JP2008150193A - Lifting magnet work machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably supply power to a lifting magnet by reducing variation in the output voltage of a generator according to change in the rotational speed of the generator. <P>SOLUTION: In this lifting magnet work machine, a lifting magnet powered by a generator 30 driven by the power of an engine is attached to the distal end of an arm. The generator 30 comprises a rotating shaft 34, a rotor 32 installed on the rotating shaft 34 rotatably with each other and having permanent magnets 35 with different magnetic poles alternately magnetized in the rotating direction, and a stator 33 having pole teeth corresponding to the rotor 30 and a field wiring 41. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lifting magnet working machine such as a hydraulic excavator in which a lifting magnet for selecting and loading metal scrap such as iron by magnetic force is attached to the tip of an arm.

  Conventionally, it is known that a lifting magnet is attached to the tip of an arm in a working machine such as a hydraulic excavator, and metal scrap such as iron is sorted and loaded by the magnetic force of the lifting magnet (Patent Document 1).

  In general, as a method of supplying power to the lifting magnet, a lifting magnet generator (hereinafter referred to as “generator”) is provided, and the generator is driven by the engine.

  The power supply to the lifting magnet in such a working machine is carried by mounting a lifting magnet generator (hereinafter referred to as a “generator”) on the working machine and driving the generator with an engine to generate electric power, Electric power is supplied to the lifting magnet. The engine here shares an engine that drives each actuator of a hydraulic excavator. That is, since one engine is used, a change in the number of revolutions of the generator frequently occurs, for example, when performing a combined operation of the actuator or when changing the number of revolutions of the engine according to the work amount.

  Moreover, the generator of the structure which has the stator provided with a field winding and the rotor provided with a field winding is used for the generator currently used for a working machine.

FIG. 6 shows the rotation speed (n) and output voltage (v) of a generator having a stator having field windings and a rotor having field windings used in a conventional hydraulic excavator. It is the characteristic view which showed the relationship. With a conventional generator, an output voltage of 200 volts (V) can be obtained at 1700 revolutions per minute (min-1) or more, but the output voltage rapidly decreases when it becomes 1700 revolutions or less. Therefore, at 1700 revolutions or less, it is not possible to supply an amount of power necessary for the lifting magnet to stably work.
JP 2006-219272 A.

  As described above, the generator used in the conventional work machine was a generator having a structure provided with a stator having a field winding and a rotor having a field winding. In this generator, when the number of revolutions of the generator becomes a predetermined number of revolutions or less, the output voltage rapidly decreases and the fluctuation is large. For this reason, in a working machine that uses a single engine to drive the actuators of the hydraulic excavator and the generator, the rotational speed of the generator frequently changes and power supply to the lifting magnet is not possible. It was easy to be stable. If the output voltage of the generator decreases during the lifting magnet suction operation, the power supply to the lifting magnet becomes unstable, and there is a risk that the suspended load will drop or the lifting magnet control device will be damaged.

  Therefore, there is a technical problem to be solved in order to reduce the fluctuation of the output voltage accompanying the change in the rotation speed of the generator and stabilize the power supply to the lifting magnet. The purpose is to solve the problem.

  The present invention has been proposed in order to achieve the above object, and the invention according to claim 1 is a lifting magnet in which a lifting magnet using a generator driven by engine power as a power source is attached to the tip of an arm. In a work machine, the generator is attached to a rotor having a rotating shaft and a permanent magnet that is attached to the rotating shaft so as to be integrally rotatable, and different magnetic poles are alternately magnetized in the rotating direction. Provided is a lifting magnet working machine constituted by a plurality of corresponding magnetic poles and a stator having field windings.

  According to this configuration, by using a rotor composed of permanent magnets, the output voltage does not rapidly decrease and gradually decreases even when the number of revolutions of the generator changes temporarily. To be able to. Therefore, since the output voltage does not drop rapidly, the engine speed is changed to a direction that temporarily decreases according to the combined operation of the actuator and the amount of work, and the generator speed is also temporarily changed accordingly. Even if the voltage decreases, the output voltage does not decrease until the lifting magnet can no longer perform stable work.

  According to the first aspect of the present invention, the engine speed is temporarily reduced in accordance with the combined operation of the actuator and the amount of work, and accordingly, the generator speed is also temporarily reduced. The output voltage does not decrease until the lifting magnet can no longer carry out stable work even if it changes to, so even if there are frequent fluctuations in the number of revolutions, the power to the lifting magnet Supply is stable and stable operation is obtained.

  In order to achieve the purpose of stabilizing the power supply to the lifting magnet by reducing the fluctuation of the output voltage due to the change in the rotation speed of the generator, a lifting magnet that uses a generator driven by the engine power as a power source In a lifting magnet working machine attached to the tip of an arm, the generator is attached to a rotating shaft and a permanent magnet which is attached to the rotating shaft so as to be integrally rotatable and has different magnetic poles alternately magnetized in the rotating direction. This is realized by comprising a rotor provided, and a stator provided with a plurality of magnetic poles corresponding to the rotor and a field winding.

  Hereinafter, the lifting magnet working machine of the present invention will be described with reference to preferred embodiments.

  FIG. 1 shows a hydraulic excavator as a lifting magnet working machine to which the present invention is applied. A hydraulic excavator 1 shown in FIG. 1 includes a lower traveling body 2 capable of self-propelling, and an upper revolving body 4 that is installed on the lower traveling body 2 through a revolving mechanism 3 so as to be freely rotatable.

  The lower traveling body 2 includes a center frame 5 and a lower frame 7 including a pair of side frames 6 and 6 provided on both sides of the center frame 5 so as to be parallel to each other. An idler 8 is supported on one end side of each of the side frames 6 and 6 so as to be movable back and forth, and a sprocket 10 that is rotationally driven by a traveling motor 9 that is a hydraulic motor is provided on the other end side.

  An endless track shoe 11 is provided between the idler 8 and the sprocket 10, and a plurality of track rollers 12, 12... Are rotatably supported on the upper and lower portions of the side frames 6, 6. The track shoe 11 is driven by the sprocket 10 and the traveling of the track shoe 11 is guided by the track rollers 12, 12,.

  The upper revolving body 4 includes a body frame 13 at the bottom, and a work machine 14 is mounted at the front center of the body frame 13.

  The work machine 14 has a base end pivotally attached to the vehicle body frame 13, a boom 16 that can be raised and lowered by a boom cylinder 15, and a base end side pivotally attached to the tip of the boom 16, and an arm 18 that can be rotated by an arm cylinder 17. And a lifting magnet 20 pivotally attached to the tip of the arm 18 and rotatable by a lifting magnet cylinder 19. The lifting magnet 20 can be removed on site according to the purpose of use of the excavator 1 and replaced with a bucket (not shown) or the like.

  A cab 21 is installed at the front of the vehicle body frame 13 on the left side of the work machine 14 and in the vicinity of the work machine 14, and at the rear part of the vehicle body frame 13 is an engine room covered with a bonnet cover 22. 23 is installed. A power engine 24 (see FIG. 2) is accommodated in the engine chamber 23, and a counterweight 25 is attached to the rear end of the vehicle body frame 13.

  FIG. 2 is a drive control circuit diagram of the lifting magnet 20. In FIG. 2, the drive shaft of the engine (diesel engine) 24 mounted on the hydraulic excavator 1 drives the cylinders 15, 17, 19, etc. of the power generation hydraulic pump 26 and the work machine 14 of the hydraulic excavator 1. A working machine hydraulic pump 27 is attached.

  An oil passage for pressure oil discharged from the generator hydraulic pump 26 is connected to a generator hydraulic motor 29 via an electromagnetic switching valve 28. The power generation hydraulic motor 29 is connected to a generator 30 that is driven by the power generation hydraulic motor 29 to generate AC power. The generator 30 serves as a power source for the lifting magnet 20, and an output terminal of the generator 30 is connected to the lifting magnet 20 via a rectifier 31 that converts generated AC power into DC power for lifting magnet excitation. It is connected to the.

  In addition, as a control circuit for controlling the operation of the lifting magnet 20, a lift magnet mode setting switch 43 is connected between the electromagnetic switching valve 28 and the DC power supply via a fuse 44.

  Next, the operation of the lifting magnet drive control circuit will be described. When the riffmag mode setting switch 43 is turned on, the solenoid of the electromagnetic switching valve 28 is excited and the electromagnetic switching valve 28 is activated. By this operation, the electromagnetic switching valve 28 is switched, the pressure oil discharged from the generator hydraulic pump 26 is supplied to the generator hydraulic motor 29, and the generator hydraulic motor 29 starts to rotate. As a result, the generator 30 is rotated by driving the generator hydraulic motor 29, and AC power is generated by the generator 30. This AC power is converted into DC power by the rectifier 31 and then supplied to the lifting magnet 20.

  Then, while the working machine actuator 27 such as the boom cylinder 15, the arm cylinder 16, and the lifting magnet cylinder 19 is driven by the working machine hydraulic pump 27, work such as adsorption and transportation of the target object is safely performed by the lifting magnet 20. Is done.

  3 and 4 show an embodiment of the generator 30. FIG. 3 is a transverse sectional view of the generator 30 and FIG. 4 is a longitudinal sectional view showing its rotor and stator.

  3 and 4, the generator 30 includes a rotor 32 and a stator 33. The rotor 32 includes a rotating shaft 34, a permanent magnet 35, and a magnet holder 36 made of an iron material.

  Both ends of the rotating shaft 34 are rotatably supported by a casing 37 and an end bracket 38 via bearings 39 and 39. One end of the rotating shaft 34 protruding outward from the casing 37 is directly connected to the driving shaft of the power generating hydraulic motor 29 or connected via a pulley and a belt, and rotates integrally with the power generating hydraulic motor 29.

  The magnet holder 36 is a member that holds a permanent magnet 35 and is attached to the rotary shaft 34 integrally, and is formed by press-molding an iron material. As shown in FIG. 4, the permanent magnet 35 is magnetized in six divisions in the rotation direction, for example, so as to alternately have opposite polarities.

  The stator 33 is wound around a stator core 40 in which a plurality of slots 40 a, 40 a... Are formed on the inner peripheral side, and a slot 40 a of the stator core 40. A field winding 41 for forming a plurality of magnetic poles corresponding to the rotor 32 on the stator core 40 is provided.

  In the generator 30, when the rotor 32 provided with the permanent magnet 35 is rotated, an alternating magnetic flux from the rotor 32 due to the rotation of the permanent magnet 35 causes the magnetic field to be generated in the field winding 41 of the stator 33. Generate electricity. The electromotive force can be taken out via the lead wire 42 and output to the lifting magnet 20 via the rectifier 31.

  Thus, in the generator 30 using the permanent magnet 35 for the rotor 32, even if the rotational speed of the rotor 32 changes in proportion to the change in the rotational speed of the engine, the output voltage fluctuation from the stator 32 varies. Is small, and the output voltage gradually decreases.

  FIG. 5 shows the relationship between the rotational speed (n) and the output voltage (v) of the generator 30 having the stator 33 having the field winding 41 and the rotor 32 having the permanent magnet 35 in the present embodiment. FIG. 5 is a characteristic diagram schematically showing results based on experiments. In this generator 30, the relationship between the rotational speed and the output voltage changes in a gentle line, and even if the rotational speed of the generator 30 decreases, the output voltage does not drop rapidly. It gradually decreases and the fluctuation is small.

  For example, when the rotational speed of the rotor 32 is 2400 revolutions per minute (min-1), an output voltage of 250 volts (V) can be obtained, and when it decreases to 1600 revolutions per minute, it reaches 200 volts (V) and 400 revolutions per minute. Even when the voltage drops, a voltage of 50 volts (V) is obtained, which is sufficient to stabilize the lifting magnet 20 and to work. That is, it can be seen that the lifting magnet 20 is a usable region where the work can be stably performed at 400 rpm or more.

  Therefore, when the generator 30 having the stator 33 including the field winding 41 and the rotor 32 including the permanent magnet 35 is used, even if the rotational speed of the engine 24 is temporarily reduced. As in the conventional structure shown in FIG. 6, the output voltage does not drop suddenly in the vicinity of 1700 revolutions per minute, the fluctuation is gradually reduced, and even if it drops to about 400 revolutions per minute, The lifting magnet 20 can work stably.

  As a result, even if the rotational speed of the engine 24 is temporarily reduced and the rotational speed of the generator 30 is also temporarily reduced, the output voltage is immediately increased by the lifting magnet. The power supply to the lifting magnet 20 is stable and stable operation can be obtained even if the rotational speed is frequently fluctuated frequently. become.

  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 drive control circuit diagram which drives the lifting magnet of a hydraulic excavator same as the above. The cross-sectional view which shows one Example of the generator of a hydraulic excavator same as the above. The longitudinal cross-sectional view of the rotor and stator of a generator same as the above. The characteristic view which shows the relationship between generator rotation speed and output voltage same as the above. The characteristic view which shows the relationship between the conventional generator rotation speed and output voltage.

Explanation of symbols

1 Hydraulic excavator (lifting magnet working machine)
20 Lifting magnet 24 Engine 26 Power generation hydraulic pump 29 Power generation hydraulic motor 30 Generator 31 Rectifier 32 Rotor 33 Stator 34 Rotating shaft 35 Permanent magnet 40 Magnetic pole 41 Field winding

Claims (1)

In a lifting magnet working machine in which a lifting magnet powered by a generator driven by engine power is attached to the tip of an arm,
The generator includes a rotating shaft, a rotor that is attached to the rotating shaft so as to be integrally rotatable, and has a permanent magnet in which different magnetic poles are alternately magnetized in a rotating direction, and a plurality of rotors corresponding to the rotor A lifting magnet working machine comprising a magnetic pole and a stator having a field winding.

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