JPH02184242A - Terminal box containing connection switching contactor for three-phase induction motor - Google Patents

Abstract

PURPOSE:To save the space between a drive amplifier and the motor body by securing an electromagnetic contactor for switching between star and delta connections integrally in a terminal box containing o motor drive amplifier, and field coil connecting terminal group. CONSTITUTION:A terminal box 10 containing a contactor for switching connection of a three-phase induction motor is made of plastic, where motor drive power lines 12 are led from a motor drive amplifier through one side end of the box and connected with power input terminals 14 including an earth terminal. Electromagnetic contactors MC1, MC2 are arranged between the power terminals 14 and power output terminals 16 connected with motor field coil. Both electromagnetic contactors MC1, MC2 are burried when the plastic terminal box 10 is molded and placed in the plastic terminal box 10 in integrally secured structure. Since such terminal box is mounted on the motor body, spacial saving is realized and the number of exposed power line can be reduced.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to the structure of a three-phase induction motor used as a motor for driving the spindle rotation of a machine tool, and in particular, to the structure of a three-phase induction motor used as a motor for driving the spindle rotation of a machine tool. In order to drive the induction motor, the magnetic contactor is integrated into a plastic terminal box mounted on the motor body when the field coil of the induction motor is switched between delta connection and star connection using an electromagnetic contactor. The present invention relates to a terminal box with a built-in connection switching contactor for a phase induction motor.

[Conventional technology]

BACKGROUND ART Recently, in the main shaft of a machine tool that uses a three-phase induction motor as a rotational output drive source, a method has been adopted in which a single three-phase induction motor covers the entire range from low-speed rotation to high-speed rotation. In other words, the field coil of a three-phase induction motor is switched between delta connection and star connection, and due to the difference in the amount of current flowing through the coil, the star connection method is used in the low speed range, and the delta connection method is used in the high speed range. The method of using When changing the connection of the field coil, as shown in Figure 3, two contactors M are connected to the boat.
An electromagnetic contactor 1 having C1 and MC2 is used, and the electromagnetic contactor 1 is disposed between a terminal box 2 containing a group of connection terminals for the body of a three-phase induction motor M and a motor drive amplifier 3, The contactor 1 is switched in accordance with a switching command signal applied via the drive amplifier 3. For example, the contactor MC
When I opens, the delta connection system operates, and conversely, the contactor MC
2, the connection is switched so that the star connection system is activated, and the power current from the drive amplifier 3 is supplied to the star connection or delta connection to obtain the desired rotational torque and speed. .

[Problem to be solved by the invention]

However, according to the conventional configuration described above, although a commercially available product can be used as the electromagnetic contactor 1, it is difficult to arrange the electromagnetic contactor for connection switching between the motor drive amplifier 3 and the body of the motor M. It is essential to secure space, and therefore, when using such a three-phase induction motor M as a spindle drive motor, it may be difficult to secure such space within the body of a machine tool, or it may be difficult to secure space from the electromagnetic contactor to the motor. Since there are both a star connection system and a delta connection system in the wiring, there is a disadvantage that the power line wiring becomes complicated. Therefore, it is an object of the present invention to provide a terminal box with a built-in connection switching contactor for a three-phase induction motor that can overcome such disadvantages.

[Means of solution and action]

That is, according to the present invention, an electromagnetic contactor for switching and driving a field coil of a three-phase induction motor between star connection and delta connection is mounted on the motor body, and is connected to a motor drive amplifier and the field coil. Provided is a terminal box with a built-in connection switching contactor for a three-phase induction motor, characterized in that the connection terminal group is integrally incorporated and fixed in a plastic terminal box housing a connection terminal group for connecting the connection terminals. .

Therefore, only a plastic terminal box mounted on the motor body is provided between the drive amplifier and the motor body, which saves space and also reduces the number of power lines exposed to the outside. will be done. Hereinafter, the present invention will be explained in more detail with reference to the accompanying drawings.

〔Example〕

FIG. 1 is a top view of a terminal box with a built-in connection switching contactor for a three-phase induction motor according to an embodiment of the present invention in an open state;
FIG. 2 is a perspective view showing the external appearance of the main shaft motor in which the connection switching contactor built-in terminal box is mounted.

According to the present invention, the terminal box IO with a built-in connection switching contactor for a three-phase induction motor is formed as a box made of plastic, and is mass-produced by molding. Inside the plastic contactor built-in terminal box 10, a power line 12 for driving the motor from the motor drive amplifier is introduced from one end of the box, and a power input terminal 14 including a ground terminal (
U, V, W, G), and magnetic contactors MCI and MC2 are inserted between this power terminal 14 and a power output terminal 16 connected to the motor field coil. MCI and MC2 are embedded in the plastic terminal box 10 during molding, and are built into the plastic terminal box 10 in an integrally fixed structure. It is clear from the illustration that the connection fittings (short bar) are also integrated at this time.

Reference numeral 18 indicates wiring within the motor body from the power output terminal 16 to the motor field coil (not shown).

The plastic terminal box 10 further includes a connector 20 for a rotation detection system signal cable and a group of power supply input/output terminals 22 and 24 for a motor fan. 26
shows a cable line in which the signal cable of the rotation detection system and the motor fan cable are integrated. The contactor built-in terminal box 10 for a three-phase induction motor formed in this way is mounted on the rear end of the body 30 of the three-phase induction motor M as shown in FIG. When incorporating the three-phase induction motor M into a machine tool and using it as a spindle motor, it is possible to use the three-phase induction motor M in a delta connection or a star connection by using the same terminal as long as the design secures a space for mounting the motor. By switching and operating the electromagnetic contactors MCI and MC2 that are housed together in the box 10, it is possible to function without using any special separate equipment.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, even when a three-phase induction motor used for driving the main shaft of a machine tool is alternately switched between star connection and delta connection, There is no need to adopt a configuration in which a separate electromagnetic contactor is placed between the motor drive amplifier and the motor as in the past, so when designing the motor placement space inside a driven object such as a machine tool, By simply securing a space, it is easy to use the motor drive method using the above-mentioned wire connection switching. Moreover, since the wiring work is done only within the terminal box, the conventional cumbersomeness is completely eliminated.

[Brief explanation of the drawing]

FIG. 1 is a top view of a terminal box with a built-in connection switching contactor for a three-phase induction motor according to an embodiment of the present invention in an open state;
Figure 2 is a perspective view showing the external shape of a spindle motor equipped with a terminal box with a built-in wiring switching contactor, and Figure 3 shows the wiring relationship between a conventional drive amplifier, electromagnetic contactor, and three-phase induction motor. Schematic diagram. 10... Terminal box with built-in connection switching contactor, MClMC
2...Magnetic contactor.

Claims (1)

[Claims] 1. An electromagnetic contactor for switching and driving the field coil of a three-phase induction motor between delta connection and star connection is mounted on the motor body, and also includes a motor drive amplifier and the field coil. A terminal box with a built-in connection switching contactor for a three-phase induction motor, characterized in that the connection terminal group is integrally incorporated and fixed in a plastic terminal box housing a connection terminal group for connecting the connection terminals. 2. A built-in connection switching contactor for a three-phase induction motor as set forth in claim 1, wherein the electromagnetic contactor is integrally fixed by molding during molding of the plastic terminal box. type terminal box.