JP2006000937A - Electric driver unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric driver unit having high operability including a power supply device.
An electric driver unit (1) includes an electric driver (2), a power supply device (3), and a connection cord (4) for connecting them together. The electric driver 2 is driven by a DC motor. The power supply device 3 has a power cord 9, converts a commercial AC voltage input through the power cord 9 into a DC voltage suitable for driving a DC motor, and supplies the DC voltage to the electric driver 2. The power supply device 2 includes a simple constant voltage circuit including a full-wave rectifier 24, a Zener diode 26, and a resistor 27, and contributes to downsizing and operability improvement of the entire electric driver unit 1.
[Selection] Figure 1

Description

  The present invention relates to an electric driver unit, and more particularly to an electric driver unit for screw tightening work in assembling an electronic device or the like.

  The assembly operation of the apparatus includes a number of screw tightening steps, and this screw tightening operation is generally performed using an electric screwdriver. As the electric driver, a stationary type (for example, the one described in JP-A-5-57542) or a portable type (for example, JP-A-8-243939, JP-A-2004-82222) is known. In particular, in response to an increase in the production volume of small electronic devices typified by digital cameras and mobile phones, there is an increasing demand for portable small electric drivers that can be suitably used for assembling them.

Furthermore, in recent years, production methods of electronic devices and the like have been diversified, and there is a demand for an electric driver unit corresponding to this. Conventionally, as an assembly / manufacturing method for electronic devices, etc., a flow work in which parts and semi-finished products that have been transported on a belt are screwed and then transported to the next process with a belt is well known. . However, instead of such a flow method, a production method has been known in which an integrated operation for assembling and completing parts and semi-finished products to a final product state is performed in place. In such a production method that does not rely on flow work, since the work posture of the screw tightening work is not single, a portable small electric driver that easily follows changes in the work position and posture is suitable.
Japanese Patent Laid-Open No. 5-57542 JP-A-8-243939 JP 2004-82222 A

  In a production system in which the final product is assembled at a fixed position, it is not preferable to enlarge the work table. Since it is also assumed that workers can freely move around the work table, it is desirable that the work table be a small space in which only products in progress and a small amount of parts can be placed. However, in the case of an electric driver, in addition to the electric driver main body, a power supply device that supplies electric power to the main body is required. As the power supply device, one that can output an input commercial voltage of 100 volts or 200 volts as a low voltage (for example, direct current 30 volts) suitable for the drive motor of the electric driver is used.

  As such a power supply device used for a conventional electric driver, a switching power supply capable of outputting a constant voltage and a low voltage by switching control of a switching element such as a thyristor and a transformer type power supply have been used.

  A switching power supply can obtain a stable voltage. However, since a large number of parts are used, the overall size of the power supply device is large. A transformer-type power supply is large in size and has a large transformer weight. It is inappropriate to place such a power supply on a narrow work table. In addition, it is assumed that an electric screwdriver or power supply device is placed on the workbench and is suspended through a balancer or the like. However, such a work form does not have a conventional heavy power supply device. Is appropriate. In addition, since the switching power supply generally forms a highly accurate voltage as a computer-related power supply device, it is economical to use the power supply for such a computer-related device as a power supply for an electric driver. Even if it says from property, it is not suitable.

  In view of the above problems, an object of the present invention is to provide an electric driver suitable for performing screw tightening work in various postures on a relatively small work table and an electric driver unit including the power supply device.

  In order to solve the above-described problems and achieve the object, the present invention includes a portable electric driver that drives a driver bit with a DC motor, and converts an input AC to a DC having a voltage suitable for driving the DC motor. The power supply device is connected to the electric driver by a connection cord, and the power supply device is connected between a rectifier circuit that rectifies an input alternating current and an output line of the rectifier circuit. A first feature is that the power supply circuit includes a Zener diode and an NPN transistor having a base connected to the cathode of the Zener diode and an emitter voltage connected to the Zener voltage of the Zener diode. There is.

  In the present invention, the power supply device includes a substrate on which the power supply circuit is mounted, and a heat sink that surrounds the substrate including the power supply circuit and is attached to the substrate. The second feature is that it is in close contact with the surface of the heat sink.

  According to the present invention having the first feature, since a small and simple power circuit composed of a Zener diode and an NPN transistor is combined with an electric driver, assembly of an electronic device or the like to be screwed can be performed in a relatively small work place or Good screw tightening operability can be obtained when it is performed on a work table.

  According to the present invention having the second feature, since a heat sink having a large size can be stored in a small power supply device in a bent shape, the power supply circuit can effectively dissipate heat.

  FIG. 1 is an overall perspective view of an electric driver unit according to an embodiment of the present invention, and FIG. 2 is a perspective view of a power supply device included in the electric driver unit. The electric driver unit 1 includes an electric driver 2 and a power supply device 3, and the electric driver 2 and the power supply device 3 are connected by a connection cord 4. The connection cord 4 has plugs 5 and 6 attached to both ends thereof. The plug 5 at one end is connected to the socket 7 of the electric driver 2, and the plug 6 at the other end is connected to the socket 8 of the power supply device 3. . A power cord 9 is pulled out from the surface of the power supply 3 opposite to the surface on which the socket 8 is provided, and a power plug 10 suitable for a commercial power outlet (not shown) is connected to the tip of the power cord 9. Yes. The power cord 9 is preferably grounded, and the power plug 10 is preferably a three-pole plug with ground as shown in FIG.

  The present invention is not limited to the case where the electric driver 2, the power supply device 3, and the connection cord 4 can be separated from each other as described above. For example, the connection cord 4 is fixedly connected to at least one of the electric driver 2 and the power supply device 3. It may be.

  The electric driver 2 is configured such that the driver bit 12 is held by a chuck 11 provided at the tip, and the driver bit 12 can be driven by a built-in DC motor (not shown). Further, the electric driver 2 includes a switch 13 for turning the DC motor on and off, and an annular fitting 14 for hanging the electric driver on a hook provided near the work table when the screw tightening operation is interrupted. Is provided.

  The power supply device 3 has an outer shape with a case 15 formed of a resin molded product such as ABS for the purpose of weight reduction. The resin forming the case 15 is preferably an antistatic resin. For example, as an antistatic resin material, Psyracac (registered trademark) series manufactured by UMG ABC Corporation, for example Psyracac CB25, can be used.

  The power supply device 3 accommodates a power supply circuit (a specific example will be described later) that converts a commercial power supply voltage (for example, 200 volts) into a direct current voltage (for example, 30 volts) suitable for driving the direct current motor. .

  FIG. 3 is a longitudinal sectional view of the power supply device 3, and FIG. 4 is a transverse sectional view (a view in which one of the two split cases is removed). Steps 16 are provided at the inner corners of the case 15, and the four corners of the substrate 17 are supported on the steps 16 and screwed with screws 18. On the substrate 17, electronic components (illustrated by a transistor 19) constituting a power supply circuit are mounted. The transistor 19 is arranged with its legs, that is, terminals bent in the vicinity of the base of the transistor element body so as to be slightly higher than the height h in accordance with the maximum height h of other parts (not shown). The transistor 19 is screwed to a heat radiating plate such as an aluminum plate 20 with screws 21. The heat radiating plate 20 is disposed so as to surround the board 17 and the electronic components on the board 17, and the shape viewed from the socket 8 side as a whole is a “U” shape, that is, a shape obtained by removing one vertical side of the rectangle. I am doing. The heat sink 20 is fixed to the substrate 17 through spacers 22a and 22b. An example of assembling the heat sink 20 using the spacers 22a and 22b will be described later with reference to FIG. Thus, by bending the heat radiating plate 20 to form a three-dimensional shape, a sufficient area for effectively radiating the heat generated in the transistor 19 is ensured despite the small volume of the case 15. be able to. In this example, the NPN transistor 19 is fixed so as to be in close contact with the heat radiating plate 20, but other components may be arranged so as to be in close contact with the heat radiating plate. In order to further enhance the heat dissipation effect, an air circulation hole may be formed in the case 15, for example, on the side surface.

  A motor control circuit is mounted on the substrate 17 separately from the power supply circuit. As the motor control circuit, a conventionally known DC motor control circuit can be used, and the description thereof will be omitted.

  FIG. 5 is a view showing an example of assembly of the heat sink 20 using the spacer. In the figure, the spacers 22a and 22b are both columnar, the upper spacer 22a in the figure has a female thread at the upper end and a male thread at the lower end, and the lower spacer 22b has a female thread at both ends. is there. The female screw at the upper end of the lower spacer 22b is formed so that the male screw of the spacer 22a can be fitted. Such spacers 22a and 22b are arranged between the substrate 17 and the heat sink 20 as shown in the figure, and set screws 25 and 25 penetrating the heat sink 20 are respectively connected to the female screw at the upper end of the spacer 22a and the spacer 22b. The assembly is completed by screwing into the female screw at the lower end.

  FIG. 6 is a circuit diagram illustrating an example of a power supply circuit. The constant voltage circuit 23 as a power supply circuit includes a full-wave rectifier 24 formed of a bridge diode, an NPN transistor 19, a Zener diode 26, and a resistor 27. The input side of the full-wave rectifier 24 is connected to a commercial power outlet (not shown) through the power plug 10. The output line of the full wave rectifier 24 is connected to the motor control circuit of the electric driver 2.

  When the switch 13 is turned on and AC is input to the full-wave rectifier 24 from the commercial power supply, the full-wave rectifier 24 rectifies the AC and outputs it to the output line. A voltage is applied to the base of the NPN transistor 19 connected to the output line via the resistor 27, and a current flows between the collector and the emitter. The voltage between the output lines, that is, the emitter voltage of the NPN transistor 19 is held at a Zener voltage (30 volts) by the function of the Zener diode 26. Therefore, a stable low voltage (30 volts) can be supplied to the motor control circuit.

  As described above, according to the present embodiment, a small and lightweight electric driver unit excellent in operability and space saving function can be realized by combining a power supply device including a simple DC power supply circuit with an electric driver. In addition, the power supply device having an antistatic function can eliminate the risk that static electricity due to electrification flows into a work to be screwed and damages the electronic circuit when the digital electronic device is assembled. Furthermore, since a large-capacity heat sink can be accommodated in the case of a small power supply device, overheating of components constituting the power supply circuit can be prevented without increasing the overall size of the power supply device.

1 is an overall perspective view of an electric driver unit according to the best embodiment of the present invention. It is an external appearance perspective view of the power supply device contained in an electric driver unit. It is sectional drawing of the power supply device contained in an electric driver unit. It is a figure of the state which removed one of the cases of the power supply device contained in an electric driver unit. It is a figure which shows the example of an assembly | attachment of a heat sink. It is a circuit diagram which shows an example of a power supply circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electric driver unit, 2 ... Electric driver, 3 ... Power supply device, 4 ... Connection cord, 19 ... NPN type transistor, 24 ... Full wave rectifier, 26 ... Zener diode

Claims (2)

A portable electric driver that drives a driver bit with a DC motor;
A power supply device for converting the input AC into a DC voltage having a voltage suitable for driving the DC motor,
The power supply device is connected to the electric driver by a connection cord,
The power supply is
A rectifier circuit for rectifying the input alternating current;
A Zener diode connected between the output lines of the rectifier circuit;
An electric driver unit comprising a power supply circuit comprising an NPN transistor having a base connected to the cathode of the Zener diode and an emitter voltage connected to the Zener voltage of the Zener diode. The power supply is
A substrate on which the power supply circuit is mounted;
A heat sink surrounding the substrate including the power supply circuit and attached to the substrate,
2. The electric driver unit according to claim 1, wherein at least a surface portion of the NPN transistor is in close contact with the surface of the heat sink.

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