JP2014058825A - Construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a construction machine that can increase efficiency of a pressing operation when a load is large in the pressing operation, and has a little influence on lifes of an inverter and an electric motor at unnecessary time.SOLUTION: A hydraulic shovel as a construction machine includes a swivel electric motor 25 as an electric actuator for driving an upper swivel body 20 to swivel. A winding provided for the swivel electric motor 25 includes windings of at least two or more systems, and a controller 80 performs switching to one of the windings of the two or more systems according to a load placed on the electric motor 25. When it is determined that a load is large in a pressing operation, low-speed high-torque characteristics are obtained by switching the windings to improve pressing operability.

Description

  The present invention relates to a construction machine, and more particularly to a construction machine suitable for a machine that uses a three-phase AC electric motor for a swing actuator.

  For example, in a construction machine such as a hydraulic excavator, a fuel such as gasoline or light oil is used as a power source, and a hydraulic pump is driven by an engine to generate hydraulic pressure to drive a hydraulic actuator such as a hydraulic motor or a hydraulic cylinder. Hydraulic actuators are small and light and capable of high output, and are widely used as construction machine actuators.

  On the other hand, in recent years, by using an electric motor and an electricity storage device (battery, electric double layer capacitor, etc.), construction that has improved energy efficiency and saved energy compared to conventional construction machines that use only hydraulic circuits and hydraulic actuators. A machine has been proposed (see, for example, Patent Document 1). The electric actuator has a higher energy efficiency than the hydraulic actuator, and has excellent energy characteristics such that kinetic energy at the time of braking can be regenerated as electric energy (in the case of a hydraulic actuator, it is released as heat).

  For example, Patent Document 1 discloses a hybrid hydraulic excavator that uses an engine as a drive source and is equipped with an electric storage device and an electric motor as a drive actuator for a revolving structure. An actuator that swings and drives an upper swing body of a hydraulic excavator with respect to a lower traveling body (usually using a hydraulic motor) is frequently used, and frequently starts and stops and accelerates and decelerates during work. At this time, the kinetic energy of the swinging body during deceleration (during braking) is discarded as heat on the hydraulic circuit in the case of a hydraulic actuator, but regeneration is expected as electric energy in the case of an electric actuator. From the viewpoint, it is effective to use an electric motor.

  Thus, when an electric motor is used for driving the revolving structure, speed feedback control is normally used as a control method for the electric motor. In speed feedback control, a deviation between a speed target value corresponding to an operation amount by an operating means represented by a lever and an actual speed acquired by a sensor is obtained, and a torque command is calculated by PID control so that the deviation is reduced. Control is performed. When the operator makes a turn to a predetermined place, the turn can be performed without any problem at the speed targeted by the operator by speed feedback control.

  However, in some construction machine operations, speed feedback control alone can be inconvenient. For example, a so-called pressing operation in which the side of the bucket is pressed against the earth and the earth to turn to level the earth and sand or form a wall surface can be mentioned. In the pressing operation, even if the lever is input, the actual speed does not increase, so the deviation between the target value and the actual speed increases, and the maximum torque is output even with a slight lever input by the PID control, impairing the operability of the operator.

  In order to cope with such a problem, there is a logic to determine a pressing operation, and when it is determined to be a pressing operation, the operability is improved by switching the control method from speed feedback control to torque control. It is known (see, for example, Patent Document 2). Patent Document 2 also discloses that the operability is improved by applying a torque limit corresponding to the lever operation to the torque calculation unit without switching the control method as the speed feedback control.

Japanese Patent No. 3647319 Japanese Patent No. 3842948

  However, the method described in Patent Document 2 has the following problems. An electric motor used for driving a revolving structure of a construction machine generally has the following rotational speed torque characteristics. That is, in order to drive a revolving body having a large inertia, the torque in the low speed range is increased, and the torque is decreased so as to have a constant output characteristic (the product of torque and speed is constant) after a certain speed range. The reason why the torque is limited in the low speed region is to prevent the electric motor and the inverter from being damaged due to excessive current flowing. The limitation on the rotational speed is determined by the magnitude of the back electromotive force of the electric motor accompanying the increase in speed.

  Here, in patent document 2, the torque which can be output is not enlarged only by switching the characteristic control system. Therefore, when the load at the time of pressing is large, the torque that can be output even if the operator inputs the lever to the maximum is determined by the characteristics, so the work efficiency is not improved. In addition, if the pressed state is maintained, the electric motor continues to output the maximum torque in the stopped state. In this case, a large current flows through the inverter and the electric motor regardless of the control method. Furthermore, when the electric motor is stopped, it continues to output torque at the same speed, which means that current continues to flow in one phase of the three-phase line connecting the inverter and the electric motor. Yes, there is a concern about the heat generation and the effect on the lifetime. It is also effective to use an electric motor that can give high torque at low speed, giving priority to the pressing work, but the torque characteristics in the normal turning speed range deteriorate and reach the target speed during turning. No longer.

  An object of the present invention is to provide a construction machine that can increase the efficiency of the pressing work when the load is large at the time of the pressing work and has little influence on the life of the inverter and the electric motor when it is not necessary. It is in.

(1) In order to solve the above-described problem, the present invention is a construction machine having an actuator that drives a driven body by electric drive, and the winding provided in the electric actuator includes at least two systems of windings. And a winding switching unit that switches to one of the two or more windings according to a load applied to the electric actuator.
With this configuration, it is possible to increase the efficiency of the pressing operation when the load is large during the pressing operation, and it is possible to reduce the influence on the life of the inverter and the electric motor when it is not necessary.

  (2) In the above (1), preferably, of the two or more windings, the winding of the second system has a larger number of windings than the winding of the first system. When switched to the second system winding by the switching unit, the rotation speed-torque characteristics of the electric actuator when switched to the first winding are low-high torque characteristics. .

  (3) In the above (2), preferably, the electric actuator is a three-phase AC electric motor, and the windings constituting each of the three phases include a first winding and a second winding. And the first winding alone constitutes the winding of the first system, and the first winding and the second winding are connected in series, and the winding of the second system A line is formed.

  (4) In any one of the above (1) to (3), preferably, a push that presses a part of the swivel body against a work object as the load depending on a swivel pilot pressure and a magnitude of a rotation speed of the electric actuator. When it is determined that the contact work state, the winding of the electric actuator among the two systems of windings is switched to a system capable of outputting high torque according to the holding time of the state. .

  (5) In any one of the above (1) to (3), preferably, a part of the swiveling body is pressed against a work object as the load depending on the swiveling pilot pressure and the magnitude of the rotation speed of the electric actuator. When it is determined to be in the pressing work state, the winding of the electric actuator among the two systems of windings is switched to a system capable of outputting a high torque based on the time integral value of the turning pilot pressure. It is a thing.

  (6) In any one of the above (1) to (3), preferably, in addition to the electric actuator, a hydraulic actuator that rotates the revolving body by hydraulic driving is provided, and the electric actuator includes a magnetic pole position detection sensor. In the case of not having a pressing work state in which a part of the swiveling body is pressed against a work object according to the magnitude of hydraulic torque obtained from the difference in pressure between the turning pilot pressure and the inlet and outlet of the hydraulic actuator as a load. When the determination is made, the winding of the electric actuator among the two systems of windings is switched to a system capable of outputting high torque.

According to the present invention, it is possible to increase the efficiency of the pressing work when the load is large at the time of the pressing work, and to reduce the influence on the life of the inverter and the electric motor when it is not necessary.

1 is a system configuration diagram showing an overall configuration of a construction machine according to a first embodiment of the present invention. 1 is a system configuration diagram of main electric and hydraulic equipment of a construction machine according to a first embodiment of the present invention. 1 is an electric circuit diagram showing a configuration of an electric system for a construction machine according to a first embodiment of the present invention. It is a block diagram of the coil | winding of the electric motor used for the electric system of the construction machine by the 1st Embodiment of this invention. It is explanatory drawing of the rotational speed torque characteristic of the electric motor used for the electric system of the construction machine by the 1st Embodiment of this invention. It is a flowchart which shows the operation | movement content of the coil switching in the electric system of the construction machine by the 1st Embodiment of this invention. It is a timing chart which shows the operation | movement content at the time of the coil switching in the electric system of the construction machine by the 1st Embodiment of this invention. It is a flowchart which shows the operation | movement content of the coil switching in the electric system of the construction machine by the 1st Embodiment of this invention. It is a timing chart which shows the operation | movement content at the time of the coil switching in the electric system of the construction machine by the 1st Embodiment of this invention. It is a flowchart which shows the operation | movement content of the coil switching in the electric system of the construction machine by the 2nd Embodiment of this invention. It is a timing chart which shows the operation | movement content at the time of the coil switching in the electric system of the construction machine by the 2nd Embodiment of this invention. It is a timing chart which shows the operation | movement content at the time of the coil switching in the electric system of the construction machine by the 2nd Embodiment of this invention. It is a flowchart which shows the operation | movement content of winding switching in the electric system of the construction machine by the 3rd Embodiment of this invention. It is a block diagram of the other coil | winding of the electric motor used for the electric system of the construction machine by each embodiment of this invention. It is explanatory drawing of the other rotational speed torque characteristic of the electric motor used for the electric system of the construction machine by each embodiment of this invention. It is a system block diagram which shows the whole structure of the construction machine by other embodiment of this invention. It is a block diagram of the other coil | winding of the electric motor used for the electric system of the construction machine by each embodiment of this invention. It is explanatory drawing of the other rotational speed torque characteristic of the electric motor used for the electric system of the construction machine by each embodiment of this invention.

Hereinafter, the configuration and operation of the construction machine according to the first embodiment of the present invention will be described with reference to FIGS.
Initially, the whole structure of the construction machine by this embodiment is demonstrated using FIG. Here, a hydraulic excavator will be described as an example of the construction machine. Note that the present invention can be applied to all construction machines including a revolving structure, and the application of the present invention is not limited to a hydraulic excavator.

  FIG. 1 is a system configuration diagram showing the overall configuration of the construction machine according to the first embodiment of the present invention.

  In FIG. 1, a lower traveling body 10 includes a pair of crawlers 11 and a crawler frame 12 (only one side is shown in the figure), and a pair of traveling hydraulic motors that independently drive and control each crawler 11 (described later in FIG. 2). Hydraulic motors 13 and 14) and their swirling wheels 28 and the like.

  The upper swing body 20 includes a swing frame 21, an engine 22 as a prime mover provided on the swing frame 21, an assist power generation motor 23 driven by the engine 22, a swing electric motor 25, and an assist power generation motor 23. And an electric double layer capacitor 24 connected to the turning electric motor 25 and a speed reducer 26 that decelerates the rotation of the turning electric motor 25, and travels downward by the driving force of the turning electric motor 25 and the turning hydraulic motor 27. The upper revolving unit 20 (the revolving frame 21) is configured to rotate with respect to the body 10 by a revolving device 29 or the like. In FIG. 1, both the turning hydraulic motor 27 and the turning electric motor 25 are mounted. However, only the turning electric motor 25 may be installed.

  A front device 30 as a work machine is mounted on the front side of the upper swing body 20. The front device 30 includes a boom 31, a boom cylinder 32 for driving the boom 31, an arm 33 pivotally supported near the tip of the boom 31, and an arm cylinder 34 for driving the arm 33. The bucket 35 includes a bucket 35 rotatably supported at the tip of the arm 33, a bucket cylinder 36 for driving the bucket 35, and the like. Further, a hydraulic pressure for driving the hydraulic actuators such as the traveling hydraulic motor, the swing hydraulic motor 27, the boom cylinder 32, the arm cylinder 34, and the bucket cylinder 36 is generated on the swing frame 21 of the upper swing body 20. A hydraulic system 40 including a hydraulic pump (hydraulic pump 41 shown in FIG. 2) and a control valve (control valve 42 shown in FIG. 2) for driving and controlling each actuator is mounted. A hydraulic pump 41 serving as a hydraulic source is driven by the engine 22.

Next, the configuration of the main electric / hydraulic equipment of the construction machine according to the present embodiment will be described with reference to FIG.
FIG. 2 is a system configuration diagram of main electric and hydraulic equipment of the construction machine according to the first embodiment of the present invention. The same reference numerals as those in FIG. 1 indicate the same parts.

  The driving force of the engine 22 is transmitted to the hydraulic pump 41. The hydraulic pump 41 supplies hydraulic pressure to the control valve 42. The control valve 42 controls the discharge amount and discharge direction of the operating oil to the boom cylinder 32, the arm cylinder 34, the bucket cylinder 36, and the traveling hydraulic motors 13 and 14 according to a command from the turning operation lever 90. Further, the control valve 42 controls the discharge amount and discharge direction of the working oil to the turning hydraulic motor 27 in accordance with a command from the operation lever 90. The command of the turning operation lever 90 is converted into an electric signal by a hydraulic pressure-electric signal conversion device 77 (for example, a pressure sensor) and input to the controller 80.

  The electric control signal output by the controller 80 is converted into a hydraulic control signal by the electro-hydraulic signal conversion device 75 and supplied to the control valve 42.

  A pilot pressure signal cutoff valve 79 is provided between the turning operation lever 90 and the control valve 42. Normally, the shut-off valve 79 is open, and the control valve 42 is controlled according to the operation amount of the turning operation lever 90. When the lock lever 92 is operated so as to be locked, the shut-off valve 79 is closed and the turning operation lever 90 and the control valve 42 are shut off.

  When the assist generator motor 23 functions as a generator, the assist generator motor 23 is rotated by the engine 22 to generate power. When the assist generator motor 23 functions as an assist motor, the assist generator motor 23 is driven by electric power stored in an electric double layer capacitor described later to assist the engine. Is configured to do. In addition to the turning hydraulic motor 27, the turning electric motor 25 is provided as a motor for driving the upper turning body 20 to turn. The driving forces of the turning electric motor 25 and the turning hydraulic motor 27 are decelerated by the reduction gear 26 and transmitted to the upper turning body 20, and the upper turning body 20 (the turning frame 21 shown in FIG. 1) is shown in FIG. It turns with respect to the lower traveling body 10 shown.

  As the assist power generation motor 23 and the turning electric motor 25, a three-phase AC electric motor (three-phase synchronous motor) is used. The assist power generation motor 23 and the turning electric motor 25 are connected to the electric double layer capacitor 24 via the power control unit 55 and the main contactor 56. The power control unit 55 is controlled by the controller 80. The turning electric motor 25 includes a rotational speed detecting means 25A such as a resolver. When the rotational speed detection means 25A is a resolver, the resolver detects the magnetic pole position of the turning electric motor 25. The power control unit 55 calculates the rotation speed of the turning electric motor 25 based on the detected magnetic pole position. When the power control unit 55 controls the speed of the turning electric motor 25, the power control unit 55 controls the inverter 52 so that the rotation speed of the turning electric motor 25 becomes a speed command value from the controller 80. The rotational speed of the electric motor 25 for turning is controlled. The rotation speed value of the turning electric motor 25 calculated by the power control unit 55 is input to the controller 80.

  The power control unit 55 includes inverters 52 and 53, a smoothing capacitor 54, and a chopper 51. The main contactor 56 includes a main relay 57. Details of these will be described later with reference to FIG.

  Note that the ON / OFF switch 203 and the monitor 202 are used in other embodiments and will be described later.

Next, the configuration of the electric system for the construction machine according to the present embodiment will be described with reference to FIG.
FIG. 3 is an electric circuit diagram showing the configuration of the electric system for the construction machine according to the first embodiment of the present invention. The same reference numerals as those in FIG. 2 indicate the same parts.

  The inverter 53 includes a bridge circuit including six switching elements such as an IGBT. The voltage accumulated in the electric double layer capacitor 24 is boosted by the chopper 51 and input to the inverter 53. The inverter 53 receives a command from the controller 80, repeats ON / OFF of the current, fluctuates the pulse width, creates a three-phase alternating current, and drives the assist power generation motor 23. When the assist generator motor 23 is driven by the engine 22 and operates as a generator, the generated AC power is rectified by the inverter 53, stepped down by the chopper 51, and stored in the electric double layer capacitor 24. .

  The inverter 52 also includes a bridge circuit composed of six switching elements, and drives the electric motor 25 by supplying three-phase AC.

  The chopper 51 includes, for example, two switching elements and a reactor, and the inverters 53 and 52 can operate the voltage of the capacitor 24 by alternately opening and closing the two switching elements in response to a command from the controller 80. While boosting to the bus voltage, an operation of controlling the bus voltage to a predetermined constant value is performed. In order to stabilize the bus voltage, a smoothing capacitor 54 is provided on the bus voltage line.

  The circuit between the capacitor 24 and the chopper 51 is opened and closed by a relay 57 in the main contactor 56. The opening and closing of the relay 57 is performed by a command from the controller 80 shown in FIG. In a state where the vehicle body is stopped with the key OFF, the relay 57 is open. The main contactor 56 includes an inrush current prevention circuit 58 made of a resistor or the like for preventing an inrush current during the relay operation.

  Depending on the type of motor, a configuration of a switching element different from the inverter circuits 52 and 53 shown in FIG. 3 may be used, and FIG. 3 is merely an example.

Next, the configuration of the winding of the electric motor used in the electric system for the construction machine according to the present embodiment will be described with reference to FIGS.
FIG. 4 is a configuration diagram of windings of the electric motor used in the electric system for the construction machine according to the first embodiment of the present invention. FIG. 5 is an explanatory diagram of the rotational speed torque characteristics of the electric motor used in the electric system for the construction machine according to the first embodiment of the present invention.

  As shown in FIG. 4, the turning electric motor 25 includes stator windings 101 and 102 that are star-connected. In the present embodiment, the turning electric motor 25 has a winding switching function.

  The stator winding of each phase of the turning electric motor 25 includes a first winding 101 and a second winding 102. The first winding 101 and the second winding 102 are connected in series, and the relay 103 is connected in parallel to the second winding. A normally closed type (B contact) is used for the relay 103.

  When the winding switching signal 201 of the controller 80 shown in FIG. 3 is OFF, the relay 103 is in a conducting state, and a current flows only through the first winding 101.

  The rotational speed torque characteristic of the turning electric motor 25 in this state is a normal characteristic indicated by a symbol A in FIG. 5 and is used in normal turning work. In the normal torque torque characteristics, the torque in the low speed range is increased to drive a revolving body with large inertia, and the constant output characteristics (the product of torque and speed are constant) after a certain speed range. Reduce torque. The reason why the torque is limited in the low speed range is to prevent the electric current for turning 25 and the inverter from being damaged due to excessive current flowing. The speed limit is determined by the magnitude of the counter electromotive force of the turning electric motor 25 as the speed increases.

  On the other hand, when the winding switching signal 201 is ON, the relay 103 is in a non-conductive state, the first winding 101 and the second winding 102 are connected in series, and the number of windings increases. The rotational speed torque characteristic of the electric motor 25 is a low speed-high torque characteristic indicated by symbol B in FIG. In the low speed-high torque characteristic, the torque at the low speed is higher than that in the normal characteristic indicated by the symbol A. On the other hand, the number of rotations on the high rotation side is kept low.

  If the relay 103 is a normally closed type, when the line of the winding switching signal 201 is disconnected, the normal rotational speed torque characteristic is obtained, so that the vehicle body can be turned normally.

Next, the operation of switching the winding in the electric system for the construction machine according to the present embodiment will be described with reference to FIGS.
FIGS. 6 and 8 are flowcharts showing the operation content of the winding switching in the electric system for the construction machine according to the first embodiment of the present invention. 7 and 9 are timing charts showing the operation content at the time of winding switching in the electric system for the construction machine according to the first embodiment of the present invention.

  6 and 7 show the content of the winding switching process at the start of the pressing operation.

  In FIG. 6, the controller 80 initializes a variable Timer for determining the pushing time (step S101), and the turning pilot pressure P and the turning pilot pressure generated when the operator inputs the turning lever for each control cycle dt. Are compared, and the actual speed N of the swing electric motor is compared with the determination value Nmin of the speed close to 0 (step S102, step S103, step S104).

  When the turning pilot pressure P is equal to or higher than the turning pilot pressure determination value Pmin and the actual speed N is equal to or lower than the determination value Nmin of the speed close to 0, the process proceeds to step S105, and the timer value Timer is counted up. In step S106, the counted pressing time determination variable Timer is compared with the pressing determination time Tc. If the pressing time determination variable Timer is equal to or less than the pressing determination time Tc, the process proceeds from step S106 to step S106. Return to S102. Here, the pressing determination time Tc is, for example, 1 or 2 seconds.

  The state in which the turning pilot pressure P is equal to or higher than the turning pilot pressure determination value Pmin and the actual speed N is equal to or lower than the speed determination value Nmin is continued, and in step S106, the pressing time determination variable Timer is pressed. When the time Tc is exceeded, it is determined that the state is pressed and the load is large, and the winding switching signal is turned ON to automatically switch to the low speed-high torque characteristic (step S107).

  If the turning pilot pressure P is less than or equal to the turning pilot pressure determination value Pmin in step S103, or if the actual speed N is less than or equal to the speed determination value Nmin in step S104, the pressing timer variable Timer is reset in step S110. Then, the process returns to step S102.

FIG. 7 shows the actual speed N of the turning electric motor and the torque T output from the electric motor when the operator operates the lever to perform the pressing operation.
In FIG. 7, the horizontal axis represents time. The vertical axis in FIG. 7A indicates the turning pilot pressure P, the vertical axis in FIG. 7B indicates the electric motor actual speed N, and the vertical axis in FIG. 7C indicates the electric motor torque T. .

  At time t0, when the lever is operated to perform the pressing operation and the side surface of the bucket is pressed against the object, if the load is large, the turning body stops despite the lever being input. doing. Therefore, the actual speed N of the turning electric motor does not increase. At this time, the torque output from the electric motor for turning reaches the maximum torque T1 that can be output with normal torque characteristics.

  When the turning pilot pressure P becomes equal to or higher than the set pilot pressure value Pmin at time t1, measurement of the pressing determination time Tc is started. If this state continues for the pressing determination time Tc or longer, at time t2, the mode is switched to the low speed-high torque characteristic, and the electric motor torque can be output up to the torque T2 larger than the torque T1, so that the pressing workability is increased. Is improved.

  Thus, by providing the pressing determination time, it can be determined that a large load is applied during the work, and frequent switching of the windings can be prevented. When switching to the low speed and high torque characteristics, in order to inform the operator of the fact, it may be configured to display on the monitor that the characteristics have been switched or to make a sound like a buzzer.

  8 and 9 show the content of the winding switching process after the pressing operation is completed.

  FIG. 8 shows a flowchart in the case where the controller 80 returns the winding from the low speed-high torque characteristic to the normal characteristic after the pressing operation is completed.

  After initializing the variable Timer for determining the end of the pressing operation in step S121, it is determined whether or not the lock lever 92 is first released every control cycle dt (step S122, step S123). The lock lever 92 being in the locked state means that the hydraulic signal is cut off and the operator cannot perform work. Therefore, the state of the lock lever is first determined, and in the locked state, the winding is switched to the normal characteristic.

  When the lock lever is in the released state, the turning pilot pressure P and the turning pilot pressure determination value Pmin are compared, and the actual speed N of the turning electric motor is compared with the determination value Nmin of a speed close to 0 (step S124). 125).

  If the turning pilot pressure P is less than or equal to the turning pilot pressure determination value Pmin and the actual speed N is less than or equal to the speed Nmin, it is considered that the pressing operation has been completed, the process proceeds to step S126, and the pressing operation is performed. An end determination variable Timer is counted up. If not, the variable Timer for determining work completion is reset in step S130.

  In step S127, the counting operation end determination variable Timer is compared with the pressing operation end determination time Tf. The state where the turning pilot pressure P is less than or equal to the turning pilot pressure determination value Pmin and the actual speed N is less than or equal to the determination value Nmin of the speed is continued. In step S127, the pressing timer variable Timer is pressed. If the work end determination time Tf is exceeded, it is determined that the pressing operation has ended, and the winding switching signal is turned OFF to automatically switch to the normal characteristics (step S128).

  FIG. 9 shows the actual speed N of the turning electric motor and the torque T output from the turning electric motor when the pressing operation is completed.

  In FIG. 9, the horizontal axis represents time. The vertical axis in FIG. 9A represents the turning pilot pressure P, the vertical axis in FIG. 9B represents the actual electric speed N for turning electric motor, and the vertical axis in FIG. 9C represents the turning electric motor torque T. Is shown.

  When the lever operation is stopped, under the control of the controller 80, at time t10, as shown in FIG. 9C, the turning electric motor outputs a braking torque. Thereby, as shown in FIG. 9B, the speed of the electric motor for turning decreases.

  At time t11, as shown in FIG. 9B, the actual speed N becomes equal to or less than the speed determination value Nmin that is close to 0, and the pressing operation end determination variable Timer is equal to or longer than the pressing work end determination time Tf. If it is determined that the pressing operation has been completed, the winding switching signal is turned off at time t12 to automatically switch to the normal characteristics. The switching to the normal characteristic is performed after the speed at which the electric motor for turning is considered to be almost stopped.

  As described with reference to FIG. 6, in the present embodiment, when the swing pilot pressure P is equal to or higher than the swing pilot pressure determination value Pmin and the actual speed N is close to 0, which is equal to or lower than the speed determination value Nmin, Since it is determined that the load is large and the load is large, the winding switching signal is turned ON to automatically switch to the low speed-high torque characteristic.

  Here, the turning pilot pressure P is a command value of a load applied to the turning electric motor (electric actuator). The actual speed N of the turning electric motor is a measured value of a load applied to the turning electric motor (electric actuator). Therefore, in the present embodiment, the low speed-high torque characteristic is switched according to the load applied to the turning electric motor (electric actuator).

  In addition, as described with reference to FIG. 4, in the present embodiment, the winding 101 and the winding 102 are provided as windings for each phase of the three-phase synchronous electric motor. When obtaining the normal characteristics, the first system winding composed of the winding 101 is used. In order to obtain a low speed-high torque characteristic, a second system winding composed of a winding 101 and a winding 102 connected in series is used.

  As described above, in this embodiment, the controller 80 switches to one of the two windings according to the load applied to the electric actuator.

  As described above, according to the present embodiment, according to the load applied to the electric actuator, the characteristic of the electric actuator can be changed to the low speed-high torque characteristic by switching to one of the two windings. If the load is large during the pressing operation, the efficiency of the pressing operation can be increased by switching to the low speed-high torque characteristic. In addition, since it is not switched to the low speed-high torque characteristic when it is not necessary, it has little influence on the life of the inverter and the electric motor for turning.

  Next, the configuration and operation of the construction machine according to the second embodiment of the present invention will be described with reference to FIGS. The overall configuration of the construction machine according to the present embodiment is the same as that shown in FIG. The configuration of the main electric / hydraulic equipment of the construction machine according to the present embodiment is the same as that shown in FIG. Further, the construction of the electric system for the construction machine according to the present embodiment is the same as that shown in FIG. Further, the configuration of the winding of the electric motor for turning used in the electric system of the construction machine according to the present embodiment is the same as that shown in FIG. Furthermore, the rotational speed torque characteristics of the electric motor for turning used in the electric system for the construction machine according to the present embodiment are the same as those shown in FIG.

  FIG. 10 is a flowchart showing the operation content of the winding switching in the electric system for construction machines according to the second embodiment of the present invention. 11 and 12 are timing charts showing the operation contents at the time of winding switching in the electric system for the construction machine according to the second embodiment of the present invention.

  This embodiment is different from the first embodiment shown in FIGS. 6 and 7 as follows. In the present embodiment, the switching to the low speed-high torque characteristic is determined not by the pressing time Tc but by the time integral value of the turning pilot pressure.

  The details will be described with reference to the flowchart shown in FIG. Note that the same step numbers as in FIG. 6 indicate the same processing contents. In this embodiment, steps 205, S206, and S210 are different from FIG.

  In steps S103 to S104 in FIG. 10, when the turning pilot pressure P is not less than the turning pilot pressure determination value Pmin and the actual speed N is not more than the speed determination value Nmin that is close to 0, the turning pilot pressure P is set in step S205. An integral value A is obtained. In step S206, the integral value A is compared with the pushing determination integrated value Ac. If the integral value A of the turning pilot pressure P is equal to or less than the pushing determination integral value Ac, the process returns from step S206 to step S102.

  When the turning pilot pressure P is greater than or equal to the turning pilot pressure determination value Pmin and the actual speed N is less than or equal to the speed determination value Nmin, and in step S206, A becomes the pushing determination integrated value Ac or more. Is determined to be in the pressed state and the load is large, and the winding switching signal is turned ON to automatically switch to the low speed-high torque characteristic (step S107).

  If the turning pilot pressure P is less than or equal to the turning pilot pressure determination value Pmin in step S103, or if the actual speed N is less than the speed determination value Nmin in step S104, the integral value A of the turning pilot pressure P is reset in step S210. Return to step S102.

  FIG. 11 shows the actual speed N of the turning electric motor and the torque T output from the turning electric motor when the operator operates the lever to perform the pressing operation.

  In FIG. 11, the horizontal axis represents time. The vertical axis in FIG. 11A indicates the turning pilot pressure P, the vertical axis in FIG. 11B indicates the actual speed N of the electric motor for turning, and the vertical axis in FIG. 11C indicates the electric motor torque T for turning. Is shown.

  At time t0, when the lever is operated to perform the pressing operation and the side surface of the bucket is pressed against the object, if the load is large, the turning body stops despite the lever being input. doing. Therefore, the actual speed N of the turning electric motor does not increase. At this time, the torque output from the electric motor for turning reaches the maximum torque T1 that can be output with normal torque characteristics.

  When the turning pilot pressure P becomes equal to or higher than the set pilot pressure value Pmin at time t1, integration of the integral value A is started. Then, when the integral value A becomes the pushing determination integral value Ac, at time t2, the operation is switched to the low speed-high torque characteristic, and the electric motor torque can be output up to the torque T2 larger than the torque T1. Improved.

  Next, the advantages of this embodiment will be described using FIG. 12 in comparison with the first embodiment. FIG. 12 shows a comparison of the timing for switching the winding between the first embodiment and the second embodiment with respect to temporal changes in the two patterns of the turning pilot pressures P1 and P2. In FIG. 12, it is assumed that the actual speed N is Nmin or less.

  As shown in FIG. 12 (A), in the first embodiment, if the turning pilot pressure is equal to or higher than Pmin, regardless of how the lever is inserted after the determination of the holding time is started (however the lever shown by P1 is inserted). In this case, the switching timing is also the same).

  On the other hand, as shown in FIG. 12B, in this embodiment, the lever is inserted after the calculation of the integral value A (in the case of the lever shown by the reference P1 and the lever shown by the reference P2). The timing until switching will vary depending on the case of inserting and). In the case of the insertion indicated by the symbol P1, the switching timing is time tx1, and in the case of the insertion indicated by the symbol P2, the switching timing is time tx2.

  When maintaining the weakened state after inputting the lever to the maximum, it is considered that a large torque is not required for the pushing operation as the operation of the hydraulic excavator intended by the operator. There is no need to switch. As described above, in the present embodiment, the winding can be switched in consideration of the operation of the hydraulic excavator intended by the operator accompanying the lever operation.

  As described above, according to the present embodiment, according to the load applied to the electric actuator, the characteristic of the electric actuator can be changed to the low speed-high torque characteristic by switching to one of the two windings. If the load is large during the pressing operation, the efficiency of the pressing operation can be increased by switching to the low speed-high torque characteristic. In addition, since it is not switched to the low speed-high torque characteristic when it is not necessary, the influence on the life of the inverter and the electric motor is small.

  Next, the configuration and operation of the construction machine according to the third embodiment of the present invention will be described with reference to FIG. The overall configuration of the construction machine according to the present embodiment is the same as that shown in FIG. The configuration of the main electric / hydraulic equipment of the construction machine according to the present embodiment is the same as that shown in FIG. Further, the construction of the electric system for the construction machine according to the present embodiment is the same as that shown in FIG. Further, the configuration of the winding of the electric motor for turning used in the electric system of the construction machine according to the present embodiment is the same as that shown in FIG. Furthermore, the rotational speed torque characteristics of the electric motor for turning used in the electric system for the construction machine according to the present embodiment are the same as those shown in FIG.

  FIG. 13: is a flowchart which shows the operation | movement content of the coil switching in the electric system of the construction machine by the 3rd Embodiment of this invention.

  This embodiment is a winding switching method in the case where there is no sensor capable of detecting the speed in the electric motor for turning. Generally, a magnetic pole position detection sensor such as a resolver or an encoder is used for an electric motor. These sensors are used not only to detect the magnetic poles but also to detect the speed of the electric motor. By detecting the magnetic pole position of the rotor with respect to the stator by these sensors when starting the electric motor for turning, the electric motor can be controlled even from a stopped state. However, attaching these sensors has the effect of increasing the size and cost of the electric motor. Although it is possible to introduce sensorless control that drives an electric motor without a magnetic pole position sensor, which is common in applications that maintain the rotation of air conditioners, etc., how to use an electric motor when starting from a stopped state when using sensorless control It is necessary to examine whether to detect the magnetic pole and the position of the magnetic field. Such a problem to be solved can be solved by the following method in the structure in which the turning is performed by the driving force of the turning electric motor 25 and the turning hydraulic motor 27 as shown in FIG. When turning starts, torque is generated only by the hydraulic motor. When the speed of the electric motor increases to a value at which the magnetic pole position can be detected, sensorless control of the electric motor is performed, and finally the total torque of the hydraulic motor and electric motor To drive the swivel.

  FIG. 13 shows a flowchart when the winding is switched at the time of pressing determination in the construction machine having the above configuration. In this embodiment, instead of the speed of the electric motor for rotation, the torque T0 of the hydraulic motor that can be calculated from the inlet pressure Pa, the outlet pressure Pb, and the displacement volume q of the hydraulic motor is used for the determination.

  Details thereof will be described with reference to a flowchart shown in FIG. Note that the same step numbers as in FIG. 6 indicate the same processing contents. In this embodiment, steps S304 and S305 are different from FIG.

  As in the first embodiment, first, the turning pilot pressure P and the turning pilot pressure determination value Pmin are compared (S103). The control valve is controlled by the turning pilot pressure, and oil is guided from the hydraulic pump to the hydraulic motor.

  Next, the controller 80 proceeds to step S304, and determines whether or not the electric monitor can detect the magnetic pole position. If the turning electric motor can be driven to a speed at which the magnetic pole position can be detected by the hydraulic motor, sensorless control of the turning electric motor becomes possible, and the turning electric motor can be output with the normal characteristics of the hydraulic motor torque. Torque can be applied.

  In step S305, the torque T0 of the hydraulic motor obtained by calculation is compared with the torque determination value Tmin close to the maximum torque that can be output by the hydraulic motor. The torque T0 of the pressure motor can be calculated as “(Pa−Pb) q / 2π”. Here, the inlet pressure Pa, the outlet pressure Pb, and the displacement volume q of the hydraulic motor. In a normal turning operation, a large torque is required at the time of starting, and a large torque is not required after the turning body starts moving. On the other hand, when the load is large during the pressing operation, the hydraulic motor continues to produce a torque close to the maximum while the turning operation lever is operated.

  The conditions of YES in Steps S303 to S305 are all satisfied during the pressing operation of the load that can drive the turning body at a speed at which the magnetic pole position of the turning electric motor can be detected, and the turning electric motor has normal characteristics. This is when the torque is insufficient even if the torque that can be output is output.

  Note that, in a situation where the load is too large and the turning body is stopped, the sensorless control of the turning electric motor cannot be performed, and therefore the winding cannot be switched in this embodiment.

  After the YES condition is established in step S305, the process proceeds to step S306, and the timer is counted up as in the first embodiment. When the timer is equal to or longer than the pressing determination time Tc, the winding switching signal is turned on. Switch to low speed-high torque characteristics. Finally, the swinging body can apply the torque of the swinging electric motor that can be output with the low speed-high torque characteristic to the torque output by the hydraulic motor, so that the pressing workability is improved.

  As described with reference to FIG. 6, in this embodiment, when the turning pilot pressure P is equal to or higher than the turning pilot pressure determination value Pmin and the torque T0 of the hydraulic motor is continuously higher than the torque determination value Tmin, the pushing is continued. It is determined that the load is large and the winding switching signal is turned on to automatically switch to the low speed-high torque characteristic.

  Here, the turning pilot pressure P is a command value of a load applied to the turning electric motor (electric actuator). The torque T0 of the hydraulic motor is a measured value of a load applied to the turning electric motor (electric actuator). Therefore, in the present embodiment, the low speed-high torque characteristic is switched according to the load applied to the turning electric motor (electric actuator).

  In addition, as described with reference to FIG. 4, in the present embodiment, the winding 101 and the winding 102 are provided as windings for each phase of the three-phase synchronous electric motor. When obtaining the normal characteristics, the first system winding composed of the winding 101 is used. In order to obtain a low speed-high torque characteristic, a second system winding composed of a winding 101 and a winding 102 connected in series is used.

  As described above, in this embodiment, the controller 80 switches to one of the two windings according to the load applied to the electric actuator.

  As described above, according to the present embodiment, according to the load applied to the electric actuator, the characteristic of the electric actuator can be changed to the low speed-high torque characteristic by switching to one of the two windings. If the load is large during the pressing operation, the efficiency of the pressing operation can be increased by switching to the low speed-high torque characteristic. In addition, since it is not switched to the low speed-high torque characteristic when it is not necessary, the influence on the life of the inverter and the electric motor is small.

  In the description of the embodiments so far, the pressing state is automatically determined. However, in addition to this, it is determined that the low-speed high torque is required in the following cases. Can do. That is, for example, if the excavator is located on the slope and the arm and boom are extended, and the bucket is swung up the slope, the rotation speed of the turning motor is low, while a large torque is generated. Necessary. Even in such a case, the present embodiment can automatically determine the state and switch to the low speed-high torque characteristic.

Next, the configuration of another winding of the electric motor for turning used in the electric system for the construction machine according to each embodiment of the present invention will be described with reference to FIGS. 14 and 15.
FIG. 14 is a configuration diagram of another winding of the electric motor for turning used in the electric system of the construction machine according to each embodiment of the present invention. FIG. 15 is an explanatory diagram of another rotational speed torque characteristic of the electric motor for turning used in the electric system of the construction machine according to each embodiment of the present invention.

  As shown in FIG. 4, the windings of the electric motor 25 for turning which is a three-phase synchronous motor are star-connected. FIG. 14 shows a winding for one of the three phases. Stator windings 101, 102, and 104 are provided as windings for one phase. In the present embodiment, the turning electric motor 25 has a winding switching function.

  The stator winding of each phase of the turning electric motor 25 includes a first winding 101, a second winding 102, and a third winding 104. The first winding 101, the second winding 102, and the third winding 104 are connected in series, and the relay 103 is connected in parallel to the second winding 102, and the third winding 104 is connected to the third winding 104. The relay 105 is connected in parallel. For the relays 103 and 105, a normally closed type (B contact) is used.

  When the winding switching signals 201 and 201A of the controller 80 shown in FIG. 3 are OFF, the relays 103 and 105 are in a conducting state, and a current flows only through the first winding 101.

  The rotational speed torque characteristic of the electric motor for turning in this state is a normal characteristic indicated by a symbol A in FIG. 15 and is used in normal turning work. In the normal torque torque characteristics, the torque in the low speed range is increased to drive a revolving body with large inertia, and the constant output characteristics (the product of torque and speed are constant) after a certain speed range. Reduce torque. The reason why the torque is limited in the low speed range is to prevent damage to the turning electric motor and the inverter due to excessive current flowing. The rotational speed limit is determined by the magnitude of the counter electromotive force of the turning electric motor as the speed increases.

  On the other hand, when the winding switching signal 201 is ON, the relay 103 is in a non-conductive state, the first winding 101 and the second winding 102 are connected in series, and the number of windings increases. The rotational speed torque characteristic of the electric motor for electric power is a low speed-high torque characteristic indicated by a symbol B in FIG. In the low speed-high torque characteristic, the torque at the low speed is higher than that in the normal characteristic indicated by the symbol A. On the other hand, the number of rotations on the high rotation side is kept low.

  Further, when both the winding switching signal 201 and the winding switching signal 201A are ON, the relays 103 and 105 are both in a non-conducting state, and the first winding 101, the second winding 102, and the third winding 104 are connected. Are connected in series and the number of windings is increased, so that the rotational speed torque characteristic of the electric motor for turning is a low speed-high torque characteristic indicated by C in FIG. In the low-speed-high torque characteristic indicated by the symbol C, the torque at the low speed is higher than the low-speed-high torque characteristic indicated by the reference symbol B. On the other hand, the number of rotations on the high rotation side is kept low.

  In each of the embodiments so far, the winding is automatically switched by the operator's operation of the turning lever. However, as shown in FIG. 2, it is also possible to provide a switch 203 for manually turning on / off the winding switching signal 201 so that the characteristics can be switched at any time of the operator. As an operator, the switch 203 can be switched when the low speed and high torque is desired based on his / her determination, rather than automatically determining the state where the low speed and high torque is desired.

  At this time, when switching to the low speed-high torque characteristic, the operator may be notified visually by the monitor 202 or aurally with a sound such as a buzzer.

  Next, the configuration and operation of a construction machine according to another embodiment of the present invention will be described with reference to FIG. Here, a wheel loader will be described as an example of the construction machine. The configuration of the main electric / hydraulic equipment of the construction machine according to this embodiment is the same as that shown in FIG. Further, the construction of the electric system for the construction machine according to the present embodiment is the same as that shown in FIG. Further, the configuration of the winding of the electric motor for turning used in the electric system of the construction machine according to the present embodiment is the same as that shown in FIG. Furthermore, the rotational speed torque characteristics of the electric motor for turning used in the electric system for the construction machine according to the present embodiment are the same as those shown in FIG.

  FIG. 16 is a system configuration diagram showing the overall configuration of a construction machine according to another embodiment of the present invention.

  In the above-described example, the present invention is applied to the hydraulic excavator. However, the present invention can be applied to all construction and work machines having a swiveling body other than the hydraulic excavator. For example, the present invention can also be applied to a wheel loader using a traveling electric motor 301a provided on the rear frame 300a.

  In a wheel loader, there is a case of a convert installed state as a case where high torque is required at low speed. When the wheel loader is advanced and the bucket is plunged into earth or sand, the rotational speed of the traveling motor 301 decreases, while the required torque increases. At this time, as described with reference to FIG. 6, since the pilot pressure P of the traveling motor is equal to or higher than the determination value Pmin and the actual speed N is equal to or lower than the determination value Nmin of the speed close to 0, Judging the installation state, the winding switching signal is turned ON to automatically switch to the low speed-high torque characteristic.

  As described above, according to the present embodiment, according to the load applied to the electric actuator, the characteristic of the electric actuator can be changed to the low speed-high torque characteristic by switching to one of the two windings. If the load is low and the load is large, the efficiency of work can be improved by switching to the low speed-high torque characteristic. In addition, since it is not switched to the low speed-high torque characteristic when it is not necessary, the influence on the life of the inverter and the electric motor is small. In the above-described example, the wheel loader provided with the traveling electric motor 301a in the rear frame 300a has been described. However, the traveling load motor 301a provided in the rear frame 300a is replaced with the traveling load motor provided in the front frame 300b. A wheel loader may be used as the electric motor 301b.

Next, the configuration of other windings of the electric motor for turning used in the electric system for the construction machine according to each embodiment of the present invention will be described with reference to FIGS. 17 and 18.
FIG. 17 is a configuration diagram of other windings of the electric motor for turning used in the electric system of the construction machine according to each embodiment of the present invention. FIG. 18 is an explanatory diagram of other rotational speed torque characteristics of the electric motor for turning used in the electric system for the construction machine according to each embodiment of the present invention.

  As shown in FIG. 4, the windings of the electric motor 25 for turning which is a three-phase synchronous motor are star-connected. FIG. 17 shows a winding for one of the three phases. Stator windings 101, 102, and 106 are provided as windings for one phase. In the present embodiment, the turning electric motor has a winding switching function.

  The stator winding of each phase of the electric motor for rotation is composed of a first winding 101, a second winding 102, and a third winding 106. The first winding 101 and the second winding 102 are connected in series, and the first winding 101 and the third winding 106 are connected in parallel. Further, a relay 103 is connected in parallel to the second winding 102, and a relay 107 is connected in series to the third winding 106. A normally closed type (B contact) is used for the relay 103. As the relay 107, a normally open type is used.

  When the winding switching signals 201 and 201B of the controller 80 shown in FIG. 17 are OFF, the relay 103 and the relay 107 are in a conductive state, and a current flows only through the first winding 101.

  The rotational speed torque characteristic of the electric motor for turning in this state is a normal characteristic indicated by a symbol A in FIG. 18, and is used in normal turning work. In the normal torque torque characteristics, the torque in the low speed range is increased to drive a revolving body with large inertia, and the constant output characteristics (the product of torque and speed are constant) after a certain speed range. Reduce torque. The reason why the torque is limited in the low speed region is to prevent the electric motor and the inverter from being damaged due to excessive current flowing. The limitation on the rotational speed is determined by the magnitude of the back electromotive force of the electric motor accompanying the increase in speed.

  On the other hand, when the winding switching signal 201 is ON, the relay 103 is in a non-conductive state, the first winding 101 and the second winding 102 are connected in series, and the number of windings increases. The rotational speed torque characteristic of the electric motor for electric power is a low speed-high torque characteristic indicated by a symbol B in FIG. In the low speed-high torque characteristic, the torque at the low speed is higher than that in the normal characteristic indicated by the symbol A. On the other hand, the number of rotations on the high rotation side is kept low.

  Further, when the winding switching signal 201 is OFF and the winding switching signal 201B is ON, the relay 103 is conductive, the relay 107 is also conductive, and the third winding 106 is in parallel with the first winding 101. Since it is connected and the number of windings is reduced, the rotational speed torque characteristic of the electric motor for turning becomes a high-speed-low torque characteristic indicated by a symbol D in FIG. In the high speed-low torque characteristic indicated by reference sign D, higher rotation is possible compared to the normal characteristic indicated by reference sign A, but the torque at low speed is low.

  A wheel loader may include two types of motors (a high-speed motor for traveling and a low-speed high-torque motor for work). In this case, a vehicle space for mounting two or more units is required.

  On the other hand, in this embodiment, it is only necessary to switch the windings of one electric motor, so that the vehicle space can be saved.

  As described above, according to the present embodiment, according to the load applied to the electric actuator, the characteristic of the electric actuator can be changed to the low speed-high torque characteristic by switching to one of the two windings. If the load is low and the load is large, the efficiency of work can be improved by switching to the low speed-high torque characteristic. In addition, since it is not switched to the low speed-high torque characteristic when it is not necessary, the influence on the life of the inverter and the electric motor is small.

In addition, it can be shared with a single motor, saving vehicle space.

DESCRIPTION OF SYMBOLS 10 ... Lower traveling body 11 ... Crawler 12 ... Crawler frame 13 ... Right traveling hydraulic motor 14 ... Left traveling hydraulic motor 20 ... Upper turning body 21 ... Turning frame 22 ... Engine 23 ... Assist power generation motor 24 ... Electric double layer capacitor 25 ... turning electric motor 25A ... rotational speed detecting means 26 ... reduction gear 27 ... turning hydraulic motor 30 ... front device 31 ... boom 32 ... boom cylinder 33 ... arm 34 ... arm cylinder 35 ... bucket 36 ... bucket cylinder 40 ... hydraulic system 41 ... hydraulic pressure Pump 42 ... Control valve 43 ... Hydraulic piping 51 ... Chopper 52 ... Rotary electric motor inverter 53 ... Assist generator motor inverter 54 ... Smoothing capacitor 55 ... Power control unit 56 ... Main contactor 57 ... Main relay 58 ... Inrush current prevention circuit 75 ... Gas → oil pressure signal conversion device 77 ... hydraulic - electric signal converting device 79 ... pilot pressure signal shut-off valve 80 ... controller (turning mode switching means)
90 ... Turning lever 92 ... Lock lever 101, 102, 104, 106 ... Winding 103, 105, 107 ... Winding switching relay 201 ... Winding switching signal 202 ... Monitor 203 ... Winding switching switch 301 ... Wheel loader switch Traveling motor

Claims (6)

A construction machine having an electric actuator for driving a driven body by electric drive,
The winding provided in the electric actuator has at least two or more windings,
A construction machine comprising a winding switching unit that switches to one of the two or more windings according to a load applied to the electric actuator. The construction machine according to claim 1,
Of the two or more windings, the second winding has a larger number of windings than the first winding, and is switched to the second winding by the winding switching unit. A construction machine characterized in that when it is switched to the first winding, it has a low speed-high torque characteristic with respect to the rotational speed-torque characteristic of the electric actuator. The construction machine according to claim 2,
The electric actuator is a three-phase AC electric motor,
The windings that make up each of the three phases have a first winding and a second winding,
The first winding alone constitutes the winding of the first system,
The construction machine, wherein the first winding and the second winding are connected in series to form a winding of the second system. In the construction machine in any one of Claims 1-3,
When it is determined that the load is a pressing work state in which a part of the swiveling body is pressed against a work object based on the turning pilot pressure and the rotation speed of the electric actuator as the load, the two systems A construction machine characterized by switching the winding of the electric actuator to a system capable of outputting a high torque. In the construction machine in any one of Claims 1-3,
Based on the time integral value of the swing pilot pressure when it is determined that the load is a pressing work state in which a part of the swing body is pressed against a work target based on the swing pilot pressure and the rotation speed of the electric actuator as the load. The construction machine is characterized in that the winding of the electric actuator among the two windings is switched to a system capable of outputting a high torque. In the construction machine in any one of Claims 1-3,
In addition to the electric actuator, a hydraulic actuator that drives the swing body to rotate by hydraulic drive, and when the electric actuator does not include a magnetic pole position detection sensor, the swing pilot pressure and the inlet of the hydraulic actuator as a load, When it is determined that a pressing work state in which a part of the swivel body is pressed against the work object, based on the magnitude of the hydraulic torque obtained from the pressure difference at the outlet, the winding of the electric actuator among the two systems of windings is determined. A construction machine characterized by switching a line to a system capable of outputting high torque.

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