JP6737545B2 - Lifting magnet device - Google Patents

Description

The present invention relates to a lifting magnet device. More specifically, the present invention relates to a lifting magnet device having a resistor for consuming regenerative power.

BACKGROUND ART Generally, a lifting magnet device for lifting an iron piece in cargo handling work, construction work, etc. is known. This lifting magnet device attracts and releases iron pieces only by exciting and demagnetizing the magnet. When adsorbing the iron piece, the control device supplies electric power for adsorbing to the lifting magnet from the power supply device. When releasing the iron piece, the control device regenerates the supplied electric power to reduce the magnetic energy to zero, and then supplies electric power for releasing the iron piece from the power supply device to the lifting magnet. Then, the control device controls the electric power supplied after the release so that the electric power is regenerated.

Although there is a method of storing electric charge by using a capacitor for the regenerated electric power, a configuration in which a resistor is provided and the regenerated electric power is consumed by this resistance is often adopted (Patent Document 1). That is, after the adsorption is finished and before the electric power for releasing is supplied, the supplied electric power is consumed by the resistor to reduce the magnetic energy to zero. Even when the power for release is supplied, it is required to consume the supplied power by the resistance and keep the magnetic energy to zero.

Here, in a circuit including a regenerative resistor for consuming this regenerative power, if a transistor or the like that opens or closes the circuit fails, either no current flows to the regenerative resistor or a current always flows to the regenerative resistor. become. When no current flows through the regenerative resistor, the voltage of the separately provided capacitor rises, and therefore a failure can be detected by detecting this voltage. However, if a current always flows through the regenerative resistor due to a failure of the transistor, etc., the failure of the transistor cannot be detected because the current flows through the regenerative resistor, just as the transistor operates normally. There is a problem. Moreover, if a current always flows through the regenerative resistor due to a failure of the transistor or the like, the regenerative resistor generates a large amount of heat, and this heat generation causes a problem such as failure of circuit components.

JP, 2010-23955, A

In view of the above circumstances, it is an object of the present invention to provide a lifting magnet device provided with a function capable of detecting an abnormal situation in which a current constantly flows through a regenerative resistor.

A lifting magnet device according to a first aspect of the present invention includes a lifting magnet that generates an attraction force by supplied electric power, a magnet control unit that supplies electric power to the lifting magnet, an input/output of an operation command, an abnormality, and an abnormality. A display/sensing unit for notifying is provided, and the magnet control unit includes a control device that controls the magnet control unit, and a regenerative resistor that consumes regenerative power from the lifting magnet, A state detecting means for detecting the state of the regenerative resistance is provided , and the control device has a physical quantity of the regenerative resistance exceeding a threshold of a predetermined physical quantity, and a time during which the threshold is exceeded. However, when a predetermined time has passed, it is determined that an abnormal state has occurred, and a command is sent to the display/sensing unit to notify the operator of the abnormal state .
A lifting magnet device according to a second invention is characterized in that, in the first invention, the state detecting means is a comparator provided corresponding to the regenerative resistor.
A lifting magnet device according to a third aspect of the present invention is the lifting magnet device according to the first or second aspect of the invention, wherein when the control device determines that there is an abnormal state based on a signal from the state detection means, it stops supplying power to the magnet control section. Is characterized by.

According to the first aspect of the present invention, in the lifting magnet device having the regenerative resistor that consumes the regenerative current, the state detecting means for detecting the state of the regenerative resistor is provided, and the control device receives the signal from the state detecting means to detect the regenerative resistance. A circuit that turns on and off the current to the regenerative resistor by sending a command to the display/sensing unit to notify the abnormal condition when the voltage is constantly applied to the included regenerative resistor circuit. The operator can know that the part is broken. As a result, the operator can remove the broken component and prevent the damage of other circuit components due to the heat generation of the regenerative resistor.
According to the second aspect of the present invention, since the state detecting means is the comparator provided corresponding to the regenerative resistor, it is possible to detect the voltage value applied only to the regenerative resistor and judge the abnormality. It can be reliably detected.
According to the third aspect of the invention, when the control device determines that there is an abnormal state from the signal from the state detection means, it stops the supply of electric power to the magnet control part, without making a large change in the configuration around the magnet control part. The supply of current to the regenerative resistor can be stopped while suppressing the cost of change.

It is a circuit block diagram of a magnet drive circuit which constitutes the lifting magnet device concerning an embodiment of the present invention. It is a block block diagram of the lifting magnet apparatus which concerns on embodiment of this invention. (A) is a graph showing a time waveform of a voltage applied to both ends of a lifting magnet. (B) is a graph showing a time waveform of the current supplied to the lifting magnet.

<Explanation of circuit configuration>
Next, the lifting magnet device 2 according to the embodiment of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description. In addition, in the following description, a transistor includes both a bipolar transistor and a field effect transistor (FET). When the transistor is a FET, the base is read as the gate, the collector is read as the drain, and the emitter is read as the source.

FIG. 2 shows a block configuration diagram of the lifting magnet device 2 according to the present embodiment. The lifting magnet 10 is used as an attachment to the end of the hanging part of the overhead crane installed in the building, to the end of a field excavator (jib crane, gate crane, etc.), or a hydraulic excavator that moves with a crawler. It will be installed. The configuration of the lifting magnet device 2 includes a lifting magnet 10 that attracts and releases iron pieces, a magnet control unit 3 that supplies electric power to the lifting magnet 10, an operation of the magnet control unit 3, and a display/sense for displaying information. The knowledge unit 4 and an AC power supply unit (AC commercial power supply or AC generator) 18 for supplying three-phase AC power to the magnet control unit 3 are provided.

The magnet control unit 3 has a magnet drive circuit 31, a bridge driver 32, a control device 33, and a communication circuit 34. Three-phase AC voltages V _{AC1 to} V _AC3 are supplied from the AC power supply unit 18 to the magnet drive circuit 31. The magnet drive circuit 31 is a circuit that supplies power to the lifting magnet 10, and is configured to include an H bridge circuit that controls the direction of the current flowing through the lifting magnet 10. The bridge driver 32 is a circuit that drives this H-bridge circuit. The control device 33 controls the current and voltage supplied to the magnet 10 via the bridge driver 32.

The control device 33 is composed of, for example, a digital arithmetic processing circuit including a memory that stores a predetermined program and a CPU or a logic circuit that reads and executes the predetermined program. , Through the communication circuit 34. The communication circuit 34 is connected via a wiring 16 to a communication circuit 43 in the display/sensing unit 4 operated by the operator of the lifting magnet device 2, and communicates with the communication circuit 43. In the present embodiment, the magnet drive circuit 31, the bridge driver 32, the control device 33, and the communication circuit 34 are housed in one housing 35.

The display/awareness unit 4 is an input/output device 40 for displaying an input/output of an operation command of the operator and an abnormality on the screen, and an abnormality notification device for making the operator aware of the abnormality when the abnormality occurs. 41 (to generate sound, vibrate the operating lever and chair, and turn on a warning light), a signal processing unit 42, and a communication circuit 43. The input/output/display device 40 has a function of receiving a setting input related to the current and voltage supplied to the lifting magnet 10 from the operator. The abnormality notification device 41 has a function of generating a sound, vibrating an operation lever or a chair, or lighting a warning light to notify an operator of the abnormality. The signal processing unit 42 makes the operator aware of the state of the control device 33 or the like by an image based on the signal received via the communication circuit 43, or via the communication circuit 43 based on the operator's input signal. , Gives a command to the control device 33 of the magnet control unit 3 or sends a signal notifying the abnormality to the abnormality notifying device 41 to make the operator aware of the abnormality of the lifting magnet device 2. The input/output/display device 40, the signal processing unit 42, and the communication circuit 43 are housed in one housing 45.

The magnet operating unit 5 is a device for an operator to operate the exciting operation and the releasing operation of the lifting magnet 10, and is arranged together with the display/awareness unit 4. The magnet operating unit 5 has two switches 51 and 52. One terminals of the switches 51 and 52 are connected to each other, and also connected to the magnet control unit 3 via a wiring 53, and are connected to a constant potential line inside the magnet control unit 3. The other terminals of the switches 51 and 52 are connected to the control device 33 of the magnet control unit 3 via wirings 54 and 55, respectively.

For example, when the operator presses the switch 51, a predetermined potential is transmitted to the control device 33 via the wiring 54, and the control device 33 operates the bridge driver 32 so that the forward direction current (excitation current) is supplied to the lifting magnet 10. Control. Further, when the operator presses the switch 52, a predetermined potential is transmitted to the control device 33 via the wiring 55, and the control device 33 operates the bridge driver 32 so that the reverse current (release current) is supplied to the lifting magnet 10. Control. Alternatively, the control device 33 recognizes only the potential of the wiring 54, and the excitation current is supplied to the lifting magnet 10 when the switch 51 is pressed once, and the release current is supplied to the lifting magnet 10 when the switch 51 is pressed again. May be.

FIG. 1 shows a circuit configuration diagram of a magnet control unit 3 that constitutes a lifting magnet device 2 according to a first embodiment of the present invention. As shown in FIG. 1, the magnet control unit 3 has a DC power supply unit 36 and an H bridge circuit unit 37 that configure the magnet drive circuit 31, in addition to the control device 33 and the bridge driver 32, and further includes a capacitor 38 and a regenerative resistor. 23, a state detection means 24, and a regenerative resistance switch 25.

The DC power supply unit 36 is a circuit portion for converting the three-phase AC voltages V _{AC1 to} V _AC3 supplied from the AC power supply unit 18 into the DC power supply voltage V _DC . The DC power supply unit 36 of this embodiment is composed of a bridge circuit including six diodes 36a to 36f, and performs three-phase full-wave rectification. In addition, the DC power supply unit 36 may be configured by, for example, a pure bridge circuit using a thyristor or a mixed bridge circuit using a diode and a thyristor. When the DC power supply unit 36 is configured by a pure bridge circuit or a mixed bridge circuit, the thyristor is phase-controlled by a phase control circuit (not shown) at a predetermined control angle.

The H-bridge circuit section 37 is a circuit section for controlling the direction of the current supplied to the lifting magnet 10. The H-bridge circuit section 37 is electrically connected between four npn-type transistors 37a to 37d and current terminals (collector-emitter or source-drain) of the four transistors 37a to 37d. The H bridge circuit includes two diodes (flywheels) 37e to 37h and terminals 37i and 37j to which a power cable for supplying a current to the lifting magnet 10 is connected.

Specifically, one current terminal of the transistor 37a is electrically connected to the positive output terminal 36g of the DC power supply unit 36, and the other current terminal of the transistor 37a is electrically connected to the terminal 37i. .. The cable connected to the positive output end 36g of the DC power supply unit 36 is referred to as the positive line 39a. One current terminal of the transistor 37b is electrically connected to the terminal 37i, and the other current terminal of the transistor 37b is electrically connected to the negative output end 36h of the DC power supply unit 36. The cable connected to the negative output end of the DC power supply unit 36 is referred to as the negative line 39b. One current terminal of the transistor 37c is electrically connected to the positive output terminal 36g of the DC power supply unit 36, and the other current terminal of the transistor 37c is electrically connected to the terminal 37j. One current terminal of the transistor 37d is electrically connected to the terminal 37j, and the other current terminal of the transistor 37d is electrically connected to the negative side output end 36h of the DC power supply unit 36. Further, the anodes of the diodes 37e to 37h are electrically connected to the other current terminals of the transistors 37a to 37d, respectively, and the cathodes of the diodes 37e to 37h are electrically connected to the one current terminals of the transistors 37a to 37d, respectively. It is connected to the.

The control terminal (base or gate) of each of the transistors 37a to 37d is electrically connected to the bridge driver 32, and the conduction state between the current terminals of each of the transistors 37a to 37d depends on the control current (provided by the bridge driver 32). Or control voltage). For example, when a control current is supplied to the control terminals of the transistors 37a and 37d, an exciting current in one direction flows in the order of the transistor 37a, the terminal 37i, the lifting magnet 10, the terminal 37j, and the transistor 37d. When a control current is provided to the control terminals of the transistors 37b and 37c, a degaussing current in a certain direction and a reverse direction flows in the order of the transistor 37c, the terminal 37j, the lifting magnet 10, the terminal 37i, and the transistor 37b.

The bridge driver 32 makes any of the transistors 37a to 37d conductive according to the output signal of the control device 33. The control device 33 determines which of the transistors 37a to 37d is made conductive based on the signal provided from the magnet operating unit 5 shown in FIG. Further, the bridge driver 32 intermittently turns on the transistors 37a to 37d as necessary, and adjusts the voltage supplied to the lifting magnet 10 by pulse width modulation (PWM). The pulse width of this PWM is controlled by the control device 33.

The capacitor 38 is provided to reduce ripples in the exciting current to the lifting magnet 10. The capacitor 38 is electrically connected between the positive output end 36g and the negative output end 36h of the DC power supply unit 36.

The first current measuring unit 21 is a measuring device that measures the magnitude of the current supplied to the lifting magnet 10, and is provided between the H bridge circuit in the H bridge circuit unit 37 and the lifting magnet 10. The second current measuring means 22 is a current measuring means provided on at least one of the positive side line 39a and the negative side line 39b.

The regenerative resistor 23 is a resistor that consumes the regenerative power from the lifting magnet 10, and has a capacity sufficient to consume the expected regenerative power. The regenerative resistor 23 does not need to be composed of one resistor, and it is also possible to arrange a plurality of resistors in parallel. The regenerative resistor 23 is electrically connected to the positive output terminal 36g and the negative output terminal 36h of the DC power supply unit 36.

The state detection means 24 is a device for detecting the state of the regenerative resistor 23. In the present embodiment, the state detecting means 24 is a comparator that detects the voltage across the regenerative resistor 23 and sends a signal when a voltage value higher than a voltage value given in advance is detected. The transmitted signal is received by the control device 33.

The regenerative resistance switch 25 is turned on and off at a prescribed timing so that the electric power supplied to the lifting magnet 10 can be regenerated by a command from the control device 33.

The breaker 26 is a device that cuts off the connection between the AC power supply unit 18 and the DC power supply unit 36, and is provided between the AC power supply unit 18 and the DC power supply unit 36.

<Operation of magnet drive circuit 31 in normal time>
Here, the operation of the magnet drive circuit 31 during normal operation will be described. FIG. 3A is a graph showing the time waveform of the voltage applied across the lifting magnet 10, and FIG. 3B is a graph showing the time waveform of the current supplied to the lifting magnet 10. FIG. 3B shows the result measured by the first current detector 21. Although the voltage applied to the lifting magnet 10 is adjusted by PWM as described above, FIG. 3A shows the value of the effective voltage obtained by averaging the voltage changes in PWM over time. .. Regarding the signs of the voltage and the current in FIGS. 3A and 3B, the direction of the exciting current in FIG. 2 (the direction in which the current flows from the terminal 37i to the lifting magnet 10) is positive.

First, at a certain time t0, the AC power supply unit 18 supplies the DC power supply unit 36 with the three-phase AC voltages V _{AC1 to} V _AC3 . The three-phase AC voltages V _{AC1 to} V _AC3 are converted into a DC power supply voltage V _DC by the DC power supply unit 36. Subsequently, when the operator presses the switch 51 (or 52) of the magnet operating unit 5 (time t1), the control device 33 starts exciting the lifting magnet 10. That is, the bridge driver 32, which receives the instruction from the control device 33, causes the transistors 37a and 37d of the H bridge circuit unit 37 to be conductive. As a result, an exciting current flows through the lifting magnet 10.

The control device 33 sets the excitation voltage (effective value) to the maximum value V _OS by setting the PWM duty ratio to 100% of the maximum in the first period T ₁ . This period T ₁ is referred to as an overshoot period (OS period), and is a period for raising the exciting current I 1 to the lifting magnet 10 in a short time. Further, in the period T ₂ subsequent to the period T ₁ , the control device 33 reduces the PWM duty ratio from the maximum (for example, 90%) and sets the excitation voltage (effective value) to V _OE (<V _OS ). .. This period T ₂ is referred to as an overexcitation period (OE period), and is a period in which the magnetic force of the lifting magnet 10 is temporarily increased so that the suspended load can be easily captured. Further, the control device 33 further reduces the duty ratio of the PWM and sets the excitation voltage (effective value) to V _RA (<V _OE ) in the period T ₃ subsequent to the period T ₂ . It referred to the period T ₃ the rated exciting period, a period for maintaining the excited state while supplying power near rated power of the lifting magnet 10. Incidentally, the rated exciting period T ₃ is continued until the process proceeds to the next release operation.

By supplying such exciting power to the lifting magnet 10, the lifting magnet 10 is excited, and it becomes possible to adsorb and lift a suspended load such as an iron piece.

Then, the operation for releasing the iron piece or the like from the lifting magnet 10 is started. When the operator presses the other switch 52 (or 51) of the magnet operating unit 5 (time t2), the control device 33 starts demagnetizing the lifting magnet 10. That is, first, the control device 33 makes all the transistors 37a to 37d forming the H-bridge circuit section 37 non-conductive, and also makes the regenerative resistance switch 25 conductive so that the electric power remaining in the lifting magnet 10 is regenerated. Consume at. The power consumed by the regenerative resistor 23 is the portion represented by the power consumption K1 in FIG. Then, the bridge driver 32, which receives the instruction from the control device 33, turns off the transistors 37a and 37d and the regenerative resistor switch 25 of the H bridge circuit section 37, and turns on the transistors 37b and 37c. As a result, the direction of the current flowing through the lifting magnet 10 is reversed, and the release current flows (time period T ₄ ). This release current approaches a predetermined value with a certain time constant due to the influence of the inductance of the lifting magnet 10. As a result, the lifting magnet 10 and the suspended load are demagnetized, and the suspended load is released.

When the magnitude of the release current reaches the set value I _LM , the control device 33 makes all the transistors 37a to 37d of the H bridge circuit unit 37 non-conductive, makes the regenerative resistance switch 25 conductive for a certain period of time, and lifts the magnet. The power remaining in 10 is consumed by the regenerative resistor 23. The power consumed by the regenerative resistor 23 is the portion represented by the power consumption K2 in FIG. Then, after the regenerative power is consumed (period T ₅ ), the regenerative resistor switch 25 is made non-conductive and the power supply is stopped like the transistors 37 a to 37 d forming the H-bridge circuit section 37.

<Operation of the magnet drive circuit 31 at the time of abnormality>
Next, the operation of the magnet drive circuit 31 at the time of abnormality will be described. The "at the time of abnormality" as used herein means a time when the regenerative resistance switch 25 is damaged and an abnormal state in which a voltage is constantly applied to the regenerative resistance circuit including the regenerative resistance occurs.

The state detection means 24, which is a comparator, sends a signal to the control device 33 when the voltage applied to the regenerative resistor exceeds a predetermined voltage value. The control device 33 determines that the regenerative resistance circuit is in an abnormal state in which a voltage is constantly applied to the regenerative resistance circuit when the signal from the state detection means 24 has passed a predetermined time. A voltage is applied to the regenerative resistor 23 even in the normal operation, but in the normal operation, since the voltage is added to consume the regenerative power, the consumption time is relatively short. Therefore, the control device 33 inputs in advance a time longer than the time for consuming regenerative electric power in normal times, and the control device 33 constantly applies a voltage to the regenerative resistance circuit based on this input value. It is determined whether there is an abnormal condition.

Then, when the regenerative resistance circuit is in the abnormal state, the control device 33 makes the operator aware of this abnormal state. There are various means for making an alarm, but in the present embodiment, for example, an alarm is issued from the abnormality notification device 41 provided in the display/awareness unit 4, or an abnormality is detected in the input/output/display device 40. The operator is notified by displaying a message. In addition, in the present embodiment, when the regenerative resistance circuit is in an abnormal state, the control device 33 causes the breaker 26 provided between the AC power supply unit 18 and the DC power supply unit 36 to remove the power from the AC power supply unit 18. Turn off the power. Note that this shutoff operation is performed in consideration of safety around the lifting magnet 10 such as whether or not the lifting magnet 10 is lifting the transported object after the control device 33 determines that the regenerative resistance circuit is in an abnormal state. Be seen.

In the lifting magnet device 2 having the regenerative resistor 23 that consumes regenerative power, the state detecting means 24 for detecting the state of the regenerative resistor 23 is provided, and the control device 33 receives the signal from the state detecting means 24 to cause the regenerative resistor 23 to operate. By determining whether or not there is an abnormal state in which a voltage is constantly applied to the included regenerative resistor circuit, and notifying the operator, the circuit component that turns on and off the current to the regenerative resistor 23 is broken. The operator can know. As a result, the operator can remove the broken component and prevent damage to other circuit components due to heat generation of the regenerative resistor 23.

Since the state detecting means 24 is a comparator provided corresponding to the regenerative resistor 23, it is possible to detect an abnormal condition by detecting a voltage value or the like applied only to the regenerative resistor 23, so that the abnormal state is surely detected. be able to.

When the control device 33 determines that the voltage applied to the regenerative resistor 23 exceeds a predetermined voltage value and the time when the voltage exceeds the predetermined value is an abnormal state, the temperature, etc. It is possible to detect an abnormality in a short time as compared with a parameter that requires time until the abnormality is detected.

When the control device 33 determines that there is an abnormal state based on the signal from the state detection means 24, it stops the supply of electric power to the magnet control unit 3 to change the configuration around the magnet control unit 3 without making a large change. It is possible to stop the supply of the current to the regenerative resistor 23 while suppressing the cost.

In the present embodiment, the comparator for measuring the voltage is used as the state detecting means 24, but the present invention is not limited to this. For example, a voltmeter that detects the voltage value applied to the regenerative resistor 23, an ammeter that measures the current flowing through the regenerative resistor 23, or a thermometer that measures the temperature of the regenerative resistor 23 can be used. When the state detecting means 24 is a device that only detects such a physical quantity and transmits a signal corresponding to the physical quantity, the control device 33 determines whether or not the physical quantity threshold value is exceeded, and when the physical quantity threshold value is exceeded. It is determined whether or not the regenerative resistance circuit is in an abnormal state, depending on whether or not the time exceeds the predetermined time.

It is also possible to provide a dedicated control device for receiving a signal from the state detecting means 24. In this case, the dedicated control device constitutes a part of the control device 33.

As the state detecting means 24, it is possible to use, for example, the second current detector 22 which is conventionally provided in the magnet control section 3. In this case, if an abnormal state in which a voltage is constantly applied to the regenerative resistor 23, a current larger than the current during normal operation is detected by the second current detector 22. When the time during which a current larger than the current during the normal operation flows exceeds a predetermined time, the control device 33 determines that the regenerative resistance circuit is in an abnormal state. Alternatively, it may be determined that the regenerative resistor circuit is in an abnormal state because a current equal to or larger than a predetermined current value flows in the second current detector 22 when the signal for adding the suction voltage is not output. It is possible.

In the present embodiment, when the regenerative resistance circuit is in an abnormal state, the breaker 26 provided between the AC power supply unit 18 and the DC power supply unit 36 cuts off the power from the AC power supply unit 18. The method of stopping the power supply to the magnet control unit is not limited to this. For example, when the DC power supply unit 36 is a thyristor, it is possible to stop the operation by stopping the operation of this portion. Further, it is also possible to cut off by stopping the operation of the device element for cutting off the direct current provided from the direct current power supply unit 36 to the regenerative resistance circuit.

3 Magnet Control Section 4 Display/Sensing Section 10 Lifting Magnet 23 Regenerative Resistance 24 State Detection Means 33 Control Device

Claims (3)

A lifting magnet that generates an attractive force by the supplied power,
A magnet control unit for supplying electric power to the lifting magnet,
It is equipped with a display/sensing unit that displays input/output of operation commands and abnormalities, and notifies of abnormalities,
The magnet control unit has
A controller for controlling the magnet controller,
A regenerative resistor that consumes regenerative power from the lifting magnet,
State detecting means for detecting the state of the regenerative resistor,
Is provided ,
The control device is
The physical quantity of the regenerative resistance exceeds a threshold of a predetermined physical quantity,
And, when the time exceeding the threshold value exceeds a predetermined time, it is determined as an abnormal state,
Sending a command to the display/sensing unit to sense an abnormal condition,
Lifting magnet device characterized in that. The state detection means is a comparator provided corresponding to the regenerative resistance,
The lifting magnet device according to claim 1, wherein: The control device is
When it is determined that the state is abnormal by the signal from the state detecting means,
Stopping the supply of power to the magnet control unit,
The lifting magnet device according to claim 1 or 2 , wherein.

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