JP2008265997A - Lifting magnet driving circuit and lifting magnet device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lifting magnet driving circuit and a lifting magnet device capable of reducing reduction in attraction force caused by a temperature rise in a lifting magnet. <P>SOLUTION: This magnet driving circuit 30 generates electric power for exciting a magnet 10. The magnet driving circuit 30 has a control part 33 and a current measuring part (a temperature detecting means) 39. The control part 33 controls exciting voltage to the magnet 10 in voltage exceeding predetermined voltage in a first period just after starting excitation, and is controlled in the predetermined voltage in a second period after the first period. The control part 33 also lengthens the first period in response to the temperature rise in the magnet 10 by inputting a signal from the current measuring part 39. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lifting magnet driving circuit and a lifting magnet device.

Generally, a lifting magnet for lifting an iron piece in cargo handling work or construction work is known. Some lifting magnets are installed in factories and others, and others are installed in vehicles. When a lifting magnet is used, current is passed through a coil to excite it, and an iron piece is attracted to the coil and lifted. When releasing the iron piece, the coil is demagnetized by passing a current in the opposite direction. Patent Document 1 describes a control device that supplies such a current for excitation and release to a lifting magnet. Moreover, the structure of a general lifting magnet is described in Patent Document 2, for example.
Japanese Patent Laid-Open No. 6-183681 JP 2004-168545 A

  When a current is continuously passed through the coil of the lifting magnet for a long time, the temperature gradually rises due to Joule heat. Moreover, the electrical resistance value of the coil increases as the temperature of the coil increases. Therefore, when the lifting magnet is continuously used, the coil temperature rises, the supply current gradually decreases, and the attractive force decreases.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a lifting magnet drive circuit and a lifting magnet device that can reduce a decrease in attractive force accompanying a temperature increase of the lifting magnet.

  In order to solve the above-described problem, a first lifting magnet driving circuit according to the present invention is a lifting magnet driving circuit that generates electric power for exciting a lifting magnet, and starts exciting the excitation voltage to the lifting magnet. A control unit that controls a voltage exceeding a predetermined voltage in the first period immediately after, and a control unit that controls the excitation voltage to a predetermined voltage in a second period after the first period, and outputs a signal corresponding to the temperature of the lifting magnet And a temperature detecting unit that receives the signal from the temperature detecting unit and lengthens the first period in accordance with the temperature rise of the lifting magnet.

  The second lifting magnet drive circuit according to the present invention is a lifting magnet drive circuit that generates electric power for exciting the lifting magnet, and applies an excitation voltage to the lifting magnet in the first period immediately after the start of excitation. A control unit that controls the excitation voltage to a predetermined voltage in a second period after the first period, and a temperature detection unit that outputs a signal corresponding to the temperature of the lifting magnet; The control unit receives a signal from the temperature detection means, and controls the excitation voltage in the second period to a voltage higher than a predetermined voltage according to the temperature rise of the lifting magnet.

  The third lifting magnet driving circuit according to the present invention is a lifting magnet driving circuit that generates electric power for exciting the lifting magnet, and applies an excitation voltage to the lifting magnet in a first period immediately after the start of excitation. A control unit that controls the excitation voltage to a predetermined voltage in a second period after the first period, and a temperature detection unit that outputs a signal corresponding to the temperature of the lifting magnet; The control unit receives a signal from the temperature detection means, and lengthens the first period and controls the excitation voltage in the second period to a voltage higher than a predetermined voltage according to the temperature rise of the lifting magnet. And

  There are the following methods for exciting the lifting magnet. First, immediately after the start of excitation, a voltage higher than the rated voltage is applied to the lifting magnet to raise the excitation current in a short time. Thereafter, the applied voltage is lowered, and the excited state is maintained while applying the rated voltage to the lifting magnet. The above-described first to third lifting magnet drive circuits include a control unit for exciting the lifting magnet in this way.

  In the first and third lifting magnet drive circuits, the control unit performs a first period (that is, a period during which a voltage higher than the rated voltage is applied) immediately after the start of excitation according to the temperature rise of the lifting magnet. Lengthen. As a result, when the coil temperature rises and the electrical resistance value of the coil increases, the excitation current increases as compared with the case where the length of the first period is constant. Can reduce power loss. In the second and third lifting magnet drive circuits, the control unit controls the excitation voltage in the second period to a voltage higher than a predetermined voltage in accordance with the temperature rise of the lifting magnet. As a result, when the coil temperature rises and the electrical resistance value of the coil increases, the excitation current increases as compared with the case where the predetermined voltage is supplied in the second period. Can be reduced.

  Further, the first to third lifting magnet driving circuits may be characterized in that the temperature detection means generates the signal based on the magnitude of the current flowing through the lifting magnet. When the temperature of the lifting magnet rises, the electrical resistance value of the coil rises (increases). Therefore, according to this lifting magnet drive circuit, the temperature detection means can suitably generate a signal corresponding to the temperature of the lifting magnet.

  A first lifting magnet device according to the present invention includes a lifting magnet and any one of the first to third lifting magnet drive circuits described above, and the lifting magnet has an inner pole extending in a predetermined axial direction, and around a predetermined axis. The ferromagnetic main body including the outer pole provided around the inner pole and the inner pole provided between the inner pole and the outer pole, and the inner pole and the inner pole are disposed between the inner pole and the predetermined pole. It has the 1st coil wound around the axis line, and the 2nd coil wound around the predetermined axis line is arranged between the interpole and the outer pole.

  The second lifting magnet device according to the present invention includes a lifting magnet and any one of the first to third lifting magnet driving circuits described above, and the lifting magnet includes the first and second coils, and the first coil. And a case containing the second coil, a fixing material for fixing the first and second coils in the case, and a material having a higher thermal conductivity than the fixing material, the first coil and the second coil And a heat conducting plate disposed between the two.

  A third lifting magnet device according to the present invention includes a lifting magnet and any one of the first to third lifting magnet drive circuits described above. The lifting magnet includes a coil, a case that houses the coil, and a coil. It has a fixing material for fixing the inside of the case, and a heat conducting plate made of a material having a higher thermal conductivity than the fixing material and disposed between the case and the coil.

  When the exciting current is increased in accordance with the temperature rise of the lifting magnet, Joule heat is further generated, and the temperature of the lifting magnet further rises. For example, in the case of the conventional lifting magnet shown in Patent Document 2, the temperature rise rate of the lifting magnet with respect to the increase of the excitation current is high, and the increase width of the excitation current is limited to be small. On the other hand, in the above-described first to third lifting magnet devices, the lifting magnet has a structure for improving heat dissipation such as an intermediate electrode and a heat conducting plate, so the temperature increase rate of the lifting magnet is low. It can be suppressed. Therefore, according to the 1st-3rd lifting magnet apparatus, the increase width of the exciting current according to the temperature rise of a lifting magnet is enlarged, and the said effect by the 1st-3rd lifting magnet drive circuit is made more effective. It can be demonstrated.

  According to the lifting magnet driving circuit and the lifting magnet device according to the present invention, it is possible to reduce the decrease in the attractive force accompanying the temperature increase of the lifting magnet.

  Embodiments of a lifting magnet driving circuit and a lifting magnet device according to the present invention will be described below in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In the following description, a transistor includes both a bipolar transistor and a field effect transistor (FET). When the transistor is an FET, the base is read as the gate, the collector as the drain, and the emitter as the source.

  FIG. 1 is a diagram showing a configuration of a lifting magnet device (hereinafter referred to as a magnet device) 1 according to the present embodiment. The magnet device 1 includes a lifting magnet (hereinafter referred to as a magnet) 10 and a lifting magnet drive circuit (hereinafter referred to as a magnet drive circuit) 30.

  The magnet drive circuit 30 is a circuit that generates electric power for exciting the magnet 10, and includes a bridge driver 32, a control unit 33, a DC conversion unit 36, an H bridge circuit unit 37, a capacitor 38, and a current measurement unit 39. ing.

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

  The H-bridge circuit unit 37 is a circuit part for controlling the direction of the current supplied to the magnet 10. The H-bridge circuit unit 37 includes four npn transistors 37a to 37d and four diodes electrically connected between current terminals (collector-emitter or source-drain) of the four transistors 37a to 37d. (Rectifier elements) 37e to 37h and H bridge circuits including terminals 37i and 37j to which wires 31a and 31b for supplying current to the magnet 10 are connected.

  Specifically, one current terminal of the transistor 37a is electrically connected to the positive output terminal 36g of the DC converter 36, and the other current terminal of the transistor 37a is electrically connected to the terminal 37i. . One current terminal of the transistor 37 b is electrically connected to the terminal 37 i, and the other current terminal of the transistor 37 b is electrically connected to the negative output terminal 36 h of the DC conversion unit 36. One current terminal of the transistor 37c is electrically connected to the positive output terminal 36g of the DC converter 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 output terminal 36h of the DC converter 36. The anodes of the diodes 37e to 37h are electrically connected to the other current terminals of the transistors 37a to 37d, respectively. 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 terminals (bases or gates) of the transistors 37a to 37d are electrically connected to the bridge driver 32, and the conduction state between the current terminals of the transistors 37a to 37d is a control current (from the bridge driver 32). Or control voltage). For example, when the control current to the control terminal of the transistor 37a and 37d are provided, the exciting current _{I 1} in the positive direction, the transistor 37a, the terminal 37i, the magnet 10, through the terminal 37j, and the order of the transistor 37d. Further, when the control current to the control terminal of the transistor 37b and 37c are provided, reverse release current (demagnetizing current) _{I 2} is, transistor 37c, the terminal 37j, magnet 10, the terminal 37i, and the order of the transistor 37b (i.e. , opposite to) flows to the excitation current _{I 1.}

  The control unit 33 determines which of the transistors 37a to 37d is turned on in accordance with the excitation operation or release operation by the operator. The control unit 33 controls the voltage applied to the magnet 10 via the bridge driver 32. The bridge driver 32 is a circuit for driving the H bridge circuit unit 37, and makes any of the transistors 37 a to 37 d conductive according to the output signal of the control unit 33. Further, the bridge driver 32 intermittently turns on the transistors 37a to 37d as necessary, and adjusts the voltage supplied to the magnet 10 by pulse width modulation (PWM). The PWM pulse width is controlled by the control unit 33. The control unit 33 is configured by a digital arithmetic processing circuit including, for example, a memory that stores a predetermined program and a CPU that reads and executes the predetermined program.

The capacitor 38 is provided to absorb and regenerate energy accumulated in the magnet 10 when the exciting current I ₁ to the magnet 10 is switched to the release current I ₂ . The capacitor 38 is electrically connected between the positive output terminal 36g and the negative output terminal 36h of the DC converter 36.

  The current measuring unit 39 is a temperature detecting unit in the present embodiment, and outputs a signal corresponding to the temperature of the magnet 10 (hereinafter referred to as magnet temperature). The current measurement unit 39 according to the present embodiment includes a shunt resistor 39a provided in series with the wiring 31b, and outputs the voltage across the shunt resistor 39a to the A / D converter 39b. In addition, the current measurement unit 39 may be configured by a circuit using a current sensor, for example. A signal (a voltage across the shunt resistor 39a) output from the current measuring unit 39 indicates the magnitude of the current flowing through the magnet 10. Since the electrical resistance value of the coil of the magnet 10 tends to increase (increase) when the magnet temperature rises, the output signal of the current measuring unit 39 becomes a value corresponding to the magnet temperature. The A / D converter 39 b converts this signal into a digital signal and provides the digital signal to the control unit 33.

Next, operations (excitation operation and release operation) of the magnet drive circuit 30 will be described. 2A shows a time waveform of the excitation (release) voltage applied to the magnet 10, and FIG. 2B shows a time waveform of the excitation (release) current supplied to the magnet 10. Yes. As described above, the excitation voltage to the magnet 10 is adjusted by the PWM, but FIG. 2A shows the value of the effective voltage obtained by averaging the voltage change in the PWM over time. Also, FIG. 2 (a), the the sign of the voltage and current in (b) is in the direction of the excitation current I ₁ shown in FIG. 1 as positive.

First, at a certain time t ₀ , the AC generator ACG is driven to provide the DC converter 36 with the three-phase AC power supply voltages V _{AC1 to} V _AC3 . The AC power supply voltages V _{AC1 to} V _AC3 are converted into the DC power supply voltage V _DC by the DC conversion unit 36. Subsequently, when the operator operates a magnet excitation switch or the like (time t ₁ ), the control unit 33 starts exciting the magnet 10. In other words, the bridge driver 32 that has received an instruction from the control unit 33 causes the transistors 37 a and 37 d of the H bridge circuit unit 37 to conduct. As a result, the exciting current I ₁ flows through the magnet 10.

Control unit 33, in the period _{T 1} of the immediately following excitation start, exciting voltage the duty ratio of the PWM to 100% of the maximum rms and maximum value _{V OS.} The period T ₁ called overshoot period (OS period) is a period for starting up the exciting current I ₁ to the magnet 10 in a short time. Further, the control unit 33 reduces the PWM duty ratio from the maximum (for example, 90%) in the period T ₂ following the OS period T ₁ , and sets the excitation voltage (effective value) to V _OE (<V _OS ). To do. The period T ₂ designated as over-excited period (OE period) is a period during which temporarily increase the magnetic force of the magnet 10 so that the suspended load can be easily captured. Note that the first time period described in the claims, in the present embodiment, refers to a period in which the OS period T ₁ and OE period T _2. Further, the excitation voltages V _OS and V _OE both have a magnitude exceeding the rated voltage (predetermined voltage) of the magnet 10. As the excitation voltage is temporarily increased in the OS period T ₁ and the OE period T ₂ , the excitation current I ₁ is larger than the rated current I _RA as shown in FIG. 2B. _OE is reached.

Control unit 33, in the next period _{T 3} of OE period _{T 2,} and further reduce the duty ratio of the PWM, and the excitation voltage (effective value) of the predetermined rated voltage _V RA _{(<V OE).} The period T ₃ is referred to as a rated exciting period, a period for maintaining the excited state while supplying an excitation voltage of the rated voltage (predetermined voltage) around the magnet 10. In this rating exciting period _{T 3,} by the rated voltage _{V RA} is applied, the exciting current _{I 1} is the rated current _{I RA.} Incidentally, the rated exciting period T ₃ is the second period in the present embodiment is continued until the process proceeds to the next release operation.

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

Subsequently, the operation moves to release (release) the iron pieces from the magnet 10. When the operator operates a magnet release switch or the like (time t ₂ ), the control unit 33 starts demagnetization of the magnet 10. That is, the bridge driver 32 that has received an instruction from the control unit 33 turns off the transistors 37a and 37d of the H bridge circuit unit 37 and turns on the transistors 37b and 37c. As a result, the direction of the current of the magnet 10 is reversed, and the release current I ₂ flows (period T ₄ ). The release current I ₂ approaches a predetermined value with a certain time constant due to the influence of the inductance of the magnet 10. Thereby, the magnet 10 and the suspended load are demagnetized, and the suspended load is released. Control unit 33, the magnitude of the release current I ₂ reaches a certain set value, and stops power supply to the transistors 37b and 37c of the H-bridge circuit portion 37 as a non-conductive.

Here, when the magnet 10 is continuously used, the magnet temperature gradually increases due to Joule heat. Since the electrical resistance value of the coil that constitutes the magnet 10 increases as the coil temperature rises, the supply current gradually decreases as the coil temperature rises. Thus, the conventional magnet apparatus, the magnet temperature rises, and decrease the exciting current is as shown in the graph Gb in FIG. 2 (b), the magnitude of the OE current becomes I _OE smaller I _OE1 described above . The size of the excitation current in the period _{T 3} also becomes a rated current _{I RA} smaller than _{I RA1.} Therefore, the control unit 33 of the present embodiment performs any one of the following first to third operations.

[First operation]
The control unit 33 inputs a signal corresponding to the magnet temperature from the current measurement unit 39, and determines whether or not the magnet temperature exceeds the set temperature based on this signal. Then, the control unit 33, when the magnet temperature exceeds the set temperature, a longer first period when the OS period T ₁ and OE period T _2. Here, FIG. 3 is a graph showing time waveforms of (a) excitation voltage and (b) excitation current in this operation. In FIGS. 3A and 3B, graphs G1 and G2 indicate cases where the control unit 33 performs the first operation. The graph Ga is the same as the graph shown in FIG. 2A, and the graph Gb is the same as the graph Gb shown in FIG.

Control unit 33, the magnet temperature exceeds the rising to the set temperature, as shown in FIG. 3 (a), OS period T ₁ and at least one greater than the previous temperature rise (OS period each OE period T ₂ T ₁₁ and OE period T ₂₁ ) are set. That is, (T ₁₁ + T ₂₁ )> (T ₁ + T ₂ ). As a result, the time during which the excitation voltages V _OS and V _OE exceeding the rated voltage of the magnet 10 are applied to the magnet 10 becomes longer, and the magnitude of the OE current reaches I _OE2 as shown in FIG. . This value _{I OE2} is greater than the value _{I OE1} if that does not change the OS period _{T 1} and OE period _{T 2.}

When the above action is shown quantitatively, for example, a magnet 10 having a diameter of 1300 [mm] and a rated current I _RA = 56 [A] is used, the output of the AC generator ACG is 220 [V], and V _OS = When 290 [V], V _OE = 240 [V], and V _RA = 200 [V] (V _OS , V _OE , and V _RA are effective values), the OE current I _OE at a magnet low temperature is, for example, 67 [A] is set. As the temperature of the magnet 10 rises, the OE current in the conventional magnet driving circuit changes to, for example, I _OE1 = 61 [A], and the current value in the rated excitation period T ₃ changes to, for example, I _RA1 = 38 [A]. Suppose you were. In such a case, when the OS period and the OE period are set to T ₁₁ and T ₂₁ shown in FIG. 3A, the OE current _IOE2 is 64 [A], which is 3 [A] compared to the conventional magnet drive circuit. ]To increase. The lengths of the periods T ₁ , T ₂ , T ₁₁ , and T ₂₁ are 3 seconds, 3 seconds, 5 seconds, and 10 seconds, respectively.

As described above, the control unit 33 lengthens the first period (T ₁ + T ₂ ) immediately after the start of excitation, that is, the period during which the voltage higher than the rated voltage is applied, as the magnet temperature increases, so that the magnet temperature is increased. When the electrical resistance value of the coil increases and increases, the excitation current increases as compared with the case where the length of the period (T ₁ + T ₂ ) is constant. Therefore, it is possible to reduce the decrease in the attractive force accompanying the increase in the magnet temperature.

[Second operation]
The control unit 33 inputs a signal corresponding to the magnet temperature from the current measurement unit 39, and determines whether or not the magnet temperature exceeds the set temperature based on this signal. Then, the control unit 33, when the magnet temperature exceeds the set temperature, the excitation voltage at the rated exciting period T _3, is controlled to a voltage higher than the rated voltage V _RA. Here, FIG. 4 is a graph showing time waveforms of (a) excitation voltage and (b) excitation current in this operation. In FIGS. 4A and 4B, graphs G3 and G4 show the case where the control unit 33 performs the second operation. The graphs Ga and Gb are the same as those in FIG.

Control unit 33, the magnet temperature exceeds the set temperature rises, as shown in FIG. 4 (a), controls the excitation voltage at the rated exciting period T ₃ in the high voltage V _RA3 than the rated voltage V _RA. Thus, the magnitude of the exciting current at the rated exciting period _{T 3} as shown in FIG. 4 (b) is _{I RA3.} This value _{I RA3} is greater than the value _{I RA1} in the case of the rated voltage _{V RA} excitation voltage at the rated exciting period _{T 3.} For example, if the excitation voltage in the rated excitation period T ₃ is set to V _RA3 = 220 [V] under the same conditions as described quantitatively in the first operation, the excitation current becomes I _RA3 = 41 [A], It increases by 3 [A] compared to the conventional magnet drive circuit.

Thus, the control unit 33, in response to an increase in the magnet temperature, by controlling the excitation voltage at the rated exciting period T ₃ in the high voltage V _RA3 than the rated voltage V _RA, electrical coil magnet temperature rises when the resistance value is increased, the exciting current is increased as compared with the case continue to supply the rated voltage V _RA to the rated exciting period T _3. Therefore, it is possible to reduce the decrease in the attractive force accompanying the increase in the magnet temperature.

[Third operation]
The control unit 33 inputs a signal corresponding to the magnet temperature from the current measurement unit 39, and determines whether or not the magnet temperature exceeds the set temperature based on this signal. Then, the control unit 33, when the magnet temperature exceeds the set temperature, the longer the first time period consisting OS period T ₁ and OE period T _2, the excitation voltage at the rated exciting period T _3, the rated voltage Control to a voltage higher than _VRA . Here, FIG. 5 is a graph showing time waveforms of (a) excitation voltage and (b) excitation current in this operation. In FIGS. 5A and 5B, graphs G5 and G6 indicate cases where the control unit 33 performs the third operation. The graphs Ga and Gb are the same as those in FIG.

When the magnet temperature rises and exceeds the set temperature, the control unit 33 makes at least one of the OS period T ₁ and the OE period T ₂ longer than before the temperature rise (each OS period), as shown in FIG. T ₁₁ and OE period T ₂₁ ) are set, and the excitation voltage in the rated excitation period T ₃ is controlled to a voltage V _RA3 higher than the rated voltage V _RA . As a result, the magnitude of the OE current reaches I _OE2 (> I _OE1 ) as shown in FIG. The size of the excitation current at the rated exciting period _{T 3} becomes _I RA3 _{(> I RA1).}

In this way, the control unit 33 lengthens the first period (T ₁ + T ₂ ) immediately after the start of excitation according to the increase in the magnet temperature, and the excitation voltage in the rated excitation period T ₃ according to the increase in the magnet temperature. Is controlled to the voltage V _RA3 (> V _RA ), the excitation current when the magnet temperature rises and the electrical resistance value of the coil increases can be increased. Accordingly, it is possible to more effectively reduce the decrease in the attractive force accompanying the increase in the magnet temperature.

  Next, the configuration of the magnet 10 suitable for the magnet device 1 of the present embodiment will be described.

  FIG. 6 is a side sectional view showing a structure of a magnet 10 </ b> A as one form of the magnet 10. FIG. 7 is a cross-sectional view showing a cross section taken along the line VII-VII of the magnet 10A shown in FIG. Note that the magnet 10A of the present embodiment has a cylindrical appearance centered on a predetermined axis C, and illustration of a cross section on one side with respect to the axis C is omitted in FIG.

  With reference to FIGS. 6 and 7, the magnet 10 </ b> A of the present embodiment includes a case 11, coils 20 and 21, and fixing members 18 and 19. The coil 20 is a first coil in the present embodiment, and is arranged between an inner pole 14 and an interpole 16 which will be described later, and a conductive wire is wound around the axis C. The coil 21 is a second coil in the present embodiment, and is arranged between an interpole 16 and an outer pole 15 described later, and a conductive wire is wound around the axis C.

  Here, FIG. 8 is an enlarged view showing in detail the structure of partial cross sections (A1 and A2 in the drawing) of the coils 20 and 21. FIG. The coils 20 and 21 have a conducting wire 22 and an insulating coating film 23. The conducting wire 22 is wound around the axis C across a plurality of layers. The conducting wire 22 is made of a conductive material such as aluminum. The insulating coating film 23 is made of, for example, insulating paper and covers the conductive wire 22. In addition, the conducting wire 22 of the coil 20 and the conducting wire 22 of the coil 21 may be connected to each other or may be independent from each other.

  Refer to FIGS. 6 and 7 again. The case 11 is a member for housing the coils 20 and 21. The case 11 includes a nonmagnetic member 17 as a bottom plate disposed on one end side of the coils 20 and 21 and a main body portion 12 made of a ferromagnetic member. Further, the main body 12 includes a yoke 13 as a top plate disposed on the other end side of the coils 20 and 21, an inner pole 14 disposed on the inner side of the coil 20, and an outer pole disposed on the outer side of the coil 21. 15 and an interpole 16 provided between the coils 20 and 21. The yoke 13, the inner pole 14, the outer pole 15, and the interpole 16 are each made of a ferromagnetic material such as iron.

  The inner pole 14 is a cylindrical member that extends in the winding axis direction of the coil 20 along the inner side surface 20 b of the coil 20 (that is, the direction parallel to the central axis C), and constitutes a first electromagnet together with the coil 20. . That is, when an exciting current flows through the coil 20, a magnetic field is formed inside the inner pole 14, and the end portion 14 a on one end side of the inner pole 14 becomes one pole of the first electromagnet. Note that the end portion 14a is configured to be removable from the main body portion 12, and is replaced according to wear.

  The interpole 16 is a cylindrical member extending in a direction parallel to the central axis C along the outer surface 20 c of the coil 20 and the inner surface 21 b of the coil 21, and constitutes a second electromagnet together with the coil 21. That is, when an exciting current flows through the coil 21, a magnetic field is formed inside the interpole 16, and the end 16 a on one end side of the interpole 16 becomes one pole of the second electromagnet. As shown in FIG. 7, the intermediate pole 16 of the present embodiment is provided in an annular shape that is continuous over the entire circumference of the coils 20 and 21. In addition to the form shown in FIG. 7, for example, a plurality of plate-like members curved along the outer side surface 20 c of the coil 20 and the inner side surface 21 b of the coil 21 are spaced apart from each other by a certain interval. A configuration in which the coils 20 and 21 are juxtaposed in the circumferential direction may be employed.

  The outer pole 15 is a cylindrical member that extends in a direction parallel to the central axis C along the outer surface 21 c of the coil 21. When an exciting current flows through the coils 20 and 21, a magnetic field is formed inside the outer pole 15, and the end 15a on one end side of the outer pole 15 becomes the other pole of the first and second electromagnets. The end portion 15a is configured to be removable from the main body portion 12 in the same manner as the end portion 14a of the inner pole 14, and is replaced according to wear. The lower ends of the end portions 14a and 15a (that is, one end of the inner pole 14 and the outer pole 15) are located in the same plane. For example, when the suction surface of the suspended load is a plane, the end portions 14a and 15a are Abuts on the suction surface.

  The yoke 13 is a disk-shaped member provided along the end surface 20 d on the other end side of the coil 20 and the end surface 21 d on the other end side of the coil 21. The other end of the inner pole 14 is fixed to the central portion of the yoke 13, the other end of the outer pole 15 is fixed near the outer peripheral portion of the yoke 13, and the other end of the interpole 16 is connected to the central portion of the yoke 13. It is fixed to an intermediate part between the outer peripheral part. In addition, welding, bolting, etc. are suitable as a fixing method of each pole 14-16 and the yoke 13. FIG. The poles 14 to 16 and the yoke 13 may be integrally formed by casting or the like. When an exciting current flows through the coils 20 and 21, the magnetic flux passes through the inside of the yoke 13. Thereby, a magnetic field can be efficiently generated in the inner pole 14, the outer pole 15, and the interpole 16.

  The nonmagnetic member 17 is a disk-shaped member provided along the end surface 20 a on one end side of the coil 20 and the end surface 21 a on one end side of the coil 21. The nonmagnetic member 17 is made of, for example, a nonmagnetic material such as high manganese austenitic steel or Ni—Cr austenitic stainless steel so as not to disturb the magnetic fields in the magnetic poles 14 to 16. In addition, the nonmagnetic member 17 has an opening 17 a through which the inner pole 14 penetrates in the central portion, and one end of the inner pole 14 is exposed downward from the nonmagnetic member 17. An outer peripheral portion (edge portion 17 b) of the nonmagnetic member 17 is fixed to the outer pole 15.

  The fixing members 18 and 19 are members for fixing the coils 20 and 21 in the case 11 by filling and hardening the gaps between the coils 20 and 21 and the case 11, respectively. The fixing members 18 and 19 are made of an insulating material such as an epoxy resin.

  In the magnet 10 </ b> A shown in FIGS. 6 to 8, the flow of magnetic flux is controlled by providing the interpolar electrode 16, and the magnetic flux leaking into the coils 20 and 21 and the gap between the magnet 10 </ b> A and the suspended load is reduced. Therefore, since the magnetic flux leaking to other than the suspended load can be reduced and the magnetic flux can be efficiently passed through the suspended load, the adsorption efficiency of the magnet 10A can be increased as compared with the conventional configuration. In addition, this makes it possible to reduce the excitation current necessary for generating the required magnetic force, so that the amount of Joule heat generated in the coils 20 and 21 can be suppressed. Furthermore, the Joule heat generated in the coils 20 and 21 can be released to the outside through the intermediate electrode 16. Therefore, the temperature rise of the coils 20 and 21 can be suppressed.

In the above-described magnet drive circuit 30 (see FIG. 1), increasing the exciting current I ₁ according to the temperature rise of the magnet 10, further generates Joule heat, the temperature of the magnet 10 rises further. In the case of a general magnet, if the increase rate of the magnet temperature with respect to the increase of the excitation current I ₁ is high, the magnet temperature easily reaches the upper limit temperature, and thus the increase width of the excitation current I ₁ is limited. In contrast, the use of high heat dissipation magnets 10A, since the rate of increase in the magnet temperature is kept low, the increase in width of the exciting current I ₁ corresponding to the increase in the magnet temperature can be increased, a decrease in the adsorption force of the magnet It can be reduced more effectively.

  FIG. 9 is a side sectional view showing the structure of the magnet 10B. The magnet 10B has a cylindrical appearance centered on the axis C, and the cross section on one side with respect to the axis C is not shown in FIG. The magnet device of this embodiment may include a magnet 10B shown in FIG. 9 instead of the magnet 10A shown in FIGS.

  Referring to FIG. 9, the magnet 10 </ b> B includes a case 41, a coil 24, heat conducting plates 51 to 54, and a fixing material 50. The case 41 includes a nonmagnetic member 17 as a bottom plate disposed on one end side of the coil 24 and a main body portion 42 made of a ferromagnetic member. Further, the main body 42 includes a yoke 13 as a top plate disposed on the other end side of the coil 24, an inner pole 14 disposed on the inner side of the coil 24, and an outer pole 15 disposed on the outer side of the coil 24. It is comprised including. The configuration of the main body portion 42 is the same as that of the main body portion 12 (see FIGS. 6 and 7) described above, except that there is no interpolar electrode. The coil 24 is formed by winding a conductive wire around the central axis C across a plurality of layers, and the details thereof are the same as the configuration shown in FIG.

  The heat conducting plates 51 to 54 are members for transmitting the Joule heat generated in the coil 24 to the case 41 and insulating the coil 24 and the case 41 from each other. The heat conducting plates 51 to 54 are disposed between the case 41 and the coil 24. Specifically, the heat conducting plate 51 is formed in a disc shape centered on the axis C, and is disposed on the inner surface of the case 41 (the lower surface of the yoke 13) along the end surface 24 a of the coil 24. The heat conducting plate 52 is formed in a cylindrical shape centered on the axis C, and is disposed on the inner surface of the case 41 (side surface of the inner pole 14) along the inner surface 24 b of the coil 24. The heat conducting plate 53 is formed in a cylindrical shape with the axis C as the center, and is disposed on the inner surface of the case 41 (the inner surface of the outer pole 15) along the outer surface 24 c of the coil 24. The heat conducting plate 54 is formed in a disc shape centered on the axis C, and is disposed on the inner surface of the case 41 (the upper surface of the nonmagnetic member 17) along the end surface 24 d of the coil 24.

  The fixing member 50 is a member for fixing the coil 24 in the case 41 by filling a space between the coil 24 and the case 41 and solidifying the gap. The fixing member 50 is made of, for example, a resin material such as an epoxy resin, and is mainly provided between the coil 24 and the heat conducting plates 51 to 54 in the present embodiment. The portion of the fixing member 50 provided between the coil 24 and the heat conducting plates 51 to 54 is compared with the distance between the surface of the coil 24 and the inner surface of the case 41 and the thickness of the heat conducting plates 51 to 54. It is formed into a very thin film (for example, a thickness of 1 mm to 2 mm).

  Here, FIG. 10 is an enlarged view showing a detailed cross-sectional structure of the heat conducting plate 51. Referring to FIG. 10, the heat conducting plate 51 includes a substrate 51a and an insulating treatment layer 51b formed on the surface of the substrate 51a. The substrate 51a is made of a material having a higher thermal conductivity than the fixing material 50, for example, a metal material such as aluminum. The insulating treatment layer 51b is a layer for ensuring insulation between the coil 24 and the case 41, and is provided because the substrate 51a of the present embodiment is a conductive material. The insulating treatment layer 51 b is formed on the surface 51 c of the heat conducting plate 51 on the side facing the coil 24. The insulating treatment layer 51b of this embodiment is formed by subjecting the surface of the substrate 51a to oxidation treatment. For example, when the substrate 51a is made of aluminum, the insulating treatment layer 51b is made of alumite.

  In addition, on the surface 51d of the heat conducting plate 51 on the side facing the inner surface of the case 41, the insulating treatment layer is not provided and the substrate 51a is exposed. When the substrate 51a is made of metal and the insulating treatment layer 51b is formed by oxidation treatment, an oxide film may be formed except for the surface 51d on the side facing the inner surface of the case 41 in the manufacturing process.

  Note that the heat conducting plates 52 to 54 also have the same cross-sectional structure as the heat conducting plate 51. That is, each of the heat conducting plates 52 to 54 includes a substrate and an insulating treatment layer formed on the substrate surface facing the coil 24. And the board | substrate surface is exposed in the surface of the heat-conducting plates 52-54 of the side facing the case 41. FIG. Further, the heat conducting plates 51 to 54 are not limited to the above configuration, and may be configured by a substrate made of an insulating material (for example, a high thermal conductivity / insulating ceramic (eg, aluminum nitride)) having a higher thermal conductivity than the fixing material 50. Good. In this case, the above-described insulating treatment layer is not necessary.

  In the magnet 10 </ b> B, the heat conductive plates 51 to 54 having higher thermal conductivity than the fixing material 50 are disposed between the case 41 and the coil 24, and the heat conductive plates 51 to 54 are surfaces facing the coil 24. It is made of a conductive material or an insulating material that has been subjected to insulation treatment. By disposing such heat conducting plates 51 to 54 between the case 41 and the coil 24, it is possible to ensure insulation between the case 41 and the coil 24 without depending on the fixing material 50. Thereby, since it becomes possible to make the fixing material 50 for fixing the coil 24 into a very thin film shape, the Joule heat of the coil 24 can be efficiently transmitted to the case 41 via the heat conducting plates 51 to 54. . Therefore, according to the magnet 10B, the Joule heat generated in the coil 24 can be released more efficiently, so that the temperature rise of the coil 24 can be suppressed.

  Fig.11 (a) is side sectional drawing which shows the structure of the magnet 10C. The magnet device of the present embodiment may include a magnet 10C shown in FIG. The difference between the magnet 10C and the magnet 10B is the number of coils and the arrangement of the heat conducting plates. That is, the magnet 10C includes two coils 25 and 26 instead of the coil 24 shown in FIG. Further, the magnet 10C further includes a heat conducting plate 55 in addition to the heat conducting plates 51 to 54 shown in FIG.

  The coil 25 (first coil) is provided near the inner pole 14 in the case 41, and the coil 26 (second coil) is provided near the outer pole 15 in the case 41. In other words, the coil 25 is formed by winding the conductive wire around the inner pole 14, and the coil 26 is formed by winding the conductive wire along the outer periphery of the coil 25.

  The heat conducting plate 55 is formed in a cylindrical shape centered on the axis C, and is disposed between the outer side surface of the coil 25 and the inner side surface of the coil 26. The fixing member 50 is also provided between the coil 25 and the heat conducting plate 55 and between the coil 26 and the heat conducting plate 55. The fixing member 50 fixes these members in the case 41 by filling the gaps between the coil 25 and the heat conducting plate 55 and between the heat conducting plate 55 and the coil 26. The surface of the heat conducting plate 55 facing the outer side surface of the coil 25 and the surface of the heat conducting plate 55 facing the inner side surface of the coil 26 are subjected to the same insulating treatment as the insulating treatment layer 51b shown in FIG. . Both ends of the heat conducting plate 55 are in contact with the heat conducting plates 51 and 54, respectively.

  When a plurality of coils 25 and 26 are arranged in a radial direction like the magnet 10 </ b> C, it is preferable that a heat conducting plate 55 is also provided between the coils 25 and 26. Normally, the coil conductor is covered with an insulating film as shown in FIG. 8, and since the thermal conductivity of the insulating film is generally smaller than that of the conductor, Joule heat is likely to accumulate in the center of the coil. . In the magnet 10C, the heat conducting plate 55 is arranged so as to divide the central portion of the coil, so that the heat inside the coil can be released more efficiently.

  FIG.11 (b) is side sectional drawing which shows the structure of magnet 10D. The magnet device of the present embodiment may include a magnet 10D shown in FIG. The magnet 10D includes two coils 27 and 28. The magnet 10 </ b> D further includes a heat conducting plate 56 in addition to the heat conducting plates 51 and 54.

  The coil 27 (first coil) is provided near the yoke 13 in the case 41, and the coil 28 (second coil) is provided near the nonmagnetic member 17 in the case 41. In other words, the coils 27 and 28 are arranged side by side in the direction along the central axis C.

  The heat conducting plate 56 is formed in a disc shape with the axis C as the center, and is disposed between the coil 27 and the coil 28. The fixing member 50 is also provided between the coil 27 and the heat conducting plate 56 and between the coil 28 and the heat conducting plate 56. The fixing member 50 fixes these members in the case 41 by filling the gaps between the coil 27 and the heat conducting plate 56 and between the heat conducting plate 56 and the coil 28. The surface of the heat conducting plate 56 facing the coil 27 and the surface of the heat conducting plate 56 facing the coil 28 are subjected to the same insulating treatment as the insulating treatment layer 51b shown in FIG. It is more preferable that the inner peripheral portion and the outer peripheral portion of the heat conducting plate 56 are in contact with the inner pole 14 and the outer pole 15, respectively, and are fitted into the inner pole 14 and the outer pole 15, respectively, as shown in FIG. It is.

  Even with the configuration of the magnet 10D, the heat inside the coil can be efficiently released. Further, since the inner peripheral portion and the outer peripheral portion of the heat conducting plate 56 are fitted into the inner pole 14 and the outer pole 15, respectively, the degree of contact between the heat conducting plate 56, the inner pole 14 and the outer pole 15 can be further increased. The heat release efficiency inside the coil is further improved.

  FIG. 12 is a side sectional view showing the configuration of the magnet 10E. The magnet device of the present embodiment may include a magnet 10E shown in FIG. The main difference between the magnet 10E and the magnet 10B (see FIG. 9) is the arrangement of the heat conducting plate. The magnet 10 </ b> E includes heat conducting plates 61 to 64 instead of the heat conducting plates 51 to 54.

  The heat conducting plate 61 is formed in a disc shape centered on the axis C, and is disposed on the end surface 24 a of the coil 24. The heat conducting plate 62 is formed in a cylindrical shape centered on the axis C, and is disposed on the inner side surface 24 b of the coil 24. The heat conducting plate 63 is formed in a cylindrical shape centered on the axis C, and is disposed on the outer side surface 24 c of the coil 24. Further, the heat conducting plate 64 is formed in a disc shape with the axis C as the center, and is disposed on the end surface 24 d of the coil 24. The fixing member 50 is mainly provided between the heat conducting plates 61 to 64 and the case 41. In addition, the part provided between the case 41 and the heat-conducting plates 61-64 among the fixing materials 50 is formed in the very thin film | membrane form similarly to what was shown in FIG.

  Here, FIG. 13 is an enlarged view showing a detailed cross-sectional structure of the heat conducting plate 61. Referring to the drawing, the heat conducting plate 61 includes a substrate 61a and an insulating treatment layer 61b formed on the surface of the substrate 61a. The insulating treatment layer 61 b is formed on the surface of the heat conducting plate 61 on the side facing the coil 24. Note that the materials of the substrate 61a and the insulating treatment layer 61b are the same as those of the substrate 51a and the insulating treatment layer 51b shown in FIG. The heat conducting plates 62 to 64 also have the same cross-sectional structure as the heat conducting plate 61.

  In the magnet 10E, the insulation between the case 41 and the coil 24 can be ensured without depending on the fixing member 50, similarly to the magnet 10B shown in FIG. Thereby, since it becomes possible to make the fixing material 50 for fixing the coil 24 into a very thin film shape, the Joule heat of the coil 24 can be efficiently transmitted to the case 41 via the heat conducting plates 61 to 64. . Therefore, since the Joule heat generated in the coil 24 can be released more efficiently, the temperature rise of the coil 24 can be suppressed.

  The lifting magnet drive circuit and the lifting magnet device according to the present invention are not limited to the above-described embodiments, and various other modifications are possible. For example, the temperature detection means in the present invention may be, for example, a thermoelectric element that measures the temperature of the lifting magnet, in addition to generating a signal based on the magnitude of the current flowing through the lifting magnet as in the above embodiment. . In the above embodiment, the control unit lengthens the first period and increases the excitation voltage in the second period when the magnet temperature exceeds the set temperature. In the present invention, The excitation voltage in the second period and the length of the period may be continuously changed according to the magnet temperature.

It is a figure which shows the structure of the magnet apparatus 1 by one Embodiment. (A) The time waveform of the excitation voltage applied to a magnet is shown. (B) The time waveform of the excitation current supplied to the magnet is shown. It is a graph which shows the time waveform of (a) exciting voltage and (b) exciting current in 1st operation | movement. It is a graph which shows the time waveform of (a) exciting voltage and (b) exciting current in 2nd operation | movement. It is a graph which shows the time waveform of (a) exciting voltage and (b) exciting current in 3rd operation | movement. It is side surface sectional drawing which shows the structure of one form of a magnet. It is sectional drawing which shows the cross section along the VII-VII line of the magnet shown in FIG. It is an enlarged view which shows the structure of the partial cross section of a coil in detail. It is side surface sectional drawing which shows the structure of one form of a magnet. It is an enlarged view which shows the detailed cross-section of a heat-conducting plate. (A) It is side surface sectional drawing which shows the structure of one form of a magnet. (B) It is side surface sectional drawing which shows the structure of one form of a magnet. It is side surface sectional drawing which shows the structure of one form of a magnet. It is an enlarged view which shows the detailed cross-section of a heat-conducting plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Lifting magnet apparatus, 10, 10A-10E ... Lifting magnet, 11, 41 ... Case, 12, 42 ... Main-body part, 13 ... Yoke, 14 ... Inner pole, 15 ... Outer pole, 16 ... Interpole, 17 ... Non Magnetic member 18, 19, 50 ... Fixing material 20, 21, 24-28 ... Coil, 30 ... Lifting magnet drive circuit, 32 ... Bridge driver, 33 ... Control unit, 36 ... DC conversion unit, 37 ... Bridge circuit unit , 39 ... current measuring section, 51 to 56, 61 to 64 ... heat conducting plate, I ₁ ... excitation current, I ₂ ... release current.

Claims (7)

A lifting magnet drive circuit that generates electric power for exciting the lifting magnet,
The excitation voltage to the lifting magnet is controlled to a voltage exceeding a predetermined voltage in a first period immediately after the start of excitation, and the excitation voltage is controlled to the predetermined voltage in a second period after the first period. A control unit;
Temperature detecting means for outputting a signal corresponding to the temperature of the lifting magnet,
The control unit receives the signal from the temperature detection unit, and lengthens the first period in accordance with a temperature rise of the lifting magnet. A lifting magnet drive circuit that generates electric power for exciting the lifting magnet,
The excitation voltage to the lifting magnet is controlled to a voltage exceeding a predetermined voltage in a first period immediately after the start of excitation, and the excitation voltage is controlled to the predetermined voltage in a second period after the first period. A control unit;
Temperature detecting means for outputting a signal corresponding to the temperature of the lifting magnet,
The control unit receives the signal from the temperature detection unit, and controls the excitation voltage in the second period to a voltage higher than the predetermined voltage in accordance with a temperature rise of the lifting magnet. , Lifting magnet drive circuit. A lifting magnet drive circuit that generates electric power for exciting the lifting magnet,
The excitation voltage to the lifting magnet is controlled to a voltage exceeding a predetermined voltage in a first period immediately after the start of excitation, and the excitation voltage is controlled to the predetermined voltage in a second period after the first period. A control unit;
Temperature detecting means for outputting a signal corresponding to the temperature of the lifting magnet,
The control unit receives the signal from the temperature detection unit, and lengthens the first period and raises the excitation voltage in the second period higher than the predetermined voltage in response to a temperature rise of the lifting magnet. A lifting magnet drive circuit characterized by being controlled to a voltage.   The lifting magnet drive circuit according to any one of claims 1 to 3, wherein the temperature detection unit generates the signal based on a magnitude of a current flowing through the lifting magnet. Lifting magnet,
A lifting magnet drive circuit according to any one of claims 1 to 4,
The lifting magnet is
A ferromagnetic main body including an inner pole extending in a predetermined axial direction, an outer pole provided around the inner pole around the predetermined axis, and an intermediate pole provided between the inner pole and the outer pole When,
A first coil disposed between the inner pole and the intermediate pole and wound around the predetermined axis;
A lifting magnet device comprising: a second coil disposed between the intermediate electrode and the outer electrode and wound around the predetermined axis. Lifting magnet,
A lifting magnet drive circuit according to any one of claims 1 to 4,
The lifting magnet is
First and second coils;
A case for housing the first and second coils;
A fixing member for fixing the first and second coils in the case;
A lifting magnet device comprising: a heat conductive plate made of a material having a higher thermal conductivity than the fixing material, and disposed between the first coil and the second coil. Lifting magnet,
A lifting magnet drive circuit according to any one of claims 1 to 4,
The lifting magnet is
Coils,
A case for housing the coil;
A fixing member for fixing the coil in the case;
A lifting magnet device comprising a heat conductive plate made of a material having a higher thermal conductivity than the fixing material and disposed between the case and the coil.

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