JP2015172428A - Control system of hybrid construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure that surplus hydraulic energy can be regenerated even when an actuator other than a boom cylinder and a slewing motor is operated.SOLUTION: A control system 100 of a hybrid construction machine comprises: circuit systems S1 and S2 including operating valve 1-5 and 14-17 that supply/discharge working fluid to/from actuators; main relief valves 8 and 19 that keep working fluid pressures of main passages 6 and 18 at a main relief pressure or less; regeneration passages 55 and 56 that branch from the main passages 6 and 18 between main pumps MP1 and MP2 and the operating valves 1-5 and 14-17; a regeneration motor M for regeneration that is rotated by the working fluid led through the regeneration passages 55 and 56; regeneration passage switching valves 57 and 58 that can open/close the regeneration passages 55 and 56; and a controller C that controls the regeneration passage switching valves 57 and 58 to switch them to opening positions when the working fluid pressures of the main passages 6 and 18 reaches a set pressure lower than the main relief pressure.

Description

  The present invention relates to a control system for a hybrid construction machine.

  2. Description of the Related Art Hybrid construction machines that perform energy regeneration by rotating a hydraulic motor using hydraulic fluid guided from an actuator are known.

  Patent Document 1 discloses that a boom cylinder and a turning motor are provided, and energy is regenerated by rotating a hydraulic motor using hydraulic oil guided from the boom cylinder and the turning motor when the boom is lowered or turning. ing.

JP 2009-287745 A

  However, the hybrid construction machine described in Patent Document 1 cannot regenerate excess hydraulic energy when an actuator other than a boom cylinder or a swing motor is operated.

  The present invention has been made in view of such a technical problem, and is a hybrid construction machine capable of regenerating excess hydraulic energy even when an actuator other than a boom cylinder and a swing motor is operated. An object of the present invention is to provide a control system.

  The present invention is a control system for a hybrid construction machine, and includes a circuit system having an operation valve for supplying and discharging a working fluid supplied from a main pump through a main passage to an actuator, and a main relief of the working fluid pressure in the main passage. Main relief valve that keeps below pressure, regenerative passage that branches from between main pump and operation valve of main passage, regenerative motor that rotates by working fluid guided through regenerative passage, and regenerative passage And a controller for switching the regeneration passage switching valve to an open position when the working fluid pressure in the main passage reaches a set pressure lower than the main relief pressure.

  According to the present invention, when the working fluid pressure in the main passage reaches a set pressure lower than the main relief pressure during operation of the actuator, the regenerative passage switching valve is switched to the open position, and the working fluid in the main passage becomes Led to. Therefore, even when an actuator other than the boom cylinder and the swing motor is operated, the fluid pressure energy of the surplus working fluid can be regenerated.

It is a circuit diagram which shows the control system of the hybrid construction machine which concerns on embodiment of this invention. It is a circuit diagram which shows the modification of the control system of the hybrid construction machine which concerns on embodiment of this invention. It is a circuit diagram which shows the modification of the control system of the hybrid construction machine which concerns on embodiment of this invention.

  Embodiments of the present invention will be described with reference to the drawings.

  First, the first embodiment will be described.

  FIG. 1 is a circuit diagram showing a control system 100 for a hybrid construction machine according to the present embodiment.

  The hybrid construction machine is, for example, a hydraulic excavator or the like, and includes a first main pump MP1 and a second main pump MP2 that discharge hydraulic oil as a working fluid, and a first circuit system S1 to which hydraulic oil is supplied from the first main pump MP1. And a second circuit system S2 to which hydraulic oil is supplied from the second main pump MP2.

  The first main pump MP1 and the second main pump MP2 are variable displacement pumps that are driven by the engine E to rotate coaxially and can adjust the tilt angle of the swash plate.

  The first circuit system S1 includes, in order from the upstream side, an operation valve 1 that controls the swing motor RM, an operation valve 2 that controls an arm cylinder (not shown), and a boom that controls a boom cylinder BC as a fluid pressure cylinder. An operation valve 3 for controlling a second speed, an operation valve 4 for controlling a spare attachment (not shown) such as a breaker or a crusher, and an operation valve for controlling a first traveling motor (not shown) for left running. And 5.

  The operation valves 1 to 5 control the operation of each actuator by controlling the flow rate of the hydraulic oil guided from the first main pump MP1 to each actuator. Each of the operation valves 1 to 5 is operated by a pilot pressure supplied when the operator of the hydraulic excavator manually operates the operation lever.

  Each operation valve 1 to 5 is connected to the first main pump MP1 through a neutral passage 6 and a parallel passage 7 as main passages parallel to each other. On the upstream side of the operation valve 1 in the neutral flow path 6, a main relief valve 8 is provided that opens when the hydraulic pressure in the neutral flow path 6 exceeds a predetermined main relief pressure and keeps the hydraulic pressure below the main relief pressure. It is done. The predetermined main relief pressure is set high enough to ensure a minimum operating pressure for each of the operation valves 1 to 5.

  A throttle 9 for generating a pilot pressure (negative control pressure) is provided downstream of the operation valve 5 in the neutral flow path 6. The throttle 9 generates a high pilot pressure on the upstream side when the flow rate passing therethrough is high, and generates a low pilot pressure on the upstream side when the flow rate passing therethrough is small.

  The throttle 9 is provided in parallel with a pilot relief valve 10 that opens when the pilot pressure generated upstream of the throttle 9 exceeds a predetermined pilot relief pressure and keeps the pilot pressure below a predetermined pilot relief pressure. The pilot relief pressure is set lower than the main relief pressure of the main relief valve 8 to such an extent that no abnormal pressure is generated in the throttle 9.

  The neutral flow path 6 guides all or part of the hydraulic oil discharged from the first main pump MP1 to the tank T when all the operation valves 1 to 5 are in the neutral position or in the vicinity of the neutral position. In this case, since the flow rate of the hydraulic oil passing through the throttle 9 increases, a high pilot pressure is generated.

  On the other hand, when the operation valves 1 to 5 are switched to the full stroke, the neutral flow path 6 is closed and the flow of hydraulic oil is lost. In this case, the flow rate of the hydraulic oil passing through the throttle 9 is almost eliminated, and the pilot pressure is kept at zero. However, depending on the operation amount of the operation valves 1 to 5, a part of the hydraulic oil discharged from the first main pump MP1 is guided to the actuator and the rest is guided from the neutral flow path 6 to the tank T. A pilot pressure corresponding to the flow rate of the hydraulic oil in the neutral flow path 6 is generated. That is, the throttle 9 generates a pilot pressure corresponding to the operation amount of the operation valves 1 to 5.

  A pilot flow path 11 is connected to the upstream side of the throttle 9, and the pilot pressure generated by the throttle 9 is guided to the pilot flow path 11. The pilot flow path 11 is connected to a regulator 12 that controls the capacity (tilt angle of the swash plate) of the first main pump MP1.

  The regulator 12 controls the tilt angle of the swash plate of the first main pump MP1 in proportion to the pilot pressure of the pilot flow path 11 (proportional constant is a negative number), and per rotation of the first main pump MP1. Controls the amount of push-out. Therefore, when the operation valves 1 to 5 are switched to the full stroke and there is no flow of hydraulic oil passing through the throttle 9, and the pilot pressure in the pilot flow path 11 becomes zero, the swash plate of the first main pump MP1 is tilted. The angle is maximized and the amount of push-out per rotation is maximized.

  The pilot flow path 11 is provided with a first pressure sensor 13 as a pressure detector that detects the pressure of the pilot flow path 11. The pressure signal detected by the first pressure sensor 13 is output to the controller C. Since the pilot pressure in the pilot flow path 11 changes according to the operation amount of the operation valves 1 to 5, the pressure signal detected by the first pressure sensor 13 is proportional to the required flow rate of the first circuit system S1.

  The second circuit system S2 includes, in order from the upstream side, an operation valve 14 for controlling a second traveling motor (not shown) for right traveling, an operation valve 15 for controlling a bucket cylinder (not shown), An operation valve 16 that controls the boom cylinder BC and an operation valve 17 for second-arm arm that controls an arm cylinder (not shown) are provided.

  Each operation valve 14-17 controls the operation | movement of each actuator by controlling the flow volume of the hydraulic fluid guide | induced to each actuator from 2nd main pump MP2. Each operation valve 14-17 is operated by the pilot pressure supplied when the operator of a hydraulic shovel manually operates an operation lever.

  Each operation valve 14-17 is connected to 2nd main pump MP2 through the neutral flow path 18 as a main channel | path. The operation valves 14 to 16 are connected to the second main pump MP <b> 2 through a parallel passage 29 parallel to the neutral flow path 18. On the upstream side of the operation valve 14 in the neutral flow path 18, a main relief valve 19 is provided that opens when the hydraulic pressure of the neutral flow path 18 exceeds a predetermined main relief pressure and keeps the hydraulic pressure below the main relief pressure. It is done. The predetermined main relief pressure is set high enough to ensure the minimum operating pressure of each operation valve 14-17.

  A throttle 20 for generating a pilot pressure (negative control pressure) is provided downstream of the operation valve 17 in the neutral flow path 18. The diaphragm 20 has the same function as the diaphragm 9 on the first main pump MP1 side.

  The throttle 20 is provided in parallel with a pilot relief valve 21 that opens when the pilot pressure generated upstream of the throttle 20 exceeds a predetermined pilot relief pressure and keeps the pilot pressure below a predetermined pilot relief pressure. The pilot relief pressure is set lower than the main relief pressure of the main relief valve 19 to such an extent that no abnormal pressure is generated in the throttle 20.

  A pilot flow path 22 is connected to the upstream side of the throttle 20, and the pilot pressure generated by the throttle 20 is guided to the pilot flow path 22. The pilot flow path 22 is connected to a regulator 23 that controls the capacity (tilt angle of the swash plate) of the second main pump MP2.

  The regulator 23 controls the tilt angle of the swash plate of the second main pump MP2 in proportion to the pilot pressure of the pilot flow path 22 (proportional constant is a negative number), so that per second rotation of the second main pump MP2. Controls the amount of push-out. Therefore, when the operation valves 14 to 17 are switched to the full stroke and there is no flow of hydraulic oil passing through the throttle 20, and the pilot pressure in the pilot flow path 22 becomes zero, the swash plate of the second main pump MP2 is tilted. The angle is maximized and the amount of push-out per rotation is maximized.

  The pilot flow path 22 is provided with a second pressure sensor 24 as a pressure detector that detects the pressure of the pilot flow path 22. The pressure signal detected by the second pressure sensor 24 is output to the controller C. Since the pilot pressure in the pilot flow path 22 changes according to the operation amount of the operation valves 14 to 17, the pressure signal detected by the second pressure sensor 24 is proportional to the required flow rate of the second circuit system S2.

  The engine E is provided with a generator 25 that generates electric power using the remaining power of the engine E. The electric power generated by the generator 25 is charged to the battery 27 via the battery charger 26. The battery charger 26 can charge the battery 27 even when connected to a normal household power supply 28.

  Next, the turning motor RM will be described.

  The turning motor RM is provided in the turning circuit 30 for driving the turning motor RM. The swing circuit 30 includes a pair of supply / discharge passages 31 and 32 that connect the operation valve 1 and the swing motor RM, and relief valves 33 and 34 that are connected to the supply / discharge passages 31 and 32 and open at a set pressure, Is provided.

  When the operation valve 1 is in the neutral position, since the actuator port of the operation valve 1 is closed, the supply and discharge of hydraulic oil to and from the swing motor RM is shut off, and the swing motor RM maintains the stopped state.

  When the operation valve 1 is switched to one side, the supply / discharge passage 31 is connected to the first main pump MP1, and the supply / discharge passage 32 communicates with the tank T. As a result, the hydraulic oil is supplied through the supply / discharge passage 31 to rotate the turning motor RM, and the return hydraulic oil from the turning motor RM is discharged to the tank T through the supply / discharge passage 32. On the other hand, when the operation valve 1 is switched to the other, the supply / discharge passage 32 is connected to the first main pump MP1, the supply / discharge passage 31 communicates with the tank T, and the turning motor RM rotates in the reverse direction.

  When the turning pressure of the supply / discharge passages 31 and 32 reaches the set pressure of the relief valves 33 and 34 during the turning operation of the turning motor RM, the relief valves 33 and 34 are opened and the excess flow on the high pressure side is low. Led to the side.

  When the operation valve 1 is switched to the neutral position during the turning operation of the turning motor RM, the actuator port of the operation valve 1 is closed, and a closed circuit is formed by the supply / discharge passages 31, 32, the turning motor RM and the relief valves 33, 34. Composed. Thus, even if the actuator port of the operation valve 1 is closed, the turning motor RM continues to rotate by inertia energy and exhibits a pump action.

  As a result, one of the supply / discharge passages 31, 32, which was at a low pressure during the turning operation, becomes a high pressure, and the other one of the supply / discharge passages 31, 32, which was at a high pressure during the turning operation, becomes a low pressure. Operation is performed. At this time, when the brake pressure in the supply / discharge passages 31 and 32 reaches the set pressure of the relief valves 33 and 34, the relief valves 33 and 34 are opened, and the brake flow on the high pressure side is guided to the low pressure side.

  When the suction flow rate of the swing motor RM is insufficient during the braking operation of the swing motor RM, the operation of the tank T is performed through the check valves 35 and 36 that allow only the flow of hydraulic oil from the tank T to the supply / discharge passages 31 and 32. Oil is inhaled.

  Next, the boom cylinder BC will be described.

  When the operation valve 16 for controlling the operation of the boom cylinder BC is switched from the neutral position to one position, the hydraulic oil discharged from the second main pump MP2 is supplied to the piston side chamber 39 of the boom cylinder BC through the supply / discharge passage 38. At the same time, the return hydraulic oil from the rod side chamber 40 is discharged to the tank T through the supply / discharge passage 37, and the boom cylinder BC extends.

  On the other hand, when the operation valve 16 is switched to the other position, the hydraulic oil discharged from the second main pump MP2 is supplied to the rod side chamber 40 of the boom cylinder BC through the supply / discharge passage 37 and returned from the piston side chamber 39. The hydraulic oil is discharged to the tank T through the supply / discharge passage 38, and the boom cylinder BC contracts.

  When the operation valve 16 is switched to the neutral position, the supply and discharge of hydraulic oil to and from the boom cylinder BC is interrupted, and the boom is kept stopped. The boom second speed operation valve 3 is switched when the operation amount of the operation lever by the operator is larger than a predetermined amount.

  When the operation valve 16 is switched to the neutral position and the movement of the boom is stopped, a force in a contracting direction acts on the boom cylinder BC by its own weight such as the bucket, arm, and boom. Thus, the boom cylinder BC holds the load by the piston side chamber 39 when the operation valve 16 is in the neutral position, and the piston side chamber 39 becomes the load side pressure chamber.

  The control system 100 for the hybrid construction machine executes regenerative control that recovers energy of the hydraulic oil from the turning circuit 30 and the boom cylinder BC and performs energy regeneration. Regenerative control is performed by the controller C. The controller C 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.

  Next, turning regeneration control that performs energy regeneration using hydraulic oil from the turning circuit 30 will be described.

  Branch passages 41 and 42 are connected to the supply / discharge passages 31 and 32 connected to the turning motor RM, respectively. The branch passages 41 and 42 are joined together and connected to a turning regeneration passage 43 for guiding the hydraulic oil from the turning circuit 30 to the regeneration motor M for regeneration. Each of the branch passages 41 and 42 is provided with check valves 44 and 45 that allow only the flow of hydraulic oil from the supply / discharge passages 31 and 32 to the turning regeneration passage 43. The turning regeneration passage 43 is connected to the regeneration motor M through the merge regeneration passage 46.

  The regenerative motor M is a variable capacity motor that can adjust the tilt angle of the swash plate, and is connected to an electric motor 47 as a rotating electric machine that also serves as a generator so as to rotate coaxially. When the electric motor 47 functions as a generator, the electric power generated by the electric motor 47 is charged to the battery 27 via the inverter 48. The regenerative motor M and the electric motor 47 may be directly connected or may be connected via a speed reducer.

  The turning regeneration passage 43 is provided with an electromagnetic switching valve 49 that is switched and controlled by a signal output from the controller C. Between the electromagnetic switching valve 49 and the check valves 44 and 45, a pressure sensor 50 is provided for detecting a turning pressure during a turning operation of the turning motor RM or a brake pressure during a braking operation. The pressure signal detected by the pressure sensor 50 is output to the controller C.

  The electromagnetic switching valve 49 is set to the closed position (the state shown in FIG. 1) when the solenoid is not energized and shuts off the turning regeneration passage 43, and is set to the open position when the solenoid is excited and opens the turning regeneration passage 43. To do. The electromagnetic switching valve 49 guides the hydraulic oil from the turning circuit 30 to the regenerative motor M when switched to the open position. Thereby, turning regeneration is performed.

  A path of hydraulic oil from the turning circuit 30 to the regenerative motor M will be described. For example, at the time of the turning operation in which the turning motor RM turns by the hydraulic oil supplied through the supply / discharge passages 31 and 32, the surplus oil in the supply / discharge passages 31 and 32 passes through the branch passages 41 and 42 and the check valves 44 and 45. 43 flows into the regenerative motor M. Further, during the brake operation in which the operation valve 1 is switched to the neutral position when the turning motor RM is turning by the hydraulic oil supplied through the supply / discharge passages 31 and 32, the hydraulic oil discharged by the pump action of the turning motor RM. Flows into the turning regeneration passage 43 through the branch passages 41 and 42 and the check valves 44 and 45 and is guided to the regeneration motor M.

  A safety valve 51 is provided on the downstream side of the electromagnetic switching valve 49 in the turning regeneration passage 43. The safety valve 51 prevents the turning motor RM from running away by maintaining the pressure in the branch passages 41 and 42 when an abnormality occurs in the turning regenerative passage 43 such as the electromagnetic switching valve 49.

  When the controller C determines that the detected pressure of the pressure sensor 50 is equal to or higher than the rotation regeneration start pressure, the controller C excites the solenoid of the electromagnetic switching valve 49. Thereby, the electromagnetic switching valve 49 is switched to the open position, and the swivel regeneration is started.

  When the controller C determines that the detected pressure of the pressure sensor 50 has become less than the turning regeneration start pressure, the controller C de-energizes the solenoid of the electromagnetic switching valve 49. As a result, the electromagnetic switching valve 49 is switched to the closed position and the turning regeneration is stopped.

  Next, boom regeneration control for performing energy regeneration using hydraulic oil from the boom cylinder BC will be described.

  An electromagnetic proportional throttle valve 52 whose opening degree is controlled by an output signal from the controller C is provided in the supply / discharge passage 38 connecting the piston side chamber 39 of the boom cylinder BC and the operation valve 16. The electromagnetic proportional throttle valve 52 maintains the fully open position in the normal state.

  A boom regeneration passage 53 that branches from between the piston side chamber 39 and the electromagnetic proportional throttle valve 52 is connected to the supply / discharge passage 38. The boom regeneration passage 53 is a passage for guiding the return hydraulic oil from the piston side chamber 39 to the regeneration motor M. The turning regeneration passage 43 and the boom regeneration passage 53 join together and are connected to the joining regeneration passage 46.

  The boom regeneration passage 53 is provided with an electromagnetic switching valve 54 that is switch-controlled by a signal output from the controller C. The electromagnetic switching valve 54 is set to the closed position (the state shown in FIG. 1) when the solenoid is not energized and shuts off the boom regeneration passage 53, and is set to the open position when the solenoid is energized and opens the boom regeneration passage 53. Thus, only the flow of hydraulic oil from the piston side chamber 39 to the merging / regenerating passage 46 is allowed.

  The operation valve 16 is provided with a sensor (not shown) that detects the operation direction and the operation amount of the operation valve 16. The signal detected by the sensor is output to the controller C. The controller C calculates the expansion / contraction direction and the expansion / contraction amount of the boom cylinder BC based on the operation direction and the operation amount of the operation valve 16 detected by the sensor.

  Instead of the above sensor, the boom cylinder BC may be provided with a sensor for detecting the movement direction and the movement amount of the piston rod, and the operation lever may be provided with a sensor for detecting the operation direction and the operation amount. .

  The controller C determines whether the operator is going to extend or contract the boom cylinder BC based on the detection result of the sensor. When the controller C determines the extension operation of the boom cylinder BC, the controller C keeps the electromagnetic proportional throttle valve 52 in the fully open position, which is the normal state, and keeps the electromagnetic switching valve 54 in the closed position.

  On the other hand, when the controller C determines the contraction operation of the boom cylinder BC, the controller C calculates the contraction speed of the boom cylinder BC requested by the operator according to the operation amount of the operation valve 16, and closes the electromagnetic proportional throttle valve 52 to electromagnetically. The switching valve 54 is switched to the open position. As a result, the entire amount of return hydraulic oil from the boom cylinder BC is guided to the regeneration motor M, and boom regeneration is performed.

  When the flow rate consumed by the regenerative motor M is less than the flow rate required to maintain the contraction speed of the boom cylinder BC determined by the operator, the controller C controls the operation amount of the operation valve 16 and the recliner of the regenerative motor M. Based on the tilt angle of the plate, the rotational speed of the electric motor 47, and the like, the opening degree of the electromagnetic proportional throttle valve 52 is controlled so that the flow rate exceeding the flow rate consumed by the regenerative motor M is returned to the tank T. Thereby, the contraction speed of the boom cylinder BC required by the operator is maintained.

  When the boom cylinder BC is lowered while turning the swing motor RM, the return hydraulic oil from the swing motor RM and the return hydraulic oil from the boom cylinder BC merge in the regenerative passage 46 and the regenerative motor M To be supplied.

  At this time, even if the pressure of the swing regeneration passage 43 increases and becomes higher than the swing pressure or the brake pressure of the swing motor RM, the backflow of the hydraulic oil in the swing regeneration passage 43 is prevented by the check valves 44 and 45. Therefore, the swing motor RM is not affected. Further, when the pressure in the turning regeneration passage 43 decreases and becomes lower than the turning pressure or the brake pressure, the controller C closes the electromagnetic switching valve 49 based on the pressure signal from the pressure sensor 50.

  Therefore, when the turning operation of the turning motor RM and the lowering operation of the boom cylinder BC are performed at the same time, regardless of the turning pressure or the brake pressure, the regenerative motor M is tilted with reference to the lowering speed required for the boom cylinder BC. The turning angle is defined.

  Further, the control system 100 for the hybrid construction machine executes surplus flow rate regeneration control that recovers energy of the hydraulic oil from the neutral flow paths 6 and 18 and performs energy regeneration. The surplus flow rate regeneration control is performed by the controller C similarly to the turning regeneration control and the boom regeneration control.

  The upstream side of the operation valve 1 in the neutral flow path 6 of the first circuit system S1 and the merging regenerative passage 46 are connected by a first regenerative passage 55. The upstream side of the operation valve 14 in the neutral flow path of the second circuit system S2 and the merging regenerative passage 46 are connected by a second regenerative passage 56. A first regeneration passage switching valve 57 that can open and close the first regeneration passage 55 is interposed in the first regeneration passage 55. The second regeneration passage 56 is provided with a second regeneration passage switching valve 58 that can open and close the second regeneration passage 56.

  The first regenerative passage switching valve 57 and the second regenerative passage switching valve 58 are switched to the open position when the pilot pressure is supplied to the pilot chambers 57a, 58a, and are operated from the neutral flow passages 6, 18 to the merging regenerative passage 46. When the oil flow is allowed and the supply of the pilot pressure is cut off, the first regenerative passage 55 and the second regenerative passage 56 are closed by switching to the closed position.

  The pilot pressure supplied to the pilot chamber 57a of the first regenerative passage switching valve 57 is supplied from the first pilot pressure source PP1 through the first pilot passage 59. The first pilot passage 59 is provided with a first electromagnetic proportional pressure reducing valve 61 as an electromagnetic switching valve capable of outputting a proportional pilot pressure in response to a command signal from the controller C. Based on the command signal output from the controller C, the first electromagnetic proportional pressure reducing valve 61 reduces the pressure of the first pilot pressure source PP1 to generate a pilot pressure corresponding to the command value when the solenoid is excited. Is supplied to the first pilot passage 59. When the solenoid is de-energized, the first pilot passage 59 is communicated with the tank T.

  The pilot pressure supplied to the pilot chamber 58a of the second regenerative passage switching valve 58 is supplied through the second pilot passage 60 from the second pilot pressure source PP2. The second pilot passage 60 is provided with a second electromagnetic proportional pressure reducing valve 62 as an electromagnetic switching valve capable of outputting a proportional pilot pressure in response to a command signal from the controller C. Based on the command signal output from the controller C, the second electromagnetic proportional pressure reducing valve 62 reduces the pressure of the second pilot pressure source PP2 to generate a pilot pressure corresponding to the command value when the solenoid is excited. Is supplied to the second pilot passage 60. When the solenoid is de-energized, the second pilot passage 60 is communicated with the tank T.

  A neutral cut valve as a main passage switching valve capable of opening and closing the neutral flow path 18 downstream of the operation valve 17 in the neutral flow path 18 of the second circuit system S2 and upstream of the connection portion of the pilot flow path 22. 63 is interposed. The neutral cut valve 63 is switched to the closed position when the pilot pressure is supplied to the pilot chamber 63a to close the neutral flow path 18, and is switched to the open position when the supply of the pilot pressure is cut off. Is released. The pilot chamber 63a of the neutral cut valve 63 is connected to the second pilot passage 60. When pilot pressure is supplied to the second regenerative passage switching valve 58 by the second electromagnetic proportional pressure reducing valve 62, the pilot chamber of the neutral cut valve 63 is simultaneously used. The pilot pressure is also supplied to 63a. That is, the neutral cut valve 63 operates in conjunction with the second regeneration passage switching valve 58.

  Between the first main pump MP1 and the operation valve 1 in the neutral flow path 6 of the first circuit system S1, a pressure sensor 64 that detects the hydraulic pressure of the neutral flow path 6 (discharge pressure of the first main pump MP1) is provided. Provided. Similarly, between the second main pump MP2 and the operation valve 14 in the neutral flow path 18 of the second circuit system S2, a pressure for detecting the hydraulic pressure of the neutral flow path 18 (discharge pressure of the second main pump MP2). A sensor 65 is provided. The pressure signals detected by the pressure sensors 64 and 65 are output to the controller C.

  The controller C excites the solenoid of the first electromagnetic proportional pressure reducing valve 61 when the hydraulic pressure of the neutral flow path 6 of the first circuit system S1 reaches a predetermined set pressure. As a result, the pilot pressure is supplied to the first regeneration passage switching valve 57, and the first regeneration passage switching valve 57 opens the first regeneration passage 55. The hydraulic oil in the neutral flow path 6 is guided to the merging regeneration passage 46 through the first regeneration passage 55, and the excess flow regeneration of the first circuit system S1 is performed. The predetermined set pressure is set to a pressure slightly lower than the main relief pressure of the main relief valve 8.

  The controller C excites the solenoid of the second electromagnetic proportional pressure reducing valve 62 when the operating hydraulic pressure of the neutral flow path 18 of the second circuit system S2 reaches a predetermined set pressure. Thereby, the pilot pressure is supplied to the second regeneration passage switching valve 58 and the second regeneration passage switching valve 58 opens the second regeneration passage 56. Further, pilot pressure is also supplied to the neutral cut valve 63, and the neutral cut valve 63 closes the neutral flow path 18. The hydraulic oil in the neutral flow path 18 is guided to the merging regeneration passage 46 through the second regeneration passage 56, and the excess flow regeneration of the second circuit system S2 is performed. The predetermined set pressure is set to a pressure slightly lower than the main relief pressure of the main relief valve 19.

  When the controller C performs surplus flow rate regeneration control by opening at least one of the first electromagnetic proportional pressure reducing valve 61 and the second electromagnetic proportional pressure reducing valve 62, the operation of the neutral flow paths 6 and 18 on the regenerating side is performed. The tilt angle of the swash plate of the regenerative motor M is controlled by the regulator 66 so that the hydraulic pressure becomes equal to or higher than the minimum operating pressure of the operation valves 1 to 5 and 14 to 17.

  Next, the sub pump SP as an assist pump that assists the outputs of the first main pump MP1 and the second main pump MP2 will be described.

  The sub-pump SP is a variable displacement pump capable of adjusting the tilt angle of the swash plate, and is connected to the regenerative motor M so as to rotate coaxially. The sub pump SP is rotated by the driving force of the electric motor 47. The rotation speed of the electric motor 47 is controlled by the controller C through the inverter 48. The tilt angle of the swash plate of the regenerative motor M and the sub pump SP is controlled by the controller C via the regulators 66 and 67.

  A discharge passage 68 as an assist passage is connected to the sub pump SP. The discharge passage 68 is formed by branching into a first discharge passage 69 that joins the first regeneration passage 55 and a second discharge passage 70 that joins the second regeneration passage 56. A high pressure selection switching valve 71 as an assist switching valve is interposed at the branch portion of the discharge passage 68. The first discharge passage 69 and the second discharge passage 70 are provided with check valves 72 and 73 that permit only the flow of hydraulic oil from the discharge passage 68 to the first regeneration passage 55 or the second regeneration passage 56, respectively. .

  The high pressure selection switching valve 71 is a three-port, three-position spool type switching valve. The high pressure selection switching valve 71 is provided with pilot chambers 71a and 71b facing both ends of the spool. The hydraulic oil in the first regenerative passage 55 is supplied to one pilot chamber 71a via a damping throttle 74, and the hydraulic oil in the second regenerative passage 56 is supplied to the other pilot chamber 71b via a damping throttle 75. Is done. The spool is supported in a neutral state by a pair of centering springs provided at both ends. The high pressure selection switching valve 71 is normally held in the normal position (the state shown in FIG. 1) by the spring force of the centering spring.

  The high pressure selection switching valve 71 supplies the hydraulic oil in the discharge passage 68 equally to the first discharge passage 69 and the second discharge passage 70 in a state where it is held at the normal position.

  The high pressure selection switching valve 71 is switched to the first switching position (the lower position in FIG. 1) when the pilot pressure in one pilot chamber 71a is higher than the pilot pressure in the other pilot chamber 71b. Thereby, a large amount of hydraulic oil in the discharge passage 68 is supplied to the first regeneration passage 55.

  When the pilot pressure in the other pilot chamber 71b is higher than the pilot pressure in one pilot chamber 71a, the high pressure selection switching valve 71 is switched to the second switching position (upper position in FIG. 1). As a result, more hydraulic oil in the discharge passage 68 is supplied to the second regeneration passage 56.

  That is, the high pressure selection switching valve 71 selects the high pressure of the first regeneration passage 55 and the second regeneration passage 56 and supplies the hydraulic fluid for the discharge passage 68. When the differential pressure between the pilot pressure in one pilot chamber 71a, 71b and the pilot pressure in the other pilot chamber 71b, 71a is sufficiently high, the total amount of hydraulic fluid in the discharge passage 68 is the same as that in the first regeneration passage 55. The second regeneration passage 56 may be supplied to the high pressure side and may not be supplied to the low pressure direction at all.

  When the sub pump SP rotates with the driving force of the electric motor 47, the sub pump SP assists the output of at least one of the first main pump MP1 and the second main pump MP2. Which of the first main pump MP1 and the second main pump MP2 is to be assisted is determined by the high pressure selection switching valve 71, and automatic assist that does not require control by the controller C is performed.

  When hydraulic oil is supplied to the regenerative motor M through the merge regenerative passage 46 and the regenerative motor M rotates, the rotational force of the regenerative motor M acts as an assist force for the electric motor 47 that rotates coaxially. Therefore, the power consumption of the electric motor 47 can be reduced by the amount of the rotational force of the regenerative motor M.

  When the regenerative motor M is used as a drive source and the electric motor 47 is used as a generator, the sub-pump SP is almost in a no-load state with the tilt angle of the swash plate set to zero.

  According to the above embodiment, there exist the effects shown below.

  When the working oil pressure of the neutral flow paths 6 and 18 reaches a predetermined set pressure, the first regeneration passage switching valve 57 of the first regeneration passage 55 or the second regeneration passage 56 connected to the neutral flow paths 6 and 18 or The second regenerative passage switching valve 58 is switched to the open position, and the high-pressure hydraulic oil of the first main pump MP1 or the second main pump MP2 is guided to the regenerative motor M.

  Here, conventionally, during the operation of the boom cylinder BC and the swing motor RM, energy regeneration can be performed from the surplus flow rate of the boom cylinder BC and the swing motor RM by the boom regeneration control and the swing regeneration control. When actuators other than the cylinder BC and the turning motor RM are being operated, energy regeneration cannot be performed.

  On the other hand, in this embodiment, for example, when a bucket, an arm, or the like is operated, when the hydraulic pressure of the neutral flow paths 6 and 18 reaches a set pressure, there is a surplus in the neutral flow paths 6 and 18. Instead of discarding the hydraulic oil from the main relief valves 8, 19, the hydraulic oil can be guided to the regenerative motor M. Therefore, since regeneration can be performed from energy that has been discarded, energy can be reduced and more energy can be regenerated, and energy consumption of the entire system can be reduced.

  Further, when all the actuators are stopped, the standby flow rate of the neutral flow paths 6 and 18 can be guided to the regenerative motor M. As a result, standby charge for generating power by rotating the regenerative motor M using the standby flow rate is performed, and the battery charge amount can be increased. In particular, since the neutral cut valve 63 is provided in the neutral flow path 18 of the second circuit system S2, the hydraulic pressure of the neutral flow path 18 can be increased to the vicinity of the main relief pressure. As a result, a higher-pressure surplus flow rate is guided to the regenerative motor M, so the time required to charge the battery 27 to a predetermined battery capacity can be shortened.

  Furthermore, when the controller C performs surplus flow rate regeneration control by sending a command signal to at least one of the first electromagnetic proportional pressure reducing valve 61 and the second electromagnetic proportional pressure reducing valve 62, the hydraulic pressure of the neutral flow paths 6 and 18 is increased. The tilt angle of the swash plate of the regenerative motor M is controlled by the regulator 66 so as to be equal to or higher than the minimum operating pressure of the operation valves 1 to 5 and 14 to 17. Thereby, energy regeneration can be performed while maintaining the hydraulic pressure in the neutral flow paths 6 and 18 on the side where the hydraulic oil is guided to the regenerative motor M.

  Further, since the neutral cut valve 63 is provided on the upstream side of the pilot relief valve 21, the operation of the neutral flow path 18 is performed when the operating hydraulic pressure of the neutral flow path 18 reaches the set pressure and the neutral cut valve 63 is switched to the closed position. The hydraulic pressure can be prevented from being relieved from the pilot relief valve 21. Thereby, since higher hydraulic pressure can be supplied to the regenerative motor M at the time of excessive flow regenerative control, more energy can be regenerated.

  Further, a high pressure selection switching valve 71 is interposed in a discharge passage 68 that guides hydraulic oil discharged from the sub pump SP to the neutral flow paths 6, 18, and the high pressure selection switching valve 71 has a first regeneration passage 55 and a second regeneration passage 56. The hydraulic oil in the discharge passage 68 is supplied by selecting the higher pressure. Thereby, when the load of the actuator is high, a large amount of assist flow is supplied to the neutral flow paths 6 and 18 on the high pressure side, so that the working speed of the hydraulic excavator can be ensured.

  Further, since the high pressure selection switching valve 71 selects the high pressure side of the first regeneration passage 55 and the second regeneration passage 56, the hydraulic oil discharged from the sub pump SP can be supplied to the high pressure side. Further, as in the conventional case in which the discharge oil of the sub pump SP is equally distributed to the first regeneration passage 55 and the second regeneration passage 56 via the proportional electromagnetic throttle valve, the throttle pressure loss is reduced in the proportional electromagnetic throttle valve. It can prevent that assist power falls and energy consumption can be reduced. Furthermore, since no proportional electromagnetic throttle valve is used, the assist system that supplies the discharge oil from the sub pump SP to the neutral flow paths 6 and 18 can be a low-cost and robust system.

  Furthermore, since the hydraulic oil can be supplied to the neutral flow paths 6 and 18 by the sub pump SP while performing the swing regeneration control and the boom regeneration control, for example, the horizontal pushing operation for operating the arm while contracting the boom cylinder BC (or In the case of leveling work), the arm can be assisted by the regenerated power while regenerating by boom regenerative control. Therefore, the energy consumption as the whole system can be reduced.

  Further, the hydraulic oil of the first regeneration passage 55 is supplied to one pilot chamber 71a of the high pressure selection switching valve 71 through the damping throttle 74, and the hydraulic oil of the second regeneration passage 56 is supplied to the other pilot chamber 71b. Supplied via a damping diaphragm 75. This prevents the spool of the high pressure selection switching valve 71 from moving suddenly, and reduces the shock that occurs when the high pressure selection switching valve 71 switches between the neutral position, the first switching position, and the second switching position. can do.

  The embodiment of the present invention has been described above. However, the above embodiment is merely one example of application of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent.

  For example, when adding the neutral cut valve 63 to the existing control valve having a neutral cut function by the neutral cut valve, both neutral cut valves may be shared. In this case, as shown in FIG. 2, a connection passage 80 that branches from between the operation valve 17 and the neutral cut valve 63 in the neutral flow path 18 is provided. Although not shown in FIG. 2, the connection passage 80 is connected to the operation valve 4 that controls the spare attachment of the first circuit system S <b> 1, and supplies hydraulic oil for driving a breaker, a crusher, and the like attached to the spare attachment. It supplies from the neutral flow path 18 of 2nd circuit system S2.

  In the second pilot passage 60, a check valve 81 that allows only the flow of pilot fluid from the second pilot pressure source PP2 to the neutral cut valve 63, and a pilot pressure source that generates a pilot pressure for operating the auxiliary attachment A check valve 82 that allows only pilot pressure to flow from the neutral cut valve 63 (not shown) is interposed.

  Thereby, the pilot pressure is supplied to the neutral cut valve 63 via the check valve 81 during the excessive flow regeneration control, and the pilot pressure is supplied to the neutral cut valve 63 via the check valve 82 when operating the auxiliary attachment. Therefore, the control system 100 can be simplified and downsized as compared with the case where a pilot passage for switching the neutral cut valve 63 is provided separately.

  Furthermore, in the said embodiment, although the 1st regeneration path switching valve 57 which opens and closes the 1st regeneration path 55 and the 2nd regeneration path switching valve 58 which opens and closes the 2nd regeneration path 56 are provided separately, FIG. Thus, these may be integrated and formed as one regenerative passage switching valve 90.

  As shown in FIG. 3, the regenerative passage switching valve 90 is a three-port, three-position spool type switching valve. The regeneration passage switching valve 90 is provided with pilot chambers 90a and 90b facing both ends of the spool. The hydraulic oil in the first pilot passage 59 is supplied to one pilot chamber 90a, and the hydraulic oil in the second pilot passage 60 is supplied to the other pilot chamber 90b. The spool is supported in a neutral state by a pair of centering springs provided at both ends. The regenerative passage switching valve 90 is normally held in the normal position (the state shown in FIG. 3) by the spring force of the centering spring.

  The regenerative passage switching valve 90 blocks communication between the first regenerative passage 55 and the second regenerative passage 56 and the merging regenerative passage 46 in a state where it is held at the normal position.

  Based on the command signal from the controller C, the regenerative passage switching valve 90 is supplied with the pilot pressure generated by the first electromagnetic proportional pressure reducing valve 61 to the pilot chamber 90b, so that the first switching position (the lower position in FIG. 3). ). As a result, the hydraulic oil in the first regeneration passage 55 is supplied to the merging regeneration passage 46.

  Based on the command signal from the controller C, the regeneration passage switching valve 90 is supplied with the pilot pressure generated by the second electromagnetic proportional pressure reducing valve 62 to the pilot chamber 90a, so that the second switching position (upper position in FIG. 3). Can be switched to. As a result, the hydraulic oil in the second regeneration passage 56 is supplied to the merging regeneration passage 46.

  By integrating the first regeneration passage switching valve 57 and the second regeneration passage switching valve 58 in this way, the number of functional parts of the control system 100 can be reduced and the cost can be reduced.

  Furthermore, in the said embodiment, the 1st regeneration path 55 is connected to the neutral flow path 6 of 1st circuit system S1, and the 2nd regeneration path 56 is connected to the neutral flow path 18 of 2nd circuit system S2, and both circuit Although the surplus flow is regenerated from the neutral flow paths 6 and 18 of the systems S1 and S2, the regenerative passage may be provided only in one of them.

  Furthermore, in the above embodiment, the neutral cut valve 63 is provided in the neutral flow path 18 of the second circuit system S2, but may be provided in the neutral flow path 6 of the first circuit system S1, or both neutral flow paths. 6 and 18 may be provided.

  Further, in the above embodiment, the first regeneration passage switching valve 57, the second regeneration passage switching valve 58 and the neutral cut valve 63 are controlled to be switched by the pilot pressure, but each valve is an electromagnetic valve driven by a solenoid. The switching may be directly controlled according to the signal from the controller C.

1-5 Operation valve 6 Neutral flow path (main passage)
8 Main relief valve 13 First pressure sensor (pressure detector)
14 to 17 Operation valve 18 Neutral flow path (main passage)
19 Main Relief Valve 20 Throttle 21 Pilot Relief Valve 23 Regulator 24 Second Pressure Sensor (Pressure Detector)
39 Piston side chamber (load side pressure chamber)
55 First regeneration passage (regeneration passage, assist passage)
56 Second regeneration passage (regeneration passage, assist passage)
57 First regeneration passage switching valve (regeneration passage switching valve)
58 Second regeneration passage switching valve (Regeneration passage switching valve)
59 First pilot passage (pilot passage)
60 Second pilot passage (pilot passage)
61 First electromagnetic proportional pressure reducing valve (electromagnetic switching valve)
62 Second electromagnetic proportional pressure reducing valve (electromagnetic switching valve)
63 Neutral cut valve (Main passage switching valve)
68 Discharge passage (assist passage)
71 High-pressure selection switching valve (assist switching valve)
74, 75 Attenuation throttle 80 Connection passage 100 Hybrid construction machine control system MP1 First main pump (main pump)
MP2 2nd main pump (main pump)
BC Boom cylinder (fluid pressure cylinder)
S1 First circuit system (circuit system)
S2 Second circuit system (circuit system)
M Regenerative motor C Controller SP Sub pump (Assist pump)

Claims (8)

A control system for a hybrid construction machine,
A circuit system having an operation valve for supplying and discharging the working fluid supplied from the main pump through the main passage to the actuator;
A main relief valve that keeps the working fluid pressure in the main passage below the main relief pressure;
A regenerative passage branching from between the main pump of the main passage and the operation valve;
A regeneration motor for regeneration that is rotated by working fluid guided through the regeneration passage;
A regeneration passage switching valve capable of opening and closing the regeneration passage;
When the working fluid pressure in the main passage reaches a set pressure lower than the main relief pressure, a controller that switches the regeneration passage switching valve to an open position, and
A control system for a hybrid construction machine, comprising: The controller controls the regenerative flow rate of the regenerative motor so that the working fluid pressure in the main passage is equal to or higher than the minimum operating pressure of the actuator when the regenerative passage switching valve is controlled to be in the open position.
The control system for a hybrid construction machine according to claim 1. A throttle that is connected to a downstream side of the operation valve of the main passage and generates a pilot pressure transmitted to a regulator that controls the capacity of the main pump;
A pilot relief valve that is connected between the operating valve and the throttle in the main passage, and that maintains the pilot pressure below a pilot relief pressure;
A main passage switching valve interposed between the operation valve and the pilot relief valve in the main passage and capable of opening and closing the main passage;
Further comprising
The controller switches the main passage switching valve to a closed position when the regeneration passage switching valve is controlled to be switched to an open position;
The hybrid construction machine control system according to claim 1 or 2, wherein the control system is a hybrid construction machine control system. The circuit system is composed of two circuit systems,
An assist pump that supplies working fluid to the main passage through an assist passage by rotating in conjunction with the regenerative motor;
An assist switching valve that is interposed in the assist passage and supplies the working fluid supplied from the assist pump to at least one of the main passages of the two circuit systems;
Further comprising
The assist switching valve is switched so that more working fluid supplied from the assist pump flows into the main passage having a higher working fluid pressure among the main passages of the two circuit systems.
The control system for a hybrid construction machine according to any one of claims 1 to 3, wherein the control system is a hybrid construction machine control system. At least one of the actuators is extended by supplying a working fluid to the load side pressure chamber to increase the load, and contracted by discharging the working fluid from the load side pressure chamber to lower the load And
The regenerative motor is rotated by a working fluid discharged from the load side pressure chamber.
The hybrid construction machine control system according to any one of claims 1 to 4, wherein the control system is a hybrid construction machine control system. The assist switching valve switches the working fluid pressure of one main passage of the two circuit systems and the working fluid pressure of the other main passage as a pilot pressure,
Both pilot pressures are guided to the assist switching valve via a damping throttle that attenuates the switching operation of the assist switching valve.
The hybrid construction machine control system according to claim 4, wherein: A pressure detector for detecting a working fluid pressure in the main passage;
An electromagnetic switching valve interposed in a pilot passage for supplying a pilot pressure for switching the regeneration passage switching valve to an open position and capable of opening and closing the pilot passage;
Further comprising
The controller switches the electromagnetic switching valve to an open position when the working fluid pressure detected by the pressure detector reaches the set pressure during operation of the actuator;
The hybrid construction machine control system according to any one of claims 1 to 6, wherein the control system is a hybrid construction machine control system. The circuit system is composed of two circuit systems,
A connection passage connecting the upstream side of the main passage switching valve in the main passage of one circuit system and the operation valve of the other circuit system;
When the main passage switching valve is switched to the closed position by a pilot pressure for switching the operation valve of the other circuit system, the working fluid of the main passage of the one circuit system is transferred to the other circuit via the connection passage. Supplied to the operation valve of the circuit system of
The control system for a hybrid construction machine according to claim 3.

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