JP2006349092A - Hybrid system of working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hybrid system of a working machine which can secure required operating speed without increasing the quantities and capacities of motor generators and pumps, and facilitate mounting on an actual machine. <P>SOLUTION: In the hybrid system, a boom cylinder circuit 51 and a left traveling motor circuit 57 are connected to a first pump 3. An arm cylinder circuit 52 and a right traveling motor circuit 58 are connected to a second pump 4. A bucket cylinder circuit 59 is connected to a third pump 6 having a fluid pressure motor function. A pump motor generator 5 for driving the third pump 6 and a swivel motor generator 7 are connected to a capacitor 14. A return fluid supply circuit 55 supplies return fluid from a boom cylinder 8 to a suction port of the third pump 6. A pressure fluid replenishing circuit 56 replenishes pressure fluid from the third pump 6 to a control valve block 17 of the boom cylinder 8 and a control valve block 18 of an arm cylinder 9. A merging flow control valve 26 is provided between discharge passages of the third pump 3 and of the second pump 4. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hybrid system for a work machine having an energy regeneration function.

  As a conventional technique of a hybrid work machine, a boom cylinder circuit for controlling a boom cylinder is configured as a closed circuit using an electric / generator and two hydraulic pumps, an arm driven by an engine, and a left traveling hydraulic pressure A pump, a bucket and a right traveling pump are provided, and hydraulic oil is supplied from one pump to the arm cylinder and the left traveling motor, and the hydraulic oil is supplied from the other pump to the bucket cylinder and the right traveling motor. Yes (see, for example, Patent Document 1).

In addition, an electric motor and a driving force transmission device are provided for each actuator of the left traveling device, right traveling device, turning device, boom, arm and bucket of the electric excavator, and these are supplied from a generator or a power storage unit driven by the engine. There is an electric construction machine that is operated by electric power (for example, see Patent Document 2).
JP 2002-322682A (page 3-4, FIG. 1) JP 2003-82707 A (page 4, FIG. 1)

  In a general hydraulic excavator system, the boom cylinder extends up to two main pumps and the lower side is driven from one main pump, and the arm cylinders up to two main pumps, the travel motor and the swing motor It is driven by one main pump. Therefore, in order to drive the boom cylinder, the shovel described in Patent Document 1 requires a large-capacity hydraulic pump corresponding to two main pumps and a large-sized electric motor / generator for driving the pump at high speed.

  Further, as in the excavator described in Patent Document 1, when divided into an arm / left traveling hydraulic pump and a bucket / right traveling pump, the arm cylinder is driven by one pump, and the conventional hydraulic shovel system May not be able to ensure the same arm operating speed.

  On the other hand, as in the excavator described in Patent Document 2, if an electric motor and a driving force transmission device are installed for each actuator, the system is complicated and the number of electric motors and driving force transmission devices is large, so it is difficult to install in an actual machine. In addition, the system becomes expensive.

  The present invention has been made in view of such points, and can ensure the required operating speed without increasing the number and capacity of motors / generators and pumps as compared with the conventional hybrid system, and can be mounted on an actual machine. An object is to provide an easy and practical work machine hybrid system.

  The invention described in claim 1 is a power generator / motor connected to an engine and functioning as a generator / motor, a power storage device connected to the power generator / motor for charging and discharging, and a power source from the power generator / motor and the power storage device. A turning electric motor / generator for revolving by converting the turning energy of the airframe into electric power, a first actuator circuit driven by the engine and the electric generator / motor, and controlling at least the first actuator for fluid in the tank, and A first pump and a second pump that are respectively supplied to a second actuator circuit that controls the second actuator; an electric motor / generator for a pump that is connected to a power storage device and functions as an electric motor and an electric generator; and an electric motor / generator for the pump A third actuator that is driven and controls at least the third actuator for fluid in the tank A third pump having a fluid pressure motor function to supply to the passage; a return fluid supply circuit for supplying return fluid from the first actuator circuit to the suction port of the third pump; and a first actuator circuit from the discharge port of the third pump. And a pressure fluid supply circuit for supplying pressure fluid to the second actuator circuit, a discharge flow rate of the first pump and a discharge flow rate of the second pump provided between the discharge passage of the first pump and the discharge passage of the second pump, Is a hybrid system for a work machine that includes a flow control valve for merging that can merge.

  According to a second aspect of the present invention, in the hybrid system of the working machine according to the first aspect, the boom cylinder, the arm cylinder, The working device is driven by a bucket cylinder, the discharge port of the first pump is connected to the boom cylinder circuit that controls the boom cylinder and the left travel motor circuit that controls the left travel motor, and the discharge port of the second pump is An arm cylinder circuit that controls the arm cylinder and a right traveling motor circuit that controls the right traveling motor are connected to each other, and a discharge port of the third pump is connected to a bucket cylinder circuit that controls the bucket cylinder.

  According to a third aspect of the present invention, the return fluid supply circuit in the hybrid system of the work machine according to the second aspect has a regeneration passage for regenerating the return fluid from the boom cylinder circuit to the suction port of the third pump when the boom is lowered. A tank flow rate control valve is provided in a tank passage branched from the passage and communicated with the tank, and controls a flow rate returned to the tank from the boom cylinder circuit.

  According to a fourth aspect of the present invention, the pressure fluid supply circuit in the hybrid system of the work machine according to the second or third aspect controls the flow rate of the pressure fluid supplied from the discharge port of the third pump to the boom cylinder circuit and the arm cylinder circuit. A replenishment flow rate control valve is provided.

  According to the first aspect of the present invention, between the first pump, the second pump, and the third pump, or the first actuator by the return fluid supply circuit, the pressure fluid supply circuit, and the merging flow control valve. Since the surplus fluid energy generated between the actuators of the second actuator and the third actuator is mutually used effectively, a large-capacity electric motor or pump is not required as compared with a hybrid system mounted on a conventional work machine. In addition, since the number of electric motors and pumps is reduced as compared with a system in which an electric motor and a driving force transmission device are individually installed in each actuator, a low-cost system can be built easily on an actual machine. Further, when the actuators of the first actuator, the second actuator, and the third actuator are operated in conjunction with each other, the pumps of the first pump, the second pump, and the third pump are assigned to these actuators. There is no load interference of the fluid pressure, energy loss can be reduced, and operability can be improved. Further, the braking energy of the turning electric motor / generator can be regenerated and used for driving the third pump, and can also be used for driving the first actuator and the second actuator via the pressure fluid supply circuit.

  According to the second aspect of the present invention, the return fluid energy at the time of lowering the boom can be regenerated to the power storage device by the pump motor / generator via the third pump by the return fluid supply circuit, and the turning motor / generator The braking energy can be regenerated in the power storage device, and the regenerative energy can be efficiently used for driving the bucket cylinder, and can be efficiently used for driving the boom cylinder and the arm cylinder via the pressure fluid supply circuit. Is required to supply sufficient pressure fluid to the boom cylinder circuit not only from the first pump but also from the second pump by opening the merging flow control valve. Power generation with the same output as the power generation / motor and main pump mounted on conventional hydraulic excavators You can configure the system in motor or pump. Further, when the actuators of the boom cylinder, the arm cylinder, and the bucket cylinder are operated in conjunction with each other, the pumps of the first pump, the second pump, and the third pump are assigned to these actuators. No load interference, energy loss can be reduced, and operability can be improved. Further, similarly to the conventional hydraulic excavator, the interlocking operation of the left traveling motor, the right traveling motor, the boom cylinder, the arm cylinder, and the bucket cylinder can be facilitated.

  According to the third aspect of the present invention, the return fluid energy at the time of lowering the boom is supplied to the pump motor / It can be regenerated appropriately with a generator, and the regenerated energy can be used to drive a bucket cylinder or the like.

  According to the fourth aspect of the present invention, the pressure fluid discharged from the third pump is maintained while maintaining a balance with the pressure fluid flow rate supplied from the third pump to the bucket cylinder circuit by the flow rate control of the replenishment flow rate control valve. The boom cylinder circuit and the arm cylinder circuit can also be replenished.

  Hereinafter, the present invention will be described in detail with reference to one embodiment shown in FIGS. The working fluid is oil and the fluid pressure is hydraulic.

  FIG. 2 shows a hybrid excavator A as a work machine according to the present invention. In this excavator A, a work device E is mounted on a machine body B together with a cab C and a power device D. The machine body B is provided with a turning electric motor / generator 7 that drives the upper turning body to turn relative to the lower traveling body, and the work device E rotates the boom bm that is axially connected to the machine body B in the vertical direction. A boom cylinder 8 as a first actuator, an arm cylinder 9 as a second actuator for rotating an arm am axially connected to the tip of the boom bm, and a third for rotating a bucket bk axially connected to the tip of the arm am A bucket cylinder 10 is provided as an actuator, and a left traveling motor 11 and a right traveling motor 12 for driving the crawler belt are provided on the lower traveling body of the airframe B.

  In FIG. 1, reference numeral 1 denotes an engine built in the power unit D, and a generator / motor 2 that functions as a generator and an electric motor is directly connected to the engine 1, and a variable capacity type first motor is connected to a rotating shaft of the generator / motor 2. The rotation shafts of the first pump 3 and the second pump 4 are connected in series. A variable displacement type third pump 6 driven by a pump motor / generator 5 is separately provided for the first pump 3 and the second pump 4. Each of these variable displacement pumps 3, 4, 6 includes swash plate controllers 3 c, 4 c, 6 c that control the tilt angle of the swash plate by an electric signal input from the outside.

  The third pump 6 functions as a fluid pressure pump and a fluid pressure motor, and the flow direction of the fluid is the same in both the pump operation and the motor operation. Pressure detectors 6a and 6b for detecting a differential pressure are installed in the front and rear passages via the third pump 6.

  Then, the working fluid supplied from these first pump 3, second pump 4 and third pump 6 to boom cylinder 8, arm cylinder 9, bucket cylinder 10, left travel motor 11 and right travel motor 12 is controlled. A fluid pressure circuit is installed.

  A controller 2c that controls the generator / motor 2 is connected to the generator / motor 2 that drives the first pump 3 and the second pump 4 together with the engine 1, and a battery that charges and discharges is connected to the controller 2c. Alternatively, a power storage device 14 such as a capacitor is connected via a controller 14c that controls the power storage device 14.

  Similarly, a controller 5c for controlling the electric motor / generator 5 for pump is connected to the electric motor / generator 5 for driving the third pump 6, and the electric motor / generator 7 for turning is A controller 7c for controlling the turning electric motor / generator 7 is connected, and these controllers 5c and 7c are connected to the power storage device 14 via the controller 14c.

  The suction ports of the first pump 3, the second pump 4 and the third pump 6 are respectively connected to the tank 16. The tank 16 contains a working fluid such as oil, and the inside of the tank is preloaded to atmospheric pressure or higher than atmospheric pressure.

  The control valve block 17 that controls the direction and flow rate of the boom cylinder 8 is formed by a plurality of flow rate control valves 17a, 17b, 17c, and 17d that form a bridge circuit.

  A control valve block 18 that controls the direction and flow rate of the arm cylinder 9 is formed by a plurality of flow rate control valves 18a, 18b, 18c, and 18d that constitute a bridge circuit. The control valve block 18 is provided with a flow rate control valve 18e for controlling the regeneration flow rate regenerated from the rod chamber of the arm cylinder 9 to the head chamber.

  A control valve block 19 that controls the direction and flow rate of the bucket cylinder 10 is formed by a plurality of flow rate control valves 19a, 19b, 19c, and 19d that form a bridge circuit. The control valve block 19 is provided with a bypass flow rate control valve 19e that controls the bypass flow rate that is discharged from the third pump 6 and then returned to the tank 16.

  The rotation direction and rotation speed of the left traveling motor 11 are controlled by a control valve 20 for left traveling control, and the rotation direction and rotation speed of the right traveling motor 12 are controlled by a control valve 21 for right traveling control. Brake brake valves 22 and 23 are provided between the left and right traveling motors 11 and 12 and the control valves 20 and 21, respectively.

  A bypass flow rate control valve 24 for controlling the bypass flow rate returned to the tank 16 is provided in the discharge passage of the first pump 3, and a similar bypass flow rate control valve 25 is provided in the discharge passage of the second pump 4, Further, the discharge flow rate of the first pump 3 and the discharge flow rate of the second pump 4 can be merged by connecting these passages between the discharge passage of the first pump 3 and the discharge passage of the second pump 4. A confluence flow control valve 26 is provided.

  The discharge passage of the third pump 6 is provided with a replenishing flow rate control valve 27 for controlling the flow rate of the pressure fluid supplied from the third pump 6 to the boom cylinder 8 and the arm cylinder 9. A tank flow rate control valve 28 is provided in the return passage from the control valve block 17 of the boom cylinder 8 to the suction side of the third pump 6 to release the return fluid from the boom cylinder circuit to the tank 16.

  A check valve 29 is provided in the discharge passage of the first pump 3, a check valve 30 is provided in the discharge passage of the second pump 4, and a third pump from the tank 16 is provided in the suction passage of the third pump 6. 6 is provided with a check valve 31 for replenishing the working fluid, and the passage from the third pump 6 through the replenishment flow rate control valve 27 is branched into two, and check passages 32, 33 are provided in each of the passages. A circuit for supplying pressure fluid to the boom cylinder 8 and the arm cylinder 9 is connected via the.

  That is, the discharge flow rate from the first pump 3 and the discharge flow rate from the third pump 6 from between the check valve 29 of the discharge passage from the first pump 3 and the check valve 32 of the discharge passage from the third pump 6. Are joined together, and are supplied to the boom cylinder 8 from between the check valve 30 for the discharge passage from the second pump 4 and the check valve 33 for the discharge passage from the third pump 6. A merging circuit for bringing the discharge flow rate from the second pump 4 and the discharge flow rate from the third pump 6 together and supplying them to the arm cylinder 9 is drawn out.

  As described above, the hybrid system of the work machine is connected to the engine 1 and the generator / motor 2 functioning as a power generator and a motor for power assisting the engine 1 and the generator / motor 2 is connected to charge and discharge. The electric storage device 14, the electric generator / motor 2 and the electric power from the electric storage device 14, and the electric motor / generator 7 for turning that regenerates the electric power generated from the electric power by converting the electric energy of the electric device B into electric power, and the engine 1 The fluid in the tank 16 driven by the electric motor 2 is supplied to at least a boom cylinder circuit 51 as a first actuator circuit for controlling the boom cylinder 8 and an arm cylinder circuit 52 as a second actuator circuit for controlling the arm cylinder 9, respectively. The first pump 3 and the second pump 4, and the electric motor and power generator connected to the power storage device 14 The pump motor / generator 5 that functions as a pump, and the fluid that is driven by the pump motor / generator 5 and supplies the fluid in the tank 16 to the bucket cylinder circuit 59 as a third actuator circuit that controls at least the bucket cylinder 10 And a third pump 6 having a pressure motor function.

  The boom cylinder circuit 51 is configured around the control valve block 17, the arm cylinder circuit 52 is configured around the control valve block 18, and the bucket cylinder circuit 59 is configured around the control valve block 19.

  A return fluid supply circuit 55 for supplying the return fluid from the boom cylinder circuit 51 to the suction port of the third pump 6, and a pressure for supplying pressure fluid to the boom cylinder circuit 51 and the arm cylinder circuit 52 from the discharge port of the third pump 6. A fluid replenishment circuit 56 is provided, and the discharge flow rate of the first pump 3 and the discharge flow rate of the second pump 4 are merged between the discharge passage of the first pump 3 and the discharge passage of the second pump 4. A possible merging flow control valve 26 is provided.

  Further, a working device E driven by a boom cylinder 8, an arm cylinder 9 and a bucket cylinder 10 is provided on a machine body B which can be driven by the left traveling motor 11 and the right traveling motor 12 and which can be rotated by the turning electric motor / generator 7. The discharge port of the first pump 3 is connected to a boom cylinder circuit 51 that controls the boom cylinder 8 and a left travel motor circuit 57 that controls the left travel motor 11, and the discharge port of the second pump 4 is connected to the arm cylinder 9. An arm cylinder circuit 52 for controlling and a right traveling motor circuit 58 for controlling the right traveling motor 12 are connected, and a discharge port of the third pump 6 is connected to a bucket cylinder circuit 59 for controlling the bucket cylinder 10.

  The return fluid supply circuit 55 is a circuit that supplies the return fluid from the boom cylinder circuit 51 to the suction port of the third pump 6. The return fluid from the boom cylinder circuit 51 is supplied to the suction port of the third pump 6 when the boom is lowered. A regeneration passage 55a for regeneration, and a tank flow rate control valve 28 for controlling the flow rate returned from the boom cylinder circuit 51 to the tank 16 provided in the tank passage 55b branched from the regeneration passage 55a and communicated with the tank 16. is doing.

  The pressure fluid supply circuit 56 includes a supply flow rate control valve 27 for controlling the flow rate of the pressure fluid supplied from the discharge port of the third pump 6 to the boom cylinder circuit 51 and the arm cylinder circuit 52, and check valves 32 and 33 for preventing backflow. And.

  The left travel motor circuit 57 is composed of the control valve 20 and the brake valve 22, the right travel motor circuit 58 is composed of the control valve 21 and the brake valve 23, and the bucket cylinder circuit 59 is supplied with pressure fluid from the third pump 6. The control valve block 19 that receives the supply is mainly configured.

  In addition, an operation electric signal input device (not shown) such as a traveling operation pedal and a work operation lever installed together with a driver's seat in the cab C, pressure detectors 6a and 6b in the circuit, and the like are input from these. Connected to an input section of a controller (not shown) for processing the processed signals, and the output section of this controller includes swash plate controllers 3c, 4c, 6c of the pumps 3, 4, 6 and various valves 17a. , 17b, 17c, 17d, 18a, 18b, 18c, 18d, 18e, 19a, 19b, 19c, 19d, 19e, 20, 21, 24, 25, 26, 27, 28 solenoids, etc. are connected to drive these And stop is controlled.

  Here, the drive of each pump 3, 4, 6 is to control the swash plate to the discharge flow rate output position, and the stop of each pump 3, 4, 6 is neutral that does not output the discharge flow rate to the swash plate. Is to control the position. Further, the driving of various valves is an energized state of the solenoid, and the stop of various valves is a non-energized state (spring return state) of the solenoid.

  Next, the operation of the embodiment shown in FIG. 1 will be described with reference to Table 1 below showing the relationship between the operation of the actuator and the operation of the pump and the valve. In Table 1, ◯ indicates driving, X indicates stop, and Δ indicates that driving is performed after ◯ driving.

(1) Boom raising When a boom raising operation is performed to rotate the boom bm upward by the operation lever, the swash plate of the first pump 3 is controlled by a controller (not shown), and at the same time, the bypass flow control valve 24 is closed. The flow control valves 17a and 17d and the tank flow control valve 28 of the control valve block 17 of the boom cylinder 8 are opened.

  When the lever operation amount for the boom is increased, the swash plate of the second pump 4 (marked in Table 1) rises, and at the same time, the bypass flow control valve 25 (marked in Table 1) closes, and the flow control valve for merging 26 (Δ mark in Table 1) is opened, and the pressure fluid is also supplied from the second pump 4 to the boom cylinder circuit.

  The pressure fluid discharged from the first pump 3 and the second pump 4 is supplied from the flow control valve 17a to the head chamber of the boom cylinder 8. On the other hand, the return fluid extruded from the rod chamber of the boom cylinder 8 is returned to the tank 16 from the flow rate control valve 17d via the tank flow rate control valve 28.

  As described above, when the lever of the boom cylinder 8 is operated, the first pump 3 and the second pump 4 are not started at the same time, but are started in order from the first pump 3 to the second pump 4 according to the lever operation amount. On the other hand, in the lever operation of the arm cylinder 9 to be described later, the second pump 4 and the first pump 3 are started in order according to the lever operation amount. By controlling in this way, the flow rate distribution of the pump is smoothed when the boom and arm are operated in conjunction.

(2) Boom lowering When the boom lowering operation is performed by rotating the boom bm downward by the operation lever, the swash plate of the first pump 3 is controlled by the controller (not shown) and at the same time the bypass flow control valve 24 is closed. The flow control valves 17b and 17c of the control valve block 17 of the boom cylinder 8 are opened. The pressure fluid discharged from the first pump 3 is supplied to the rod chamber of the boom cylinder 8 from the flow control valve 17b.

  On the other hand, since the tank flow rate control valve 28 is kept closed, the return fluid pushed out from the head chamber of the boom cylinder 8 is guided from the flow rate control valve 17c to the suction port of the third pump 6, and the third pump. Since 6 functions as a variable load of the boom cylinder 8, the swash plate of the third pump 6 is controlled to adjust the lowering speed of the boom cylinder 8.

  At this time, the third pump 6 generates electric power by driving the pump motor / generator 5 by a motor action, and the generated electric power is charged to the power storage device 14 from the controller 5c via the controller 14c.

(3) Arm raising / lowering When the arm raising / lowering operation is performed by rotating the arm am upward or downward by the operation lever, the swash plate of the second pump 4 is controlled by the controller (not shown). Pressure fluid is discharged from the pump 4, and at the same time, the bypass flow rate control valve 25 is closed, and pressure fluid is supplied to the control valve block 18 of the arm cylinder 9.

  In the case of the arm raising operation, the arm cylinder 9 is contracted so that the flow control valves 18b and 18c are opened. In the case of the arm lowering operation, the arm cylinder 9 is extended, so that the flow control valves 18a, 18d, 18e are opened. The flow control valve 18e is a regeneration valve and closes when a load is applied to the arm cylinder 9.

  When the lever operation amount for the arm increases, the swash plate of the first pump 3 (△ in Table 1) rises, and at the same time, the bypass flow control valve 24 (△ in Table 1) closes, and the merging flow control valve 26 (Δ mark in Table 1) is opened, and the pressure fluid is also supplied from the first pump 3 to the arm cylinder circuit.

(4) Bucket excavation / discharging When bucket excavation or excavation operation is performed by rotating the bucket bk in the excavation direction and the excavation direction by the operation lever, it is driven by the pump motor / generator 5 by the controller (not shown). The swash plate of the third pump 6 is controlled, and at the same time, the bypass flow rate control valve 19e is closed, and the pressure fluid whose direction and flow rate are controlled by the flow rate control valves 19a to 19d of the control valve block 19 is supplied to the bucket cylinder 10. Is done. In the case of bucket excavation operation, the flow control valves 19a and 19d are opened, and in the case of bucket earthing operation, the flow control valves 19b and 19c are opened.

(5) Right travel When a right travel operation is performed to drive the right crawler track of the lower traveling body with the operation pedal or lever, the swash plate of the second pump 4 is controlled by a controller (not shown), and at the same time, the bypass flow control valve At the same time as 25 is closed, the control valve 21 on the right side of the travel is controlled to supply pressure fluid to the right travel motor 12.

(6) Left travel When a left travel operation is performed to drive the left crawler track of the lower traveling body with the operation pedal or lever, the swash plate of the first pump 3 is controlled by a controller (not shown), and at the same time, the bypass flow control valve 24 is closed and the control valve 20 on the left side of the travel is controlled so that the pressure fluid is supplied to the left travel motor 11.

(7) Boom raising and arm interlocking operation When the boom raising and arm interlocking operation is performed by the operation lever, the swash plate of the first pump 3 is controlled by the controller (not shown), and at the same time, the bypass flow control valve 24 is The flow control valves 17a and 17d and the tank flow control valve 28 of the control valve block 17 of the boom cylinder 8 are opened.

  Further, the swash plate of the second pump 4 is controlled, and at the same time, the bypass flow rate control valve 25 is closed, and the pressure fluid is supplied to the control valve block 18 of the arm cylinder 9.

  If it is desired to increase the boom cylinder speed, the swash plate of the third pump 6 driven by the pump motor / generator 5 is controlled, and the bypass flow control valve 19e is closed and the replenishment flow control valve 27 is opened. The pressure fluid can be supplied from the third pump 6 to the control valve block 17 of the boom cylinder 8 via the replenishment flow rate control valve 27 and the check valve 32.

(8) Boom lowering and arm interlocking operation When the boom lowering and arm interlocking operation are performed by the operation lever, the swash plate of the first pump 3 is controlled by the controller (not shown), and at the same time the bypass flow control valve 24 is The flow control valves 17b and 17c of the control valve block 17 of the boom cylinder 8 are opened. The pressure fluid supplied from the first pump 3 is supplied from the flow control valve 17b to the rod chamber of the boom cylinder 8.

  On the other hand, since the tank flow control valve 28 is kept closed, the return fluid pushed out from the head chamber of the boom cylinder 8 is guided from the flow control valve 17c to the suction port of the third pump 6, and this third The pump 6 is driven as a fluid pressure motor. At this time, the speed of the boom cylinder 8 is adjusted by controlling the swash plate of the third pump 6 that functions as a variable load of the boom cylinder 8.

  The third pump 6 drives the pump motor / generator 5 by a motor action. The pump motor / generator 5 generates power, and the generated power is charged from the controller 5c to the power storage device 14 via the controller 14c.

  Further, the swash plate of the second pump 4 is controlled, and at the same time, the bypass flow rate control valve 25 is closed and the pressure fluid is supplied to the control valve block 18 of the arm cylinder 9. The operating speed is controlled.

  Further, the bypass flow rate control valve 19e is closed and the replenishment flow rate control valve 27 is opened to supply the pressure fluid that has passed through the third pump 6 acting as a motor from the replenishment flow rate control valve 27 to the control valve block 18 of the arm cylinder 9. Thus, the return fluid from the boom cylinder circuit can be used for driving the arm cylinder 9 to increase the working speed.

(9) Boom raising and bucket linkage operation When the boom raising and bucket linkage operation is performed by the operation lever, the swash plate of the first pump 3 is controlled by the controller (not shown), and at the same time, the bypass flow control valve 24 is The flow control valves 17a and 17d and the tank flow control valve 28 of the control valve block 17 of the boom cylinder 8 are opened.

  Further, the swash plate of the third pump 6 driven by the pump motor / generator 5 is controlled, and at the same time, the bypass flow rate control valve 19e of the control valve block 19 is closed, and the flow rate control valves 19a to 19d of the control valve block 19 are closed. Thus, the pressure fluid whose direction is controlled and whose flow rate is controlled is supplied to the bucket cylinder 10.

  When the lever operation amount for the boom is increased, the swash plate of the second pump 4 (marked in Table 1) rises, and at the same time, the bypass flow control valve 25 (marked in Table 1) closes, and the flow control valve for merging 26 (Δ mark in Table 1) is opened, and the pressure fluid is also supplied from the second pump 4 to the boom cylinder circuit.

(10) Boom lowering and bucket interlocking operation When the boom lowering and bucket interlocking operation is performed by the operation lever, the controller (not shown) controls the swash plate of the first pump 3 and the bypass flow control valve 24 is closed. At the same time, the flow control valves 17b and 17c of the control valve block 17 of the boom cylinder 8 are opened. The pressurized fluid supplied from the first pump 3 is supplied from the flow control valve 17b to the rod chamber of the boom cylinder 8. On the other hand, since the tank flow control valve 28 is kept closed, the return fluid pushed out from the head chamber of the boom cylinder 8 is guided from the flow control valve 17c to the suction port of the third pump 6.

  At the same time, the bypass flow control valve 19e of the third pump 6 is closed, and the pressure fluid discharged from the third pump 6 is subjected to direction control and flow control by the flow control valves 19a to 19d of the control valve block 19, so that the bucket cylinder 10 To be supplied.

  At this time, the swash plate of the third pump 6 is controlled at a larger flow rate by comparing the return flow rate from the boom cylinder 8 to the suction port of the third pump 6 and the required flow rate of the bucket cylinder 10.

  That is, when the required flow rate of the bucket cylinder 10 is large, the third pump 6 supplies the pressure fluid to the bucket control valve block 19 by a pump action. At this time, the lowering speed of the boom cylinder 8 is controlled by the flow rate control valve 17c.

  On the other hand, when the return flow rate from the boom cylinder 8 is large, the third pump 6 operates as a motor, drives the pump motor / generator 5 to generate electric power, and the generated electric power is transferred from the controller 5c to the controller 14c. The power storage device 14 is charged via At this time, the swash plate of the third pump 6 that functions as a variable load of the boom cylinder 8 is controlled to adjust the lowering speed of the boom cylinder 8, and the pressure fluid that has passed through the third pump 6 acting as a motor is used for the bucket. It is supplied to the control valve block 19.

  Whether the third pump 6 is pumped or motor-operated is determined from pressure detectors 6a and 6b that detect the differential pressure between the input and output of the third pump 6, or a means that detects the shaft torque of the third pump 6. Based on the detection signal, the controller determines and controls the controller 5c to switch the pump motor / generator 5 from the drive state to the power generation state.

(ll) Boom raising and arm / bucket linking operation When the boom is raised and the arm / bucket linking operation is performed by the operation lever, the swash plate of each pump 3, 4, 6 is controlled by the controller (not shown). The first pump 3 supplies pressure fluid to the control valve block 17 of the boom cylinder 8, the second pump 4 supplies pressure fluid to the control valve block 18 of the arm cylinder 9, and the third pump 6 supplies pressure fluid to the control valve block 19 of the bucket cylinder 10. Drive the actuator.

(12) Boom lowering and arm / bucket linking operation When the boom lowering and arm / bucket linking operation are performed by the operation lever, the swash plate of each pump 3, 4, 6 is controlled by the controller (not shown). The first pump 3 supplies pressure fluid to the control valve block 17 of the boom cylinder 8, the second pump 4 supplies pressure fluid to the control valve block 18 of the arm cylinder 9, and the third pump 6 controls the control valve of the bucket cylinder 10. Pressure fluid is supplied to the block 19 to drive each actuator.

  The swash plate of the third pump 6 is controlled with a larger flow rate by comparing the return flow rate from the boom cylinder 8 and the required flow rate of the bucket cylinder 10.

  That is, when the required flow rate of the bucket cylinder 10 is large, the third pump 6 has a pump action and supplies pressure fluid to the bucket control valve block 19. At this time, the lowering speed of the boom cylinder 8 is controlled by the flow rate control valve 17c.

  On the other hand, when the return flow rate from the boom cylinder 8 to the third pump 6 is large, the third pump 6 operates as a motor and drives the pump motor / generator 5 to generate electric power. The power storage device 14 is charged from 5c via the controller 14c. At this time, the lowering speed of the boom cylinder 8 is adjusted by the control of the swash plate of the third pump 6 functioning as a variable load of the boom cylinder 8, and the pressure fluid passing through the third pump 6 acting as a motor is controlled by the bucket cylinder 10. Supplied to the valve block 19.

  Whether the third pump 6 is pumped or motor-operated is determined from pressure detectors 6a and 6b that detect the differential pressure between the input and output of the third pump 6, or a means that detects the shaft torque of the third pump 6. Based on the detection signal, the controller determines and controls the controller 5c to switch the pump motor / generator 5 from the drive state to the power generation state.

(13) Interlocking operation of traveling, boom, arm, and bucket When the operating, boom, arm, and bucket are interlocked by operating pedal or lever, the swash plate of each pump 3, 4, 6 is operated by a controller (not shown). The first pump 3 supplies the pressure fluid to the boom cylinder 8 via the control valve block 17 and supplies the pressure fluid to the left travel motor 11 via the control valve 20 for left travel. Supplies the pressure fluid to the arm cylinder 9 via the control valve block 18 and supplies the pressure fluid to the right travel motor 12 via the control valve 21 for right travel.

  The third pump 6 supplies pressure fluid to the bucket cylinder 10 via the control valve block 19 and supplies pressure fluid from the replenishment flow rate control valve 27 to the boom cylinder 8 via the check valve 32 and the control valve block 17 for replenishment. By supplying pressure fluid from the flow control valve 27 to the arm cylinder 9 via the check valve 33 and the control valve block 18, the left and right traveling motors 11, 12, the boom cylinder 8, the arm cylinder 9, and the bucket cylinder 10 are linked. Realize operation.

  Next, the effect of the embodiment shown in FIG. 1 will be described.

  The return fluid supply circuit 55, the pressure fluid supply circuit 56, and the merging flow control valve 26, between the pumps of the first pump 3, the second pump 4, and the third pump 6, or the boom cylinder 8, the arm cylinder 9, and Since the surplus fluid energy generated between the actuators of the bucket cylinder 10 is mutually effectively used, a large-capacity electric motor or pump is not required compared to the hybrid system mounted on the conventional work machine, and each actuator Compared to the conventional system in which the electric motor and the driving force transmission device are individually installed, the number of electric motors and pumps is reduced, so that it can be easily installed in an actual machine and a low-cost system can be constructed.

  Further, when the actuators of the boom cylinder 8, the arm cylinder 9 and the bucket cylinder 10 are operated in conjunction with each other, the pumps of the first pump 3, the second pump 4 and the third pump 6 are assigned to these actuators. There is no load interference of fluid pressure between the actuators, energy loss can be reduced, and operability can be improved. Further, the braking energy of the turning electric motor / generator 7 can be regenerated and used for driving the third pump 6, and can also be used for driving the boom cylinder 8 and the arm cylinder 9 via the pressure fluid supply circuit 56.

  As with the conventional excavator, the interlocking operation of the left traveling motor 11, the right traveling motor 12, the boom cylinder 8, the arm cylinder 9, and the bucket cylinder 10 can be facilitated.

  With the return fluid supply circuit 55, the return fluid energy at the time of lowering the boom can be regenerated to the power storage device 14 by the pump motor / generator 5 via the third pump 6, and the braking energy of the turning motor / generator 7 can be stored. The regenerative energy can be efficiently used for driving the bucket cylinder 10, and can be efficiently used for driving the boom cylinder 8 and the arm cylinder 9 via the pressure fluid supply circuit 56. When the circuit 51 requires a sufficient flow rate, by opening the merging flow control valve 26, not only the first pump 3 but also the second pump 4 supplies sufficient pressure fluid to the boom cylinder circuit 51. Because the required speed of the boom cylinder 8 can be satisfied, the power generation of the same level as the power generation / motor and main pump mounted on the conventional hydraulic excavator A system can be configured with the electric motor 2 and the pumps 3, 4, 6.

  By controlling the regeneration flow rate in the regeneration passage 55a by the tank flow rate control valve 28 of the return fluid supply circuit 55, the return fluid energy at the time of lowering the boom is appropriately adjusted by the pump motor / generator 5 via the third pump 6. The regenerative energy can be used for driving the bucket cylinder 10 and the like.

  By controlling the flow rate of the replenishment flow rate control valve 27, the pressure fluid discharged from the third pump 6 is supplied to the boom cylinder circuit 51 and the arm cylinder while maintaining a balance with the pressure fluid flow rate supplied from the third pump 6 to the bucket cylinder 10. The circuit 52 can also be replenished and the boom cylinder 8 and the arm cylinder 9 can be operated at the required speed.

  In addition, this invention can be utilized also for working machines other than a hydraulic shovel, for example, a crushing specification machine, a dismantling specification machine, etc.

1 is a circuit diagram showing an embodiment of a hybrid system for a work machine according to the present invention. It is a side view of the working machine provided with the hybrid system same as the above.

Explanation of symbols

B Machine body E Working device 1 Engine 2 Generator / motor 3 First pump 4 Second pump 5 Pump motor / generator 6 Third pump 7 Turning electric motor / generator 8 Boom cylinder 9 as first actuator 9 As second actuator Arm cylinder
10 Bucket cylinder as third actuator
11 Left travel motor
12 Right travel motor
14 Power storage device
16 tanks
26 Flow control valve for merging
27 Supply flow control valve
28 Tank flow control valve
51 Boom cylinder circuit as the first actuator circuit
52 Arm cylinder circuit as second actuator circuit
55 Return fluid supply circuit
55a Regeneration passage
55b Tank passage
56 Pressure fluid supply circuit
57 Left travel motor circuit
58 Right travel motor circuit
59 Bucket cylinder circuit as third actuator circuit

Claims (4)

A generator / motor connected to the engine and functioning as a generator and motor;
A power storage device connected to a generator / motor to charge and discharge; and
A motor / generator for turning that regenerates the power by rotating the airframe with electric power from the generator / motor and the power storage device and converting the turning energy of the airframe into electric power;
A first pump and a second pump, which are driven by an engine and a generator / motor, respectively, to supply fluid in the tank to at least a first actuator circuit for controlling the first actuator and a second actuator circuit for controlling the second actuator;
A motor / generator for a pump connected to a power storage device and functioning as a motor and a generator;
A third pump having a fluid pressure motor function that is driven by a pump electric motor / generator and supplies a fluid in the tank to a third actuator circuit that controls at least the third actuator;
A return fluid supply circuit for supplying the return fluid from the first actuator circuit to the suction port of the third pump;
A pressure fluid supply circuit for supplying pressure fluid to the first actuator circuit and the second actuator circuit from the discharge port of the third pump;
And a merging flow control valve provided between the discharge passage of the first pump and the discharge passage of the second pump and capable of merging the discharge flow rate of the first pump and the discharge flow rate of the second pump. A hybrid system of working machines. A machine that can be driven by a left traveling motor and a right traveling motor and that can be swung by a turning electric motor / generator is provided with a working device driven by a boom cylinder, an arm cylinder, and a bucket cylinder,
The discharge port of the first pump is connected to a boom cylinder circuit that controls the boom cylinder and a left travel motor circuit that controls the left travel motor,
The discharge port of the second pump is connected to an arm cylinder circuit that controls the arm cylinder and a right traveling motor circuit that controls the right traveling motor,
The discharge system of the third pump is connected to a bucket cylinder circuit that controls the bucket cylinder. The return fluid supply circuit
A regeneration passage for regenerating the return fluid from the boom cylinder circuit to the suction port of the third pump when the boom is lowered;
3. A working machine according to claim 2, further comprising: a tank flow rate control valve that is provided in a tank passage that is branched from the regeneration passage and communicates with the tank, and that controls a flow rate returned to the tank from the boom cylinder circuit. Hybrid system. The pressure fluid supply circuit
4. The work machine hybrid system according to claim 2, further comprising a replenishment flow rate control valve for controlling a flow rate of the pressure fluid replenished from the discharge port of the third pump to the boom cylinder circuit and the arm cylinder circuit.

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