JP2006104811A - Slewing control device of construction equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an upper rotating body from being rotated backward because of the lack of torque of a motor just at the moment of releasing a mechanical brake on slewing startup of the upper rotating body. <P>SOLUTION: When slewing operation is performed by an operating lever 25 during the operation of the mechanical brake 21, a controller 50 measures the current of the motor with all the transistors of either the upper arm comprising the output part of an inverter 30 or the lower arm in the ON position before releasing the mechanical brake 21, and computes load torque which acts on the upper rotating body 13. Then the inverter 30 is controlled so that the torque of the motor against the load torque is generated at the motor 14, and the mechanical brake 21 is released. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a turning control device for a construction machine, and more particularly, to a turning control device for a construction machine including an electric motor that drives a turning of an upper turning body and a mechanical brake that holds a stop position of the upper turning body. .

  2. Description of the Related Art Conventionally, in a swing construction machine such as an excavator or a crane, a hydraulic motor swing drive system using a hydraulic motor that is rotated by oil discharged from a hydraulic pump as a swing drive source of an upper swing body is generally widely known. In this hydraulic motor turning drive system, the operating direction, speed, and the like of the hydraulic motor are changed by controlling the direction and flow rate of the pressure oil by a control valve provided between the hydraulic pump and the hydraulic motor. However, this method has a problem in that the amount of hydraulic energy cut off by the control valve is large and energy loss is large.

  On the other hand, an electric motor turning drive system using an electric motor as a turning drive source of the upper-part turning body is known (for example, see Patent Document 1). In this electric motor turning drive system, the turning direction and speed of the upper turning body are controlled by changing the rotation direction and speed of the electric motor, and energy efficiency can be greatly improved as compared with the hydraulic motor drive system.

  Here, as the turning means for the upper turning body, in the case of the hydraulic motor turning drive system described above, the control valve shuts off the oil passage at the neutral position of the operation lever, stops the rotation of the hydraulic motor, and applies the braking force. generate.

On the other hand, in the case of the electric motor turning drive system, the energization to the electric motor is cut off at the neutral position of the operation lever, and neither the driving force nor the braking force acts on the electric motor, so that only the inertia works. For this reason, there is provided a turning control device that includes a mechanical brake for holding the upper turning body at the turning stop position when turning is stopped and that releases the mechanical brake after holding the electric motor at a speed of 0 by servo lock control when turning is started. It is known (see, for example, Patent Document 2).
JP 2000-289983 A Japanese Patent Laid-Open No. 2001-10783

  In the case of the conventional electric motor turning drive system, the mechanical brake is operated in the neutral position of the operation lever to hold the upper turning body at the turning stop position.For example, when the construction machine turns toward the upward inclination on the slope, With the mechanical brake activated, the motor is held at speed 0 by servo lock control, and the mechanical brake is released to start turning. However, when the mechanical brake is released, the upper swinging body reverses due to insufficient motor torque. There is a risk that it will rotate.

  There is also a configuration that prevents reverse rotation of the upper swing body by applying dynamic brake before releasing the mechanical brake, but usually the dynamic brake is operated by a mechanical switch such as a relay. It may rotate in the reverse direction.

  Therefore, at the time of turning the upper swing body, as soon as the mechanical brake is released, a technical problem to be solved arises to prevent reverse rotation due to insufficient torque of the electric motor. It aims at solving.

The present invention has been proposed in order to achieve the above object, and the invention according to claim 1 is a permanent magnet type synchronous motor that drives the upper swing body to rotate, an inverter that controls the permanent magnet type synchronous motor, An output unit of an inverter is configured in a construction machine including a current detector that detects a current of an electric motor, speed detection means that detects a turning speed of the upper swing body, and a mechanical brake that holds a stop position of the upper swing body A turning control device for a construction machine, comprising a controller for calculating a load torque acting on an upper swing body by measuring a current of an electric motor in a state where any one of the upper arm and lower arm transistors is turned on.
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  According to this configuration, under the control of the controller, all the upper arm transistors constituting the output part of the inverter are turned on and all the lower arm transistors are turned off, or all the lower arm transistors are turned on and the upper arm is turned on. If all of the transistors are turned off, the input of the permanent magnet type synchronous motor is short-circuited, the dynamic brake is activated, and a torque is generated against an external force that attempts to rotate the permanent magnet type synchronous motor. In this state, the electric current of the electric motor is measured, and the controller calculates the load torque acting on the upper swing body based on the measured current.

  According to a second aspect of the present invention, there is provided a permanent magnet synchronous motor that drives the upper swing body to swing, an inverter that controls the permanent magnet synchronous motor, a current builder that detects electric current of the motor, and a swing of the upper swing body. In a construction machine having a speed detecting means for detecting a speed and a mechanical brake for holding the stop position of the upper swing body, the turning operation means when the mechanical brake for holding the stop position of the upper swing body is operating. When the turning operation is performed by the above, before releasing the mechanical brake, all the transistors of either the upper arm or the lower arm constituting the output part of the inverter are turned on, and then the mechanical brake is released. The load torque acting on the upper swing body is calculated by measuring the current of the motor, and the motor torque against the load torque is further calculated. Providing a construction machine of the turning control apparatus having a controller for generating the motive.

  According to this configuration, when the turning operation is performed by the turning operation means when the mechanical brake is operated and the stop position of the upper turning body is held, the controller is controlled before releasing the mechanical brake. If all the upper arm transistors that constitute the output part of the inverter are turned on and all the lower arm transistors are turned off, or all the lower arm transistors are turned on and all the upper arm transistors are turned off, the permanent magnet The input of the synchronous motor is short-circuited and the dynamic brake works. If the mechanical brake is released in this state, the permanent magnet type synchronous motor generates a torque that opposes the external force to be rotated. The electric current of the electric motor at this time is measured, and the controller calculates the load torque acting on the upper swing body based on the measured current. Further, the inverter is controlled so that the electric motor torque that opposes the load torque is generated in the electric motor.

  The invention according to claim 1 calculates the load torque that acts on the upper swing body by measuring the current of the motor in a state where all the transistors of either the upper arm or the lower arm constituting the output portion of the inverter are turned on. Therefore, the load torque acting on the upper swing body can be calculated from the current when the controller controls the inverter to short-circuit the input of the permanent magnet synchronous motor. Therefore, if the electric motor is driven based on the load torque at the start of turning, there is no risk of torque shortage.

  According to the second aspect of the present invention, if the turning operation is performed by the turning operation means when the mechanical brake that holds the stop position of the upper turning body is operating, the output portion of the inverter is released before the mechanical brake is released. After turning on all the transistors of either the upper arm or the lower arm constituting the mechanical brake, the mechanical brake is released. At this time, the dynamic brake works and the electric motor is generated against the load torque acting on the upper swing body. Further, it is possible to calculate the load torque by measuring the electric current of the electric motor, and to start turning by adding a torque component that opposes the load torque. Therefore, for example, even when the construction machine turns toward an uphill slope on an inclined ground, it is possible to prevent the upper swing body from rotating backward due to insufficient torque of the electric motor.

  Hereinafter, a turning control device for a construction machine according to the present invention will be described with reference to preferred embodiments. Upper arm or lower arm constituting the output part of the inverter for controlling the motor for the purpose of preventing reverse rotation due to insufficient torque of the motor when the mechanical brake is released at the start of turning of the upper swing body This was realized by providing a controller that calculates the load torque acting on the upper swing body by measuring the current of the motor with any one of the transistors turned on.

  FIG. 1 shows a hydraulic excavator 10 as an example of a construction machine, and an upper swing body 13 is mounted on a lower traveling body 11 via a swing mechanism 12 so as to be rotatable. The turning mechanism 12 includes a turning electric motor 14 provided in the upper turning body 13, a speed reducer 15 that decelerates the rotation of the electric motor 14, a ring gear 16 fixed to the lower traveling body 11, and meshing with the ring gear 16. The pinion gear (not shown) is rotated by the electric motor 14 and the like.

  A cab 17 is provided on one front side of the upper swing body 13, and a boom 18 is attached to the front center portion so as to be able to be raised and lowered. Further, an arm 19 is attached to the tip of the boom 18 so as to be rotatable up and down, and a bucket 20 is attached to the tip of the arm 19.

  FIG. 2 is a block diagram of the turning control device according to the present invention. In this embodiment, a permanent magnet synchronous motor (PM motor) is used as the electric motor 14 that drives the upper turning body 13 to turn. Permanent magnet synchronous motors have the advantage that they can be mounted on a vehicle such as a construction machine because they are driven by an inverter to obtain a highly efficient drive amount and are small and light. The electric motor 14 is supplied with electric power from a generator or a battery (both not shown) via an inverter 30.

  The electric motor 14 is provided with a mechanical brake 21 that generates a mechanical braking force. When the electric motor 14 is energized with the mechanical brake 21 released under the control of the controller 50, the electric motor 14 rotates and the rotational force is increased. Is transmitted to the upper swing body 13 via a speed reducer (shown in FIG. 1), and the upper swing body 13 rotates left or right. The rotation speed of the electric motor 14 is detected by the speed detector 23 and input to the controller 50.

  The motor 14 and the inverter 30 are connected by a first input wiring 23a, a second input wiring 23b, and a third input wiring 23c, and current detectors 24a, 24b, 24c for detecting the current of the motor 14 are connected to each input wiring. Is provided, and each of the U-phase, V-phase, and W-phase currents is detected, and the detected current is input to the inverter 30.

  An operation lever 25 for turning is provided as a turning operation means, and for example, a potentiometer or the like is incorporated. If the operation lever 25 is operated to the left or right, a command signal corresponding to the operation amount is input to the controller 50.

  FIG. 3 is a circuit diagram of the output unit of the inverter 30. The anode-side wiring 31 is connected to the first parallel wiring 32a, the second parallel wiring 32b, and the third parallel wiring 32c, and the first parallel wiring 32a is connected to the first parallel wiring 32a. Connected to the input wiring 23a, the second parallel wiring 32b is connected to the second input wiring 23b, and the third parallel wiring 32c is connected to the third input wiring 23c. These wirings constitute a so-called upper arm. A transistor T1 and a diode D1 are provided in parallel in the first parallel wiring 32a of the upper arm, a transistor T2 and a diode D2 are provided in parallel in the second parallel wiring 32b, and a transistor T3 and a diode are provided in the third parallel wiring 32c. D3 is provided in parallel.

  On the other hand, the cathode-side wiring 33 is connected to the fourth parallel wiring 34a, the fifth parallel wiring 34b, and the sixth parallel wiring 34c, the fourth parallel wiring 34a is connected to the first input wiring 23a, and the fifth parallel wiring 34b. Are connected to the second input wiring 23b, and the sixth parallel wiring 34c is connected to the third input wiring 23c. These wires constitute a so-called lower arm. A transistor T4 and a diode D4 are provided in parallel in the fourth parallel wiring 34a of the lower arm, a transistor T5 and a diode D5 are provided in parallel in the fifth parallel wiring 34b, and a transistor T6 and a diode are provided in the sixth parallel wiring 34c. D6 is provided in parallel.

  Next, a control procedure in the turning control device according to the present invention will be described. The controller 50 detects the load torque that acts on the upper swing body 13 in advance, and calculates the motor torque that counters the detected load torque. In order to detect the load torque, for example, under the control of the controller 50, all the upper-arm transistors T1 to T3 constituting the output unit of the inverter 30 are turned on, and all the lower-arm transistors T4 to T6 are turned off. Alternatively, all of the lower arm transistors T4 to T6 constituting the output section of the inverter 30 may be turned on, and all of the upper arm transistors T1 to T3 may be turned off.

  As described above, when all the transistors of either the upper arm or the lower arm are turned on, the input terminal of the electric motor 14 is short-circuited and the dynamic brake is applied, and a torque is generated against the external force that tries to rotate the electric motor 14. . For example, when a load torque is applied to the motor 14 from the outside when all the upper arm transistors T1 to T3 are turned on and all the lower arm transistors T4 to T6 are turned off, the broken line arrows in FIG. As shown, the direction from the first parallel wiring 32a to the first input wiring 23a, the direction from the second parallel wiring 32b to the second input wiring 23b, and the direction from the third input wiring 23c to the third parallel wiring 32c, respectively. Current flows.

  Each current is detected by the current detectors 24a, 24b, and 24c, and the controller 50 calculates a load torque that acts on the upper swing body 13 based on the measured current value. And at the time of turning start, the electric motor torque which opposes this load torque is generated in the electric motor 14, and the mechanical brake 21 is released to start the turning of the upper turning body 13, thereby preventing reverse rotation due to insufficient torque. can do.

  Thus, when the excavator 10 turns, for example, uphill on an inclined ground, when the controller 50 starts turning the upper turning body 13 with the operation lever 25, the controller 50 does not release the mechanical brake 21. In addition, all the transistors of either the upper arm or the lower arm constituting the output section of the inverter 30 are turned on to short-circuit the input of the motor 14, the current of the motor 14 is measured, and the load torque applied to the turn is calculated. Calculate.

  Then, the inverter 30 is controlled so as to cause the electric motor 14 to generate electric motor torque that opposes the load torque, and the mechanical brake 21 is released to start the turning of the upper revolving structure 13. Therefore, when the mechanical brake 21 is released, the electric motor 14 is driven by the electric torque that opposes the load torque, and therefore the reverse rotation of the upper swing body 13 can be prevented.

  It should be noted that the present invention can be variously modified without departing from the spirit of the present invention, and the present invention naturally extends to the modified ones.

1 is a side view of a hydraulic excavator to which the present invention is applied. The block diagram of the turning control apparatus which concerns on this invention. The circuit diagram of the output part of the inverter shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Hydraulic excavator 12 Turning mechanism 13 Upper turning body 14 Electric motor 21 Mechanical brake 23a-23c 1st-3rd input wiring 24a-24c Current detector 30 Inverter 31 Anode side wiring 32a-32c 1st-3rd parallel wiring 33 Cathode side Wiring 34a-34c 4th-6th parallel wiring T1-T6 Transistor D1-D6 Diode 50 Controller

Claims (2)

A permanent magnet type synchronous motor that drives the upper swing body to swing, an inverter that controls the permanent magnet type synchronous motor, a current detector that detects the current of the motor, and a speed detection means that detects the swing speed of the upper swing body In a construction machine with a mechanical brake that holds the stop position of the upper swing body,
A controller for calculating the load torque acting on the upper swing body by measuring the current of the motor with all the transistors of either the upper arm or the lower arm constituting the output part of the inverter turned on is provided. A turning control device for construction machinery. When the mechanical brake that holds the stop position of the upper-part turning body is operating, if the turning operation is performed by the turning operation means, the output part of the inverter is configured before the mechanical brake is released. Turn on all the transistors on either the upper arm or the lower arm, then release the mechanical brake, measure the electric current of the motor at this time, calculate the load torque acting on the upper swing body, A turning control device for a construction machine, comprising a controller that causes the motor to generate a motor torque that opposes a load torque.

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