JP2880437B2 - Lifting magnet and its demagnetization method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lifting magnet with a built-in hydraulic motor-driven generator which can be mounted on a normal work vehicle without installation of dedicated equipment and which can be easily mounted. The present invention relates to a method of demagnetizing a lifting magnet that quickly releases a material to be adsorbed from a magnet portion when a hydraulically operated valve is closed.

[0002]

2. Description of the Related Art A lifting magnet mounted on a work cart such as a backhoe requires a strong electromagnetic force to reliably attract and hold a heavy material to be adsorbed such as a metal plate. Very large, such as 10 kW. With such a large amount of power consumption, the capacity of the battery for engine start and control mounted on the work vehicle is insufficient, and the battery cannot be used.

A conventional lifting magnet is disclosed in, for example, Japanese Utility Model Laid-Open No. 57-99882 and Japanese Utility Model Laid-Open No. 57-120.
As disclosed in Japanese Patent No. 587, a dedicated hydraulic motor and a generator are separately mounted on the main body of the work vehicle, or the dedicated generator is directly driven by an engine of the main body of the work vehicle. Therefore, when attaching the lifting magnet to the arm tip of the work cart, it is necessary to attach a generator to the main body of the work cart and to extend a power supply cable from the generator to the lifting magnet. For these lifting magnets, a dedicated operation switching valve is installed in the cab of the work vehicle, and the switching valve excites and demagnetizes the magnet unit via a hydraulic motor or a generator.

[0004]

In the above-mentioned lifting magnet, it is necessary to install a power supply cable for supplying drive power, an operation switching valve, a generator, and other special equipment on the work vehicle to be mounted. Without the preparation, the lifting magnet cannot be mounted.

In addition, when a material to be adsorbed such as a metal plate is attracted and transferred by a lifting magnet, the magnetism can be reduced if the material to be adsorbed is relatively light due to residual magnetism of the material to be adsorbed even when power supply to the magnet unit is stopped. May not be automatically dropped from the unit, which may hinder the transfer operation. In this case, in order to temporarily apply reverse excitation to the generator, it is sufficient to perform a valve operation such that the hydraulic motor stops after a momentary reverse rotation when the power supply is stopped, but such a valve operation cannot be performed unless a skilled driver is used. It is possible. Hydraulic motor-driven generators generally have large inertia and are not suitable for sudden stops and reversals, causing not only delays in operation, but also damaging hydraulic equipment when sudden high pressure acts on the hydraulic circuit. become.

The present invention has been proposed in order to improve the above-mentioned problems with respect to the conventional lifting magnet, and can be easily mounted on a normal work vehicle having no dedicated equipment. It is an object of the present invention to provide a lifting magnet that can be easily attached to and detached from a cart. Another object of the present invention is to provide a lifting magnet that can quickly and safely carry out the operation of transferring the material to be adsorbed by quickly releasing the material to be adsorbed from the magnet portion when the operation valve of the work cart body is closed. It is.

[0007]

In order to achieve the above object, as shown in FIG. 1, a lifting magnet 1 according to the present invention comprises a work cart such as a backhoe 4 via a bracket 3 above a magnet 2. (FIG. 2), which is detachably mounted, and houses a generator 5 for excitation electrically connected to the magnet unit 2 and a hydraulic motor 7 for driving the generator between a pair of brackets 3 and 3. ing. The work cart on which the lifting magnet 1 is mounted can be applied to not only the backhoe 4 but also a power shovel, a tractor shovel, a truck crane, a crawler crane, and the like.

In the lifting magnet 1, the generator 5 and the hydraulic motor 7 are fixed via a coupling 37 or the like above the magnet unit 2, and when the lifting magnet is mounted on the work cart, the hydraulic motor 7 is mounted on the bracket unit 2. It is connected to the mounting pipe 10 of the work cart via the upper oil connector 8. The pair of brackets 3 and 3 have a height and a width capable of accommodating a small generator 5 for excitation and a hydraulic motor 7 for driving the generator by opposing the generator and the hydraulic motor. This prevents exposure to the outside.

The lifting magnet 1 is provided with an operation valve 31 (FIG. 3) mounted on a work cart such as the backhoe 4.
(See FIG. 1), the magnet section 2 can be excited and demagnetized, and the valves include a control valve branch valve and a service valve. Since the mounting pipe 10 extends to the vicinity of the tip of the arm 17 in the normal backhoe 4, the connection with the oil connector 8 by the hydraulic hose 13 is easy, and the length of the hose 13 depends on the position of the mounting pipe. Should be determined.

The demagnetizing method of the present invention is not limited to the lifting magnet 1 shown in FIG. 1, but can be applied to any lifting device including a generator for excitation electrically connected to the magnet unit and a hydraulic motor. In order to achieve this demagnetization method, as shown in FIGS. 3 and 4, a bypass passage 34 that allows only the flow of hydraulic oil from the return side to the supply side is provided in the hydraulic circuit of the hydraulic motor 32. It is necessary to interpose a circuit switching mechanism 50 including a voltage detection mechanism in an electric connection path between the magnet unit 40 and the generator 36.

The degaussing method of the present invention can also be achieved with the hydraulic and electrical circuits shown in FIGS. FIG.
6, in the hydraulic circuit of the hydraulic motor 32, a bypass passage 34 that allows only the flow of the hydraulic oil from the return side to the supply side, and a pressure detection member (for example, a pressure switch 35) on the supply side are provided. The circuit switching mechanism 70 is interposed in the electrical connection path between the magnet unit and the generator. In addition to the pressure switch 35, a known electric or mechanical pressure detector may be used as the pressure detector.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a lifting magnet 1 according to the present invention
The generator 5 and the hydraulic motor 7 are housed between the three, and the entire apparatus is configured in this manner. For this reason, there is no need to previously install a special generator 5, a hydraulic motor 7, and the like on the main body of the backhoe 4, and the lifting magnet 1 can be mounted on a normal backhoe without special equipment. In the lifting magnet 1, although the weight of the generator 5 and the hydraulic motor 7 burdens the driving of the lifting magnet 1, the generator 5 and the hydraulic motor 7 are much lighter than the lifting magnet 1, so there is almost no effect. .

When the lifting magnet 1 is mounted on the backhoe 4, the hydraulic motor 7 is connected to the mounting pipe 10 of the backhoe 4 via the oil connector 8 on the bracket.
And the connection is completed only by the connection of the oil passage by the two hydraulic hoses 13. In the lifting magnet 1, the magnet unit 2 can be excited and demagnetized using an operation valve 31 generally mounted on the backhoe 4.
The transfer operation by suction and desorption of the material to be adsorbed can be performed in the operation room 14 of the backhoe 4.

In the demagnetizing method according to FIGS. 3 and 4, even if the supply of the hydraulic oil to the hydraulic motor 32 is stopped by switching the operation valve 31, the return side of the hydraulic motor 32 is bypassed to the supply side through the bypass passage 34. And generator 3
Numeral 6 continues to rotate while reducing its output voltage, and supplies power to the magnet unit 40 even during this inertial rotation. As soon as the output voltage of the generator 36 falls below the set value, the circuit switching mechanism is activated by a signal from the voltage detection mechanism. As a result, the electrical connection path to the magnet unit 40 is temporarily reversed to perform reverse excitation. In addition, a material to be adsorbed such as a metal plate is quickly desorbed. The circuit switching mechanism is configured to return to a normal electrical connection after a predetermined time has elapsed.

In the degaussing method shown in FIGS. 5 and 6, even if the supply of the hydraulic oil to the hydraulic motor 32 is stopped by switching the operation valve 31, the output voltage of the generator 36 is gradually reduced as described above. Continue to rotate. When the supply of the hydraulic oil to the hydraulic motor 32 is stopped and the supply oil pressure decreases, the circuit switch mechanism 70 is operated by a signal from the pressure switch 35, so that the electric connection path to the magnet unit 40 is temporarily reversed. The reverse excitation is applied to quickly desorb the adsorbed material.

[0016]

Next, the present invention will be described based on embodiments.
FIG. 1 shows an overall side view of a lifting magnet 1 according to the present invention, and FIG.
An example of the backhoe 4 in a state where is attached.

The lifting magnet 1 has a magnet part 2 of a circular plane arranged horizontally at the lowermost part. The pair of bracket parts 3 and 3 are magnet part 2
The front end of the arm 17 of the backhoe 4 and the front end of the bucket link 18 are respectively pin-connected to the connection pin holes 15 and 16 provided in each bracket portion. The lifting magnet 1 can be freely moved and rotated up and down and back and forth along a vertical plane including the arm 17 and the boom 19 of the backhoe 4 by the expansion and contraction operations of the cylinders of the arm 17, the bucket link 18 and the boom 19 of the backhoe 4. is there.

A small generator 5 and a hydraulic motor 7 are housed between the pair of brackets 3, 3, which are fixed to the upper part of the magnet 2. The generator 5 is connected to the magnet unit 2 by a power supply cable 20, and the generator and the hydraulic motor 7 are arranged to face each other via a coupling 37 or the like. Each port of the hydraulic motor 7 is connected to an oil connector 8 attached to each of the pair of brackets 3 by a hose (not shown). The oil connector is connected to an arm of the backhoe 4 via a hydraulic hose 13. Connect to the installed pipes 10,10. Mounting piping 1
Numeral 0 is previously installed in a normal backhoe for supplying hydraulic pressure to the working machine, and extends from the inside of the main body of the backhoe 4 along the boom 19 and the arm 17 to near the tip of the arm. The hydraulic oil for the mounting pipe 10 also serves as the oil for the hydraulic pump for driving the backhoe 4.

FIGS. 3 and 4 show a hydraulic motor 3 that drives a generator 36 in the lifting magnet 1.
2 shows an example of a hydraulic circuit including a hydraulic circuit 2 and an electric circuit including a generator 36 for controlling excitation and demagnetization of the magnet unit 40. In FIG. 3, the hydraulic motor 32 is a hydraulic hose 1
It communicates with an operation valve 31 in the cab of the backhoe 4 via 3 and 13 and is connected to a hydraulic source 30 from a backhoe driving hydraulic pump and a tank 33 via the operation valve. The bypass passage 34 is short-circuited to the supply side and the return side of the hydraulic motor 32, and only the flow of the hydraulic oil from the return side to the supply side is possible by the check valve 34a of the bypass passage.

FIG. 4 shows the magnet unit 40 and the generator 3
6 shows a circuit switching mechanism 50 including a voltage detecting mechanism interposed in an electrical connection path with the circuit 6. In the circuit switching mechanism 50, the connection terminals 51 and 52 are connected to the output terminals G and H of the generator 36, and the other terminals 43 and 44 are connected to the terminals of the magnet unit 40, respectively. The magnet unit 40 is a known electromagnet in which an electromagnetic coil 42 is wound around an iron core 41, and is excited by a generator 36 to attract and hold the material to be adsorbed.

In this voltage detection mechanism, terminals 51 and 52
, A connection path 53 in which a voltage drop detection relay VR is interposed, a connection path 54 in which a forward connection relay X and an open time delay relay T0 are interposed in parallel, and a connection path in which a reverse connection relay Y is interposed. 55. The connection path 54 has a relay V
The R-a contact VC and the B-contact YC of the relay Y are inserted in series with the relays X and T0 connected in parallel. The connection path 55 has an a contact TC for time-return of the relay T0 and a b contact of the relay X.
The contact XC is inserted in series with the relay Y.

In the circuit switching mechanism 50, the terminal 51-
A relay contact X1 is connected to the connection path 43, a relay contact X2 is connected to the connection path of the terminals 52-44, a relay contact Y1 is connected to the connection path of the terminals 51-44, and a relay contact Y2 is connected to the connection path of the terminals 52-43. Provide. The contacts X1 and X2 are the a contacts of the relay X, and the contacts Y1 and Y2 are the a contacts of the relay Y.

In the lifting magnet 1, the operation valve 31 is switched to start the generator 36, the output voltage rises sharply, and the set value of the detection relay VR (for example, about 17
0 V), the a-contact VC is closed. As a result,
The relay X and the relay T0 are simultaneously excited, and the relay T0
Even if the a-contact TC is closed with a momentary delay, the relay X opens the b-contact XC to prevent the reverse connection relay Y from being energized, and further closes the a-contacts X1 and X2 to close the magnet. The unit 40 is excited.

On the other hand, when the operation valve 31 is switched to the illustrated position, the generator 36 rotates by inertia even when the supply of the hydraulic oil is stopped. Due to this inertial rotation, the hydraulic motor 32
The hydraulic oil is sucked from the supply passages AC, and the oil pressure drops rapidly and the pressure drops below the return passages DB, so that the hydraulic oil passes through the check valve 34a of the bypass passage 34. The generator 36 maintains the inertial rotation by flowing from the return side to the supply side and circulating the hydraulic oil. Then, the output voltage of the generator 36 decreases due to the load of the magnet unit 40, and when the output voltage falls below the set value (for example, 160 V) of the detection relay VR, the a-contact VC is immediately opened. As a result, the relay X and the relay T0 are simultaneously de-energized, and the a contact X
1 and X2 are opened to de-energize the magnet unit 40 and close the b contact XC.

The a-contact TC for time recovery is kept closed for a set time (for example, about 2 seconds) even when the open-time delay relay T0 shifts from excitation to non-excitation. At this time, the connection path 55 is closed, so The connection relay Y is excited. This gives b
Do not operate the positive connection relay X by opening the contact YC.
When the relay Y is excited, the a contacts Y1, Y
2 is closed and the magnet unit 40 is reversely excited. The reverse excitation state of the magnet unit 40 is performed under the inertial rotation of the generator 36, and the voltage rapidly drops as the rotation speed of the generator 36 decreases.
When C returns to the time limit, the connection path 55 is automatically opened, and the magnet section 40 is reliably returned to the non-excitation state. In this way, by reversely exciting the magnet portion 40 for a very short time, the material to be attracted that is to be attracted by the residual magnetism of the magnet portion 40 is reliably desorbed.

FIGS. 5 and 6 show modifications of the hydraulic and electric circuits used in the present invention. In FIG. 5, which is a hydraulic circuit substantially similar to FIG. 3, a bypass passage 34 having a check valve 34a for flowing hydraulic oil from the return side to the supply side is provided, and a pressure switch 35 is provided in the supply paths AC. . The pressure switch 35 serving as a pressure detecting member may be replaced with another known pressure detector.

FIG. 6 shows the magnet unit 40 and the generator 3
6 shows a circuit switching mechanism 70 interposed in an electrical connection path with the circuit 6. In the circuit switching mechanism 70, between the terminals 71 and 72, a connection path 73 having a closed-circuit delay relay Ta interposed, an open-circuit delay relay Tb, a b-contact PS of the pressure switch 35, and an a-contact for timed operation of the relay Ta. T1 and a connection path 74 interposed in series, a reverse connection switching relay S and a relay Tb
And a connection path 75 on which an a-contact T2 for time recovery is interposed. Also, the b-contact S1 of the relay S is connected to the connection path between the terminals 71-43, the b-contact S2 is connected to the terminals 72-44, and the terminal 71-4.
4 is provided with an a contact S3, and the terminals 72-43 are provided with an a contact S4. Each of the contacts S1, S2, S3, and S4 is a switch that operates mechanically in conjunction with each other.

When the operation valve 31 of the lifting magnet is switched, the pressure switch 35 is operated prior to the start of the generator 36, and the b-contact PS connected to the pressure switch is opened. Then, the output voltage of the generator 36 rises and the closed-circuit time delay relay Ta is excited, and even if the contact a T1 is closed after a set time (for example, about 1 second), the connection path 74 is already open. . As a result, since the open-time relay Tb is in the non-excited state, the a-contact T2 is also kept open, the relay S is in the non-excited state, and the contacts S1, S
2, S3 and S4 maintain the state shown in FIG.
Is excited by positive connection.

On the other hand, when the operation valve 31 is switched to the position shown in the figure, the supply of the hydraulic oil is stopped, the generator 36 becomes an inertial rotation, the oil pressure in the supply passages AC decreases, and the pressure switch 35 returns. The contact b is closed. a contact T1
Is already closed, the open time relay Tb is excited to close the a-contact T2, so that the relay S is energized so that the contacts S1, S2, S3 and S4 are reversed from the state shown in the figure. Then, the magnet unit 40 is reversely excited.

The reverse excitation state of the magnet unit 40 is performed under the inertial rotation of the generator 36, and the voltage rapidly drops as the rotation speed of the generator 36 decreases. When the time is restored, the connection path 75 is automatically opened, and the magnet section 40 is reliably returned to the non-excitation state. In this way, the magnet unit 40 is reversely excited for a very short time,
The material to be adsorbed, which should be attracted by the residual magnetism, is surely desorbed. If the voltage drops significantly, the relay Ta is de-energized, and the a-contact T1 returns to open.

[0031]

According to the lifting magnet of the present invention, since the generator and the hydraulic motor are housed between the pair of brackets, the power supply cable for supplying drive electric power to the work cart to be mounted, and the operation switching valve. It is not necessary to attach special equipment such as a generator in advance, and it can be attached to an ordinary backhoe where these equipments are not prepared. With this lifting magnet, there is no problem such as the limitation of operation of the work cart itself and the arm due to the installation of a long power supply cable,
Since the cables are housed in the brackets, no accidents occur due to the breakage or damage of the power supply cables during field work.

The lifting magnet only needs to connect the oil connector of the bracket portion to the mounting pipe of the work vehicle when mounted on the work vehicle, and since no electrical connection is required, the lifting magnet can be easily attached to and detached from the work vehicle. It is.
This lifting magnet can excite and demagnetize the magnet part by using an operation valve generally mounted on the work cart, which facilitates the transfer work by suction and desorption of the material to be adsorbed from the operation room of the work cart. Can be implemented.

According to the demagnetization method of the present invention, even if the supply of the hydraulic oil to the hydraulic motor is stopped, the generator continues to rotate while gradually decreasing its output voltage, and during this inertial rotation, the electric power to the magnet unit is reduced. The connection path is temporarily reversed and reverse excitation is applied to quickly detach the material to be adsorbed such as a metal plate.
When the material to be adsorbed such as a metal plate is sucked and transferred by the lifting magnet, the magnet portion is immediately reverse-excited as soon as the supply of the hydraulic oil is stopped. Fall automatically. In this case, the valve operation itself is exactly the same as usual,
Even an unskilled driver can quickly and safely carry out the operation of transferring the material to be adsorbed, and since a shocking high pressure does not act on the hydraulic circuit when applying the reverse excitation, the installed hydraulic equipment can be used without any trouble for a long time.

[Brief description of the drawings]

FIG. 1 is a side view of a lifting magnet according to the present invention.

FIG. 2 is an overall side view showing a state where the lifting magnet of the present invention is mounted on a backhoe.

FIG. 3 is an explanatory diagram of a hydraulic circuit used in the present invention.

FIG. 4 is an explanatory diagram of an electric circuit used together with the hydraulic circuit of FIG. 3;

FIG. 5 is an explanatory view showing a modification of the hydraulic circuit used in the present invention.

6 is an explanatory diagram of an electric circuit used together with the hydraulic circuit of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lifting magnet 2 Magnet part 3 Bracket part 4 Backhoe 5 Generator for excitation 7 Hydraulic motor 8 Oil connector 10 Mounting piping

Claims (4)

(57) [Claims] 1. A lifting magnet mounted on a work carriage via a bracket portion above a magnet portion, comprising: an excitation generator electrically connected to the magnet portion; and a hydraulic motor driving the generator, inside the bracket portion. And a circuit switching mechanism is interposed in an electrical connection path between the magnet part and the generator, and the magnet part is excited or demagnetized by the operation of a relay or a switch of the circuit switching mechanism, and the generator and the hydraulic motor are magnetized. fixed in the upper parts, by connecting the oil connectors of the hydraulic motor to the pipe attached to the arm of the work carriage performs excitation and demagnetization of the magnet portion by opening and closing the operating valves in work vehicles, power close operation valve Machine output power
A lifting magnet configured to apply a reverse excitation to the magnet part when the pressure decreases . 2. A small generator for excitation and a hydraulic motor for driving the generator are opposed to each other in a bracket portion above the magnet portion, and the generator and the hydraulic motor are connected via a coupling. And the hydraulic pressure of the hydraulic motor
Only the flow of hydraulic oil from the return side to the supply side is possible in the circuit
2. The lifting magnet according to claim 1, wherein a simple bypass passage is provided . 3. A lifting magnet including an excitation generator electrically connected to a magnet unit and a hydraulic motor driving the generator, wherein a lifting oil is supplied from a return side to a supply side in a hydraulic circuit of the hydraulic motor. A power supply is provided by providing a bypass passage that allows only the flow of air, and by interposing a circuit switching mechanism including a voltage detection mechanism in the electrical connection path between the magnet and the generator, and stopping the supply of hydraulic oil to the hydraulic motor. As soon as the rotation speed of the machine decreases and the output voltage decreases, the circuit switching mechanism is actuated by a signal from the voltage detection mechanism.As a result, the electric connection path to the magnet unit is temporarily reversed and reverse excitation is applied. A demagnetizing method for lifting magnets that quickly releases a material to be adsorbed such as a metal plate. 4. A lifting magnet including an excitation generator electrically connected to a magnet unit and a hydraulic motor driving the generator, wherein a lifting oil is supplied from a return side to a supply side in a hydraulic circuit of the hydraulic motor. Supply path and a pressure detection member on the supply side, and a circuit switching mechanism is interposed in the electric connection path between the magnet and the generator to stop the supply of hydraulic oil to the hydraulic motor. As a result, the circuit switching mechanism is actuated by a signal from the pressure detecting member as soon as the supply oil pressure is reduced. As a result, the electrical connection path to the magnet unit is temporarily reversed to apply reverse excitation, and a metal plate or the like is applied. Demagnetizing method of lifting magnet that quickly achieves desorption of the material to be adsorbed.