JP2011017431A - Electrohydraulic swing drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrohydraulic swing drive device capable of generating power on braking even if an operation lever is returned to neutral suddenly to decelerate as a normal operation, in swing drive devices for a construction machine with large inertia.SOLUTION: A hydraulic closed circuit is configured with a hydraulic pump and a hydraulic motor, the rotation speed of an electric motor for driving the hydraulic pump is variably controlled and the hydraulic pump is rotated in one direction, connection of the hydraulic pump and the hydraulic motor is switched by switching the direction of a discharge quantity of the hydraulic pump by a control valve. When a swing operation is braked by returning an operation means to neutral, a hydraulic fluid flowing out from the hydraulic motor is controlled by the control valve to be connected to an intake part of the hydraulic pump in accordance with an operation quantity of the operation means and a detection value of a rotation detection means of the hydraulic motor and power regeneration braking is performed by the electric motor.

Description

  The present invention relates to a turning drive device for a construction machine driven by electric hydraulic pressure.

  A hydraulic drive device using a hydraulic pump or a hydraulic motor is often used as a drive device for operating an inertial body having a large inertial mass, such as a turning operation of a hydraulic excavator. In recent years, an electric drive system that controls the operation of an inertial body with an electric motor with a small energy loss is being adopted instead of a hydraulic drive system that uses a hydraulic drive device with a large energy loss in order to throttle hydraulic energy with a control valve. . The electric drive system also has an advantage that power can be regenerated using the electric motor as a generator when the inertial body is decelerated.

  However, since the volume of the electric motor is much larger than the volume of the hydraulic motor, the adoption of the electric drive system has a problem that it is difficult to mount the electric excavator in a predetermined space. In particular, in a small excavator called a mini excavator, a turning hydraulic motor and a speed reducer are mounted under the floor plate of the driver's seat, and there is no room in the vertical direction. When adopting the electric drive system as described above, it is necessary to take measures such as breaking through the floor plate to install the electric motor or raising the floor plate to raise the driver's seat. In the former case, a protruding object is created near the driver's seat, obstructing the driving operation, and in the latter case, the driver's seat becomes higher and unstable, and in either case, the usability as a mini excavator is greatly reduced. To do.

  In order to solve such a problem, as shown in FIG. 7, the drive of the turning hydraulic pump is controlled at a variable speed by an electric motor to reduce loss, and the hydraulic motor and control valve are electrically operated in the same way as a conventional hydraulic drive device. There is a hydraulic drive.

  In addition, there is a means for configuring an electrohydraulic closed circuit using a hydraulic cylinder as an actuator and regenerating power with an electric motor when braking the load of the hydraulic cylinder (see, for example, Patent Document 1).

JP 2008-157407 A

  As shown in FIG. 7, in the case of an open circuit electrohydraulic drive device in which the drive of the swing hydraulic pump is controlled at a variable speed by an electric motor and the hydraulic motor and control valve are similar to the conventional hydraulic drive device, There is a merit that the motor can be stored under the floor plate, but there is a problem that power regeneration cannot be performed when braking the turning operation. In other words, by driving the hydraulic pump with an electric motor and supplying the hydraulic motor with a flow rate necessary for turning driving, it is possible to reduce a loss of relief of a wasteful flow rate from the brake valve at the time of turning acceleration. However, at the time of turning deceleration, the control valve is returned to the neutral position, the hydraulic oil from the hydraulic motor is shut off, and the braking torque is generated by the relief by the brake valve, so that the power cannot be regenerated.

  In the case of the means described in Patent Document 1, the operation of the hydraulic cylinder is controlled while performing the flow rate control (= cylinder speed control) by slowly returning the switching control valve by operating the operation lever (not shown). Therefore, power regenerative braking can be performed when the cylinder is driven by an external force. However, when the operating lever is suddenly operated to return to neutral, the switching control valve also suddenly returns to neutral and power regenerative braking cannot be performed. However, if such a sudden stop is performed, a very large impact is generated and the rear end of the construction machine is lifted. Therefore, such a driving operation is not usually performed.

  When the above means is applied to the turning of a construction machine by changing the actuator from a hydraulic cylinder to a hydraulic motor, the turning load is a load with a large inertia, so that the operation lever is returned to neutral to stop the turning operation and braking is performed. Then, the switching control valve returns to the neutral position, the brake valve operates, the hydraulic oil does not return to the hydraulic pump, and the problem that regenerative braking by the electric motor cannot be performed similarly occurs. Unlike the operation method of the boom cylinder, in the case of turning operation, the normal operation method is to operate the brake valve by returning the operation lever to neutral and perform turning braking with the hydraulic motor torque determined by the set pressure. It is.

  Accordingly, an object of the present invention is to provide an electro-hydraulic swivel capable of power regeneration during braking even when a normal driving operation in which a control lever is suddenly returned to neutral and decelerated is performed in a swing drive device for a construction machine having large inertia. It is to provide a driving device.

  (1) In order to solve the above-described problems, the electric hydraulic swing drive device of the present invention forms a hydraulic closed circuit with the hydraulic pump and the hydraulic motor, and variably controls the rotation speed of the electric motor that drives the hydraulic pump. Accordingly, the discharge amount of the hydraulic pump is variably controlled, the rotation direction of the hydraulic pump is set to one direction, and the discharge amount of the hydraulic pump is switched by the control valve to switch the connection between the hydraulic pump and the hydraulic motor. In a turning drive device for a construction machine provided with a rotation detection means for detecting the rotation state of the hydraulic motor, when the operation means is returned to neutral and the turning operation is braked, the operation amount of the operation means and the rotation detection means The hydraulic oil flowing out from the hydraulic motor according to the detected value is controlled to be connected to the suction portion of the hydraulic pump by the control valve. Employing the configuration, characterized by a power regenerative braking by the electric motor.

  (2) Further, the electric hydraulic swing drive device of the present invention flows out of the hydraulic motor according to the operation amount of the operation means and the detection value of the rotation detection means when the swing operation is stopped and held. A configuration was adopted in which hydraulic oil was shut off by the control valve.

  (1) In the electric hydraulic swing drive device of the present invention, a hydraulic closed circuit is constituted by the hydraulic pump and the hydraulic motor, and the discharge amount of the hydraulic pump is controlled by variably controlling the rotational speed of the electric motor that drives the hydraulic pump. Variable control is performed, the rotation direction of the hydraulic pump is set to one direction, and the discharge amount of the hydraulic pump is switched by a control valve to switch the connection between the hydraulic pump and the hydraulic motor, and the rotation state of the hydraulic motor is detected. In the turning drive device for a construction machine provided with the rotation detecting means, the hydraulic motor according to the operation amount of the operating means and the detected value of the rotation detecting means when the operating means is returned to neutral and the turning operation is braked. The hydraulic oil flowing out of the hydraulic pump is controlled to be connected to the suction part of the hydraulic pump by the control valve, and the power regeneration is performed by the electric motor. By operating, even during turning acceleration, the hydraulic pump is driven by an electric motor like the conventional device, the flow required for turning driving is supplied to the hydraulic motor, and the wasteful flow is relieved from the turning brake valve. Not only can it be reduced, but hydraulic oil flowing out of the hydraulic motor at the time of turning braking can be sucked in by the hydraulic pump and regeneratively braked by the electric motor to generate electric power, which has the effect of increasing the energy saving effect.

  (2) Further, the electric hydraulic swing drive device of the present invention flows out of the hydraulic motor according to the operation amount of the operation means and the detection value of the rotation detection means when the swing operation is stopped and held. By shutting off the hydraulic oil with the control valve, it becomes possible to stop and hold the turning operation with the control valve, and there is an effect that it is not necessary to rely on power regenerative braking of the hydraulic pump and the electric motor.

  For example, when excavating a hydraulic excavator, a turning torque is generated by a turning force component of the excavating force. The turning drive system is equipped with a mechanical parking brake to stop and hold the turning. However, the parking brake is released during excavation in order to prevent the parking brake from slipping and wearing due to the turning force component of the excavation force. In the case of the conventional open circuit hydraulic drive device, since the inflow / outflow port to the hydraulic motor is blocked by the control valve, the outflow of the hydraulic oil from the hydraulic motor is blocked and a braking torque is generated in the hydraulic motor. However, if a normal closed circuit drive device consisting of a hydraulic pump and a hydraulic motor is applied to the swing as it is, the port of the hydraulic pump and the port of the hydraulic motor are directly connected by a pipe line, so it is generated with the above swing torque. The pressure to be received is received by the hydraulic pump. Because it is a braking torque, power regeneration is possible, but the speed is very low and moves only a small amount, and the amount of power that can be regenerated is negligible. Due to the power regeneration, a regenerative current corresponding to the magnitude of the turning torque flows to the electric motor or inverter that drives the hydraulic pump, and heat is generated by the internal resistance to raise the temperature of the electric motor or inverter. Since the duty of use of the electric motor and the inverter is determined by the temperature, it is not preferable that the temperature of the device rises even though there is no regenerative power. When the hydraulic motor is stopped, the hydraulic oil flowing out from the hydraulic motor is shut off by the control valve, so that the turning operation is stopped and held by the control valve so that no pressure is applied to the hydraulic pump. As a result, it is possible to reduce the unnecessary power regeneration operation of the electric motor and the inverter without any effect.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a hydraulic excavator incorporating an electrohydraulic turning drive device according to the present invention. The hydraulic excavator includes a crawler type lower traveling body 20, an upper revolving body 30 as an inertial body that swings left and right on the lower traveling body 20, and an inertial body that is attached to the front portion of the revolving body 30. And the excavation attachment 40. The lower traveling body 20 travels by the left and right crawlers 23 being individually driven by the traveling hydraulic motor 21 and the speed reducer 22. The excavation attachment 40 includes a boom 41, an arm 42, and a bucket 43, and a boom cylinder 41a, an arm cylinder 42a, and a bucket cylinder 43a for operating them.

The revolving body 30 is equipped with a revolving electric motor 31, a hydraulic pump 32, a main electric pump 33, a power storage device 34 such as a battery and a capacitor, and a hydraulic motor 1 and a speed reducer 2 for revolving the revolving body 30. . In the final stage of the speed reduction mechanism, the output shaft pinion of the speed reducer 2 meshes with the internal gear of the swing bearing 36 to rotate the swing body 30. The oil discharged from the main electric pump 33 is supplied to the traveling hydraulic motor 21, the boom 41, the arm 42, and the cylinders 41a, 43a of the bucket 43 through control valves.

  FIG. 2 is a hydraulic circuit diagram showing an embodiment of the electrohydraulic turning drive device of the present invention. The swing motor 31 and the hydraulic pump 32 are connected by a drive shaft and rotate in one direction. The swing motor 31 is variable speed controlled by the inverter 13 shown in FIG. The hydraulic pump draws hydraulic oil from the hydraulic oil tank 9 and drives the hydraulic motor 1 via the control valve 5. When the control valve 5 is in the neutral position 5c, the inflow / outflow of hydraulic oil to the hydraulic motor 1 is blocked. When the pilot line a is pressurized, the control valve 5 is switched to the left position 5a, the oil discharged from the hydraulic pump 32 is guided to the A port of the hydraulic motor 1, and the hydraulic motor 1 rotates (turns to the right). . The hydraulic oil flowing out from the B port of the hydraulic motor 1 is guided to the suction port 32S of the hydraulic pump 32 through the control valve 5. When the pilot line b is pressurized, the control valve 5 is switched to the right position 5b, the oil discharged from the hydraulic pump 32 is guided to the B port of the hydraulic motor 1, and the hydraulic motor 1 rotates counterclockwise. The hydraulic oil flowing out from the A port of the hydraulic motor 1 is guided to the suction port 32S of the hydraulic pump 32 through the control valve 5. The pilot lines a and b are controlled by electromagnetic valves 6a and 6b. When the solenoid valve is neutral (non-excited), no pressure is applied. When the solenoid valve is energized, the solenoid valve is switched to pressurize the connected pilot ports. The brake valve 4 and the main relief valve 7 have the same structure as the open circuit turning drive device, but the relief valve function does not operate during normal acceleration / deceleration and is used for emergency. The check valve 8 is a load check valve. The check valves 10 and 11 are for sucking hydraulic oil from the hydraulic oil tank 9 when the suction port 32S or the discharge port 32D of the hydraulic pump 32 becomes negative pressure. The rotation detecting means 3 detects the rotation of the hydraulic motor, and is a normal rotation sensor such as a rotary encoder, a pulse counter, or a tachometer. The rotation direction and rotation speed are detected by calculation.

  FIG. 3 is a control block diagram of the electrohydraulic turning drive device of the present invention. At the time of driving, the power flows in order from the power storage device 34 to the inverter 13 → the swing motor 31 → the hydraulic pump 32 → the control valve 5 → the hydraulic motor 1 → the swing speed reducer 2 → the swing body 30. At the time of braking, power flows in the reverse direction to regenerate power, and the power storage device 34 is charged with electric power. The operation amount X of the operation means 51 and the detection value N of the rotation detection means 3 are input to the controller 12. The controller 12 calculates these signals, and outputs a control signal M to the inverter 13 that controls the swing motor 31, control signals Va and Vb to the solenoid valves 6a and 6b, and a release signal to a swing parking brake (not shown). . The control signal M may be a speed command value of the electric motor 31 (for example, Japanese Patent Laid-Open No. 2001-10783) or a torque command value of the electric motor 31 (for example, WO 2008/041395 A1). In any case, the control signal M and the control signals Va and Vb are calculated according to the operation amount X of the operation means 51 and the detection value N of the rotation detection means 3. The solenoid valves 6a and 6b are controlled to open and close by control signals Va and Vb.

  FIG. 4 shows the relationship between the operation amount X of the operation means 51, the control signal M to the inverter 13, and the control signals Va and Vb to the electromagnetic valves 6a and 6b. The operation amount X has a neutral range between −X2 and X2 across the zero point, and the control signal M is zero in this range. When the absolute value of X becomes larger than X2, the control signal M increases, and the control signal M changes according to the detected value N of the rotation detecting means 3 (not shown in FIG. 4). The control signal Va to the electromagnetic valve 6a is output when the manipulated variable X becomes X1 or more within the neutral range, and the electromagnetic valve 6a is switched. The control signal Vb to the electromagnetic valve 6b is output when the absolute value of the manipulated variable X becomes X1 or more within the neutral range, and the electromagnetic valve 6b is switched. As shown in FIG. 5, the electromagnetic valves 6a and 6b return to the neutral position when the manipulated variable X becomes a value in the range from -X1 to X1, and the detected value N of the rotation detecting means 3 is zero or a predetermined value near zero. This is the case where

  FIG. 5 is an example of a time history waveform showing the operation of the electro-hydraulic turning drive device of the present invention, and is a case where the operating means 51 is suddenly operated. With the horizontal axis as time t, the upper stage shows the operation amount X of the operating means 51, the middle stage shows the control signal Va to the electromagnetic valve 6a, and the lower stage shows the detected value N of the rotation detecting means 3 on the vertical axis. Only one direction of rotation is illustrated, and the same applies to the other directions.

  The operation of the electrohydraulic turning drive device of the present invention will be described with reference to FIGS. 2, 3, 4, and 5. The operation means 51 can be operated in both directions from the neutral position. When it is tilted to the left, it turns left (the hydraulic motor also rotates left), and when it tilts to the right, it turns right (the hydraulic motor also rotates right).

  Stop turning. The operation amount X of the operation means 51 is in the neutral range (−X2 <X <X2), the control signal M = 0, and the turning electric motor 31 is stopped. Further, the control signals Va and Vb are also zero in the range of -X1 <X <X1, the electromagnetic valves 6a and 6b are neutral, and the control valve 5 is in the neutral position 5c. The turning parking brake is also in an activated state, but the hydraulic motor 1 is stopped and held by the control valve 5 as in the prior art even when the turning parking brake is released after excavation work. Even if pressure is generated in the A port or B port of the hydraulic motor due to the turning force of the excavation reaction force, the pressure is not transmitted to the discharge port 32D or the suction port 32S of the hydraulic pump 32, and braking torque is generated in the swing motor 32. do not do. Therefore, since the swing motor 32 does not generate power regeneration, it is possible to prevent the swing motor 32 and the inverter 13 from performing unnecessary power regeneration operation without any effect. The brake valve 4 prevents excessive pressure from being generated in the hydraulic motor 1.

  Rotating acceleration. When the operation means 51 is suddenly operated to turn right (first quadrant in FIG. 4), when the operation amount X of the operation means 51 becomes X1 or more, the control signal Va is output from the controller 2 and the electromagnetic valve 6a is switched. Instead, the pilot pressure is established at the pilot port a of the control valve 5, and the control valve 5 is switched to the left position 5a. At the same time, the turning parking brake is released. When the manipulated variable X is equal to or greater than X2, a control signal M is output from the controller 12 to the inverter 13 and the electric motor 31 starts to accelerate. The hydraulic pump 32 is driven by the electric motor 31 and sucks hydraulic oil from the hydraulic oil tank 9 through the check valve 10 into the suction port 32S and discharges it from the discharge port 32D. The oil discharged from the hydraulic pump 32 flows into the A port of the hydraulic motor 1 through the control valve 5, drives the hydraulic motor 1, flows out of the B port of the hydraulic motor 1, and passes through the control valve 5 to the hydraulic pump. 32 flows into the suction port 32S. Since the drain of the hydraulic pump 32 returns from the drain line 32Dr and the drain of the hydraulic motor returns from the drain line 1Dr to the tank, the flow rate from the hydraulic motor 1 to the hydraulic pump 32 becomes smaller than the discharge flow rate. Through the tank.

  As shown in FIG. 5, when the operating means is suddenly operated, the operation amount X becomes the maximum value in a short time. The rotation speed of the electric motor 31, the hydraulic pump 32, and the hydraulic motor 1 and the detection value N of the rotation detection means 3 increase with time to reach the maximum speed.

  Swivel deceleration. As shown in FIG. 5, when the operating means 51 is suddenly operated to return to neutral, the operation amount X decreases from time t3 and becomes zero at time t4. As shown in FIG. 4, the control signal M decreases as the operation amount X decreases, the rotational speed of the swing motor 31 decreases, and the discharge amount of the hydraulic pump 32 gradually decreases. When the flow rate to the hydraulic motor 1 decreases, the hydraulic motor 1 is driven by the revolving body 30 to serve as a pump function, and the hydraulic pump 31 enters a braking state that serves as a motor function. The hydraulic pump 32 having the motor function drives the swing motor 31 having the generator function to generate electric power, and charges the power storage device 34 with the electric power. At time t5 when the detected value N of the rotation detecting means 3 becomes zero or a predetermined value near zero, the solenoid valve 6a is switched from excitation to non-excitation, and the control valve 5 returns from the left switching position 5a to the neutral position 5c. To stop and hold the turning operation.

  FIG. 6 is a hydraulic circuit diagram showing a second embodiment of the present invention. Back pressure is raised by the back pressure valve 14 in the pipeline where the discharge oil of the main electric pump 33 returns from the main hydraulic drive system 54 to the hydraulic oil tank 9, and the discharge port 32D or the suction port 32S of the hydraulic pump 32 does not become negative pressure. Thus, the flow rate is supplied through the check valves 15 and 16. Alternatively, as shown in Patent Document 1, since the hydraulic pump 32 rotates in one direction, a boost pump for preventing cavitation may be arranged coaxially with the hydraulic pump 32.

  In the above-described embodiment, the case where the operating means 51 is suddenly operated has been described. However, the present invention provides the same result even in the case of a loose operation.

  Furthermore, in the above-described embodiment, the control valve is switched on and off by the electromagnetic valve. However, the switching of the control valve can be transiently controlled using the electromagnetic proportional pressure reducing valve, and in that case, It is also possible to transiently control the connection / disconnection of the hydraulic pump and hydraulic motor circuit by the notch formed in the spool of the control valve.

  Furthermore, the present invention can be applied not only to a mini excavator but also to a large excavator.

The side view which shows the hydraulic excavator incorporating the electrohydraulic turning drive device concerning the present invention Hydraulic circuit diagram showing the configuration of the electrohydraulic turning drive device of the present invention The block diagram which shows the control system of the electrohydraulic turning drive device of this invention Static relationship diagram of control signal of electro-hydraulic turning drive device of the present invention Example of time history data indicating the operation of the electrohydraulic turning drive device of the present invention Hydraulic circuit diagram showing a second embodiment of the present invention Open circuit electrohydraulic swivel drive device according to the prior art

DESCRIPTION OF SYMBOLS 1 Hydraulic motor 2 Turning reduction gear 3 Rotation detection means 4 Brake valve 5 Control valve 6a, 6b Solenoid valve 7 Relief valve 8 Check valve 9 Hydraulic oil tank 10 Check valve 11 Check valve 12 Controller 13 Inverter 14 Back pressure valve 15 Check valve 16 Check Valve 21 Traveling hydraulic motor 22 Reducer 30 Swivel body 31 Swivel motor 32 Hydraulic pump 33 Main electric pump 34 Power storage device 36 Swivel bearing 40 Excavation attachment 41 Boom 41a Boom cylinder 42 Arm 42a Arm cylinder 43 Bucket 43a Bucket cylinder 51 Operation lever 52 Floor Plate 53 Driver's seat 54 Main hydraulic drive system

Claims (2)

  The hydraulic pump and the hydraulic motor constitute a hydraulic closed circuit, and the discharge amount of the hydraulic pump is variably controlled by variably controlling the rotation speed of the electric motor that drives the hydraulic pump, and the rotation direction of the hydraulic pump is one direction And a swing drive device for a construction machine provided with a rotation detecting means for switching the connection between the hydraulic pump and the hydraulic motor by switching the direction of the discharge amount of the hydraulic pump by a control valve, and detecting the rotation state of the hydraulic motor. In this case, when the operation means is returned to neutral and the turning operation is braked, hydraulic oil flowing out from the hydraulic motor in accordance with the operation amount of the operation means and the detected value of the rotation detection means is controlled by the control valve. An electric hydraulic swivel drive that is controlled so as to be connected to a suction portion of the motor and is powered regeneratively braked by the electric motor. Apparatus.   The hydraulic oil flowing out from the hydraulic motor is shut off by the control valve in accordance with an operation amount of the operation means and a detection value of the rotation detection means when the turning operation is stopped and held. The electrohydraulic turning drive device according to Item 1.

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