JP6246733B2 - Work machine with riff mug - Google Patents

Description

  The present invention relates to a work machine that performs work using a lifting magnet.

  A working machine provided with a lifting magnet (generally referred to as “a riff mug”) as a work attachment is used as a work machine for transporting or moving a steel material or a steel product. Such a work machine is referred to as a “work machine with a riff mug” or a “riff mug machine”.

  Lifting magnets (lift magnets) are electromagnets that attract and hold steel and steel products by electromagnetic force. Therefore, when working with a riffmag, it is necessary to supply an electric current to the riffmag to be excited to generate an electromagnetic attracting force.

  For example, a hydraulic drive device for a generator for driving a riff mug installed in a work machine has been proposed. This generator hydraulic drive device is driven by an engine mounted on a work machine and drives a hydraulic actuator of the work machine main body, a hydraulic pump and a variable displacement hydraulic motor for driving a riffmag generator And have. The generator hydraulic drive device has two types of setting means: a mode in which the engine is operated at a high speed during a relatively high load operation, and a mode in which the engine is operated at a low speed with emphasis on fuel efficiency, And a control device for controlling the rotation of the variable displacement hydraulic motor to be constant by changing the tilt angle of the variable displacement hydraulic motor in accordance with the setting of each mode by the setting means. According to the above configuration, even when the engine speed changes, the generator speed can be kept constant (see, for example, Patent Document 1).

JP 2002-349503 (pages 2 to 4, FIG. 1).

  When the riffmag (electromagnet) is excited, the power generated by the generator is supplied to the riffmag. By applying the voltage output from the riffmag generator to the riffmag, current flows through the riffmag and the riffmag is excited. As a result, the riff mug generates an electromagnetic attracting force.

  In the riff mug, a voltage that can be continuously applied is determined in consideration of heat generation due to current flow. Therefore, as the riffmag generator, a generator that generates a voltage of the voltage or lower is used.

  Here, the riffmag (electromagnet) has a large inductance, and after the riffmag excitation starts (that is, after the voltage starts to be applied to the riffmag), the current flowing through the riffmag becomes a predetermined magnitude. , Take some time. That is, a certain amount of time is required from when the driver turns on the switch for driving the riffmag until the riffmag actually exhibits a predetermined electromagnetic attraction force. For this reason, the driver may feel that the reaction of the riff mug is bad or may feel that the power of the riff mug is insufficient.

  The present invention has been made in view of the above-described problems. A large excitation current is supplied at the start of driving of the riffmag to quickly increase the electromagnetic attracting force, thereby causing the driver to feel that the reaction of the riffmag is bad or the power is insufficient. The purpose is to avoid dissatisfaction with operability by making it feel that there is no.

According to an embodiment of the present invention, an engine that is controlled to rotate at a set target rotational speed out of two predetermined target rotational speeds, a hydraulic pump coupled to the engine, a load driven by a hydraulic fluid from said hydraulic pump, a synchronous generator is controlled to a predetermined speed based on the driving force of the engine, the power from the synchronous generator is supplied, the electromagnetic attractive force A lifting magnet including an electromagnet that is generated, and a drive control unit that controls a voltage applied to the electromagnet, wherein the drive control unit is a case where a switch that activates the lifting magnet is turned on, when the target rotational speed of the higher of the two out of the target speed is set, applying a first voltage higher than the rated voltage to the electromagnet, then the voltage applied to the electromagnet Switching to lower than first voltage second voltage, the output of the hydraulic pump in response to switching to the second voltage from the first voltage of the voltage applied to the electromagnet by the drive control unit, An increased riff mug work machine is provided.
According to another embodiment of the present invention, an engine that is controlled to rotate at a set target rotational speed out of two target rotational speeds that are defined in advance, and a hydraulic pressure coupled to the engine. A pump, a load driven by pressure oil from the hydraulic pump, a synchronous generator controlled to a predetermined rotational speed based on the driving force of the engine, and electric power from the synchronous generator are supplied, A lifting magnet including an electromagnet that generates an attracting force; and a drive control unit that controls a voltage applied to the electromagnet. The drive control unit is a case where a switch that activates the lifting magnet is turned on. Then, when the higher target rotational speed of the two target rotational speeds is set, the first voltage higher than the rated voltage is applied to the electromagnet, and then the electromagnet applied to the electromagnet is applied. Is switched to a second voltage lower than the first voltage, and when the lifting magnet is started, the flow rate is controlled by a swash plate included in the hydraulic pump, the output of the hydraulic pump is reduced, and the drive control unit The hydraulic pump is configured in such a manner that the flow rate is controlled by the swash plate and the output of the hydraulic pump is increased in accordance with switching of the voltage applied to the electromagnet from the first voltage to the second voltage. Is provided with a lifting magnet that controls the output of the lifting magnet in accordance with the driving status of the lifting magnet.

  According to the above-described embodiment, since a large voltage can be applied to the riffmag at the initial stage of driving the riffmag and a large current can flow, the electromagnetic attraction force of the riffmag can be quickly increased, and the operability is not satisfactory. It is possible to provide a work machine with a riff mug that can be prevented from being held.

It is a side view of the shovel with a riff mug by one Embodiment of this invention. It is a block diagram which shows an example of a structure of the drive system of a shovel with a riff mug. It is a circuit diagram which shows the structural example of the power supply circuit (inverter) for riff mugs. It is a graph which shows the pressure flow characteristic (PQ diagram) of a main pump. It is a graph which shows the relationship between generator rotation speed and output voltage. It is a graph which shows the change of a voltage when a voltage higher than the rated voltage of a riffmag is applied in steps. It is a graph which shows the change of the excitation current which flows into a riffmag when the voltage as shown in FIG. 6 is applied to a riffmag. It is a block diagram which shows the other example of a structure of the drive system of a shovel with a riffmag.

  Hereinafter, a working machine with a riff mug according to an embodiment of the present invention will be described.

  FIG. 1 is a side view of a shovel with a riff mug that is an example of a working machine with a riff mug. The excavator with a riff mug has a lifting magnet (hereinafter referred to as “a riff mug”) instead of a bucket as an attachment to be attached to the tip of an excavator arm.

  An upper swing body 3 is mounted via a swing mechanism 2 on the lower traveling body 1 of the excavator with a riffmag shown in FIG. Mounted on the upper swing body 3 are a boom 4, an arm 5, a lifting magnet (a lift magnet) 6, and a boom cylinder 7, an arm cylinder 8, and a lift magnet cylinder 9 for hydraulically driving them. The upper swing body 3 is equipped with a cabin 10 having a cab and a power source including an engine and an electric motor.

  FIG. 2 is a block diagram showing an example of the configuration of a drive system of a shovel with a riffmag. A main pump 14 and a generator hydraulic pump 40 that are hydraulic pumps for driving the cylinders 7 to 9 as working devices in the excavator are commonly attached to a drive shaft 11a of the engine 11 mounted on the excavator. ing. The hydraulic pressure generated by the main pump 14 is supplied to the control valve 17 and distributed to the cylinders 7-9 and the like.

  The main pump 14 is provided with a regulator 14A for controlling the discharge flow rate of the hydraulic oil. For example, the regulator 14 </ b> A controls the discharge flow rate of the main pump 14 by adjusting the swash plate tilt angle of the main pump 14 according to the discharge pressure of the main pump 14 and the control signal from the control unit 30.

  The hydraulic oil discharged from the generator hydraulic pump 40 is supplied to the hydraulic motor 42. The hydraulic motor 42 is mechanically connected to a riffmag generator 44. The riffmag generator 44 is driven by the output of the hydraulic motor 42 to generate AC power. The output terminal of the lift magnet generator 44 is connected to a lifting magnet (lift magnet) 6 via an inverter 46 that functions as a drive control unit. The inverter 46 has a rectifying function for converting AC power output from the riffmag generator 44 into DC power for riffmag excitation. The voltage applied to the riff mug is controlled by the inverter 46.

  The inverter 46 serving as a drive control unit may be configured as an arbitrary power supply circuit as long as the AC power output from the riffmag generator 44 is converted into DC power and the voltage applied to the riffmag can be controlled. Here, a configuration example of the inverter 46 will be described.

  FIG. 3 is a circuit diagram showing an example of the configuration of the riffmag power supply circuit (inverter 46). The inverter 46 includes a DC conversion unit 300, an H bridge circuit unit 400, and a demagnetization energy absorption unit 500, and performs excitation and demagnetization of the riffmag 6.

  The DC converter 300 is a rectifier that converts three-phase AC power (AC voltages VAC1 to VAC3) supplied from the riffmag generator 44 into DC power (DC voltage VDC). In the present embodiment, the DC voltage VDC is equal to the output voltage of the riffmag generator 44. The DC converter 300 has a positive output terminal 300a and a negative output terminal 300b, and provides the generated DC voltage VDC between the positive output terminal 300a and the negative output terminal 300b. When the riffmag generator 44 is a single-phase AC generator, the DC conversion unit 300 may be configured to convert single-phase AC power into DC power. Further, when the riffmag generator 44 is a DC generator, the DC conversion unit 300 may be provided.

  The DC conversion unit 300 includes a bridge circuit (rectifier) including six diodes 310a to 310f, and performs three-phase full-wave rectification. Specifically, the diodes 310a and 310b are connected in series, the diodes 310c and 310d are connected in series, and the diodes 310e and 310f are connected in series. In addition, the set of diodes 310a and 310b, the set of diodes 310c and 310d, and the set of diodes 310e and 310f are connected in parallel to each other. One end on the cathode side of the set of these diodes is electrically connected to the positive output end 300a, and one end on the anode side is electrically connected to the negative output end 300b.

  In addition, an AC power supply line 46a extending from a one-phase terminal in the riffmag generator 44 is electrically connected between the diode 310a and the diode 310b. Further, an AC power supply line 46b extending from another one-phase terminal in the riffmag generator 44 is electrically connected between the diode 310c and the diode 310d. In addition, an AC power supply line 46c extending from another one-phase terminal in the riffmag generator 44 is electrically connected between the diode 310e and the diode 310f.

  The DC conversion unit 300 can be arbitrarily configured as long as it can convert (three-phase) AC power into DC power. For example, it may be configured by a pure bridge circuit using a thyristor, a mixed bridge circuit using a diode and a thyristor, or the like. When the DC conversion unit 300 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 400 controls excitation and demagnetization of the riff mug 6. The H-bridge circuit unit 400 includes first to fourth switching elements 410a to 410d and first to fourth switching elements electrically connected between drains and sources of the first to fourth switching elements 410a to 410d. Of the commutation diodes 420a to 420d.

  Specifically, one end of the first switching element 410a is connected to the positive output terminal 300a of the DC converter 300, and the other end of the first switching element 410a is connected to one end of the second switching element 410b. The The other end of the second switching element 410b is connected to the negative side output terminal 300b of the DC converter 300. On the other hand, one end of the third switching element 410c is connected to the positive output terminal 300a of the DC converter 300, and the other end of the third switching element 410c is connected to one end of the fourth switching element 410d. The other end of the fourth switching element 410d is connected to the negative side output terminal 300b of the DC converter 300. A connection line extending from one end of the riff mug 6 is connected between the first switching element 410a and the second switching element 410b. A connection line extending from the other end of the riff mug 6 is connected between the third switching element 410c and the fourth switching element 410d.

  The anodes of the first, second, and fourth commutation diodes 420a, 420b, and 420d are connected to the other ends of the first, second, and fourth switching elements 410a, 410b, and 410d, respectively. The cathodes of the first, second, and fourth commutation diodes 420a, 420b, and 420d are connected to one ends of the first, second, and fourth switching elements 410a, 410b, and 410d, respectively.

  The anode of the third commutation diode 420c is connected to the other end of the third switching element 410c, and the cathode is connected to one end of the third switching element 410c (the positive polarity of the DC converter 300) via the resistance element 460e. Side output terminal 300a). Accordingly, when demagnetizing the riffmag 6, part of the energy stored in the riffmag 6 can be consumed by the resistance element 460 e, so that it is not necessary to increase the capacity of the capacitor element 510 described later, and the inverter 46 can be reduced in size.

  The demagnetizing energy absorbing unit 500 is provided to absorb energy accumulated in the riff mug 6 when demagnetizing the riff mug 6. The demagnetizing energy absorbing unit 500 is connected between the positive output terminal 300 a and the negative output terminal 300 b of the DC converter 300 and includes a capacitive element 510. As the demagnetizing energy absorbing unit 500, any circuit configuration can be applied as long as it can absorb the energy accumulated in the riffmag 6 when demagnetizing the riffmag 6.

  Next, the operation of the riffmag power circuit (inverter 46) will be briefly described.

  When the riffmag 6 is excited, the first switching element 410a and the fourth switching element 410d are made conductive. As a result, the DC voltage VDC output from the DC converter 300 is applied to the riff mug 6 (at both ends). Then, an exciting current flows from the positive output terminal 300a of the DC converter 300 toward the negative output terminal 300b of the DC converter 300 via the first switching element 410a, the riffmag 6 and the fourth switching element 410d. Flows. In the present embodiment, when the riff mug 6 is activated, the first switching element 410a and the fourth switching element 410d are kept in a conductive state. In this way, by applying a voltage to the riff mag 6 and flowing a current, the riff mag 6 can be excited and a steel material or the like can be adsorbed to the riff mag 6.

  Further, when demagnetizing the riffmag 6, the first switching element 410a and the fourth switching element 410d are made non-conductive. As a result, a degaussing current flows from the riffmag 6 through the third commutation diode 420c, the resistance element 460e, the capacitive element 510, and the second commutation diode 420b in a path returning to the riffmag 6. Thereby, the energy accumulated in the riff mug 6 is transferred to the capacitive element 510 while being partially consumed as thermal energy by the resistance element 460e. Therefore, the riffmag 6 is demagnetized, and the steel material or the like adsorbed on the riffmag 6 can be released.

  Here, the riffmag 6 has residual magnetism due to hysteresis characteristics. Therefore, the second switching element 410b and the third switching element 410c are made conductive. As a result, a current flows from the capacitive element 510 through the third switching element 410c, the riff magnet 6, and the second switching element 410b. That is, due to the electric charge accumulated in the capacitive element 510, a current (demagnetization current of residual magnetism) opposite to the demagnetization current flows in the riff magnet 6. Thereby, the residual magnetism of the riff mug 6 is demagnetized and the steel material etc. which were adsorbed can be released completely.

  Next, the operation of the power generation circuit that generates power to be supplied to the riffmag 6 will be described. The engine speed is detected by a rotation sensor 11c attached to the engine 11. An engine speed signal indicating the detected engine speed is input to the control unit 30 together with the set engine speed signal. The control unit 30 calculates a control signal for controlling the engine speed to a set constant speed based on these input signals.

  The fuel injection amount in the fuel injection pump is controlled based on the control signal generated by the calculation in the control unit 30. Thereby, the engine speed is maintained at the set constant speed. Therefore, the riffmag generator 44 is driven at the set constant rotation speed via the generator hydraulic pump 40 and the hydraulic motor 42, and AC power of a predetermined magnitude is output from the riffmag generator 44. The AC power is converted into DC power by the inverter 46, and DC power that is stable at a predetermined magnitude is supplied to the riff mug 6.

  Then, while the hydraulic actuators of the working devices such as the boom cylinder 7, the arm cylinder 8, and the riff magnet cylinder 9 are driven by the hydraulic pressure supplied from the main pump 14, work such as adsorption and transportation of an object can be performed by the riff magnet 6. it can.

  In the drive system that drives the riff mug 6 described above, the load of the engine 11 changes according to the voltage applied to the riff mug 6. Therefore, the horsepower of the main pump 14 is controlled according to the output status of the riff mug 6 by controlling the discharge amount of the main pump 14 by the regulator 14A. Specifically, when the riffmag adsorption switch 32 is turned on, a high voltage of 320 V is applied to the riffmag 6. At this time, since the output of the generator hydraulic pump 40 also increases, the load applied to the engine 11 also increases. For this reason, the horsepower of the main pump 14 is reduced by the regulator 14 </ b> A so that the output of the engine 11 can be largely distributed to the riff mug 6. That is, an excitation drive system (such as a generator hydraulic pump 40) that excites the riff magnet 6 and a hydraulic drive system (such as the main pump 14) that drives the hydraulic actuators (boom cylinder 7, arm cylinder 8, riff magnet cylinder 9). Either of them can be preferentially driven. Thereafter, when the voltage applied to the riff mug 6 decreases to the rated voltage, the load on the engine 11 also decreases. Accordingly, the horsepower of the main pump 14 can be adjusted by adjusting the regulator 14A. When the output of the riff mug 6 is small, the output of the hydraulic drive unit such as the boom 4 and the arm 5 can be increased, and the operability can be improved.

  FIG. 4 is a graph showing the pressure flow characteristics (PQ diagram) of the main pump 14. The output (pressure P × flow rate Q) of the main pump 14 can be controlled by adjusting the swash plate tilt angle by the regulator 14A. When a voltage higher than the rated voltage is applied to the riffmag 6 when the riffmag 6 starts to be driven, the swash plate tilt angle is adjusted by the regulator 14A so that the output of the main pump 14 becomes a low output indicated by, for example, the solid line A. adjust. When the rated voltage is applied after the driving of the riffmag 6 is started, the swash plate tilt angle is adjusted by the regulator 14A so that the output of the main pump 14 becomes a medium output shown by the solid line B, for example. When the riffmag 6 is not driven, the swash plate tilt angle is adjusted by the regulator 14A so that the output of the main pump 14 becomes a high output, for example, shown by the solid line C.

  By the way, the size of the riff mug 6 mounted on the work machine is usually about 1.2 to 1.6 meters in diameter depending on the size of the work machine to which the riff mug 6 is attached and the size of the object to be adsorbed. The one is selected. The size of the electromagnet arranged in the riff mug 6 is also selected within a certain range. The coil resistance of the electromagnet in the riff mug 6 is a value fixed within a substantially constant range. For this reason, by changing the voltage applied to the riffmag 6, the current flowing through the riffmag 6 changes and the magnetic flux density also changes. As a result, the suction force generated by the riff mug 6 can be changed.

  In the riff mug 6, the rated voltage is set to 200V as a voltage that can hold the object for a long time. The voltage when the riffmag 6 is strongly excited is set to 290V. Note that 290 V, which is the voltage at the time of strong excitation, may be set as the maximum voltage that can be continuously applied to the riffmag 6 in consideration of a decrease in the attractive force due to the heat generated by the riffmag 6.

  FIG. 5 is a graph showing the relationship between the rotational speed of the IPM motor and the output voltage. In FIG. 5, the output voltage characteristic of the IPM motor is shown by a solid line, and the output voltage characteristic from a conventional induction generator is shown by a dotted line for comparison.

  In the induction generator, the output voltage rapidly increases from around 1700 rpm, and the output voltage reaches the rated voltage of 200 V around 2000 rpm. In the case of an induction motor generator, even if the rotational speed is increased to 2000 rpm or more, the output voltage is saturated and remains at the rated voltage of 200V.

  In the present embodiment, an IPM motor (Interior Permanent Magnet Motor) is used as the riffmag generator 44 described above. When the IPM motor operates as a generator, it can output a voltage proportional to the rotational speed. By using the IPM motor as the riffmag generator 44, for example, a voltage higher than the voltage at the time of strong excitation of the riffmag 6 can be output. That is, a voltage exceeding 290 V, which is the voltage at the time of strong excitation of the riffmag 6, can be output from the riffmag generator 44 and applied to the riffmag 6. However, the generator used as the riff mag generator 44 is not limited to the IPM motor, and can generate a high voltage exceeding 290 V, for example, a synchronous generator, which is proportional to the rotational speed. Any generator that can output voltage is suitable.

  The output voltage of the IPM motor used in this embodiment increases in proportion to the rotational speed as the rotational speed increases from zero. When the rotational speed is 2000 rpm, the output voltage is 200 V as in the induction motor generator. However, as the rotational speed increases, the output voltage also increases proportionally. The output voltage exceeds 290V when the rotation speed is around 2600 rpm, and the output voltage rises to about 330V around 3000 rpm.

  As described above, if a synchronous motor generator such as an IPM motor is used as the riffmag generator 44 and the rotational speed is set to 2600 rpm or more, the output voltage can be made higher than 290V. Therefore, as can be seen from FIG. 5, for example, by rotating the riffmag generator 44 at 3000 rpm, a high voltage exceeding 290 V, such as 320 V, can be applied to the riffmag 6.

  Here, when the output voltage of the riffmag generator 44 is increased, the withstand voltage performance of the switching element included in the inverter 46 becomes a problem. That is, when the output voltage of the riffmag generator 44 increases, the voltage at both ends when the switching element included in the inverter 46 is turned off increases, so that the voltage at both ends may exceed the withstand voltage. However, the switching elements (the first switching element 410a and the fourth switching element 410d) are continued as in the configuration example of the inverter 46 described above (FIG. 3) when the riffmag 6 is started (excitation). It is good to control so that it will be in an ON state. Thereby, since the state in which a current flows through the switching elements (the first switching element 410a and the fourth switching element 410d) can be maintained, the problem of withstand voltage performance of the switching elements can be avoided. Therefore, a voltage sufficiently higher than the rated voltage of the inverter 46 determined from the withstand voltage performance of the switching element can be applied to the riff mug 6 for a short time (for example, 2 seconds) as will be described later.

  The driving of the riffmag generator 44 is controlled by an inverter 46 as a drive control unit. The inverter 46 adjusts the voltage applied to the riff mug 6 based on the control signal from the control unit 30. The driving of the riffmag generator 44 may be controlled by the control unit 30. That is, the control unit 30 may control the hydraulic motor 42, the riffmag generator 44, and the inverter 46 to control the voltage applied to the riffmag 6. In the present embodiment, when the riffmag 6 is excited, a first voltage (for example, 320 V) that is sufficiently higher than the rated voltage is applied for the first few seconds (for example, 2 seconds). More preferably, the first applied voltage (first voltage) is 1.5 times or more the rated voltage. Then, for the next several seconds (for example, 2 seconds), a second voltage (for example, 290 V) that is lower than the first voltage is applied, and then the rated voltage (for example, 200 V) of the riff mug 6 is applied. Thereby, the rise of the excitation current flowing through the riffmag 6 is accelerated, and the electromagnetic attraction force can be quickly increased.

  FIG. 6 is a graph showing a change in voltage when a voltage higher than the rated voltage is applied stepwise as described above. FIG. 7 is a graph showing a change in excitation current flowing through the riffmag 6 when a voltage as shown in FIG. 6 is applied to the riffmag 6. In FIG. 6, the voltage when the voltage adjustment according to the present embodiment is performed is indicated by a solid line, and the voltage when the rated voltage 200 V is applied to the riff magnet 6 from the beginning is indicated by a dotted line. Similarly, in FIG. 7, the excitation current flowing through the riffmag 6 when the voltage adjustment according to the present embodiment is performed is indicated by a solid line, and the excitation current when a rated voltage of 200 V is applied to the riffmag 6 from the beginning is indicated by a dotted line. ing.

  As shown in FIG. 6, in the present embodiment, when the driver turns on the drive switch of the riffmag 6 (the riffmag adsorption switch 32) to drive the riffmag 6, the drive control unit (inverter 46) is the first 2 The riffmag generator 44 is rotated at a rotational speed corresponding to 320 V so that 320 V is applied to the riffmag 6 as a voltage sufficiently higher than the voltage at the time of strong excitation of the riffmag 6 for a second. During this time, the voltage output from the riffmag generator 44 is not limited. Then, for the next 2 seconds, the drive control unit applies 290V, which is a voltage when the riffmag 6 is strongly excited, to the riffmag 6, and thereafter applies 200V, which is the rated voltage of the riffmag 6, to the riffmag 6. While applying 290 V and 200 V, the inverter 46 as the drive control unit limits the voltage applied to the riff magnet 6 to 290 V and 200 V. By applying a voltage higher than the rated voltage stepwise in this way, the exciting current flowing in the riff mag 6 suddenly rises as shown by the solid line in FIG. 7, becomes the rated current after about 3 seconds, and the current is maintained as it is. The Thereby, it is possible to realize the control of the riff mug 6 having a quick rise of the attractive force while preventing the riff mug generator 44 and the inverter 46 from being damaged. On the other hand, when the rated voltage is applied from the beginning as in the prior art, approximately 5.5 seconds elapse until the rated current is reached. That is, according to the voltage adjustment at the time of driving the riffmag according to the present embodiment, the rated current can be passed through the riffmag 6 in a shorter time than before, and the electromagnetic attraction force of the riffmag 6 can be increased rapidly.

  Here, the voltage applied to the riffmag 6 as described above is an output voltage from the riffmag generator 44. Therefore, in order to adjust the voltage applied to the riffmag 6, the rotation speed of the riffmag generator 44 is controlled so that at least 320V can be output for the first 2 seconds and at least 290V can be output for the next 2 seconds. It is necessary to increase the number of revolutions.

  Since the riffmag generator 44 is directly connected to the hydraulic motor 42, the rotation speed of the riffmag generator 44 is equal to the rotation speed of the hydraulic motor 42. Further, since the hydraulic motor 42 is driven by the pressure oil discharged from the generator hydraulic pump 40, the rotation speed of the hydraulic motor 42 changes in proportion to the rotation speed of the generator hydraulic pump 40. Furthermore, since the generator hydraulic pump 40 is directly connected to the engine 11, the rotational speed of the generator hydraulic pump 40 is equal to the rotational speed of the engine 11. Thus, it can be considered that the rotational speed of the riffmag generator 44 depends on the rotational speed of the engine 11.

  On the other hand, the engine 11 is also directly connected to a main pump 14 for hydraulically driving other working elements such as the boom cylinder 7, the arm cylinder 8, and the riff magnet cylinder 9. Therefore, the rotational speed of the engine 11 is maintained at the rotational speed for driving the main pump 14. For this reason, conventionally, the rotational speed of the generator hydraulic pump 40 directly connected to the engine 11 as in the main pump 14 is equal to the rotational speed of the main pump 14, and the generator hydraulic pump 40 is at this rotational speed. When rotating, the output voltage of the riff mag generator 44 (that is, the output voltage of the inverter 46 as a drive control unit) becomes the rated voltage of the riff mag 6 (for example, 200 V).

  Here, as in this embodiment, in order to increase the rotational speed of the riffmag generator 44 and generate a voltage higher than the rated voltage, it is necessary to increase the rotational speed of the engine 11. However, since the engine 11 is mechanically connected to the main pump 14, the rotational speed of the engine 11 cannot be changed based only on the power demand to the riff mug 6. For this purpose, in order to increase the rotational speed of the riffmag generator 44 and generate a voltage higher than the rated voltage, in the present embodiment, the rotational speed of the hydraulic motor 42 and the generator that are conventionally set to 1: 1 are used. The ratio with the rotational speed of the hydraulic pump 40 is set so that the rotational speed of the hydraulic motor 42 is larger. Specifically, the rotational speed of the hydraulic motor 42 is set to be at least 1.1 times the rotational speed of the generator hydraulic pump 40 (the ratio is 1.1: 1). That is, the rotational speed of the riffmag generator 44 is set to be at least 1.1 times the rotational speed of the engine 11. Further, the rotational speed of the generator hydraulic pump 40 may be increased to a rotational speed corresponding to the maximum voltage defined by the characteristics of the coil of the riff mug 6. In the present embodiment, an example is shown in which the engine 11 is controlled so that the number of revolutions of the engine 11 is maintained at one predetermined constant number of revolutions. However, a plurality of predetermined constant number of revolutions may be provided. . For example, you may enable it to set two fixed rotational speeds, the high rotational speed when wanting to make a motion quick, and the low rotational speed which made much the fuel consumption important. In this case, if it is desired to reduce the movement in consideration of fuel consumption, the rated voltage may be output from the riffmag generator 44 by setting the minimum number of revolutions when the engine 11 is driven.

  Here, in the configuration example (FIG. 2) of the excavator with the riffmag described above, the driving force of the engine 11 is transmitted to the riffmag generator 44 via the generator hydraulic pump 40 and the hydraulic motor 42, and the riffmag The generator 44 generates electricity. However, the riffmag generator 44 may be driven directly by the engine 11 to generate power. Hereinafter, the configuration of the drive system of the shovel with the riffmag including the riffmag generator 44 directly driven by the engine 11 will be described.

  FIG. 8 is a block diagram showing another example of the configuration of the drive system of the shovel with the riff mug. In FIG. 8, the mechanical power system is indicated by a double line, the high-pressure hydraulic line is indicated by a thick solid line, the pilot line is indicated by a broken line, and the electric drive / control system is indicated by a thin solid line. In addition, about the component similar to the structural example (FIG. 2) mentioned above, the same code | symbol is attached | subjected and it demonstrates centering on a different part.

  A drive shaft 11 a of the engine 11 mounted on the shovel is connected to an input shaft of the transmission 13. The transmission 13 has one input shaft and two output shafts. An input shaft 44 a of a riffmag generator 44 as a power generation unit for supplying power to the riffmag 6 is mechanically coupled to one of the output shafts of the transmission 13. A main pump 14 and a pilot pump 15 are connected to another output shaft of the transmission 13. A control valve 17 is connected to the main pump 14 via a high pressure hydraulic line 16. Further, the main pump 14 is provided with a regulator (not shown) as in the configuration example shown in FIG. The regulator controls the discharge flow rate of the main pump 14 by adjusting the swash plate (tilt angle) of the main pump 14.

  The riffmag generator 44 generates AC power by the driving force of the engine 11. The power output terminal of the riffmag generator 44 is electrically connected to the DC bus 110 via an inverter 46 that functions as a drive control unit. The inverter 46 has a rectifying function for converting AC power output from the riffmag generator 44 into DC power for riffmag excitation. The riff mug 6 is electrically connected to the DC bus 110. The riff mug 6 is driven by power supplied from the DC bus 110 and generates an electromagnetic attracting force.

  Further, the inverter 46 controls the operation of the riffmag generator 44 based on a command from the control unit 30. Thus, the electric power obtained by the inverter 46 causing the riffmag generator 44 to perform a power generation operation is supplied to the riffmag 6 via the DC bus 110.

  The DC-DC converter 46 </ b> B is provided between the riff magnet 6 and the DC bus 110. The DC-DC converter 46 </ b> B boosts the voltage of the DC bus 110 to a predetermined voltage and supplies the boosted voltage to the riffmag 6 when the riffmag 6 is started based on a command from the control unit 30. The predetermined voltage is, for example, the above-described rated voltage (200V), voltage at strong excitation (290V), voltage at the start of excitation (320V), and the like. In this example, the DC-CD converter 46B is provided to boost the voltage of the DC bus 110 and supply power to the riff mag 6. However, the voltage of the DC bus 110 may be directly applied to the riff mag 6. That is, in this case, a predetermined voltage (for example, 320 V) may be generated in the DC bus 110 in accordance with the output voltage of the riffmag generator 44.

  Here, the shovel with the riff mug according to the present example also exhibits the same operations and effects as the shovel with the riff mug shown in FIG.

  That is, the control unit 30 controls the inverter 46, the DC bus 110, and the DC-DC converter 46B, so that the voltage applied to the riffmag 6 when the riffmag 6 is activated (when the riffmag adsorption switch 32 is turned on). It is good to adjust. Specifically, as shown in FIG. 6 described above, when the riffmag adsorption switch 32 is turned on, 320 V higher than the voltage at the time of strong excitation is applied to the riffmag 6 for the first two seconds. In the next 2 seconds, 290 V, which is a voltage during strong excitation, is applied to the riff magnet 6. And after that, it is good to control so that 200V which is the rated voltage of the riffmag 6 may be applied to the riffmag 6. Thereby, a rated current can be sent through the riff mug 6 in a short time, and the electromagnetic attraction force of the riff mug 6 can be rapidly increased. Therefore, the driver does not feel poor operability.

  Also in this example, as the inverter 46, the riffmag power supply circuit (combination of a rectifier and an H bridge circuit) shown in FIG. 3 may be used. Further, at the time of starting the riffmag 6, it is preferable to control the switching elements (the first switching element 410a and the fourth switching element 410d) to be continuously turned on. As a result, it is possible to maintain a state in which a current flows through the switching element. Therefore, in order to increase the voltage applied to the riff mag 6 more than the voltage during strong excitation, the output voltage of the riff mag generator 44 is increased. However, the problem of withstand voltage performance of the switching element can be avoided.

  The output of the main pump 14 may be controlled according to the driving status of the riff mug 6. Specifically, when the riffmag is driven, the riffmag generator 44 is preferentially driven, and the swash plate (tilt angle) of the main pump 14 is controlled by the regulator 14A to suppress the discharge flow rate. The output of the pump 14 may be reduced. Further, after the driving of the riffmag 6 is stopped, the output of the main pump 14 may be increased by controlling the swash plate (tilt angle) of the main pump 14 to increase the discharge flow rate. Thereby, the operativity at the time of starting of the riff mug 6 can be improved, without mounting a big engine. That is, it is necessary to increase the output of the engine 11 for driving the riffmag 6 by increasing / decreasing the output of the main pump 14 driven by the engine 11 according to the driving situation of the riffmag 6 similarly to the riffmag generator 44. Absent. Therefore, it is possible to improve the operability by applying a voltage sufficiently higher than the rated voltage when starting the riffmag 6 without mounting a large engine.

  As mentioned above, although the form for implementing this invention was explained in full detail, this invention is not limited to this specific embodiment, In the range of the summary of this invention described in the claim, it is various. Deformation / change is possible.

  Moreover, this application claims the priority based on the Japan patent application 2012-286070 for which it applied on December 27, 2012, and uses all the content of the Japan patent application for this application by reference.

DESCRIPTION OF SYMBOLS 1 Lower traveling body 1A, 1B Hydraulic motor 2 Turning mechanism 2A Turning hydraulic motor 3 Upper turning body 4 Boom 5 Arm 6 Lifting magnet (lifting magnet)
7 Boom Cylinder 8 Arm Cylinder 9 Riff Mug Cylinder 10 Cabin 11 Engine 14 Main Pump 14A Regulator 17 Control Valve 30 Control Unit 32 Rif Mag Adsorption Switch 40 Generator Hydraulic Pump 42 Hydraulic Motor 44 Riff Mag Generator 46 Inverter 46B DC-DC Converter 300 DC converter (rectifier)
310a-310f Diode 400 H bridge circuit part (H bridge circuit)
410a-410d 1st-4th switching element 420a-420d 1st-4th commutation diode 460e Resistance element 500 Energy absorption part for demagnetization 510 Capacitance element

Claims (4)

An engine controlled to rotate at a set target rotational speed out of two predetermined target rotational speeds;
A hydraulic pump coupled to the engine;
A load driven by pressure oil from the hydraulic pump;
A synchronous generator controlled to a predetermined rotational speed based on the driving force of the engine;
A lifting magnet including an electromagnet which is supplied with electric power from the synchronous generator and generates electromagnetic attraction;
A drive control unit for controlling a voltage applied to the electromagnet;
Have
The drive control unit is rated for the electromagnet when a switch that activates the lifting magnet is turned on and a higher target rotational speed of the two target rotational speeds is set. Applying a first voltage higher than the voltage, and then switching the voltage applied to the electromagnet to a second voltage lower than the first voltage;
The output of the hydraulic pump is a work machine with a riff mug that is increased in accordance with switching of the voltage applied to the electromagnet by the drive control unit from the first voltage to the second voltage . A work machine with a riff mug according to claim 1 ,
During activation of the lifting magnet, wherein by controlling the flow rate by the swash plate hydraulic pump obtain Bei, lifting magnet with a work machine that reduces the output of the hydraulic pump. An engine controlled to rotate at a set target rotational speed out of two predetermined target rotational speeds;
A hydraulic pump coupled to the engine;
A load driven by pressure oil from the hydraulic pump;
A synchronous generator controlled to a predetermined rotational speed based on the driving force of the engine;
A lifting magnet including an electromagnet which is supplied with electric power from the synchronous generator and generates electromagnetic attraction;
A drive control unit for controlling a voltage applied to the electromagnet;
Have
The drive control unit is rated for the electromagnet when a switch that activates the lifting magnet is turned on and a higher target rotational speed of the two target rotational speeds is set. Applying a first voltage higher than the voltage, and then switching the voltage applied to the electromagnet to a second voltage lower than the first voltage;
At the time of starting the lifting magnet, the flow rate is controlled by a swash plate included in the hydraulic pump to reduce the output of the hydraulic pump, and from the first voltage of the voltage applied to the electromagnet by the drive control unit In accordance with the switching to the second voltage, the flow rate is controlled by the swash plate to increase the output of the hydraulic pump, and the lift magnet controls the output of the hydraulic pump according to the driving status of the lifting magnet. Work machine with. A work machine with a riff mug according to claim 2 or 3 ,
A working machine with a lift magnet that controls the flow rate by the swash plate and increases the output of the hydraulic pump after the lifting magnet is stopped.

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