JP2010119290A - Inverter control driving system and excavator using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that a counter-electromotive force is generated in a motor winding of a general-purpose motor by a slip of a motor and a backlash of a drive unit (gear) even if output frequencies of each inverter of a plurality of general-purpose motors are kept the same. <P>SOLUTION: The inverters 8a and 8b to control 2 pieces of general-purpose motors 5a and 5b have converters 14a and 14b, capacitors 15a and 15b to smooth output voltages from the converters 14a and 14b, output bridge portions 16a and 16b to convert direct-current voltages smoothed by the capacitors 15a and 15b into three-phase alternating currents, inrush-current control resistances 18a and 18b connected in series between the converters 14a and 14b and the capacitors 15a and 15b, and first switches 19a and 19b connected in parallel to the inrush-current control resistances 18a and 18b. The first switches 19a and 19b are turned ON when capacitor voltages of the capacitors 15a and 15b reach a first prescribed voltage. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an inverter control drive device and an excavator using the same. Specifically, an inverter control drive device including a rotation shaft, two general-purpose motors that rotate the rotation shaft, and an inverter that is provided corresponding to each general-purpose motor and drives and controls the general-purpose motor, and the same are used. Related to the excavator.

  As an excavating machine for creating a tunnel, a rotary cutter is driven and controlled by a plurality of general-purpose motors, and each motor is provided with a general-purpose inverter.

  In this excavating machine, the output shafts of three general-purpose motors (three-phase induction motors) are respectively connected to pinions via reduction gears. Since the three pinions are connected to the rotary cutter, the three general-purpose motors have the same rotational speed. The three general-purpose motors are driven and controlled by general-purpose inverters (three-phase inverters) provided individually. The output shafts of the three motors are connected to the same load. In this case, if there is a difference in the output frequency from each inverter due to an error in each inverter, a shift in synchronous rotation will occur. Therefore, the output frequency of each inverter is made the same and the load of the three general-purpose motors is balanced. (For example, Patent Document 1).

JP 2000-265784 A

  However, in the conventional excavating machine, it is based on the premise that the output torque of the three general-purpose motors becomes the same by making the output frequency of each inverter of the three general-purpose motors the same. Even if the output frequency is the same, the output torque of the general-purpose motor will not be the same due to the motor slip and the backlash of the drive device (gear), and the difference in current flowing through the three general-purpose motors will occur, causing the motor winding of the general-purpose motor to Back electromotive force is generated on the line. Furthermore, when the general-purpose motor is decelerated in this state, a larger back electromotive force is generated in the motor winding of the general-purpose motor, and the back electromotive force is rectified in the inverter, increasing the bus voltage of the inverter DC circuit. End up. If the increase in bus voltage due to the counter electromotive force exceeds the rating of the rectifier or switching element connected to the bus, there is a risk of voltage breakdown in these devices.

  The present invention has been made in view of the above problems, and is not affected by regenerative electric power generated in a general-purpose motor, and can control an inverter control drive device that can reliably rotate the motor, an excavator using the same, and a motor drive method The purpose is to provide.

  In order to solve the above-described problems and achieve the above object, the first aspect of the present invention is an inverter provided with an inverter for driving and controlling a general-purpose motor, which is provided corresponding to each of two general-purpose motors. The inverter is a control drive device, and the inverter includes a converter unit that converts an AC voltage from an AC power source into a DC voltage, a capacitor unit that smoothes an output voltage from the converter unit, and a DC voltage smoothed by the capacitor unit. An output bridge unit that converts to three-phase AC and outputs to a general-purpose motor, an inrush current suppression resistor unit connected in series between the converter unit and the capacitor unit, and a first switch connected in parallel to the inrush current suppression resistor unit The capacitor part of one general-purpose motor and the capacitor part of the other general-purpose motor are connected in parallel and connected in series in the parallel circuit. The first switch further switches from OFF to ON when the capacitor voltage of the capacitor portion of the general-purpose motor to which the first switch is connected reaches the first specified voltage. The capacitor voltage of the capacitor portions of the two general-purpose motors is switched from OFF to ON when the capacitor voltage reaches a second specified voltage higher than the first specified voltage.

  In the initial stage where the capacitor unit is charged by the AC power supply, the instantaneous voltage drops due to the influence of the rush current. According to the present invention, the first switch is a capacitor of a general-purpose motor to which the first switch is connected. When the capacitor voltage of the part reaches the first specified voltage, the switch is switched from OFF to ON, so that the rush current is suppressed and no instantaneous voltage drop occurs. In addition, the second switch is switched from OFF to ON when the capacitor voltage of the capacitor section of the two general-purpose motors reaches the second specified voltage higher than the first specified voltage, so the slip of the general-purpose motor and the drive device (gear) Even if a backlash causes a difference in current flowing through two general-purpose motors and a back electromotive force (regenerative power) is generated in the motor winding of one general-purpose motor, the regenerative power can be consumed by the other general-purpose motor. And increase in the capacitor voltage of the capacitor portion can be reduced. Thereby, energy efficiency can be improved.

  In order to solve the above problems and achieve the above object, the second aspect of the present invention is an inverter provided with an inverter for driving and controlling a general-purpose motor, respectively, corresponding to two general-purpose motors. An inverter unit includes a converter unit that converts an AC voltage from an AC power source into a DC voltage, a capacitor unit that smoothes an output voltage from the converter unit, and a DC voltage that is smoothed by the capacitor unit. Is converted into a three-phase alternating current and output to a general-purpose motor, an inrush current suppression resistor unit connected in series between the converter unit and the capacitor unit, and a first connected in parallel to the inrush current suppression resistor unit A capacitor part of one of the general-purpose motors and a capacitor part of the other general-purpose motor are connected in parallel and connected in series in the parallel circuit. The first switch is switched from OFF to ON when the capacitor voltage of the capacitor portion of the general-purpose motor to which the first switch is connected reaches the first specified voltage. Is characterized in that it is switched from OFF to ON when the first switches of the two general-purpose motors are switched from OFF to ON.

  In the initial stage where the capacitor unit is charged by the AC power supply, the instantaneous voltage drops due to the influence of the rush current. According to the present invention, the first switch is a capacitor of a general-purpose motor to which the first switch is connected. When the capacitor voltage of the part reaches the first specified voltage, the switch is switched from OFF to ON, so that the rush current is suppressed and no instantaneous voltage drop occurs. In addition, since the second switch is switched from OFF to ON when the first switch of the two general-purpose motors is switched from OFF to ON, the two general-purpose motors can be switched to two general-purpose motors by slipping of the general-purpose motor or backlash of the driving device (gear). Even if there is a difference in the flowing current and back electromotive force (regenerative power) is generated in the motor winding of one general-purpose motor, the regenerative power can be consumed by the other general-purpose motor, and the capacitor voltage of the capacitor increases. Can be reduced. Thereby, energy efficiency can be improved.

  According to a third aspect of the present invention, there is provided an inverter-controlled drive device according to the first or second aspect, wherein a discharge resistor is connected in parallel to a parallel circuit provided with a second switch, and the discharge resistor is A third switch connected in series is further provided in the provided parallel circuit, and the third switch is switched from OFF to ON after the second switch is switched from OFF to ON.

  When the general-purpose motor is decelerated, a larger back electromotive force (regenerative power) is generated in the motor winding of the general-purpose motor. According to the present invention, the third switch is switched to the second switch. Since it is switched from OFF to ON later, the regenerative power can be passed through the discharge resistor and converted into thermal energy. Further, even when the power supply voltage of the AC power supply fluctuates, it can be converted into thermal energy by this discharge resistance. Thereby, even if the bus voltage rises due to the electromotive force or the counter electromotive force, it is possible to prevent voltage breakdown of the rectifier and the switching element connected to the bus.

  According to a fourth aspect of the present invention, there is provided an inverter-controlled drive device according to the third aspect, the motor current detector for detecting the current of each general-purpose motor that rotates the rotating shaft, and the motor current detection Current difference detection means for detecting a current difference between two general-purpose motors detected by the detector, and a motor current detector so as to eliminate the current difference between the two general-purpose motors detected by the current difference detection means. Control is performed to increase the inverter output frequency of the general-purpose motor having the smaller detected current value.

  According to a fifth aspect of the present invention, there is provided an excavator that uses the inverter-controlled drive device according to the fourth aspect, covering a sun gear that rotates integrally with a rotating shaft, and an outer periphery of the sun gear. An internal gear coaxially disposed in the sun gear via a gap, a planetary gear disposed in the gap and meshing with the sun gear and the internal gear, a drill attached to the rotary shaft, It has a digging blade attached to a gear, and it is characterized by excavating with a drill and a digging blade.

  According to the present invention, the sun gear that rotates integrally with the rotating shaft, the internal gear that is coaxially disposed in the sun gear via the gap so as to cover the outer periphery of the sun gear, and the gap that is disposed in the gap. Because it has a planetary gear that is installed and meshes with the sun gear and the internal gear, a drill attached to the rotating shaft, and a drilling blade attached to the internal gear, excavation while obtaining a large reduction ratio with a small number of gears The excavator can be downsized.

  If slipping or backlash of the drive unit (gear) occurs in two general-purpose motors, the output torque of the general-purpose motors will not be the same, resulting in a difference in current flowing through the two general-purpose motors, and the smaller current The motor is pulled by the general-purpose motor with the larger number of motors, and the maximum output cannot be supplied to the general-purpose motor as a whole. According to the present invention, the inverter output frequency of the general-purpose motor with the smaller current value detected by the motor current detector is increased so as to eliminate the current difference between the two general-purpose motors detected by the current difference detection means. The sharing ratio of each general-purpose motor can be made equal, and the maximum output of the general-purpose motor as a whole can be given to the load.

  According to a sixth aspect of the present invention, there is an excavator using the inverter control drive device according to the fourth aspect, a sun gear that rotates integrally with a rotating shaft that is rotated by a general-purpose motor, An internal gear that is coaxially disposed in the sun gear via a gap so as to cover the outer periphery of the sun gear, a planetary gear that is disposed in the gap and meshes with the sun gear and the internal gear, and rotation of the rotating shaft And a drilling blade rotated by the revolving motion of the planetary gear, and the drilling is performed by the drill and the drilling blade.

  According to the present invention, a sun gear that rotates integrally with a rotating shaft that is rotated by a general-purpose motor, and an inner shaft that is coaxially disposed via a gap so as to cover the outer periphery of the sun gear. Since it has a gear, a planetary gear that is disposed in the gap and meshes with the sun gear and the internal gear, a drill that rotates by the rotation of the rotating shaft, and a drilling blade that rotates by the revolving motion of the planetary gear, The excavator can be excavated with a small number of gears while obtaining a large reduction ratio, and the excavator can be downsized.

  According to the present invention, the motor can be reliably rotated without being affected by the regenerative power generated in the general-purpose motor.

(A) It is a top view of the excavator in which the inverter control drive apparatus in one Embodiment of this invention was used. It is a side view of a X-axis direction. (B) Top view of the excavator. Side view in the Y-axis direction. (C) It is a top view of the excavator. It is AA sectional drawing of FIG.1 (b) and FIG.1 (c). It is BB sectional drawing of Fig.1 (a). It is a figure which shows the circuit diagram of the inverter control drive device in one Embodiment of this invention. It is a flowchart which shows the underground solid body formation process of an excavator using the same inverter control drive device. It is a figure which shows the switch control process which is a subroutine program of the underground solid body formation process of FIG. (A) It is a top view of the excavator in which the inverter control drive device in 2nd embodiment of this invention was used. It is a side view of a X-axis direction. (B) Top view of the excavator. Side view in the Y-axis direction. (C) It is a top view of the excavator. It is CC sectional drawing of Fig.7 (a). It is DD sectional drawing of FIG. It is a figure which shows the excavation blade of the excavator in which the inverter control drive device in 2nd embodiment of this invention was used.

(First embodiment)
Hereinafter, an embodiment of an inverter control drive device of the present invention will be described with reference to the drawings. FIG. 1A is a side view in the X-axis direction of a top view of the excavator using the inverter control drive device according to the embodiment of the present invention, and FIG. 1B is a top view of the excavator in the Y-axis direction. FIG. 1C is a top view of the excavator.

  As shown in FIG. 1 (a), an excavator 1 includes an upper case 2 having general-purpose motors 5a and 5b and a U-shaped (government-shaped) cross section, and fixing means such as bolts and pins to the upper case 2. A hollow middle case 3 fixed by (not shown) and a hollow lower case 4 fixed to the middle case 3 by fixing means (not shown) such as bolts and pins. A hollow lower member 7 is attached to the lower case 4.

As will be described later, the output shaft 11 is rotated by general-purpose motors 5 a and 5 b and protrudes from the lower portion of the hollow lower member 7. A drill 12 is attached to the output shaft 11 by fixing means (not shown) such as bolts and pins. When the fixing means referred to in the present embodiment is a bolt, a screw hole corresponding to the bolt may be provided on the fixed side, and a nut to be screwed with the bolt may be provided on the opposite side. The drill 12 is hollow and has a circular cross section. By supplying cement milk or the like from the ground to a hollow portion (not shown) inside the drill 12, the cement milk or the like can be jetted from the tip of the drill 12. it can. In this way, drilling is performed while sequentially connecting the drills 12, and the drill 12 is inserted into the ground.
In the present embodiment, the drills 12 are sequentially connected. However, the present invention is not limited to this, and drilling may be performed while sequentially connecting a joint (not shown) to the drill 12 at the tip.

  Next, the internal structure of the excavator 1 will be described with reference to FIG. 2 is a cross-sectional view taken along the line AA in FIGS. 1B and 1C, and FIG. 3 is a cross-sectional view taken along the line BB in FIG.

  General-purpose motors 5a and 5b composed of three-phase induction motors (induction motors) rotate motor rotating shafts 6a and 6b, and are respectively provided in the upper case 3 (see FIGS. 1A and 2). ). The general-purpose motors 5a and 5b are provided with a cooling fan (not shown) at the top, and the cooling fan (not shown) is configured to rotate from a fan drive shaft (not shown) of the general-purpose motors 5a and 5b. . This cooling fan (not shown) is provided on the upper part of the upper case 2. Thus, since the general-purpose motors 5a and 5b are provided with the cooling fans (not shown), the general-purpose motors 5a and 5b whose temperature has been increased by the rotation can be cooled.

  In this embodiment, for convenience of explanation, the motor rotation shaft 6 (6a, 6b) and the fan drive shaft (not shown) are described as separate members, but originally the motor rotation shaft 6 (6a, 6b). The fan drive shaft (not shown) is a rotating shaft of a general-purpose motor 5 (5a, 5b) integrally formed, and this rotating shaft is driven by the driving force of the general-purpose motors 5a, 5b.

  Electric motor gears 9a and 9b that are press-fitted using motor rotation shaft mounting bosses (motor rotation shaft mounting means (not shown)) are fixed to the motor rotation shafts 6a and 6b of the two general-purpose motors 5a and 5b, respectively. Yes. Thus, since the electric gears 9a and 9b are fixed to the motor rotation shafts 6a and 6b, they can rotate concentrically with the motor rotation shafts 6a and 6b.

  The input gear 10 is arranged so as to circumscribe the two motor gears 9a and 9b, and can be rotated by the rotation of the motor gears 9a and 9b (see FIGS. 2 and 3). An output shaft 11 press-fitted using an input shaft mounting boss (input shaft mounting means (not shown)) is fixed to the input gear 10.

  Next, a circuit diagram of the inverter control drive device according to the present embodiment will be described with reference to FIG. Here, FIG. 4 is a diagram showing a circuit diagram of the inverter control drive device in one embodiment of the present invention. As described above, the inverters 8a and 8b provided corresponding to the two general-purpose motors 5a and 5b drive and control the general-purpose motors 5a and 5b, respectively.

  The inverter control drive device 13 provided in the excavator 1 includes converter units 14a and 14b that convert an AC voltage from an AC power source into a DC voltage, and a capacitor unit 15a that smoothes an output voltage from the converter units 14a and 14b. 15b, output bridge portions 16a and 16b for converting the DC voltage smoothed by the capacitor portions 15a and 15b into three-phase alternating current and outputting the same to general-purpose motors (induction motors) 5a and 5b, and the output bridge portions 16a and 16b A control device (not shown) for driving and controlling, an inrush current suppression resistor unit 18a, 18b connected in series between the converter unit 14a, 14b and the capacitor unit 15a, 15b, and the inrush current suppression resistor unit 18a, 18b. The first switch 19a, 19b connected in parallel and one of the general-purpose motors 5a, 5b (5a, 5b) ) Capacitor portion 15 (15a or 15b) and capacitor portion 15 (15a or 15b) of the other general-purpose motor are connected in parallel, and second switch 20 connected in series in the parallel circuit, and second switch 20 A discharge resistor 21 is connected in parallel to the provided parallel circuit, and a third switch 22 is connected in series to the parallel circuit provided with the discharge resistor 21. The inverter control drive device 13 includes a motor current detector (not shown) for detecting the currents of the general-purpose motors 5a and 5b that rotate the motor rotating shafts 6a and 6b, and the motor current detector (not shown). Current difference detecting means (not shown) for detecting the current difference between the two general-purpose motors 5a and 5b detected by the above and capacitor voltage detecting means (not shown) for detecting the capacitor voltage of the capacitor portions 15a and 15b are provided. It has been. The motor current detector (sensor), current difference detection means, and capacitor voltage detection means (sensor) are processed by a CPU (not shown) built in a control device (not shown). The current difference and the capacitor voltage are stored in a memory (not shown) built in the control device (not shown).

  Next, the operation of the excavator using the inverter control drive device according to the present embodiment will be described with reference to FIGS. Here, FIG. 5 is a flowchart showing the underground solid body forming process of the excavator using the inverter control drive device according to the embodiment of the present invention, and FIG. 6 is the underground solid body of FIG. It is a figure which shows the switch control process which is a subroutine program of a creation process.

  As shown in FIG. 5, in the underground consolidated body formation step, it is first determined in S1 whether the power switch (not shown) of the excavator 1 is ON. This power switch (not shown) is a main power source of the excavator 1, and a start switch (not shown) described later can be turned on by turning on the power switch (not shown). Here, if the power switch (not shown) is OFF, NO is determined in S1, and the process of S1 is performed until the power switch (not shown) is turned ON. If a power switch (not shown) is turned ON, YES is determined in S1, and the process proceeds to S2.

  In S2, it is determined whether a start switch (not shown) is ON. This start switch (not shown) is a switch for starting excavation by the excavator 1. That is, when this start switch (not shown) is turned on, an alternating current is supplied, and the drill 12 is rotated by the general-purpose motors 5a and 5b to start excavation. Here, if the start switch (not shown) is OFF, NO is determined in S2, and the process of S2 is performed until the start switch (not shown) is turned ON. If the start switch (not shown) is turned on, YES is determined in S2, and the process proceeds to S3. In this way, the drill 12 is inserted into the ground by the driving force of the general-purpose motors 5a and 5b, and excavation is started (see S3). Then, the process proceeds to S4.

  In S4, a switch control process is performed. This switch control process is a process for smoothly rotating the general-purpose motors 5a and 5b so as to ensure excavation. The specific contents of the switch control process will be described later with reference to FIG. Then, the process proceeds to S5, where it is determined whether the drill 12 has been inserted to a predetermined depth by S5. Here, if it is determined in S5 that the drill 12 has not been inserted to a predetermined depth, the processes of S5 → S3 → S4 → S5 are repeated until the drill 12 is inserted to a predetermined depth. Drilled to a predetermined depth. When the drill 12 is inserted to a predetermined depth in S5, YES is determined in S5, and the process proceeds to S6.

  In S <b> 6, the drill 12 is pulled up from the hole drilled by the drill 12. When the drill 12 is pulled up, the process proceeds to S7, where the start switch (not shown) is turned off, and when digging is finished, the power switch (not shown) is turned off at S8. In the present embodiment, the description is simplified and the start switch (not shown) is turned off (S7) after the completion of lifting the drill 12 (S6). When another place is excavated by the drill 12 after completion, the process of S3 is further performed after the process of S6.

  Next, the switch control process which is a subroutine program of the underground consolidated body formation process of FIG. 6 will be described.

  6 is started when a start switch (not shown) is turned on (FIG. 5S2), current is supplied to the general-purpose motors 5a and 5b, and excavation is started by the drill 12 (FIG. 5S3). Later.

  In S21, it is determined whether or not the capacitor voltage V of the capacitor portions 15a and 15b of the general-purpose motors 5a and 5b to which the first switches 19a and 19b are connected has reached the first specified voltage, and the first switches 19a and 19b are connected. When it is determined that the capacitor voltage V of the capacitor portions 15a and 15b of the general-purpose motors 5a and 5b has reached the first specified voltage, the second corresponding to the capacitor portions 15a and 15b having reached the first specified voltage in S22. One switch 19a, 19b (see FIG. 4) is turned ON, and the process of S23 is performed after the first switch 19a, 19b is turned ON by S22. Here, the first switches 19a and 19b that are turned on are connected to the general-purpose motors 5a and 5b that are determined that the capacitor voltage V of the capacitor portions 15a and 15b of the general-purpose motors 5a and 5b has reached the first specified voltage. The first switches 19a and 19b.

  As described above, in the initial stage where the capacitor units 15a and 15b are charged by the AC power supply, the instantaneous voltage drops due to the influence of the rush current, but the general-purpose motors 5a and 5b to which the first switches 19a and 19b are connected. Since the first switches 19a and 19b are switched from OFF to ON when the capacitor voltage V of the capacitor portions 15a and 15b reaches the first specified voltage, the rush current is suppressed and the instantaneous voltage drop can be eliminated. Here, when it is determined in S21 that the capacitor voltage V of the capacitor portions 15a and 15b of the general-purpose motors 5a and 5b to which the first switches 19a and 19b are connected does not reach the first specified voltage, switch control is performed. The process ends.

  In S23, it is determined whether the capacitor voltage V of the capacitor portions 15a and 15b of the general-purpose motors 5a and 5b to which the first switches 19a and 19b are connected has reached the second specified voltage higher than the first specified voltage described above. When it is determined that the capacitor voltage V of the capacitor parts 15a and 15b has also reached the second specified voltage, the second switch 20 (see FIG. 4) is turned ON by S24, and the second switch 20 is turned ON by S24. After that, the process of S25 is performed.

  As described above, when the capacitor voltage V of the two capacitor portions 15a and 15b reaches the second specified voltage higher than the first specified voltage, the switching is performed from OFF to ON. Therefore, the sliding of the general-purpose motors 5a and 5b and the motor gears 9a and 9b are performed. And the input gear 10 (drive device (gear)) causes a difference in current flowing in the two general-purpose motors 5a and 5b due to backlash, and counter electromotive force (regenerative power) is generated in the motor windings of the one general-purpose motor 5a and 5b. Even if this occurs, the regenerative power can be consumed by the other general-purpose motors 5a and 5b, and the rise in the capacitor voltage V of the capacitor portions 15a and 15b can be reduced. Thereby, energy efficiency can be improved. Here, when it is determined by S23 that the capacitor voltage V of any one of the capacitor units 15a and 15b has not reached the second specified voltage, the switch control process ends. In this embodiment, it is determined whether the capacitor voltage V of the two capacitor portions 15a and 15b has reached the second specified voltage higher than the first specified voltage, and the capacitor voltage V of the two capacitor portions 15a and 15b is When it is determined that the two specified voltages have been reached, the second switch 20 (see FIG. 4) is turned on by S24. However, the present invention is not limited to this, and the two first switches 19a and 19b have been switched from OFF to ON. When the two first switches 19a and 19b are switched from OFF to ON, the second switch 20 (see FIG. 4) may be switched from OFF to ON. Even if it does in this way, it will have the effect similar to the effect mentioned above.

  If it is determined by S25 whether the deceleration speeds of the general-purpose motors 5a and 5b (deceleration speeds within a predetermined time) have reached the specified deceleration speed, and if it is determined that the deceleration speeds of the general-purpose motors 5a and 5b have reached the specified deceleration speed , S26 turns the third switch 22 (see FIG. 4) from OFF to ON. If the third switch 22 is turned from OFF to ON in S26, or if it is determined in S25 that the deceleration speeds of the general-purpose motors 5a and 5b have not reached the specified deceleration speed, the switch control process ends. .

  Thus, when the general-purpose motors 5a and 5b are decelerated, a larger back electromotive force (regenerative power) is generated in the motor windings of the general-purpose motors 5a and 5b, but the deceleration speed of the general-purpose motors 5a and 5b is reduced. When it is determined that the specified speed has been reached, the third switch 22 is switched from OFF to ON, so that the regenerative power can be passed through the discharge resistor to be converted into thermal energy. Thereby, even if the bus voltage rises due to the electromotive force or the counter electromotive force, it is possible to prevent voltage breakdown of the rectifier and the switching element connected to the bus. In the present embodiment, the third switch 22 is switched from OFF to ON when it is determined that the deceleration speed of the general-purpose motors 5a and 5b has reached the specified deceleration speed. When it is determined that the capacitor voltage V of the capacitor portions 15a and 15b of the general-purpose motors 5a and 5b to which the first switches 19a and 19b are connected has reached a third specified voltage higher than the second specified voltage, the third switch 22 may be switched from OFF to ON, or the second switch 20 may be switched from OFF to ON, and the third switch 22 may be switched from OFF to ON after a predetermined time has elapsed. That is, the third switch 22 may be switched from OFF to ON after the second switch 20 is switched from OFF to ON. In this way, as described above, regenerative power can be passed through the discharge resistor to be converted into thermal energy, and when the power supply voltage of the AC power supply fluctuates, it can be converted into thermal energy with this discharge resistor. it can.

(Second embodiment)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. FIG. 7A is a side view in the X-axis direction of the top view of the excavator in which the inverter control drive device according to one embodiment of the present invention is used, and FIG. 7B is a top view of the excavator in the Y-axis direction. FIG. 7C is a top view of the excavator.

  The difference between the second embodiment of the present invention and the first embodiment is that the inside of the lower case 4 of the first embodiment is hollow, whereas in the second embodiment, the lower case 4 The planetary gear unit 24 is provided inside, and excavation is performed with the drill 12 attached to the output shaft 11, and the excavation blade 26 attached to the internal gear 25 of the planetary gear unit 24 can be excavated via the lower member 7. is there. In FIG. 7, the drill 12 attached to the output shaft 11 is omitted, but in the second embodiment, excavation is performed with the drill 12 as in the first embodiment. This will be specifically described below.

  As shown in FIG. 7, the excavating blade 26 is attached to the lower member 7 by fixing means (not shown) including bolts and nuts.

  Next, the planetary gear device 24 provided in the lower case 4 will be described. 8 is a cross-sectional view taken along the line CC in FIG. 7A, and FIG. 9 is a cross-sectional view taken along the line DD in FIG.

  As shown in FIGS. 8 and 9, the planetary gear device 24 includes a sun gear 27 press-fitted to the output shaft 11 (rotating shaft) using a sun gear mounting boss (sun gear mounting means (not shown)), The sun gear 27 is arranged in a space between the sun gear 27 and the internal gear 25 so as to cover the outer periphery of the sun gear 27, and the sun gear 27 is arranged coaxially via the space. And a planetary gear 28 that meshes with the internal gear 25 and rotates around the sun gear 27. A plurality of planetary gears 28 (three in this embodiment) are arranged at equal intervals around the sun gear 27 arranged on the rotation shaft.

  The sun gear 27 includes a substantially cylindrical gear portion 29 having teeth formed on the outer peripheral surface, and a fitting portion 30 that has a smaller diameter than the gear portion 29 and is fitted to the output shaft 11. The gear portion 29 is configured to mesh with the planetary gear 28, and the fitting portion 30 rotates integrally with the output shaft 11 by fitting with the fitting portion 31 of the output shaft 11.

  Each planetary gear 28 is formed with a through hole 32 penetrating in the axial direction in the central portion, and can rotate around a pin 34 inserted into the through hole 32. Here, the planetary gear 28 is inserted into the pin 34 via a needle bearing (not shown). The pin 34 is rotatably attached to a casing 51 formed integrally with the lower case 4 via a needle bearing (not shown).

  The internal gear 25 is rotatably attached to the lower case 4 via a bearing 50. Thus, each planetary gear 28 rotates around the pin 34 as the sun gear 27 rotates, and the internal gear 25 can be rotated by the rotation of the planetary gear 28.

  The lower member 7 is attached to the internal gear 25 by fixing means such as a bolt 52. Further, as described above, the excavating blade 26 (see FIG. 10) is attached to the internal gear 25 via the lower member 7. Thus, the excavating blade 26 can rotate at the same rotational speed as the internal gear 25 via the lower member 7 as the internal gear 25 rotates, and the circular hole is excavated as the excavating blade 26 rotates. be able to. And inside this circular hole, it is excavated while scraping up the soil with the drill 12 inside the excavating blade 26, and a cylindrical hole can be formed. In this manner, excavation is performed while the joints of the excavation blades 26 are sequentially connected, and the excavation blades 26 are inserted into the ground. In the present embodiment, the aspect in which the excavating blade 26 is attached to the internal gear 25 via the lower member 7 is shown, but the present invention is not limited to this, and the excavating blade 26 may be directly attached to the internal gear 25. That is, the excavation blade 26 may be attached to the internal gear 25 directly or indirectly. Here, FIG. 10 is a diagram showing an excavating blade of an excavator in which the inverter control drive device according to the second embodiment of the present invention is used.

  As described above, the planetary gear device 24 is provided, and the excavating blade 26 is provided on the internal gear 25 of the planetary gear device 24, so that excavation can be performed while obtaining a large reduction ratio with a small number of gears. Miniaturization can also be achieved.

(Third embodiment)
Next, a third embodiment of the present invention will be described. The difference between the third embodiment and the second embodiment of the present invention is that, in the second embodiment, the planetary gear 28 of the planetary gear device 24 rotates and the internal gear 25 rotates. In the third embodiment, the internal gear 25 of the planetary gear unit 24 is attached to the lower case 4 while the excavating blade 26 is attached via the lower member 7 and the excavating blade 26 cuts the ground. The planetary gear 28 is revolved while rotating without being fixed and rotated, and the excavation blade 26 is attached to the planetary gear 28 via the lower member 7, and the excavation blade 26 cuts the ground. In addition, description is abbreviate | omitted about the same structure as 2nd embodiment, Suppose that only a different part is demonstrated, referring FIG. 8 and FIG. 9 used by 2nd Embodiment.

  As shown in FIG. 8, the pin 34 inserted into the through hole 32 of each planetary gear 28 is attached to the lower member 7 via a needle bearing (not shown) so as to be rotatable (spinning). A lower member 7 is rotatably attached to the lower case 4 via a bearing (not shown). Thereby, each planetary gear 28 revolves around the sun gear 27 while rotating around the position of the pin 34 as the sun gear 27 rotates, and the lower member 7 attached to the planetary gear 28 is moved to the planetary gear 28. It is rotated at the same speed as the revolution speed. Thereby, the excavation blade 7 attached to the lower member 7 can rotate with the lower member 7 at a rotational speed.

  Thus, a circular hole can be excavated by rotating the excavation blade 26 attached to the lower member 7. And inside this circular hole, it is excavated while scraping up the soil with the drill 12 inside the excavating blade 26, and a cylindrical hole can be formed.

  As described above, the planetary gear device 24 is provided, and the excavating blade 26 is provided on the internal gear 25 of the planetary gear device 24. Therefore, excavation can be performed while obtaining a large reduction ratio with a small number of gears. The size can be reduced.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. Further, the scope of the present invention is shown not by the above description but by the description of the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

DESCRIPTION OF SYMBOLS 1 Excavator 2 Upper case 3 Middle case 4 Lower case 5a, 5b General-purpose motor 6a, 6b Motor rotating shaft 7 Lower member 8a, 8b Inverter 9a, 9b Electric motor gear 10 Input gear 11 Output shaft 12 Drill 13 Inverter control drive device 14a, 14b Converter unit 15a, 15b Capacitor unit 16a, 16b Output bridge unit 17 Controller 18a, 18b Inrush current suppression resistor unit 19a, 19b First switch 20 Second switch 21 Discharge resistor 22 Third switch 24 Planetary gear mechanism 25 Internal gear 26 Excavation blade 27 Sun gear 28 Planetary gear 29 Gear portion 30 Fitting portion 31 Fitting portion 32 Through hole 34 Pin 50 Bearing 51 Casing 52 Bolt

Claims (6)

An inverter control drive device provided with an inverter for driving and controlling the general-purpose motor, each provided corresponding to two general-purpose motors,
The inverter is
A converter unit for converting an AC voltage from an AC power source into a DC voltage;
A capacitor unit for smoothing the output voltage from the converter unit;
An output bridge unit that converts a DC voltage smoothed by the capacitor unit into a three-phase AC and outputs it to the general-purpose motor;
Inrush current suppression resistor unit connected in series between the converter unit and the capacitor unit,
A first switch connected in parallel to the inrush current suppression resistor unit,
A capacitor part of one general-purpose motor of the general-purpose motor and a capacitor part of the other general-purpose motor are connected in parallel, and further includes a second switch connected in series in the parallel circuit,
The first switch is switched from OFF to ON when the capacitor voltage of the capacitor portion of the general-purpose motor to which the first switch is connected reaches the first specified voltage,
2. The inverter control drive device according to claim 2, wherein the second switch is switched from OFF to ON when the capacitor voltages of the capacitor portions of the two general-purpose motors reach a second specified voltage higher than the first specified voltage. An inverter control drive device provided with an inverter for driving and controlling the general-purpose motor, each provided corresponding to two general-purpose motors,
The inverter unit is
A converter unit for converting an AC voltage from an AC power source into a DC voltage;
A capacitor unit for smoothing the output voltage from the converter unit;
An output bridge unit that converts a DC voltage smoothed by the capacitor unit into a three-phase AC and outputs it to the general-purpose motor;
Inrush current suppression resistor unit connected in series between the converter unit and the capacitor unit,
A first switch connected in parallel to the inrush current suppression resistor unit,
A capacitor part of one general-purpose motor of the general-purpose motor and a capacitor part of the other general-purpose motor are connected in parallel, and further includes a second switch connected in series in the parallel circuit,
The first switch is switched from OFF to ON when the capacitor voltage of the capacitor portion of the general-purpose motor to which the first switch is connected reaches the first specified voltage,
The inverter control drive device, wherein the second switch is switched from OFF to ON when the first switches of the two general-purpose motors are switched from OFF to ON. A discharge resistor is connected in parallel to the parallel circuit provided with the second switch, and a third switch connected in series to the parallel circuit provided with the discharge resistor is further provided.
3. The inverter control drive device according to claim 1, wherein the third switch is switched from OFF to ON after the second switch is switched from OFF to ON. A motor current detector for detecting the current of each general-purpose motor that rotates the rotating shaft;
A current difference detecting means for detecting a current difference between the two general-purpose motors detected by the motor current detector;
Control is performed to increase the inverter output frequency of the general-purpose motor with the smaller current value detected by the motor current detector so as to eliminate the current difference between the two general-purpose motors detected by the current difference detection means. The inverter control drive device according to claim 3, wherein A sun gear that rotates integrally with a rotating shaft that is rotated by the general-purpose motor;
An internal gear coaxially disposed in the sun gear via a gap so as to cover the outer periphery of the sun gear;
A planetary gear disposed in a gap and meshing with the sun gear and the internal gear;
A drill attached to the rotating shaft;
A drilling blade attached to the internal gear,
The excavator using the inverter-controlled drive device according to claim 4, wherein excavation is performed by the drill and the excavation blade. A sun gear that rotates integrally with a rotating shaft that is rotated by the general-purpose motor;
An internal gear coaxially disposed in the sun gear via a gap so as to cover the outer periphery of the sun gear;
A planetary gear disposed in the gap and meshing with the sun gear and an internal gear;
A drill that rotates by rotation of the rotating shaft;
A drilling blade that rotates by the revolving motion of the planetary gear,
The excavator using the inverter control drive device according to claim 4, wherein excavation is performed by the drill and the excavation blade.

Images