JP2004122343A - Wiring structure of inverter circuit of inverter circuit and power tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring structure of an inverter circuit in consideration of a radiating structure and the wiring structure and an electric tool using it. <P>SOLUTION: A collector terminal and an electric power line of transistors Q3 to Q6 on the upper stage side are wired by a bus bar 48 made of a copper plate, in the wiring structure of the inverter circuit to realize a bipolar driving method by using the non-isolated type transistors Q1 to Q6 on which a radiating fin doubly serves as a connector terminal. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wiring structure of an inverter circuit and a power tool using the same.
[0002]
[Prior art]
An inverter circuit used for an electric tool or the like needs a heat dissipation structure to flow a large current.
[0003]
Therefore, non-insulated transistors are used as the six transistors used in the inverter circuit. When wiring is performed on the drive circuit board, a large number of thick wiring patterns are wired. Therefore, there is a problem that the size of the drive circuit board is increased and the cost is increased.
[0004]
Further, an inverter device considering heat dissipation has been proposed (Japanese Patent Application Laid-Open No. 2001-145387). The structure of Patent Document 1 is based on a two-phase power semiconductor connected in parallel to one end of a stator of a motor in an inverter circuit and connected to the other end of a stator winding of the motor in a three-phase inverter circuit. The remaining one-phase power semiconductor is located on the low-temperature side.
[0005]
[Patent Document 1]
JP-A-2001-145387
[0006]
[Problems to be solved by the invention]
However, in the structure of the inverter circuit in Patent Document 1, although the heat radiation structure is taken into consideration, the wiring is not taken into consideration at all, and in particular, the relationship with the power supply line is not taken into account. Still requires a thick wiring pattern.
[0007]
In view of the above problems, the present invention provides a wiring structure of an inverter circuit in consideration of a heat radiation structure and a wiring structure, and a power tool using the same.
[0008]
[Means for Solving the Problems]
The invention according to claim 1 is a wiring structure of an inverter circuit for realizing a bipolar driving method using six non-insulated transistors whose radiating fins also serve as a collector terminal or a drain terminal. The wiring structure of the inverter circuit is characterized in that the collector terminal or the drain terminal of the upper three transistors and the power supply line are wired with a bus bar made of a copper plate.
[0009]
According to a second aspect of the present invention, the heat radiation fin is driven by a brushless DC motor that is driven and controlled by an inverter circuit that implements a bipolar driving method using six non-insulated transistors that also function as collector terminals or drain terminals. In the power tool, a casing of the power tool is a pistol type including a body and a grip protruding from a rear part of the body, and the six transistors are fixed to a heat sink, and among the six transistors, A drive circuit board in which collector terminals or drain terminals of the upper three transistors and a power supply line are wired with a bus bar made of a copper plate, and electronic components other than the six transistors are wired in the inverter circuit. The brushless DC motor is arranged at the rear of the body of the casing, Below the scan DC motor with placing the drive circuit board, a power tool, characterized in that placing the heat sink behind the brushless DC motor.
[0010]
[Operation]
According to the wiring structure of the inverter circuit of the first aspect, since the collector terminal or the drain terminal of the upper three transistors and the power supply line are wired by the bus bar made of the copper plate, the wiring also serves as the radiation fin. Heat dissipation from the collector terminal or the drain terminal is promoted, and the bus bar serves as a wiring pattern, so that a conventional wiring pattern toward the power supply line can be omitted.
[0011]
According to the power tool of the second aspect, the heat radiation from the transistor provided in the inverter circuit is promoted as described above, and not only the wiring pattern for the power supply line can be omitted, but also the drive circuit board is provided below the brushless motor. Since the heat sink to which the six transistors are fixed is provided behind the brushless DC motor, the size of the casing of the pistol-type power tool can be reduced.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
(Example)
An embodiment of the present invention will be described below with reference to FIGS.
[0013]
(1) Structure of Electric Screwdriver 10 The structure of the cordless electric screwdriver 10, which is one of the electric tools, will be described.
[0014]
FIG. 1 is a side view of the electric screwdriver 10.
[0015]
The casing 12 of the electric screwdriver 10 includes a substantially cylindrical body portion 14 and a grip portion 16 protruding from below a rear portion of the body portion 14, and has a pistol shape as a whole.
[0016]
A brushless DC motor (hereinafter simply referred to as “motor”) is built in a rear portion of the body 14 of the pistol-type casing 12, and a transmission mechanism 20 for performing a speed change or the like is disposed in front of the motor 18. Is connected to the chuck portion 22 at the front of the. For example, a driver 24 is fixed to the chuck section 22.
[0017]
A drive circuit board 26 is disposed below the motor 18. The drive circuit board 26 will be described later in detail.
[0018]
A trigger switch 28 is provided below the drive circuit board 26 and in front of the upper end of the grip 16.
[0019]
A battery 30 that can be charged from a 100 V commercial power supply is fixed to a lower portion of the grip 16.
[0020]
(2) Configuration of Drive Circuit The configuration of the drive circuit that drives the motor 18 as the drive source of the electric driver 10 will be described based on the electric circuit of FIG.
[0021]
The brushless DC motor as the motor 18 is a three-phase brushless DC motor including a V-phase, a U-phase, and a W-phase. The Y-connected stator windings 34U, 34V, and 34W of the motor 18 have bidirectional currents. Is performed by inverter control.
[0022]
In FIG. 2, the inverter circuit 32 includes bipolar transistors Q1 to Q6, which are six switching elements, and a power supply line from the positive side of the battery 30 is connected to the collector terminals of the upper-stage transistors Q1 to Q3, respectively. I have. The emitter terminals of the upper transistors Q1 to Q3 are connected to the collector terminals of the lower transistors Q4 to Q6, and their connection points are connected to the three-phase stator windings 34U, 34W and 34V of the motor 18, respectively. Have been.
[0023]
The base terminals of the six transistors Q1 to Q6 are connected to the control unit 36.
[0024]
The control unit 36 performs PWM control (pulse width modulation control) on the six transistors Q1 to Q6 in order to perform bipolar driving.
[0025]
The power of the control unit 36 is also supplied from the battery 30.
[0026]
(3) Wiring Structure of Driving Circuit Next, a wiring structure for realizing the driving circuit described above will be described with reference to FIGS.
[0027]
The mounting structure of the six bipolar transistors Q1 to Q6 forming the inverter circuit 32 will be described with reference to FIG.
[0028]
A heat sink 38 made of a metal plate and having a substantially L-shaped cross section, that is, a heat sink 38 is composed of a metal bottom plate 40 and an erect plate 42 that stands vertically from one end of the bottom plate 40.
[0029]
On the other hand, the six transistors Q1 to Q6 are non-insulated transistors, and the radiation fins 44 also serve as collector terminals. Then, three connection terminals 46 protrude from the lower portions of the transistors Q1 to Q6. Two of the three connection terminals are a base terminal and an emitter terminal, and the other one is a collector terminal.
[0030]
A configuration for fixing the six non-insulated transistors to the heat sink 38 will be described.
[0031]
The transistors Q1 to Q3 on the upper side of the inverter circuit 32 are attached to the lower surface of the bottom plate 40. In this case, as shown in FIG. 3, the non-insulating radiating fins 44, ie, the three collector terminals are fixed by pan head screws 50 by a bus bar 48 made of a copper plate so that all three collector terminals are electrically connected.
[0032]
The bus bar 48 includes a connection plate 52 for connecting to the drive circuit board 26. More specifically, the connection plate 52 is bent downward from the end of the fixed plate 54 connecting the collector terminals of the three transistors.
[0033]
On the other hand, the lower three transistors Q4 to Q6 are attached to the upright plate 42 of the heat sink 38. However, since the voltage values of the collector terminals of the transistors Q3 to Q6 are different from each other, the lower transistors 3 Is fixed via an insulating sheet 56, and then fixed with pan head screws 60 via an insulating bushing 58. Regarding the lower transistors Q4 to Q6, three connection terminals 46, which are a base terminal, an emitter terminal, and a collector terminal, protruding from the lower part of the transistor, are electrically connected to the drive circuit board 26.
[0034]
FIG. 4 is an exploded perspective view in which the six transistors Q <b> 1 to Q <b> 6 are mounted on the heat sink 38 as described above, and are to be mounted on the drive circuit board 26.
[0035]
On the drive circuit board 26, electronic components such as a control unit 36 and a resistance element constituting a drive circuit other than the six transistors Q1 to Q6 are wired, and a power supply line from the battery 30 is wired. When the heat sink 38 to which the six transistors Q1 to Q6 described above are fixed is fixed to the drive circuit board 26, the connection plate 52 of the bus bar 48 is attached to the rear end of the drive circuit board 26. 26, and the three connection terminals 46 of the upper transistors Q1 to Q3 are soldered to the drive circuit board 26, and the three connection terminals 46 of the lower transistors Q4 to Q6 are further soldered. Is soldered to the drive circuit board 26. Then, the heat sink 38 is located behind the motor 18 as shown in FIG. 1 and the drive circuit board 26 is located below the motor 18. The collector terminals of the three connection terminals 46 of the transistors Q1 to Q3 on the upper stage are soldered for fixing, but need not be electrically connected as dummy terminals.
[0036]
With the wiring structure of the drive circuit board 26 as described above, the bus bar 48 is attached to the radiating fins 44 of the transistors Q1 to Q3 also serving as collector terminals and connected to the power supply line, so that the wiring pattern as the power supply line becomes unnecessary. The cost can be reduced, and disconnection and the like can be prevented. Further, since the bus bar 48 is connected to the three radiating fins 44 by a copper plate, the radiating effect can be further promoted.
[0037]
By arranging the heat sink 38 behind the motor 18 and arranging the drive circuit board 26 below the inside of the casing 12, the space can be effectively used, so that the size of the entire casing 12 can be reduced. it can.
[0038]
Further, the drive circuit board 26 and the heat sink 38 can be securely fixed.
[0039]
(Modification 1)
Although a bipolar transistor is used as the transistor in the above embodiment, an FET may be used as a non-insulating transistor instead. In this case, since the radiation fin and the drain terminal are common in place of the collector terminal, the drain terminals of the three FETs on the upper side are connected by a bus bar.
[0040]
(Modification 2)
In the above embodiment, the electric screwdriver 10 is described as the electric tool. However, the present invention is not limited to this, and an electric screwdriver drill or an electric tool having a hardness may be used.
[0041]
【The invention's effect】
As described above, according to the wiring structure of the inverter circuit of the present invention, the wiring of the collector terminal or the drain terminal of the upper transistor can be reliably performed, and the wiring pattern of the power supply line can be omitted.
[0042]
Further, according to the electric power tool of the present invention, the space can be effectively used, so that the casing can be downsized.
[Brief description of the drawings]
FIG. 1 is a side view of an electric screwdriver showing one embodiment of the present invention.
FIG. 2 is an electric circuit diagram of a drive circuit.
FIG. 3 is an exploded perspective view in which six transistors are to be mounted on a heat sink.
FIG. 4 is an exploded perspective view in which a heat sink is to be mounted on a drive circuit board.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Electric screwdriver 12 Casing 14 Body 16 Gripping part 18 Motor 26 Drive circuit board 32 Inverter circuit 38 Heat sink 44 Heat radiation fin 46 Connection terminal 48 Bus bar

Claims (2)

In a wiring structure of an inverter circuit realizing a bipolar driving method using six non-insulated transistors in which a radiation fin also serves as a collector terminal or a drain terminal,
A wiring structure for an inverter circuit, wherein a collector terminal or a drain terminal of the upper three transistors of the six transistors and a power supply line are wired by a bus bar made of a copper plate. In a power tool driven by a brushless DC motor driven and controlled by an inverter circuit realizing a bipolar driving method using six non-insulated transistors whose radiation fins also serve as a collector terminal or a drain terminal,
The casing of the power tool is a pistol type including a trunk portion and a grip portion protruding from a rear portion of the trunk portion,
Fixing the six transistors to a heat sink,
Of the six transistors, the power supply line and the collector terminal or the drain terminal of the upper three transistors are wired with a bus bar made of a copper plate,
The bus bar is connected to a drive circuit board on which electronic components other than the six transistors are wired in the inverter circuit,
A brushless DC motor is arranged at the rear of the body of the casing,
An electric tool, wherein the drive circuit board is arranged below the brushless DC motor, and the heat sink is arranged behind the brushless DC motor.

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