Description

VIBRATOR DRIVING APPARATUS OF INVERTER METHOD USING THREE PHASE INDUCTION MOTOR

Technical Field

[1] The present invention relates to a concrete vibrator driving apparatus and, more particularly, to an inverter type vibrator driving apparatus using a three-phase induction motor, in which an inverter circuit is mounted in the vicinity of the three-phase induction motor, cool air discharged from a cool fan of the three-phase induction motor may be directly supplied to the inverter circuit through a side cover and an upper cover (guide) to increase cooling efficiency, a product may be miniaturized by directly mounting the inverter circuit in the vibrator driving apparatus, and disadvantages of a conventional vibrator driving apparatus using a single-phase induction motor may be obviated. Background Art

[2] As generally known in the art, concrete vibrators are a device that may eccentrically drive a vibration body using a motor to produce vibration, to remove bubbles and the like in concrete during concrete work to increase the density thereof, thereby obtaining a high quality concrete structure with an uniformly distributed aggregate.

[3] A conventional vibrator is divided into a first type in which a small motor is mounted in a vibration bar and a second type in which only an eccentric body is provided in the vibration bar and a rotary force of a large motor is transferred through a flexible hose.

[4] However, in the first type vibrator, since an output is small, a vibration force is not high. Because the second type vibrator is a power on/off product using a single-phase induction motor, an output becomes unstable or there are no safety devices for preventing overheating or short-circuit. Disclosure of Invention Technical Problem

[5] The prevent invention is made in view of the above problem, it is an object to provide an inverter type vibrator driving apparatus using a three-phase induction motor, in which an inverter circuit is mounted in the vicinity of the three-phase induction motor, cool air discharged from a cool fan of the three-phase induction motor may be directly supplied to the inverter circuit through a side cover and an upper cover (guide) to increase cooling efficiency, a product may be miniaturized by

directly mounting the inverter circuit in the vibrator driving apparatus, and disadvantages of a conventional vibrator driving apparatus using a single-phase induction motor may be obviated. Technical Solution

[6] In accordance with an exemplary embodiment of the present invention, there is provided an inverter type vibrator driving apparatus using a three-phase induction motor comprising: a three-phase induction motor having a cooling unit formed in a rear surface of the three-phase induction motor; a frame portion fixing the three-phase induction motor, first and second side covers, and upper and lower covers; the first and second side covering both sides of the three-phase induction motor, respectively, and guiding cool air discharged from the cooling unit of the three-phase induction motor from a side part to an inverter circuit; the upper cover covering an upper portion of the three-phase induction motor, and guiding the cool air discharged from the cooling unit of the three-phase induction motor from an upper part to the inverter circuit; the lower cover covering and supporting a lower portion of the three-phase induction motor; and the inverter circuit fixed and attached to a lower surface of the upper cover, being spaced apart from an upper surface of the three-phase induction motor so that the cool air discharged from the cooling unit of the three-phase induction motor is readily supplied.

[7] Preferably, the cooling unit includes a cooling fan driven in association with the rotation of the rotating shaft; an air introduction hole through which external air is introduced; and a blowing hole formed in an overlapping part between an end of the cooling unit and the body of the three-phase induction motor.

[8] More preferably, the frame portion includes first and second side fixing portions formed to enclose both sides of the three-phase induction motor, and having a rectangular shape; and a handle connecting respective upper center ends of the first and second side fixing portions with each other.

[9] Most preferably, each of the first and second side covers includes an upper bending portion bent from an upper end of a cover body by a predetermined distance; a groove formed in a center of the upper bending portion and in which a handle of the frame portion is inserted; and a lower bending portion bent from a lower end of the cover body by a predetermined distance, and the upper bending portion and the lower bending portion are structured to be fixed to a side fixing portion of the frame portion.

[10] Further, a front surface of the upper cover is bent by a predetermined distance, the upper cover is fixed to respective upper bending portions of the first side cover and the

second side cover under a handle of the frame portion.

[11] Furthermore, the inverter circuit includes a radiating portion having a ' ¹ ^ ' shape, a plurality of radiating grooves are formed in a lower portion and both sides of the radiating portion; an inverter circuit printed circuit board positioned inside the radiating portion and having a vertical front portion in which an error display lamp, a speed selection switch, and a power switch are mounted; and a cover covering respective upper portions of the radiating portion and the inverter circuit printed circuit board.

[12] Moreover, a printed circuit board of the inverter circuit includes: a switch unit having an error display lamp, a speed selection switch, and a power switch, and switching supply of a common AC voltage ranging from 180 to 250 V to the inverter circuit or a supply interception threof, and connected to the switch controller turning-on/off the error display lamp under the control of the switch controller or automatically turning- off the power switch; a rectifier rectifying an AC input power input from the switch unit into a DC power; a drive power supply generating a three-phase drive DC power to drive the three-phase induction motor using the DC power input from the rectifier; a power module controller generating a switching signal aαjording to a set frequency, and outputting a three-phase wave for driving a load; an output controller receiving the three-phase wave input from the power module controller, nixing an AC power with an externally input DC power, and outputting the nixed power to the load; a voltage sensor sensing a voltage input to the drive power supply, intercepting an output of the power module controller when the sensed input voltage is less than or equal to a reference voltage, and providing a first error signal for circuit interruption to the switch controller upon supply of a surge voltage to the drive power supply; an abnormal signal sensor detecting a low voltage and an over-current signal and feeding a detection result to the power module controller, and providing a second error signal for circuit interruption to the switch controller when overheating or short oxurs; a current sensor sensing an electric current input through the switch unit and flowing through a power line and providing a third error signal for circuit interruption to the switch controller when an abnormal electric current (leakage current) oxurs; and a switch controller turning-on the error display lamp of the switch unit and turning-off the power switch to thereby protect the inverter circuit when the first error signal from the voltage sensor, the second error signal from the abnormal signal sensor, and the third error signal from the current sensor are input to the switch controller.

[13] In addition, a PCB mounting unit is provided to be integrated with an upper end of a

body of the three-phase induction motor, the PCB mounting unit includes a rectangular shaped body having an insertion hole in which the inverter circuit is inserted and mounted, and a handle provided in an upper portion of the body, and the PCB mounting unit is spaced apart from a blowing hole of the three-phase induction motor so that the cool air discharged from the cooling unit of the three-phase induction motor is readily supplied.

Advantageous Effects

[14] In the present invention, an inverter circuit is mounted in the vicinity of the three- phase induction motor, cool air discharged from a cool fan of the three-phase induction motor may be directly supplied to the inverter circuit through a side cover and an upper cover (guide) to increase cooling efficiency, a product may be miniaturized by directly mounting the inverter circuit in the vibrator driving apparatus. In addition, disadvantages of a conventional vibrator driving apparatus using a single-phase induction motor may be obviated. Brief Description of Drawings

[15] The present invention will be better understood from the following detailed description of preferred embodiments of the invention, taken in conjunction with the accompanying drawings, in which:

[16] FIG. 1 is a view illustrating a connection relationship between a vibrator driving apparatus and a vibration bar in accordance with an embodiment of the present invention;

[17] FIG. 2 is an enlarged view illustrating a construction of a vibrator driving apparatus in accordance with an embodiment of the present invention;

[18] FIG. 3 is an exploded perspective view illustrating the vibrator driving apparatus in accordance with an embodiment of the present invention;

[19] FIG. 4 is an exploded perspective view illustrating an inverter circuit in accordance with an embodiment of the present invention;

[20] FIG. 5 is a view of main side parts illustrating a relationship between a three-phase induction motor and an inverter circuit in accordance with an embodiment of the present invention;

[21] FIG. 6 is a view of main rear parts illustrating a relationship between a three-phase induction motor and an inverter circuit in accordance with an embodiment of the present invention;

[22] FIG. 7 is a block diagram illustrating the inverter circuit in accordance with an

embodiment of the present invention; and

[23] FIG. 8 is a view illustrating a constriction of a vibrator driving apparatus in accordance with another embodiment of the present invention. Best Mode for Carrying out the Invention

[24] Hereinafter, exemplary embodiments of the present invention are described in detail with reference to the accompanying drawings.

[25] FIG. 1 is a view illustrating a connection relationship between a vibrator driving apparatus and a vibration bar in accordance with an embodiment of the present invention. FIG. 2 is an enlarged view illustrating a construction of a vibrator driving apparatus in accordance with an embodiment of the present invention. FIG. 3 is an exploded perspective view illustrating the vibrator driving apparatus in accordance with an embodiment of the present invention.

[26] As shown, the vibrator driving apparatus 100 of the present invention produces vibration, and connects a rotating shaft 114 of a three-phase induction motor 110 to a connecting portion 210 of a flexible hose 200 through a guide portion 113.

[27] When the three-phase induction motor 110 is rotated and driven, a flexible cable mounted in the flexible hose 200 is also rotated and driven according to the rotation and driving thereof. The driving of the flexible cable rotates an eccentric body mounted in a vibration bar 200 to be connected to the flexible cable, with the result that that the vibrating bar 220 performs a vibration operation.

[28] In this case, the connecting portion 210 of the flexible hose 200 is connected or separated to or from the rotating shaft 114 by a one teach operation using a locking portion 115, which is mounted in the guide portion 113 of the three-phase induction motor 110. The locking portion 115 is well known in the art, and thus the detailed description thereof is omitted.

[29] The following is a detailed explanation of the vibrator driving apparatus 100 in accordance with an embodiment of the present invention.

[30] The vibration driving apparatus 100 includes a three-induction motor 110, a frame portion 120, first and second side covers 130 and 140, an upper cover 150, a lower cover 160, and an inverter circuit 170. A cooling unit 112 is formed in a rear surface of the three-phase induction motor 110. The frame portion 120 fixes the three-phase induction motor 110, the first and second side covers 130 and 140, and the upper and lower covers 150 and 160. The first and second side covers 130 and 140 cover both sides of the three-phase induction motor 110, respectively. The first and second side covers 130 and 140 guide cool air discharged from the cooling unit 112 of the three-

phase induction motor 110 from a side part to the inverter circuit 110. The upper cover 150 covers an upper portion of the three-phase induction motor 110. The upper cover 150 guides the cool air discharged from the cooling unit 112 of the three-phase induction motor 110 from an upper part to the inverter circuit 110. The lower cover 160 covers and supports a lower portion of the three-phase induction motor 110. The inverter circuit 170 is fixed and attached to a lower surface of the upper cover 150. The inverter circuit 170 is structured to be spaced apart from an upper surface of the three- phase induction motor 110 so that the cool air discharged from the cooling unit 112 of the three-phase induction motor 110 may be readily supplied.

[31] The three-phase induction motor 110 includes a cylindrical body 111, a guide portion

113, a locking portion 115, and a cooling unit 112. The guide portion 113 is provided in a front surface of the body 111. The locking portion 115 is provided in an upper end of the guide portion 113. The locking portion 115 connects or separates the connecting portion 210 of a flexible hose 200 to or from the rotating shaft 114. The cooling unit 112 is provided in a rear surface of the body 111.

[32] As shown in FIG. 5, the cooling unit 112 includes a cooling fan 116, an air induction hole 117, and a blowing hole 118. The cooling fan 116 is driven in association with the rotation of the rotating shaft 114. External air is introduced through the air introduction hole 117. The blowing hole 118 is formed in an overlapping part between an end of the cooling unit 112 and the body 111 of the three-phase induction motor 110.

[33] During driving of the three-phase induction motor 110 structured as above, when the rotating shaft 114 rotates, the cooling fan 116 is rotated in association with the rotation of the rotating shaft 114. When the cooling fan 116 is rotated, external air is introduced in the body 111 through the air introduction hole 117 to cool an inside of the body 111, and is discharged through the blowing hole 118, thereby preventing overheating of the body 111.

[34] The frame portion 120 includes first and second side fixing portions 122 and 123, and a handle 121. The first and second side fixing portions 122 and 123 are formed to enclose both sides of the three-phase induction motor 110, and have a rectangular shape. The handle 121 connects respective upper center ends of the first and second side fixing portions 122 and 123 with each other.

[35] The first side cover 130 includes an upper bending portion 131, a groove 132, and a lower bending portion 133. The upper bending portion 131 is bent from an upper end of a cover body by a predetermined distance. The groove 132 is formed in a center of the upper bending portion 131. The handle 121 of the frame portion 120 is inserted in

the groove 132 of the first side cover 130. The lower bending portion 133 is bent from a lower end of the cover body by a predetermined distance. The upper bending portion 131 and the lower bending portion 133 are structured to be fixed to the first side fixing portion 122 of the frame portion 120.

[36] The second side cover 140 includes an upper bending portion 141, a groove 142, and a lower bending portion 143. The upper bending portion 141 is bent from an upper end of a cover body by a predetermined distance. The groove 142 is formed in a center of the upper bending portion 141. The handle 121 of the frame portion 120 is inserted in the groove 142 of the second side cover 140. The lower bending portion 143 is bent from a lower end of the cover body by a predetermined distance. The upper bending portion 131 and the lower bending portion 143 are structured to be fixed to the second side fixing portion 123 of the frame portion 120.

[37] The upper cover 150 is structured in such a way that a front surface thereof is bent by a predetermined distance. The upper cover 150 is fixed to the upper bending portion 131 of the first side cover 130 and the upper bending portion 141 of the second side cover 140 under the handle 121 of the frame portion 120.

[38] As seen in FIG. 5, the inverter circuit 170 is fixed to a lower surface of the upper cover 150. The inverter circuit 170 is spaced apart from an upper surface of the three- phase induction motor 110 by a predetermined distance so that cool air discharged through the blowing hole 118 may be readily supplied.

[39] As illustrated in FIG. 4, the inverter circuit 170 includes a radiating portion 171, an inverter circuit printed circuit board (PCB) 172, and a cover 173. The radiating portion 171 has a 'T= ' shape. A plurality of radiating grooves 171a are formed in a lower portion and both sides of the radiating portion 171. The inverter circuit PCB 172 is positioned inside the radiating portion 171. The inverter circuit PCB 172 has a vertical front portion 172a in which an error display lamp 172b, a speed selection switch 172c, and a power switch 172d are mounted. The cover 173 covers respective upper portions of the radiating portion 171 and the inverter circuit PCB 172.

[40] The inverter circuit 170 constructed as above has a primary cooling structure to discharge heat radiated from the inverter circuit PCB 172 to an outside during driving of the inverter circuit 170.

[41] The following is an explanation of an operation of the vibrator driving apparatus 100 of the present invention having a structure as described above. FIG. 5 is a view of main side parts illustrating a relationship between a three-phase induction motor and an inverter circuit in accordance with an embodiment of the present invention. FIG. 6 is a

view of main rear parts illustrating a relationship between a three-phase induction motor and an inverter circuit in aαjordance with an embodiment of the present invention;

[42] When the three-phase induction motor 110 is driven to rotate the rotating shaft 113, the cooling fan 116 of the cooling unit 112 is also rotated in association with the rotation of the rotating shaft 113.

[43] Next, cool air discharged to a front direction 360 through the blowing hole 118 by the rotation of the cooling fan 116 is directly supplied to the inverter circuit 170 under guidance of the first side cover 130, the second side cover 140, and the upper cover 150, as shown in FIG. 5 and FIG. 6. Accordingly, the inverter circuit 170 may be sufficiently cooled.

[44] As a result, the inverter circuit 170 performs a primary radiation function by the radiating portion 170 structure itself, and then a secondary cooling function is performed by external cool air. This may basically prevent erroneous operation due to overheating caused by characteristics of the inverter circuit 170.

[45] FIG. 7 is a block diagram illustrating an inverter circuit PCB 172 of the inverter circuit 170 in accordance with an embodiment of the present invention.

[46] As illustrated in FIG. 7, the inverter circuit PCB 172 of the inverter circuit 170 includes a switch unit 10, a rectifier 20, a drive power supply 30, a power module controller 40, an output controller 50, a voltage sensor 60, an abnormal signal sensor 70, a current sensor 80, and a switch controller 90.

[47] The switch unit 10 includes an error display lamp 172b, a speed selection switch

172c, and a power switch 172d. The switch unit 10 switches supply of a common AC voltage ranging from 180 to 250 V to the inverter circuit 100 or intercepts a supply thereof. The switch unit 10 is connected to the switch controller 90. The switch unit 10 turns-on/off the error display lamp 172b under the control of the switch controller 90 or automatically turns-off the power switch 172d.

[48] The rectifier 20 rectifies an PC input power input from the switch unit 10 into a DC power. The drive power supply 30 generates a three-phase drive DC power to drive the three-phase induction motor 110 using the DC power input from the rectifier 20. The power module controller 40 generates a switching signal according to a set frequency, and outputs a three-phase wave for driving a load.

[49] The output controller 50 receives the three-phase wave input from the power module controller 40, nixes an AC power with an externally input DC power, and outputs the nixed power to the three-phase inductor motor 110 being the load.

[50] The voltage sensor 60 senses a voltage input to the drive power supply 30. When the sensed input voltage is less than or equal to a reference voltage, the voltage sensor 60 intercepts an output of the power module controller 40. Upon supply of a surge voltage to the drive power supply 30, the voltage sensor 60 provides a first error signal for circuit interruption to the switch controller 90.

[51] The abnormal signal sensor 70 detects a low voltage and an over-current signal, and feeds a detection result to the power module controller 50. When overheating or short oxurs, the abnormal signal sensor 50 provides a second error signal for circuit interruption to the switch controller 90.

[52] The current sensor 80 senses an electric current input through the switch unit 60 and flowing through a power line. When an abnormal electric current (leakage current) oxurs, the current sensor 80 provides a third error signal for circuit interruption to the switch controller 90.

[53] When the first error signal from the voltage sensor 60, the second error signal from the abnormal signal sensor 70, and the third error signal from the current sensor 80 are input to the switch controller 90, it turns-on the error display lamp 172a of the switch unit 10 and turns-off the power switch 172d to thereby protect the inverter circuit.

[54] In the inverter type vibrator driving apparatus of the present invention having the structure described above, since a miniaturized device may extremely redire the size of the PCB 172, the inverter circuit 170 may be mounted in the vibrator driving apparatus 100 itself. Overheating may be prevented through the above-described cooling function to prevent erroneous operation.

[55] FIG. 8 is a view illustrating a constriction of a vibrator driving apparatus IOOA in accordance with another embodiment of the present invention.

[56] As shown in FIG. 8, in the vibrator driving apparatus IOOA in accordance with another embodiment of the present invention, a PCB mounting unit 180 is provided to be integrated with an upper end of a body 111 of a three-phase induction motor 110. An inverter circuit 170 may be inserted and mounted in the PCB mounting unit 180.

[57] The PCB mounting unit 180 includes a body 181 and a handle 183. The body 181 has an insertion hole 182 in which the inverter circuit is inserted and mounted. The body 181 has a rectangular shape. The handle 183 is provided in an upper portion of the body 181.

[58] Moreover, the PCB mounting unit is spaced apart from a blowing hole 118 of the three-phase induction motor 110 so that cool air discharged from a cooling unit 112 of the three-phase induction motor 110 may be readily supplied.