JP2009001379A - Driving system of lifting magnet machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently increase the applied voltage of a lifting magnet when starting the attraction work. <P>SOLUTION: A driving system of a lifting magnet machine comprises a hydraulic motor 15 to be driven by pressurized oil from a pump 13 for a lifting magnet, a generator 16 for generating the power by the drive of the hydraulic motor 15, a lifting magnet 10 which is mounted on a working front to perform the attraction work by the magnetic force generated by the power generated by the generator 16, a hydraulic cylinder 4a which is driven by pressurized oil from a pump 12 for a working machine to vertically turn the working front, a command means 22 for commanding the start of the attraction work, and a merging means 21 which merges a return oil discharged from the hydraulic cylinder with a conduit L1 to form a flow passage so as to guide the return oil to the hydraulic motor 15 when the start of the attraction work is commanded by the command means 22. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a driving system for a lifting magnet machine having a hydraulically driven generator.

  Conventionally, the generator is driven by driving the hydraulic motor, the electric power generated by the generator is supplied to the lifting magnet to generate electromagnetic force, and the lifting magnet is made to adsorb the adsorbed material such as scrap to perform the adsorption work. Such a lifting magnet machine is known (for example, see Patent Document 1). In the lifting magnet machine described in Patent Document 1, a hydraulic pump dedicated to a lift magnet is provided, and a hydraulic motor is driven by pressure oil from the hydraulic pump to perform an adsorption operation.

  By the way, in this kind of lifting magnet machine, in order to work efficiently, the voltage applied to the lifting magnet is increased at the start of the adsorption work, the current flowing through the lifting magnet is quickly raised, and the adsorption capacity of the lifting magnet is accelerated. There are some which are made to raise (for example, refer to patent documents 2).

JP 2002-348087 A JP 2002-359112 A

  However, the above-described patent document has a problem in efficiency because the applied voltage of the lifting magnet is increased only by the control of the controller at the start of the adsorption work.

A driving system for a lifting magnet machine according to the present invention includes a hydraulic motor that is driven by pressure oil from a first hydraulic source, a generator that generates electric power by driving the hydraulic motor, and a work front that is attached to the generator to generate electric power. Lifting magnet that performs suction work by magnetic force generated by electric power, a hydraulic cylinder that is driven by pressure oil from the second hydraulic power source to rotate the work front in the vertical direction, and command means that commands the start of the suction work And a joining means for forming a flow path so that the return oil discharged from the hydraulic cylinder is joined to the pressure oil from the hydraulic source and guided to the hydraulic motor when at least the command means instructs the start of the suction operation. It is characterized by providing.
An operation detecting means for detecting the lowering operation of the work front due to the contraction of the hydraulic cylinder is further provided, and when the operation detecting means detects the lowering operation of the work front when the command means starts the suction work, A flow path can also be formed so that the discharged return oil merges with the pressure oil from the hydraulic source.
The first hydraulic source may be configured as a dedicated hydraulic pump for driving the hydraulic motor.

  According to the present invention, since the return oil from the hydraulic cylinder is joined and guided to the hydraulic motor for driving the generator at the start of the adsorption work, the number of rotations of the hydraulic motor can be increased, and the lifting magnet The applied voltage can be increased efficiently.

Hereinafter, an embodiment of a driving system for a lifting magnet machine according to the present invention will be described with reference to FIGS.
FIG. 1 is an external side view of a lifting magnet machine having a drive system according to an embodiment of the present invention. This lifting magnet machine uses a hydraulic excavator as a base machine, and includes a traveling body 1, a revolving body 2 that is turnably supported on the traveling body 1, and a work front 3 that is rotatably attached to the revolving body 2. Have

  The work front 3 is pivotally supported by the swing body 2 so as to be pivotally supported, an arm 5 pivotally supported by the tip of the boom, and pivotally supported by the tip of the arm. Lifting magnet 10. The boom 4 is rotated in the vertical direction by the expansion and contraction of the boom cylinder 4a, and the arm 5 is clouded or dumped by the expansion and contraction of the arm cylinder 5a. The lifting magnet 10 is tilted by the expansion and contraction of the tilt cylinder 6a via the link mechanism (links 6b and 6c). In addition, the dotted line of a figure has shown the adsorption | suction work state which adsorb | sucked adsorbents 50, such as iron and scrap, to the lifting magnet 10. FIG.

  FIG. 2 is a hydraulic circuit diagram showing the overall configuration of the driving system for the lifting magnet machine according to the present embodiment. In this embodiment, separate hydraulic pumps 13 (lifting mag pumps) for driving lifting magnets are provided separately from the hydraulic pumps 11 and 12 (working machine pumps) for driving the working machines. Driven by. The work machine pumps 11 and 12 are variable displacement pumps, and the riffmag pump 13 is a fixed displacement pump.

  The pressure oil discharged from the riff mug pump 13 is supplied to the hydraulic motor 15 via the pipe line L1, and returned to the tank via the pipe line L2. The hydraulic motor 15 is rotated by the driving pressure from the riffmag pump 13, and the generator 16 is driven by the rotation of the hydraulic motor 15, and the generator 16 generates power. The controller 17 rectifies the electricity generated by the generator 16 and causes a current to flow through the lifting magnet 10. The lifting magnet 10 generates a magnetic force in response to the current from the controller 17 and performs cargo handling by attracting iron or scrap.

  The pressure oil discharged from the work machine pumps 11 and 12 is supplied to each hydraulic actuator 20 via a control valve 18 provided corresponding to the hydraulic actuator 20 for driving the work machine. In the figure, only the boom cylinder 4a and one hydraulic motor (for example, a turning hydraulic motor) are shown as the hydraulic actuator 20, and the other hydraulic actuators 20 such as the arm cylinder 5a and the tilt cylinder 6a are not shown. The control valve 18 is operated by operating an operation lever in the cab and controls the flow of pressure oil to the hydraulic actuator 20.

  FIG. 3 is a diagram illustrating an example of a drive circuit for the boom cylinder 4a including an operation circuit. The pilot valve 32 is driven according to the operation of the operation lever 31, and the pilot pressure from the hydraulic pressure source 33 acts on the pilot port of the control valve 18 by driving the pilot valve 32. Thereby, the pressure oil from the work machine pump 12 is supplied to the boom cylinder 4a, and the boom cylinder 4a expands or contracts.

  As a characteristic configuration of the present embodiment, as shown in FIG. 2, an electromagnetic switching valve 21 is provided in a pipe L3 connecting the control valve 18 and the bottom chamber 40a of the boom cylinder 4a. A switch 22 is connected to the solenoid of the electromagnetic switching valve 21. The switch 22 is an operation switch for instructing the start / end of the suction operation of the lifting magnet 10, and the worker turns on the operation switch 22 at the start of the suction operation and turns off at the end command. The operation switch 22 is provided on the operation lever 31, for example.

  In FIG. 2, the control valve 21 and the bottom chamber 40 a of the boom cylinder 4 a communicate with each other when the electromagnetic switching valve 21 is switched to the position “a”. As a result, the pressure oil from the work machine pump 12 is supplied to the bottom chamber 40a, or the pressure oil in the bottom chamber 40a is returned to the tank. On the other hand, in the state where the electromagnetic switching valve 21 is switched to the position B, the bottom chamber 40a of the boom cylinder 4a communicates with the upstream line L1 of the hydraulic motor 15 via the check valve 24. Thereby, the return oil of the bottom chamber 40a can be merged with the pipe line L1.

  The main operation of this embodiment will be described. When the suction work is not performed, the worker turns off the operation switch 22. In this state, the electromagnetic switching valve 21 is always switched to the position a. For this reason, when boom raising is instructed by the operation lever 31, pressure oil from the work machine pump 12 is supplied to the bottom chamber 40a of the boom cylinder 4a via the electromagnetic switching valve 21, and pressure oil in the rod chamber 40b is supplied. Returned to the tank, the boom cylinder 4a extends. On the other hand, when the boom is instructed by the operation lever 31, the pressure oil from the work machine pump 12 is supplied to the rod chamber 40b, and the pressure oil in the bottom chamber 40a is returned to the tank via the electromagnetic switching valve 21, The boom cylinder 4a is degenerated.

  When performing the suction work, the worker turns on the operation switch 22. As a result, the electromagnetic switching valve 21 is switched to the position B. Further, the worker instructs the lowering of the boom by the operation lever 31 at the same time as the operation switch 22 is turned on in order to bring the lifting magnet 10 close to the attracted object below the lifting magnet 10. As a result, the pressure oil from the work machine pump 12 is supplied to the rod chamber 40 b and the boom cylinder 4 a is retracted, and the return oil from the bottom chamber 40 a merges into the pipe line L 1 via the check valve 24. As a result, the amount of pressure oil supplied to the hydraulic motor 15 increases, and the rotational speed of the hydraulic motor 15 increases.

  FIG. 4 is a diagram showing the relationship between the rotational speed N of the hydraulic motor 15 and the voltage Vd generated by the electric motor 16. Before the return oil of the boom cylinder 4a joins the pipe L1, the hydraulic motor 15 rotates only by the pressure oil from the riffmag pump 13. Therefore, the motor rotation speed is N1, and the generated voltage Vd of the generator 16 is Vd1. When the return oil of the boom cylinder 4a joins the pipe L1 at the start of the suction operation, the motor rotation speed becomes N2 (> N1), and the generated voltage Vd becomes Vd2 (> Vd1).

  FIG. 5 is a timing chart showing changes in the applied voltage Vm and current I acting on the lifting magnet 10 at the start of the adsorption work. When the operation switch 22 is turned on at time t1 to start the suction work, the controller 17 raises the applied voltage Vm to Vm2. As a result, the current I flowing through the lifting magnet 10 gradually increases, and a magnetic force is generated in the lifting magnet 10. When the current I increases to I2 at time t2, the controller 17 decreases the applied voltage Vm to Vm1. As a result, the current I decreases to I1, and thereafter, the state of constant voltage (= Vm1) and constant current (= I1) is maintained.

  Thus, by making the applied voltage Vm2 at the start of the attracting work larger than the applied voltage Vm1 at the steady state, the attracting ability of the lifting magnet 10 is increased early, and the work can be performed efficiently. In this case, in conjunction with the lowering operation of the boom 4 at the start of the adsorption work, the return oil of the bottom chamber 40a joins the pipe L1, and the generated voltage Vd of the generator 16 rises to Vd2, so the applied voltage Vm It can be easily increased to Vm2. That is, by using the oil that returns to the tank to increase the motor rotation speed, the generated voltage Vd of the generator 16 can be increased and the applied voltage Vr can be increased, so the power stored in the battery or the like is discharged. This is more efficient than increasing the applied voltage Vm.

According to the present embodiment, the following operational effects can be achieved.
(1) The electromagnetic switching valve 21 is interposed in the pipe line L3 communicating with the bottom chamber 40a of the boom cylinder 4a, and the electromagnetic switching valve 21 is switched at the start of the suction operation so that the return oil from the bottom chamber 40a is supplied to the hydraulic motor 15 The flow path was formed so as to merge with the driving pressure supply pipe L1. As a result, the generated voltage Vd of the generator 16 increases, and the applied voltage Vm of the lifting magnet 10 can be increased efficiently.
(2) The increase (Vd2−Vd1) of the generated voltage Vd of the generator 16 can contribute to the increase of the applied voltage Vm as it is, and compared with the controller 17 which increases the applied voltage only by the control of the controller 17. The configuration can be simplified.
(3) Since the hydraulic motor 15 is driven by the hydraulic pump 13 dedicated to the riffmag, there is no need for a diversion valve for guiding the pressure oil from the work machine pumps 11 and 12 to the hydraulic motor 15, and the combined operation of the hydraulic actuator 20. Sometimes, stable adsorption performance can be demonstrated.

  In the embodiment described above, it is assumed that the operation lever 31 is lowered when the operation switch 22 is turned on, and the electromagnetic switching valve 21 is switched to the position B when the operation switch 22 is turned on. When the lowering operation of the boom 4 is detected at the time of turning on, the electromagnetic switching valve 21 may be switched to the position B. In this case, for example, as shown in FIG. 6, a detection switch 23 that operates in conjunction with the boom lowering operation may be connected to the operation switch 22 in series. The detection switch 23 may be turned on when the lowering operation of the front 3 is detected by the pressure sensor. The boom lowering operation may be detected when the operation lever 31 is lowered. For example, a pressure switch may be provided in the pilot circuits P1 and P2 in FIG. 3, and the detection switch 23 may be configured by the pressure switch. Good. Operation detecting means other than the switch 23 may be provided.

  In the above embodiment, the system is configured on the assumption that the lowering operation of the boom 4 is accompanied at the start of the sucking operation. However, considering the case where the sucking operation is started when the boom 4 is already in the lowering state, It may be configured as shown in FIG. In FIG. 7, the electromagnetic switching valve 25 is provided in the pipe line L1. When the electromagnetic switching valve 25 is switched to the position A, the entire amount of pump pressure oil is supplied to the hydraulic motor 15, whereas when it is switched to the position B, a part of the pump pressure oil is supplied to the hydraulic motor 15. The rest is returned to the tank.

  The electromagnetic switching valve 25 is switched by operating the selection switch 26. The selection switch 26 is normally turned off, and is turned on when the motor rotational speed is forcibly increased, such as when the suction work is started when the boom 4 is in the lowered state. When the selection switch 26 is turned on at the start of the riff mug operation, the electromagnetic switching valve 25 is switched to the position A, and the amount of pressure oil supplied from the riff mug pump 13 to the hydraulic motor 15 increases. Thereby, the adsorption work can be started efficiently. The riffmag pump 13 may be configured as a variable pump, and the amount of pressure oil supplied to the hydraulic motor 15 may be adjusted by controlling the pump tilt amount in accordance with the operation of the selection switch 26. In this case, the pressure oil supply amount increase command may be automatically canceled after a lapse of a predetermined time from when the selection switch 26 is turned on or when it is detected that the current I of the magnet 10 has increased to I2.

  In the above embodiment, the hydraulic motor 15 is driven by pressure oil from the riffmag pump 13 (first hydraulic power source), and the boom cylinder is driven by pressure oil from the work machine pump 12 (second hydraulic power source). Although 4a was driven (FIG. 2), the structure of a hydraulic circuit is not restricted to this. The return oil from the boom cylinder 4a is joined to the pipe line L1 at the start of the suction operation, but the return oil from another hydraulic cylinder (for example, the arm cylinder 5a) that rotates the work front 3 in the vertical direction is used. You may make it merge with the pipe line L1. Although the start of the suction work is instructed by operating the operation switch 22, the instruction means is not limited to this. The return oil is joined to the pipe L1 by switching the electromagnetic switching valve 21, but at least when the start of the suction operation is instructed, the return oil discharged from the cylinder 4a is compressed with the pressure oil from the riffmag pump 13. As long as the flow path is formed so as to join to the hydraulic motor 15, any joining means may be used.

  If the lifting magnet 10 is attached to the work front 3, the configuration of the lifting magnet machine is not limited to that described above. That is, as long as the features and functions of the present invention can be realized, the present invention is not limited to the driving system for the lifting magnet machine of the embodiment.

1 is an external side view of a lifting magnet machine according to an embodiment of the present invention. 1 is a hydraulic circuit diagram showing an overall configuration of a drive system according to an embodiment of the present invention. The figure which shows the drive circuit of the boom cylinder of FIG. 2 including the operation circuit. The figure which shows the relationship between the rotation speed of a hydraulic motor, and the voltage which generate | occur | produces with an electric motor. The timing chart which shows an example of the operation | movement at the time of a suction work start. The figure which shows the modification of FIG. The figure which shows another modification of FIG.

Explanation of symbols

4a Boom cylinder 10 Lifting magnets 11 and 12 Working machine pump 13 Lifting magnet pump 15 Hydraulic motor 16 Generator 21 Electromagnetic switching valve 22 Operation switch 23 Detection switch

Claims (3)

A hydraulic motor driven by pressure oil from a first hydraulic source;
A generator for generating electric power by driving the hydraulic motor;
A lifting magnet that is attached to the front of the work and performs an adsorption work by a magnetic force generated by the electric power generated by the generator;
A hydraulic cylinder that is driven by pressure oil from a second hydraulic source and rotates the working front in the vertical direction;
Command means for commanding the start of suction work;
A merging means for forming a flow path so that the return oil discharged from the hydraulic cylinder is merged with the pressure oil from the hydraulic source and guided to the hydraulic motor when at least the command means instructs the start of the suction operation. And a lifting magnet machine drive system. In the lifting magnet machine drive system according to claim 1,
An operation detecting means for detecting a lowering operation of the work front due to the contraction of the hydraulic cylinder;
When the operation detecting means detects the lowering operation of the front of the work when the instruction means starts the suction operation, the merging means supplies the return oil discharged from the hydraulic cylinder to the pressure from the hydraulic source. A drive system for a lifting magnet machine, characterized in that a flow path is formed so as to join oil. In the drive system of the lifting magnet machine according to claim 1 or 2,
The drive system for a lifting magnet machine, wherein the first hydraulic power source is a dedicated hydraulic pump for driving the hydraulic motor.

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