended position 54b for extending the boom cylinder 50, and a contracted position 54c for contracting the boom cylinder 50. . Like the control valve 54, the control valves 64 and 74 are 6-port 3-position switching valves having neutral positions 64a and 74a, extended positions 64b and 74b, and contracted positions 64c and 74c.

  Hereinafter, the first and second operating positions 34b and 34c, the extended positions 54b, 64b and 74b, and the contracted positions 54c, 64c and 74c may be simply referred to as “operating positions”.

  A pilot pressure generator 14 is provided on the downstream side of the control valves 34, 54, 64, 74 in the neutral passage 23. The pilot pressure generation unit 14 generates a higher pilot pressure on the upstream side as the flow rate of the hydraulic oil passing through the pilot pressure generation unit 14 increases, and generates a lower pilot pressure on the upstream side as the flow rate of the hydraulic oil decreases.

  When all of the control valves 34, 54, 64, 74 are in the neutral positions 34 a, 54 a, 64 a, 74 a or in the vicinity thereof, the neutral passage 23 receives all or part of the hydraulic oil discharged from the main pump 11. Lead to. At this time, since the flow rate of the hydraulic oil passing through the pilot pressure generating unit 14 is large, the pilot pressure generating unit 14 generates a high pilot pressure.

  When at least one of the control valves 34, 54, 64, 74 is switched to the operating position, the flow of hydraulic oil in the neutral passage 23 is blocked. At this time, since the flow rate of the hydraulic oil passing through the pilot pressure generation unit 14 is substantially zero, the pilot pressure from the pilot pressure generation unit 14 is kept at zero.

  However, depending on the operation amount of the control valves 34, 54, 64, 74, a part of the hydraulic oil discharged from the main pump 11 is guided to the actuators 30, 50, 60, 70, and the rest is from the neutral passage 23 to the tank 13. Led to. Therefore, the pilot pressure generator 14 generates a pilot pressure corresponding to the flow rate of the hydraulic oil in the neutral passage 23. That is, the pilot pressure generating unit 14 generates a pilot pressure corresponding to the operation amount of the control valves 34, 54, 64, and 74.

  The pilot pressure generator 14 is connected to the regulator 11 a through the pilot passage 24. A first pressure sensor 15 is provided in the pilot passage 24, and the pressure in the pilot passage 24 is detected by the first pressure sensor 15.

  The regulator 11 a controls the tilt angle of the main pump 11 in inverse proportion to the pilot pressure supplied from the pilot passage 24, thereby controlling the push-out amount per rotation of the main pump 11. Therefore, when at least one of the control valves 34, 54, 64, 74 is switched to the operating position and the pilot pressure in the pilot passage 24 becomes zero, the tilt angle of the main pump 11 is maximized, and the pressure per rotation is increased. The amount of ablation is maximized.

  Next, the turning motor 30 will be described.

  The turning motor 30 is a hydraulic motor that generates torque by operating and discharging hydraulic oil from a pair of ports. One port of the swing motor 30 is connected to the control valve 34 through the first supply / discharge passage 35a, and the other port of the swing motor 30 is connected to the control valve 34 through the second supply / discharge passage 35b.

  A first relief valve 36a and a first check valve 37a are connected to the first supply / discharge passage 35a. The first relief valve 36 a opens when the pressure in the first supply / discharge passage 35 a exceeds a predetermined set pressure, and guides the hydraulic oil in the first supply / discharge passage 35 a to the tank 13. The first check valve 37a blocks the flow of hydraulic oil from the first supply / discharge passage 35a to the tank 13, while allowing the flow of hydraulic oil from the tank 13 to the first supply / discharge passage 35a.

  A second relief valve 36b and a second check valve 37b are connected to the second supply / discharge passage 35b. The second relief valve 36 b opens when the pressure in the second supply / discharge passage 35 b exceeds a predetermined set pressure, and guides the hydraulic oil in the second supply / discharge passage 35 b to the tank 13. The second check valve 37b blocks the flow of hydraulic oil from the second supply / discharge passage 35b to the tank 13 and allows the flow of hydraulic oil from the tank 13 to the second supply / discharge passage 35b.

  The first check valve 37a is connected to the second relief valve 36b. When the second relief valve 36b is opened, the hydraulic oil is supplied from the second supply / discharge passage 35b to the first supply / discharge passage 35a through the first check valve 37a. Flow is allowed. The second check valve 37b is connected to the first relief valve 36a. When the first relief valve 36a is opened, the hydraulic oil is supplied from the first supply / discharge passage 35a to the second supply / discharge passage 35b through the second check valve 37b. Flow is allowed.

  When the control valve 34 is in the neutral position 34 a, the control valve 34 allows the hydraulic oil to flow in the neutral passage 23. In this case, the control valve 34 blocks the flow of hydraulic oil from the supply passage 21 to the first and second supply / discharge passages 35a, 35b, and from the first and second supply / discharge passages 35a, 35b to the discharge passage 22. Shut off the flow of hydraulic oil. Therefore, the supply / discharge of hydraulic oil to / from the swing motor 30 is shut off, and the swing motor 30 does not operate.

  When the control valve 34 switches to the first operating position 34b, the control valve 34 cuts off the flow of hydraulic oil in the neutral passage 23, connects the supply passage 21 and the first supply / discharge passage 35a, and connects the discharge passage 22 and the second supply passage. The exhaust passage 35b is connected. As a result, the hydraulic oil discharged from the main pump 11 is supplied to the turning motor 30 through the control valve 34 and the first supply / discharge passage 35a, and the return hydraulic oil from the turning motor 30 is supplied to the second supply / discharge passage 35b and It is discharged to the tank 13 through the control valve 34, and the turning motor 30 rotates. At this time, the pressure in the first supply / discharge passage 35a is higher than the pressure in the second supply / discharge passage 35b.

  When the control valve 34 switches to the second operating position 34c, the control valve 34 cuts off the flow of hydraulic oil in the neutral passage 23, connects the supply passage 21 and the second supply / discharge passage 35b, and connects the discharge passage 22 and the first supply passage. The exhaust passage 35a is connected. As a result, the hydraulic oil discharged from the main pump 11 is supplied to the swing motor 30 through the control valve 34 and the second supply / discharge passage 35b, and the return hydraulic oil from the swing motor 30 is supplied to the first supply / discharge passage 35a and the second supply / discharge passage 35b. It is discharged to the tank 13 through the control valve 34, and the turning motor 30 rotates in the reverse direction. At this time, the pressure in the second supply / discharge passage 35b is higher than the pressure in the first supply / discharge passage 35a.

  As the turning motor 30 rotates, the turning unit 3 (see FIG. 1) turns about the vertical axis with respect to the traveling unit 2.

  When the control valve 34 is switched to the neutral position 34a during the turning operation of the turning unit 3, the supply and discharge of hydraulic oil to and from the turning motor 30 is cut off. However, the turning motor 30 rotates with the inertia energy possessed by the turning unit 3. Continue to demonstrate pumping action. As a result, the pressure of one of the first and second supply / discharge passages 35a and 35b, which was high during the turning operation, decreases, and the other of the first and second supply / discharge passages 35a, 35b, which was low during the turning operation, Pressure increases. The increased pressure acts on the swing motor 30 as a brake pressure, and the swing motor 30 is decelerated and stopped.

  When the brake pressure in the first or second supply / discharge passage 35a, 35b reaches the set pressure of the first or second relief valve 36a, 36b, the first or second relief valve 36a, 36b is opened. As a result, the hydraulic oil on the high pressure side of the first and second supply / discharge passages 35a, 35b is guided to the low pressure side of the first and second supply / discharge passages 35a, 35b through the first or second check valves 37a, 37b. It is burned.

  When the suction flow rate of the swing motor 30 is insufficient when the swing motor 30 is decelerated, the hydraulic oil in the tank 13 is sucked into the swing motor 30 through the first or second check valve 37a, 37b.

  Next, the boom cylinder 50 will be described.

  The boom cylinder 50 is a double-acting cylinder having a piston 52 that partitions the inside of the cylinder tube 51 into an anti-rod side chamber 51a and a rod side chamber 51b. A piston rod 53 is connected to the piston 52. The non-rod side chamber 51a is connected to the control valve 54 through the first supply / discharge passage 55a, and the rod side chamber 51b is connected to the control valve 54 through the second supply / discharge passage 55b.

  A check valve 55c is provided in the first supply / discharge passage 55a. The check valve 55c allows the flow of hydraulic oil from the control valve 54 to the anti-rod side chamber 51a, while blocking the flow of hydraulic oil from the anti-rod side chamber 51a to the control valve 54.

  Further, a bypass passage 55d is connected to the first supply / discharge passage 55a. The bypass passage 55d bypasses the check valve 55c and connects the control valve 54 and the non-rod side chamber 51a.

  The control valve 54 has pilot chambers 56a and 56b, and is operated by a pilot pressure supplied from the pilot pump 57 to the pilot chambers 56a and 56b through the pilot valve 58. The pilot valve 58 operates in accordance with the operation of the operation lever 59 by the operator.

  When the pilot pressure is supplied to the pilot chamber 56a, the control valve 54 is switched to the extended position 54b. When the pilot pressure is supplied to the pilot chamber 56b, the control valve 54 is switched to the contracted position 54c. When pilot pressure is not supplied to the pilot chambers 56a and 56b, the control valve 54 is switched to the neutral position 54a by a spring not shown.

  When the control valve 54 is in the neutral position 54 a, the control valve 54 allows the hydraulic oil to flow in the neutral passage 23. In this case, the control valve 54 blocks the flow of hydraulic oil from the supply passage 21 to the first and second supply / discharge passages 55a and 55b, and from the first and second supply / discharge passages 55a and 55b to the discharge passage 22. Shut off the flow of hydraulic oil. Therefore, the supply and discharge of the hydraulic oil to and from the boom cylinder 50 is shut off, and the boom cylinder 50 does not operate.

  When the control valve 54 is switched to the extended position 54b, the flow of hydraulic oil in the neutral passage 23 is interrupted, and the supply passage 21 and the first supply / discharge passage 55a are connected, and the discharge passage 22 and the second supply / discharge passage. 55b is connected. As a result, the hydraulic oil discharged from the main pump 11 is supplied to the non-rod side chamber 51a through the control valve 54, the first supply / discharge passage 55a and the check valve 55c, and the return hydraulic oil from the boom cylinder 50 is the first. 2 is discharged to the tank 13 through the supply / discharge passage 55b and the control valve 54, and the boom cylinder 50 extends.

  When the control valve 54 is switched to the contracted position 54c, the flow of hydraulic oil in the neutral passage 23 is blocked, and the supply passage 21 and the second supply / discharge passage 55b are connected to each other, and the discharge passage 22 and the first supply / discharge passage are connected. 55a is connected. As a result, the hydraulic oil discharged from the main pump 11 is supplied to the rod side chamber 51b through the control valve 54 and the second supply / discharge passage 55b, and the return hydraulic oil from the boom cylinder 50 is bypassed 55d and the control valve 54. Or the boom cylinder 50 is contracted by being discharged to the tank 13 through a boom regeneration passage 93 and a common regeneration passage 82 described later.

  As the boom cylinder 50 expands and contracts, the boom 5 (see FIG. 1) moves up and down with respect to the turning unit 3.

  When the control valve 54 is switched to the neutral position 54a and the movement of the boom 5 is stopped, a force in a contracting direction acts on the boom cylinder 50 by its own weight such as the boom 5, the arm 6, and the bucket 7. Thus, when the control valve 54 is in the neutral position 54a, the boom cylinder 50 holds the load by the anti-rod side chamber 51a, and the anti-rod side chamber 51a functions as a load side pressure chamber.

  The arm cylinder 60 and the bucket cylinder 70 are double acting cylinders. Since the structures of the arm cylinder 60 and the bucket cylinder 70 are the same as the structure of the boom cylinder 50 and the structures of the control valves 64 and 74 are the same as the structure of the control valve 54, their description is omitted here.

  Next, a regenerative device that recovers energy of hydraulic oil and performs energy regeneration will be described.

  The regeneration control by the regeneration device is performed by the controller 80. The controller 80 includes a CPU that executes regenerative control, a ROM that stores control programs and setting values necessary for processing operations of the CPU, and a RAM that temporarily stores information detected by various sensors.

  The energy regeneration system 100 includes a regeneration motor 81 that is operated by hydraulic oil. The regenerative motor 81 is connected to the rotation shaft of the main pump 11 and rotates coaxially with the main pump 11. Thus, the engine 12, the main pump 11, and the regenerative motor 81 rotate coaxially.

  The regenerative motor 81 is a variable capacity motor that can adjust the tilt angle of the swash plate, and the tilt angle of the regenerative motor 81 is controlled by the controller 80 through the regulator 81a. The smaller the tilt angle of the swash plate, the smaller the capacity of the regenerative motor 81, and the less energy is collected with respect to the flow rate of the supplied hydraulic oil. The greater the tilt angle of the swash plate, the greater the capacity of the regenerative motor 81, and the greater the amount of energy recovered with respect to the flow rate of hydraulic oil supplied.

  A common regeneration passage 82 is connected to the regeneration motor 81. Hereinafter, the common regeneration passage 82, the turning regeneration passage 87 and the boom regeneration passage 93, which will be described later, may be simply referred to as “regeneration passages”.

  The common regeneration passage 82 guides the hydraulic oil from the first and second supply / discharge passages 35 a and 35 b to the regeneration motor 81 and guides the hydraulic oil from the first supply / discharge passage 55 a to the regeneration motor 81. When the hydraulic oil is supplied to the regenerative motor 81, the regenerative motor 81 is operated and the energy of the hydraulic oil is regenerated.

  An accumulator 84 is connected to the common regeneration passage 82 via a branch passage 83. A switching valve 85 is provided in the branch passage 83. The switching valve 85 allows the flow of hydraulic oil in the branch passage 83 when the valve is opened.

  When the flow of hydraulic oil in the branch passage 83 is allowed, the accumulator 84 accumulates the hydraulic oil from the common regeneration passage 82 or supplies the hydraulic oil in the accumulator 84 to the common regeneration passage 82. When the hydraulic oil in the accumulator 84 is supplied to the regenerative motor 81 through the common regenerative passage 82, the regenerative motor 81 is activated to assist the rotation of the main pump 11.

  First, energy regeneration performed by supplying hydraulic oil from the first and second supply / discharge passages 35a and 35b to the regeneration motor 81 (hereinafter, this regeneration is referred to as “swing regeneration”) will be described.

  First and second branch passages 86a and 86b are connected to the first and second supply / discharge passages 35a and 35b, respectively. The first and second branch passages 86 a and 86 b are connected to the common regeneration passage 82 through the turning regeneration passage 87.

  First and second check valves 88a and 88b are provided in the first and second branch passages 86a and 86b, respectively. The first check valve 88a allows the flow of hydraulic oil from the first supply / discharge passage 35a to the turning regeneration passage 87, while blocking the flow of hydraulic oil from the turning regeneration passage 87 to the first supply / discharge passage 35a. To do. The second check valve 88b allows the flow of hydraulic oil from the second supply / discharge passage 35b to the turning regeneration passage 87, while blocking the flow of hydraulic oil from the turning regeneration passage 87 to the second supply / discharge passage 35b. To do.

  A turning regeneration control valve 89 is provided in the turning regeneration passage 87. Hereinafter, the turning regeneration control valve 89 and a boom regeneration control valve 94 described later may be simply referred to as a “regeneration control valve”.

  The turning regeneration control valve 89 has a shut-off (closed) position 89a for blocking the flow of hydraulic oil, and a communication (open valve) position 89b for allowing the flow of hydraulic oil. The operation of the swing regeneration control valve 89 is controlled by a signal output from the controller 80. The switching of the turning regeneration control valve 89 by the controller 80 will be specifically described.

  The turning regeneration control valve 89 is provided with a pilot chamber 89c. The pilot chamber 89 c is connected to the pilot pump 57 and the tank 13 through the electromagnetic proportional valve 90. When the pilot pressure is supplied to the pilot chamber 89c, the turning regeneration control valve 89 is switched to the communication position 89b. When the supply of the pilot pressure to the pilot chamber 89c is cut off, the turning regeneration control valve 89 is switched to the cut-off position 89a by a spring not shown.

  The electromagnetic proportional valve 90 has a first position 90a and a second position 90b. When the electromagnetic proportional valve 90 is in the first position 90a, the hydraulic oil flow from the pilot chamber 89c to the tank 13 is allowed, while the hydraulic oil flow from the pilot pump 57 to the pilot chamber 89c is blocked. When the electromagnetic proportional valve 90 is in the second position 90b, the flow of hydraulic oil from the pilot pump 57 to the pilot chamber 89c is allowed while the flow of hydraulic oil from the pilot chamber 89c to the tank 13 is blocked. .

  The electromagnetic proportional valve 90 is provided with a solenoid 90c. The solenoid 90 c is electrically connected to the controller 80.

  When the controller 80 outputs an electrical signal to the solenoid 90c, the solenoid 90c is excited and the electromagnetic proportional valve 90 is switched to the second position 90b. As a result, the pilot pressure is supplied from the pilot pump 57 to the pilot chamber 89c, and the turning regeneration control valve 89 is switched to the communication position 89b.

  When the controller 80 stops outputting the electrical signal to the solenoid 90c, the solenoid 90c is de-energized, and the electromagnetic proportional valve 90 is switched to the first position 90a by a spring not shown. As a result, the supply of pilot pressure from the pilot pump 57 to the pilot chamber 89c is cut off, and the turning regeneration control valve 89 is switched to the cutoff position 89a.

  Thus, the turning regeneration control valve 89 is switched by the controller 80.

  A second pressure sensor 92 as a pressure detector is provided upstream of the turning regeneration control valve 89 in the turning regeneration passage 87. The second pressure sensor 92 detects the turning pressure during the turning operation of the turning motor 30 and the brake pressure during the braking operation. The pressure signal detected by the second pressure sensor 92 is output to the controller 80.

  Detecting the swing pressure and the brake pressure is equivalent to detecting the swing operation and the brake operation of the swing motor 30. Therefore, the second pressure sensor 92 functions as an operation state detector that detects the operation state of the turning motor 30.

  When the controller 80 determines that the detected pressure of the second pressure sensor 92 has reached a preset turning regeneration start pressure, the controller 80 switches the electromagnetic proportional valve 90 to the second position 90b and pilots the turning regeneration control valve 89. The communication position 89b is switched by pressure. Accordingly, the hydraulic oil from the first or second supply / discharge passages 35 a and 35 b is supplied to the regeneration motor 81 through the turning regeneration passage 87 and the common regeneration passage 82.

  The hydraulic oil supplied to the regeneration motor 81 drives the regeneration motor 81. Since the regeneration motor 81 is connected to the main pump 11, the regeneration motor 81 drives the main pump 11. Thus, turning regeneration is performed.

  The setting of the turning regeneration start pressure for switching the turning regeneration control valve 89 to the communication position 89b will be described.

  For example, during a turning operation in which the turning motor 30 is rotated by the hydraulic oil supplied through the first supply / discharge passage 35a, excess hydraulic oil in the first supply / discharge passage 35a is removed from the first branch passage 86a, the first check valve 88a, The regenerative motor 81 is guided through the turning regeneration passage 87 and the common regeneration passage 82. When the control valve 34 is switched to the neutral position 34 a while the swing motor 30 is rotated by the hydraulic oil from the first supply / discharge passage 35 a, the hydraulic oil is discharged from the swing motor 30 by the pump action of the swing motor 30. The discharged hydraulic oil is guided to the swivel regeneration passage 87 through the second branch passage 86b and the second check valve 88b.

  It is assumed that the turning regeneration start pressure is set to a pressure that is considerably lower than the set pressure of the first and second relief valves 36a, 36b. In this case, the swivel regeneration control valve 89 switches to the communication position 89b before the pressure in the first and second supply / discharge passages 35a and 35b reaches the set pressure of the first and second relief valves 36a and 36b. . Therefore, the pressure in the first and second supply / discharge passages 35a and 35b may not be maintained at a pressure required for the turning operation or the braking operation of the turning motor 30.

  It is assumed that the turning regeneration start pressure is set to be equal to the set pressure of the first and second relief valves 36a and 36b. In this case, when the pressure in the first and second supply / discharge passages 35a and 35b reaches the set pressure of the first and second relief valves 36a and 36b, the turning regeneration control valve 89 is switched to the communication position 89b. Change. Therefore, most of the surplus hydraulic fluid during the swing operation of the swing motor 30 or the hydraulic fluid during the brake operation flows to the first and second relief valves 36a and 36b, and there is a possibility that the regenerative amount becomes small.

  For this reason, the turning regeneration starting pressure does not affect the turning operation or the braking operation of the turning motor 30 and the set pressure of the first and second relief valves 36a and 36b in order to ensure the amount of regeneration. Also set to a slightly lower pressure.

  Next, energy regeneration performed by supplying hydraulic oil from the boom cylinder 50 to the regeneration motor 81 (hereinafter, this regeneration is referred to as “boom regeneration”) will be described.

  The non-rod side chamber 51a of the boom cylinder 50 is connected to the common regeneration passage 82 through a boom regeneration passage 93 connected to the first supply / discharge passage 55a. A boom regeneration control valve 94 is provided in the boom regeneration passage 93. The bypass passage 55d bypasses the check valve 55c through the boom regeneration control valve 94.

  The boom regeneration control valve 94 has a first position 94a and a second position 94b. When in the first position 94a, the boom regeneration control valve 94 blocks the flow of hydraulic oil in the boom regeneration passage 93 and allows the flow of hydraulic oil in the bypass passage 55d. When the boom regenerative control valve 94 is in the second position 94b, the hydraulic fluid flow in the boom regenerative passage 93 is allowed and the hydraulic oil flow in the bypass passage 55d is allowed through the throttle 94c.

  From the viewpoint of boom regeneration, the first position 94a is the closing position of the boom regeneration control valve 94, and the second position 94b is the opening position of the boom regeneration control valve 94.

  The operation of the boom regeneration control valve 94 is controlled by the pilot pressure via the electromagnetic proportional valve 91a. The electromagnetic proportional valve 91a is controlled by a signal output from the controller 80. That is, switching of the boom regeneration control valve 94 is controlled by a signal from the controller 80 that switches the electromagnetic proportional valve 91a. Since the switching of the boom regeneration control valve 94 by the controller 80 is the same as the switching of the turning regeneration control valve 89 by the controller 80, description thereof is omitted here.

  The control valve 54 is provided with a sensor 95 as an operation detector that detects the operation direction and the operation amount of the control valve 54. A signal detected by the sensor 95 is output to the controller 80.

  Detecting the operation direction and the operation amount of the control valve 54 is equivalent to detecting the expansion / contraction direction and the expansion / contraction speed of the boom cylinder 50. Therefore, the sensor 95 functions as an operation state detector that detects the operation state of the boom cylinder 50.

  Instead of the sensor 95, a sensor for detecting the moving direction and the moving amount of the piston rod 53 may be provided in the boom cylinder 50, and such a sensor may be used as an operation state detector. Further, a sensor for detecting the operation direction and the operation amount of the operation lever 59 may be provided in the pilot valve 58, and such a sensor may be used as an operation state detector.

  Based on the detection result of the sensor 95, the controller 80 determines whether the operator is going to extend or contract the boom cylinder 50. When the controller 80 determines the extension operation of the boom cylinder 50, the controller 80 keeps the boom regeneration control valve 94 at the first position 94a.

  On the other hand, if the controller 80 determines the contraction operation of the boom cylinder 50, the controller 80 calculates the contraction speed of the boom cylinder 50 requested by the operator according to the operation amount of the control valve 54 (hereinafter referred to as "required contraction speed"). ). If the controller 80 determines that the required contraction speed is particularly high, the controller 80 keeps the boom regeneration control valve 94 at the first position 94a.

  Assume that the boom regenerative control valve 94 is switched to the second position 94b when the required contraction speed is particularly high. When the boom regeneration control valve 94 is switched to the second position 94b, most of the hydraulic oil in the anti-rod side chamber 51a is supplied to the regeneration motor 81 through the boom regeneration passage 93 and the common regeneration passage 82.

  The regenerative motor 81 functions as a load that consumes the energy of the supplied hydraulic oil. Therefore, when the hydraulic oil in the non-rod side chamber 51a is supplied to the regenerative motor 81, it is not discharged at a sufficient flow rate. As a result, the actual contraction speed of the boom cylinder 50 may not reach the contraction speed requested by the operator.

  For this reason, when it is determined that the required contraction speed is particularly high, the boom regenerative control valve 94 is kept at the first position 94a, and the hydraulic oil in the non-rod side chamber 51a is transferred to the control valve 54 and the discharge passage 22. It is preferable to discharge to the tank 13 through. Since the discharge passage 22 is connected to the tank 13 without passing through a load such as the regenerative motor 81, the hydraulic oil in the anti-rod side chamber 51a can be discharged at a sufficient flow rate, and the actual contraction speed of the boom cylinder 50 can be determined by the operator. The shrinkage rate that is required can be achieved.

  When it is determined that the required contraction speed is particularly high, the actual contraction speed of the boom cylinder 50 may be further increased by regenerating the energy of the hydraulic oil in the anti-rod side chamber 51a. The regeneration of the energy of the hydraulic oil is realized by connecting the anti-rod side chamber 51a and the rod side chamber 51b through a regeneration control valve. By opening the regeneration control valve during the contraction operation, the hydraulic oil from the non-rod side chamber 51a is supplied to the rod side chamber 51b. Since the hydraulic oil in the non-rod side chamber 51a decreases faster and the hydraulic oil in the rod side chamber 51b increases faster, the contraction speed of the boom cylinder 50 can be increased.

  Whether or not the required contraction speed is particularly high is determined based on, for example, a preset boom regeneration limit speed (a limit contraction speed at which boom regeneration is recommended).

  When the controller 80 determines the contraction operation of the boom cylinder 50 and determines that the required contraction speed is low (for example, less than a preset boom regeneration limit speed), the controller 80 controls the boom regeneration control valve 94 to the second position 94b. Switch to. The boom regenerative control valve 94 allows the flow of hydraulic oil in the bypass passage 55d through the throttle 94c, so that the return hydraulic oil from the boom cylinder 50 is guided to the bypass passage 55 immediately after switching, and then gradually the boom regeneration passage 93. Led to.

  The hydraulic oil guided to the boom regeneration passage 93 is supplied to the regeneration motor 81 through the common regeneration passage 82 and drives the regeneration motor 81. Thus, boom regeneration is performed similarly to turning regeneration by switching the boom regeneration control valve 94 to the 2nd position 94b.

  Next, accumulation of hydraulic fluid from the common regeneration passage 82 to the accumulator 84 and supply of hydraulic fluid from the accumulator 84 to the common regeneration passage 82 will be described.

  The switching valve 85 has a shutoff (valve closing) position 85a for blocking the flow of hydraulic oil in the branch passage 83 and a communication (opening) position 85b for allowing the flow of hydraulic oil in the branch passage 83 through the throttle 85c. . The operation of the switching valve 85 is controlled by the pilot pressure via the electromagnetic proportional valve 91b. The electromagnetic proportional valve 91b is controlled by a signal output from the controller 80. That is, switching of the switching valve 85 is controlled by a signal from the controller 80 that switches the electromagnetic proportional valve 91b. Since the switching of the switching valve 85 by the controller 80 is the same as the switching of the turning regeneration control valve 89 by the controller 80, the description thereof is omitted here.

  The accumulator 84 includes a housing 84a and a diaphragm 84d that divides the interior of the housing 84a into an oil chamber 84b and a gas chamber 84c. The branch passage 83 communicates with the oil chamber 84b. Compressed air is sealed in the gas chamber 84c.

  When the switching valve 85 is in the communication position 85b, when the pressure in the common regeneration passage 82 is higher than the pressure in the oil chamber 84b, hydraulic oil is supplied from the common regeneration passage 82 to the oil chamber 84b. The gas chamber 84c contracts due to the inflow of hydraulic oil into the oil chamber 84b, and the pressure in the gas chamber 84c increases. That is, the hydraulic oil from the common regeneration passage 82 is accumulated in the accumulator 84.

  When the pressure in the gas chamber 84c and the pressure in the common regeneration passage 82 become the same, the supply of hydraulic oil from the common regeneration passage 82 to the oil chamber 84b is stopped.

  When the switching valve 85 is in the communication position 85b, when the pressure in the common regeneration passage 82 is lower than the pressure in the oil chamber 84b, hydraulic oil is supplied from the oil chamber 84b to the common regeneration passage 82. The gas chamber 84c is expanded by the outflow of the hydraulic oil from the oil chamber 84b, and the pressure of the gas chamber 84c is reduced. That is, the hydraulic oil accumulated in the accumulator 84 is supplied to the common regeneration passage 82.

  When the pressure in the gas chamber 84c and the pressure in the common regeneration passage 82 become the same, the supply of hydraulic oil from the oil chamber 84b to the common regeneration passage 82 stops.

  As described above, the accumulator 84 accumulates the hydraulic oil from the common regenerative passage 82 according to the difference between the pressure in the accumulator 84 and the pressure in the common regenerative passage 82, or the common regenerative fluid in the accumulator 84. Supply to the passage 82.

  The pressure in the common regenerative passage 82 rises when the regenerative motor 81 cannot recover all of the hydraulic oil energy guided to the common regenerative passage 82. When the pressure in the common regenerative passage 82 exceeds the pressure in the oil chamber 84b, the working oil is supplied from the common regenerative passage 82 to the oil chamber 84b. Therefore, the accumulator is a part of the working oil guided to the common regenerative passage 82. Is stored as surplus hydraulic fluid.

  The pressure in the common regenerative passage 82 decreases when the regenerative motor 81 recovers all of the hydraulic oil energy guided to the common regenerative passage 82. When the pressure in the common regeneration passage 82 drops below the pressure in the gas chamber 84 c, the accumulator 84 supplies hydraulic oil to the common regeneration passage 82.

  The member that divides the inside of the housing 84a into the oil chamber 84b and the gas chamber 84c is not limited to the diaphragm 84d, and may be, for example, a free piston slidably accommodated in the housing 84a. The gas chamber 84c may be filled with a gas other than air, for example, nitrogen.

  The controller 80 switches the switching valve 85 to the communication position 85b when at least one of the regenerative control valves 89, 94 is switched to the valve opening positions 89b, 94b. Thereby, when the pressure in the common regeneration passage 82 is higher than the pressure in the accumulator 84, the hydraulic oil in the common regeneration passage 82 is accumulated in the accumulator 84. That is, excess hydraulic oil that cannot be recovered by the regenerative motor 81 is accumulated in the accumulator 84.

  When the pressure in the common regeneration passage 82 is lower than the pressure in the accumulator 84, the hydraulic oil accumulated in the accumulator 84 is supplied to the common regeneration passage 82. That is, the hydraulic oil from the accumulator 84 is supplied to the regenerative motor 81 to assist the main pump 11.

  In order to prevent the pressure in the accumulator 84 from exceeding the pressure upper limit value of the accumulator 84, the controller 80 may switch the switching valve 85 according to the pressure in the accumulator 84.

  Specifically, a pressure sensor (not shown) detects the pressure in the accumulator 84 and outputs the detected pressure signal to the controller 80. When the controller 80 determines that the pressure detected by the pressure sensor has reached a preset pressure value, even when at least one of the regenerative control valves 89 and 94 is switched to the valve opening positions 89b and 94b. The switching valve 85 is switched to the cutoff position 85a. As a result, the flow of hydraulic oil in the branch passage 83 is blocked, and the pressure in the accumulator 84 can be prevented from exceeding the pressure upper limit value of the accumulator 84.

  The output shaft 12a of the engine 12 is provided with a sensor 12b as a rotational speed detector that detects the rotational speed of the engine 12. The rotation speed signal detected by the sensor 12b is output to the controller 80.

  Since the main pump 11 is connected to the output shaft 12a of the engine 12, detecting the rotational speed of the output shaft 12a is equivalent to detecting the operating state of the main pump 11. Therefore, the sensor 12b functions as an operation state detector that detects the operation state of the main pump 11. The operating state detector is not limited to the sensor 12b that detects the rotation speed of the engine 12, but may be a pressure sensor that detects the discharge pressure of the main pump 11.

  When the swing regeneration control valve 89 is switched to the shut-off position 89a and the boom regeneration control valve 94 is switched to the first position 94a, that is, when regeneration is not performed, the controller 80 is based on the detection result of the sensor 12b. Thus, it is determined whether the main pump 11 needs assistance. Whether or not the main pump 11 needs assist is determined based on, for example, a preset assist start rotational speed.

  When the controller 80 determines that the detected rotational speed of the sensor 12b is equal to or lower than the preset assist start rotational speed, the controller 80 switches the switching valve 85 to the communication position 85b. Thus, the hydraulic oil accumulated in the accumulator 84 is supplied to the regenerative motor 81 through the common regenerative passage 82 to assist the main pump 11.

  Even when the switching valve 85 is switched to the communication position 85b, if the hydraulic oil is not sufficiently accumulated in the accumulator 84, the hydraulic oil is not supplied from the accumulator 84 to the regenerative motor 81, and the main pump 11 Is not assisted.

  When the controller 80 determines that the detected rotational speed of the sensor 12b exceeds the preset assist start rotational speed, the controller 80 switches the switching valve 85 to the cutoff position 85a. As a result, the supply of hydraulic oil from the accumulator 84 to the regenerative motor 81 is shut off. Therefore, the assist for the main pump 11 is stopped.

  Next, the operation of the energy regeneration system 100 will be described.

  First, the case where the control valves 54, 64, 74 are in the neutral positions 54a, 64a, 74a and the control valve 34 is switched will be described with reference to FIGS.

  As shown in FIG. 3, when the control valve 34 is switched to the first operating position 34b, the hydraulic oil discharged from the main pump 11 is supplied to the turning motor 30 through the first supply / discharge passage 35a, and the turning motor 30 is also supplied. The hydraulic oil inside is discharged to the tank 13 through the second supply / discharge passage 35b, and the turning motor 30 rotates.

  When the pressure (swinging pressure) in the first supply / discharge passage 35a reaches a preset turning regeneration start pressure, the controller 80 switches the turning regeneration control valve 89 to the communication position 89b. As a result, the hydraulic oil from the first supply / discharge passage 35 a is guided to the common regeneration passage 82 through the turning regeneration passage 87. That is, part of the hydraulic oil discharged from the main pump 11 is guided to the common regeneration passage 82 through the control valve 34, the first supply / discharge passage 35 a, and the turning regeneration passage 87.

  The controller 80 switches the regenerative control valve 89 to the communication position 89b and simultaneously switches the switching valve 85 to the communication position 85b. Therefore, when the pressure in the common regeneration passage 82 is higher than the pressure in the accumulator 84, the accumulator 84 accumulates a part of the hydraulic fluid guided to the common regeneration passage 82 as surplus hydraulic fluid. The remaining hydraulic oil is supplied to the regeneration motor 81 and drives the regeneration motor 81.

  The accumulator 84 supplies hydraulic oil accumulated in the accumulator 84 to the regeneration motor 81 through the common regeneration passage 82 when the pressure in the common regeneration passage 82 is lower than the pressure in the accumulator 84. In other words, the regenerative motor 81 is supplied with the hydraulic oil from the accumulator 84 in addition to the hydraulic oil guided from the first supply / discharge passage 35a to the common regeneration passage 82.

  As described above, in this embodiment, when the pressure in the common regeneration passage 82 is higher than the pressure in the accumulator 84, a part of the hydraulic oil guided to the common regeneration passage 82 is accumulated in the accumulator 84 as surplus hydraulic fluid. The When the pressure in the common regeneration passage 82 is lower than the pressure in the accumulator 84, the hydraulic oil accumulated in the accumulator 84 is supplied to the regeneration motor 81 to drive the regeneration motor. Therefore, more energy of the hydraulic oil can be recovered by the regenerative motor 81, and the energy of the hydraulic oil can be efficiently regenerated.

  When the regenerative control valve 89 is opened and energy regeneration is performed, the switching valve 85 is opened. Therefore, at the time of energy regeneration, surplus hydraulic fluid is accumulated in the accumulator 84 or hydraulic fluid accumulated in the accumulator 84 is supplied to the regeneration motor 81. Therefore, the energy of hydraulic oil can be regenerated more efficiently during energy regeneration.

  As shown in FIG. 4, when the control valve 34 is switched from the first operating position 34b to the neutral position 34a, the supply and discharge of the hydraulic oil to and from the turning motor 30 is shut off. Since the turning motor 30 continues to rotate with the inertial energy of the turning portion 3 (see FIG. 1) and exhibits a pump action, the pressure in the first supply / discharge passage 35a decreases and the rotation in the second supply / discharge passage 35b. Pressure increases.

  When the pressure (brake pressure) in the second supply / discharge passage 35b reaches a preset turning regeneration start pressure, the controller 80 switches the turning regeneration control valve 89 to the communication position 89b. As a result, the hydraulic oil from the second supply / discharge passage 35 b is guided to the common regeneration passage 82 through the turning regeneration passage 87. That is, the hydraulic oil from the turning motor 30 is guided to the common regeneration passage 82 through the second supply / discharge passage 35 b and the turning regeneration passage 87.

  The controller 80 switches the regenerative control valve 89 to the communication position 89b and simultaneously switches the switching valve 85 to the communication position 85b. Accordingly, the energy of the hydraulic oil can be efficiently regenerated as in the case where the control valve 34 is switched to the first operating position 34b.

  In the present embodiment, the swing regeneration control valve 89 is opened based on the detection result of the swing pressure or the brake pressure, and energy regeneration is performed. Therefore, even during the turning operation or the braking operation, energy regeneration is not performed if the turning pressure or the brake pressure does not satisfy a predetermined condition. Therefore, for example, when the turning pressure or the brake pressure is not sufficiently high, it is possible to prevent a situation in which the required turning operation cannot be realized by performing energy regeneration.

  Further, since the accumulator 84 is connected to the common regeneration passage 82 via the throttle 85c of the control valve 85, the pressure fluctuation of the hydraulic oil from the first or second supply / discharge passage 35a, 35b is absorbed by the accumulator 84. However, it is attenuated by the diaphragm 85c. Accordingly, the pressure fluctuation of the hydraulic oil in the common regenerative passage 82 is reduced, and the load fluctuation and impact in the regenerative motor 81, the main pump 11 and the engine 12 can be reduced. The throttle 85c may be provided in the branch passage 83 instead of the switching valve 85.

  Next, the case where the control valves 34, 64, 74 are in the neutral positions 34a, 64a, 74a and the control valve 54 is switched will be described with reference to FIGS.

  As shown in FIGS. 5 and 6, when the control valve 54 is switched to the extended position 54b, the hydraulic oil discharged from the main pump 11 is supplied to the anti-rod side chamber 51a of the boom cylinder 50 through the first supply / discharge passage 55a. At the same time, the hydraulic oil in the rod side chamber 51b is discharged to the tank 13 through the second supply / discharge passage 55b, and the boom cylinder 50 extends.

  At this time, when the controller 80 determines the extension operation of the boom cylinder 50 based on the detection result of the sensor 95, the controller 80 keeps the boom regeneration control valve 94 at the first position 94a. Moreover, the controller 80 determines whether the main pump 11 needs assistance based on the detection result of the sensor 12b.

  Since the control valve 34 is maintained at the neutral position 34a, the pressure in the turning regeneration passage 87 does not reach a preset turning regeneration start pressure. Therefore, the controller 80 determines that the pressure detected by the second pressure sensor 92 is less than the turning regeneration start pressure, and keeps the turning regeneration control valve 89 at the shut-off position 89a.

  Since the boom regenerative control valve 94 is maintained at the first position 94a and the turning regeneration passage 87 is maintained at the shut-off position 89a, the controller 80 determines that the rotational speed detected by the sensor 12b is less than or equal to the assist start rotational speed. Then, it is determined that the assistance of the main pump 11 is necessary, and the switching valve 85 is switched to the communication position 85b as shown in FIG. As a result, the hydraulic oil accumulated in the accumulator 84 is supplied to the regenerative motor 81 through the common regenerative passage 82 to assist the main pump 11.

  When the rotational speed detected by the sensor 12b exceeds the assist start rotational speed, the controller 80 determines that the assist of the main pump 11 is unnecessary, and as shown in FIG. 6, the switching valve 85 is moved to the shut-off position 85a. Switch to. As a result, the supply of hydraulic oil from the accumulator 84 to the regenerative motor 81 is shut off, and the assist to the main pump 11 is stopped.

  As described above, in this embodiment, when it is determined that the assist of the main pump 11 is necessary at the time of non-energy regeneration, the switching valve 85 is opened. Therefore, the hydraulic oil accumulated in the accumulator 84 as surplus hydraulic oil during energy regeneration is supplied to the regeneration motor 81 during non-energy regeneration, assisting the main pump 11 and reducing the load on the engine 12. Therefore, the fuel efficiency of the energy regeneration system 100 can be improved even during non-energy regeneration.

  As shown in FIGS. 7 and 8, when the control valve 54 is switched to the contracted position 54c, the hydraulic oil discharged from the main pump 11 is supplied to the rod side chamber 51b of the boom cylinder 50 through the second supply / discharge passage 55b.

  At this time, the controller 80 determines the contraction operation of the boom cylinder 50 based on the detection result of the sensor 95. The controller 80 further calculates the contraction speed (required contraction speed) of the boom cylinder 50 requested by the operator according to the operation amount of the control valve 54.

  When the required contraction speed is particularly high, the controller 80 keeps the boom regeneration control valve 94 at the first position 94a as shown in FIG. As a result, the hydraulic oil in the non-rod side chamber 51a is discharged to the tank 13 through the bypass passage 55d and the control valve 54, and the boom cylinder 50 contracts. At this time, the controller 80 determines whether the main pump 11 needs assistance based on the detection result of the sensor 12b. Since it is the same as the case where the extension operation | movement of the boom cylinder 50 is determined about determination of necessity of assistance, and switching of the switching valve 85 after this determination, the description is abbreviate | omitted here.

  When the required contraction speed is low, the controller 80 switches the boom regeneration control valve 94 to the second position 94b as shown in FIG. The hydraulic oil in the non-rod side chamber 51a is discharged to the tank 13 through the bypass passage 55 and the control valve 54 immediately after the switching of the boom regeneration control valve 94, and then gradually, the boom regeneration passage 93, the common regeneration passage 82, and the regeneration motor 81. Through the tank 13. As a result, the boom cylinder 50 contracts.

  At this time, the controller 80 switches the switching valve 85 to the communication position 85b. Accordingly, the energy of the hydraulic oil can be efficiently regenerated as in the case where the control valve 34 is switched to the first operating position 34b.

  According to the present embodiment, when the boom cylinder 50 is contracted, the boom regeneration control valve 94 is opened according to the required contraction speed. Therefore, even when the boom cylinder 50 is contracting, energy regeneration is not performed if the required contraction speed does not satisfy a predetermined condition. Therefore, for example, when the contraction speed required by the operator is particularly high, it is possible to prevent a situation in which the actual contraction speed does not reach the contraction speed required by performing energy regeneration.

  Next, the case where the control valves 34 and 54 are in the neutral positions 34a and 54a and the control valves 64 and 74 are switched will be described with reference to FIGS.

  When the control valve 64 is switched to the extended position 64b or the contracted position 64c, the arm cylinder 60 extends or contracts. When the control valve 74 is switched to the extended position 74b or the contracted position 74c, the bucket cylinder 70 extends or contracts.

  At this time, since the control valve 34 is in the neutral position 34a, the pressure in the first and second supply / discharge passages 35a and 35b does not exceed the turning regeneration start pressure. Therefore, the controller 80 keeps the turning regeneration control valve 89 at the cutoff position 89a.

  Further, since the control valve 54 is in the neutral position 54a, the controller 80 determines that the operation required for the boom cylinder 50 is neither the extension operation nor the contraction operation. Therefore, the controller 80 keeps the boom regeneration control valve 94 at the first position 94a.

  Since the swing regeneration control valve 89 is at the cutoff position 89a and the boom regeneration control valve 94 is at the first position 94a, energy regeneration is not performed. The controller 80 determines whether the main pump 11 needs assistance based on the detection result of the sensor 12b.

  When the rotation speed detected by the sensor 12b is equal to or less than the assist start rotation speed, the controller 80 determines that the assist of the main pump 11 is necessary, and the switching valve 85 is moved to the communication position 85b as shown in FIG. Switch to. As a result, the hydraulic oil accumulated in the accumulator 84 is supplied to the regenerative motor 81 through the common regenerative passage 82 to assist the main pump 11.

  When the rotational speed detected by the sensor 12b exceeds the assist start rotational speed, the controller 80 determines that the assist of the main pump 11 is unnecessary, and as shown in FIG. 10, the switching valve 85 is moved to the cutoff position 85a. Switch to. As a result, the supply of hydraulic oil from the accumulator 84 to the regenerative motor 81 is shut off, and the assist to the main pump 11 is stopped.

  As described above, in this embodiment, when it is determined that the assist of the main pump 11 is necessary at the time of non-energy regeneration, the switching valve 85 is opened. Therefore, the hydraulic fluid accumulated in the accumulator 84 as surplus hydraulic fluid during energy regeneration is supplied to the regeneration motor 81 during non-energy regeneration and assists the main pump 11. Therefore, the fuel efficiency of the energy regeneration system 100 can be improved even during non-energy regeneration.

  According to the embodiment described above, the following effects can be obtained.

  In the energy regeneration system 100, the accumulator 84 and the regeneration passage 82 communicate with each other when the flow of hydraulic oil in the branch passage 83 is permitted by the switching valve 85. Therefore, when the pressure in the regenerative passage 82 is higher than the pressure in the accumulator 84, a part of the hydraulic oil guided to the regenerative passage 82 is accumulated in the accumulator 84 as surplus hydraulic oil. When the pressure in the regenerative passage 82 is lower than the pressure in the accumulator 84, the hydraulic oil accumulated in the accumulator 84 is supplied to the regenerative motor 81 to drive the regenerative motor 81. Therefore, more energy of the hydraulic oil can be recovered by the regenerative motor 81, and the energy of the hydraulic oil can be efficiently regenerated.

  In the energy regeneration system 100, when the regeneration control valves 89 and 94 are opened and energy regeneration is performed, the switching valve 85 is opened. Therefore, excess hydraulic oil is accumulated in the accumulator 84, or hydraulic oil accumulated in the accumulator 84 is supplied to the regenerative motor 81. Therefore, the energy of hydraulic oil can be regenerated more efficiently during energy regeneration.

  Moreover, in the energy regeneration system 100, when it determines with the assistance of the main pump 11 being required at the time of non-energy regeneration, the switching valve 85 is opened. Therefore, hydraulic oil accumulated in the accumulator 84 as surplus hydraulic oil during energy regeneration is supplied to the regeneration motor 81 to drive the regeneration motor 81 and assist the main pump 11. Therefore, the fuel efficiency of the energy regeneration system 100 can be improved even during non-energy regeneration.

  In the energy regeneration system 100, the boom regeneration control valve 94 is opened according to the required contraction speed when the boom cylinder 50 is contracted. Therefore, even when the boom cylinder 50 is contracting, energy regeneration is not performed if the required contraction speed does not satisfy a predetermined condition. Therefore, for example, when the required contraction speed by the operator is particularly high, it is possible to prevent a situation in which the actual contraction speed does not reach the required contraction speed by performing energy regeneration.

  Further, in the energy regeneration system 100, the swing regeneration control valve 89 is opened based on the detection result of the swing pressure or the brake pressure, and energy regeneration is performed. Therefore, even during the turning operation or the braking operation, energy regeneration is not performed if the turning pressure or the brake pressure does not satisfy a predetermined condition. Therefore, for example, it is possible to prevent a situation in which the turning operation required by performing energy regeneration when the turning pressure or the brake pressure is not sufficiently high cannot be realized.

  Further, in the energy regeneration system 100, the accumulator 84 is connected to the regeneration passage 82 via the restriction 85c of the control valve 85, so that the pressure fluctuation of the hydraulic oil in the regeneration passage 82 is reduced. Therefore, load fluctuations and shocks in the regenerative motor 81, the main pump 11, and the engine 12 can be reduced.

  Hereinafter, the configuration, operation, and effect of the embodiment of the present invention will be described together.

  The energy regeneration system 100 is operated by the rotation of the output shaft 12a of the engine 12 and discharges hydraulic oil. The actuators 30, 50, 60, and 70 are operated by hydraulic oil discharged from the main pump 11. A regenerative passage 82 for guiding surplus hydraulic oil from the first and second supply / discharge passages 35 a and 35 b connecting the pump 11 and the actuator 30 and hydraulic oil discharged from the actuators 30 and 50, and a regenerative passage 82 is supplied. A regenerative motor 81 that is actuated by hydraulic oil to rotate the output shaft 12a of the engine 12, a branch passage 83 that branches from the regenerative passage 82, an accumulator 84 that is connected to the regenerative passage 82 via the branch passage 83, and a branch passage 83, and a switching valve 85 that allows the flow of hydraulic oil when the valve is opened. 4, the switching valve 85 is at to permit the flow of hydraulic fluid, accumulates the hydraulic fluid from the regeneration passage 82, or and supplying the hydraulic oil in the accumulator 84 to the regeneration path 82.

  In this configuration, when the flow of hydraulic oil in the branch passage 83 is allowed by the switching valve 85, the accumulator 84 and the regenerative passage 82 communicate with each other. Therefore, when the pressure in the regenerative passage 82 is higher than the pressure in the accumulator 84, a part of the hydraulic oil guided to the regenerative passage 82 is accumulated in the accumulator 84 as surplus hydraulic oil. When the pressure in the regenerative passage 82 is lower than the pressure in the accumulator 84, the hydraulic oil accumulated in the accumulator 84 is supplied to the regenerative motor 81 to drive the regenerative motor 81. Therefore, more energy of the hydraulic oil can be recovered by the regenerative motor 81, and the energy of the hydraulic oil can be efficiently regenerated.

  The energy regeneration system 100 is provided in the regeneration passages 87 and 93, and when the valve is opened, the regeneration control valves 89 and 94 for guiding the hydraulic oil from the actuators 30 and 50 to the regeneration motor 81 through the regeneration passages 82, 87, and 93, and the actuators 30, 50, and a controller 80 for controlling the operations of the regenerative control valves 89 and 94 and the switching valve 85. The controller 80 is based on the detection results of the sensors 92 and 95. When energy regeneration is performed by opening the regeneration control valves 89 and 94, the switching valve 85 is opened.

  In this configuration, when the regeneration control valves 89 and 94 are opened and energy regeneration is performed, the switching valve 85 is opened. Therefore, excess hydraulic oil is accumulated in the accumulator 84, or hydraulic oil accumulated in the accumulator 84 is supplied to the regenerative motor 81. Therefore, the energy of hydraulic oil can be regenerated more efficiently during energy regeneration.

  The energy regeneration system 100 further includes a sensor 12b that detects the operation state of the main pump 11, and the controller 80 is in a non-energy regeneration mode in which the regeneration control valves 89 and 94 are closed based on the detection results of the sensors 92 and 95. When it is determined that the assistance of the main pump 11 is necessary based on the detection result of the sensor 12b, the switching valve 85 is opened.

  In this configuration, when it is determined that the main pump 11 needs to be assisted during non-energy regeneration, the switching valve 85 is opened. Therefore, hydraulic oil accumulated in the accumulator 84 as surplus hydraulic oil during energy regeneration is supplied to the regeneration motor 81 to drive the regeneration motor 81 and assist the main pump 11. Therefore, the fuel efficiency of the energy regeneration system 100 can be improved even during non-energy regeneration.

  In the energy regeneration system 100, the actuators 30 and 50 are the boom cylinders 50, the sensors 92 and 95 are the sensors 95 that detect the direction and speed of the boom cylinder 50 that is required, and the controller 80 is based on the sensor 95. When the extension operation of the boom cylinder 50 is determined from the detection result of the expansion / contraction direction, the boom regeneration control valve 94 is closed, and when the contraction operation of the boom cylinder 50 is determined from the detection result of the expansion / contraction direction by the sensor 95, the sensor Based on the detection result of the contraction speed by 95, the boom regeneration control valve 94 is opened to perform energy regeneration.

  In this configuration, when the boom cylinder 50 is contracted, the boom regeneration control valve 94 is opened according to the contraction speed detected by the sensor 95. Therefore, even when the boom cylinder 50 is contracting, energy regeneration is not performed if the contraction speed does not satisfy a predetermined condition. Therefore, for example, when the required contraction speed is particularly high, it is possible to prevent a situation in which the required contraction speed cannot be realized by performing energy regeneration.

  In the energy regeneration system 100, the actuators 30 and 50 are the turning motor 30, and the sensors 92 and 95 are sensors 92 that detect the turning pressure when the turning motor 30 is turning or the braking pressure when the braking operation is performed. Is characterized in that the energy regeneration is performed by opening the turning regeneration control valve 89 based on the detection result of the turning pressure or the brake pressure by the sensor 92.

  In this configuration, the swing regeneration control valve 89 is opened based on the detection result of the swing pressure or the brake pressure, and energy regeneration is performed. Therefore, even during the turning operation or the braking operation, energy regeneration is not performed if the turning pressure or the brake pressure does not satisfy a predetermined condition. Therefore, for example, when the turning pressure or the brake pressure is not sufficiently high, it is possible to prevent a situation in which the required turning operation cannot be realized by performing energy regeneration.

  The energy regeneration system 100 is characterized in that the branch passage 83 is connected to the regeneration passage 82 via a restriction 85c.

  In this configuration, since the accumulator 84 is connected to the regenerative passage 82 via the restriction 85c, the fluctuation of the hydraulic oil energy in the regenerative passage 82 is reduced. Therefore, load fluctuations and shocks in the regenerative motor 81, the main pump 11, and the engine 12 can be reduced.

  The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

  DESCRIPTION OF SYMBOLS 11 ... Main pump (fluid pressure supply part), 12 ... Engine, 12a ... Output shaft, 12b ... Sensor (operation state detector), 30 ... Turning motor (actuator), 35a ..First supply / discharge passage, 35b ... Second supply / discharge passage, 50 ... Boom cylinder (actuator), 80 ... Controller, 81 ... Regenerative motor, 82 ... Common regeneration passage (Regeneration) Passage), 83 ... branch passage, 84 ... accumulator, 85 ... switching valve, 87 ... turning regeneration passage (regeneration passage), 89 ... turning regeneration control valve (regeneration control valve), 92 ... Pressure sensor (operation state detector, pressure detector), 93 ... Boom regeneration passage (regeneration passage), 94 ... Boom regeneration control valve (regeneration control valve), 95 ... Sensor (operation state) Detector, operation detector), 100 ... Energy regeneration system

Claims (6)

A fluid pressure supply unit that operates by rotating the output shaft of the engine and discharges the working fluid;
An actuator operated by a working fluid discharged from the fluid pressure supply unit;
A regenerative passage for guiding surplus working fluid from a passage connecting the fluid pressure supply unit and the actuator and a working fluid discharged from the actuator;
A regenerative motor that operates by a working fluid supplied from the regenerative passage and rotates the output shaft of the engine;
A branch passage branched from the regeneration passage;
An accumulator connected to the regenerative passage through the branch passage;
A switching valve provided in the branch passage and allowing the flow of the working fluid when the valve is opened,
The accumulator accumulates the working fluid from the regeneration passage when the switching valve allows the flow of the working fluid, or supplies the working fluid in the accumulator to the regeneration passage. system. A regenerative control valve that is provided in the regenerative passage and guides a working fluid from the actuator to the regenerative motor through the regenerative passage when the valve is opened;
An operation state detector for detecting an operation state of the actuator;
A controller for controlling operations of the regenerative control valve and the switching valve, and
2. The controller according to claim 1, wherein the controller opens the switching valve when performing the energy regeneration by opening the regeneration control valve based on the detection result of the operation state detector. Energy regeneration system. An operation state detector for detecting an operation state of the fluid pressure supply unit;
In the non-energy regeneration in which the regenerative control valve is closed based on the detection result of the operation state detector, the controller needs the assistance of the fluid pressure supply unit based on the detection result of the operation state detector. The energy regeneration system according to claim 2, wherein when it is determined that there is, the switching valve is opened. The actuator is a cylinder;
The operation state detector is an operation detector that detects the expansion / contraction direction and expansion / contraction speed of the cylinder,
The controller is
When the extension operation of the cylinder is determined based on the detection result of the expansion / contraction direction by the operation state detector, the regeneration control valve is closed,
When the contraction operation of the cylinder is determined based on the detection result of the expansion / contraction direction by the operation state detector, the regeneration control valve is opened based on the detection result of the contraction speed by the operation state detector to regenerate energy. It performs, The energy regeneration system of Claim 2 or 3 characterized by the above-mentioned. The actuator is a turning motor;
The operation state detector is a pressure detector that detects a turning pressure during a turning operation of the turning motor or a brake pressure during a braking operation,
The energy regeneration system according to claim 2 or 3, wherein the controller performs energy regeneration by opening the regeneration control valve based on a detection result of a turning pressure or a brake pressure by the pressure detector.   The energy regeneration system according to any one of claims 1 to 5, wherein the branch passage is connected to the regeneration passage through a restriction.

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