JPH09320429A - Electromagnetic contactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent switching noise taking place at an electromagnet operating coil from being transmitted to a power supply line by performing the switching operation of a switching element connected with the electromanget operating coil. SOLUTION: Electric power consumption is attempted by performing switching operations in such a way that the electromagnetic contactor allows a switching transistor Tr connected with an electromagnet operating coil MC to supply continuous pulses when the aforesaid contactor is charged, and also to supply intermittent pulses when it is held in neutral. In this case, since switching noise taking place at the electromagnet operating coil MC, which is caused by the switching operation of the switching transistor Tr, is transmitted to the side of a power supply AC, a noise filter NF is thereby provided to absorb the aforesaid switching noise. The noise filter NF is formed out of a capacitor C2 absorbing normal mode noise, and of a common mode coil CC absorbing common mode noise.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a fixed iron core around which an electromagnet operating coil is wound, and a movable iron core arranged opposite to the fixed iron core, and fixed by applying a current to the electromagnet operating coil. It is an electromagnetic contactor that attracts the movable iron core to the iron core, and the movable iron core is attracted to the fixed iron core so that the movable contact comes into contact with the fixed contact.In particular, when the electromagnet is turned on, a continuous current is applied to the electromagnet operating coil. The movable core is drawn by flowing the fixed core, and when holding the movable core after it is adsorbed to the fixed core, an intermittent current sufficient to maintain the adsorbed state between the movable core and the fixed core is supplied to reduce power consumption. Regarding an electromagnetic contactor.

[0002]

2. Description of the Related Art The structure of a conventional electromagnetic contactor of this type is shown in FIG.
Shown in FIG. 7 is a side sectional view of the electromagnetic contactor in a closed state, in which an E-shaped fixed iron core 51 is arranged in an insulator frame 50, and a winding frame 53 is wound around a central leg of the fixed iron core 51. An electromagnet operating coil MC is attached. Fixed iron core 51
A movable iron core 52 is disposed so as to face the movable iron core 52, and a movable contact support 54 is coupled to the movable iron core 52. Movable contact support 54
A movable contact 56 having a movable contact 56a is attached to the movable contact 56a via a contact spring 55, and the movable contact 56a is an insulator frame.
It faces a fixed contact 57a of a fixed contact 57 fixed to 50. A case 58 is attached to a lower portion of the insulator frame 50, and a printed circuit board 60 on which electric parts 59 such as resistors, capacitors and ICs are mounted is resin-sealed with a curing resin 61 in the case 58. . Incidentally, 62 is a shield plate arranged along the inner wall of the insulator case 50, and 63 is a return spring.

FIG. 8 is a circuit diagram of an electromagnet device of an electromagnetic contactor, in which AC is a single-phase AC power supply, and a single-wave AC power supply is connected to an AC terminal of a full-wave rectification circuit DB composed of a diode bridge by turning on a switching switch SW. AC voltage of AC power supply AC is applied. The DC terminal of the full-wave rectification circuit DB is a coil for operating an electromagnet
It is connected to the series circuit of MC and the collector-emitter passage of the switching transistor Tr, and is connected to the drive circuit DS. As shown in the time chart of FIG. 9, when the closing switch SW is turned on, the drive circuit DS outputs a pulse of a constant time width T necessary for attracting the movable iron core of the electromagnet to the fixed iron core of the switching transistor Tr. An intermittent pulse is applied to the base, and after a lapse of a certain period of time T, an intermittent pulse that is repeatedly turned on and off at a period required to maintain the attracted state of the movable iron core to the fixed iron core is applied to the base of the switching transistor Tr. Note that D is a freewheeling diode of the electromagnet operating coil MC, and C1 is a noise absorbing capacitor.

As shown in FIG. 9, when the closing switch SW is turned on, a pulse having a constant time width T is supplied from the drive circuit DS to the base of the switching transistor Tr, and a continuous current flows through the electromagnet operating coil MC. A large suction force is generated between the fixed iron core 51 and the movable iron core 52 shown in FIG. As a result, the movable iron core 52 is attracted to the fixed iron core 51, moves, and is attracted to the fixed iron core 51. The time width (constant time width T) in which a continuous current is applied to the electromagnet operating coil DC is based on the time from when the continuous current is applied to the electromagnet operating coil MC to when the movable iron core 52 is attracted to the fixed iron core 51. Have been set. Therefore, the movable iron core 52 is attracted to the fixed iron core 51 after a lapse of a predetermined time T after the closing switch SW is turned on, and the movable contact 56 of the movable contact 56 is moved by the movement of the movable contact support 54 connected to the movable iron core 52. 56a is the fixed contact 57 of the fixed contact 57
It enters the contact state with a. Fixed core 51 of movable core 52
Since a small attraction force is required to maintain the attracted state after being attracted to the drive circuit DS, the drive circuit DS supplies intermittent pulses to the base of the switching transistor Tr, which repeats on and off at a predetermined cycle, for operating the electromagnet. In the coil MC, while the switching transistor Tr is off, the current continues to flow through the freewheeling diode D 1 and the attracted state is maintained. When the closing switch SW is opened, the electromagnet device is released, and the movable iron core 52 returns to the original position (the position where the upper end of the movable iron core 52 contacts the inner wall of the frame 50) by the spring force of the return spring 63. As a result, the movable contact 56a of the movable contactor 56 separates from the fixed contact 57a of the fixed contactor 57 and enters the cutoff state.

[0005]

As described above, since the intermittent current is applied to the electromagnet operating coil MC after the movable iron core 52 is attracted to the fixed iron core 51, the electromagnet device is kept in the closed state. Power consumption can be suppressed. However, since the switching transistor Tr is caused to perform the switching operation in order to supply the intermittent current to the electromagnet operating coil, the switching operation causes high-frequency switching noise from the electromagnet operating coil MC. When this switching noise is conducted to the power line of the single-phase AC power supply AC, it is radiated from the power line, and in environments where precision electronic devices such as medical devices are used in the vicinity of electromagnetic contactors, switching noise causes precision electronic devices. May malfunction. A noise absorbing capacitor C1 is inserted in order to prevent the switching noise from being conducted and radiated from the power supply line. However, this noise absorbing capacitor has a drawback that only normal mode noise of switching noise can be blocked, and common mode noise is radiated to the outside by being conducted through the power supply line. Also,
When the electromagnetic contactor is used in the vicinity of precision electronic equipment, it is necessary to prevent switching noise from conducting and radiating the power supply line. As described above, it is not necessary to take measures against the switching noise conducted and radiated from the power supply line. Therefore, as an electromagnetic contactor used in an environment where measures against switching noise conducted and radiated from the power supply line are unnecessary, an electromagnetic contactor provided with measures against conduction and radiated switching noise from the power supply line should be used. If you use it, the cost will increase by the amount of countermeasures taken, and to avoid this, if you manufacture an electromagnetic contactor that corresponds to the environment where the electromagnetic contactor is installed, the types of electromagnetic contactors will increase and it will take time and effort to store and manage them. There is a problem.

Therefore, a first object of the present invention is to eliminate the above-mentioned drawbacks of the conventional device and to obtain an electromagnetic contactor in which switching noise, which is high frequency noise, is prevented from being radiated by being conducted through a power supply line. The second purpose is that there is no need for an electromagnetic contactor of a type suitable for the environment in which the electromagnetic contactor is installed,
An object of the present invention is to obtain an electromagnetic contactor capable of installing one type of electromagnetic contactor in a plurality of places of use environments.

[0007]

In order to achieve the above-mentioned first object, the invention described in claim 1 is such that an electromagnet operating coil and a switching element are connected in series to a power source, and when the electromagnet is turned on to the switching element. In an electromagnetic contactor provided with a drive circuit that supplies continuous pulses and supplies intermittent pulses during holding, switching noise generated in the electromagnet operating coil by the switching operation of the switching element by the drive circuit is conducted to the power supply side. It is characterized in that a noise filter for preventing the noise is provided. According to the invention described in claim 1, the switching noise is blocked by the noise filter, and the switching noise is prevented from being radiated by being conducted through the power supply line.

Further, in order to achieve the second object, claim 3
The invention described in 1 is an electromagnetic contact provided with a drive circuit in which a coil for operating an electromagnet and a switching element are connected in series to a power source, and a continuous pulse is supplied to the switching element when the electromagnet is turned on, and an intermittent pulse is supplied when the electromagnet is held. In the device, a noise filter that blocks the switching noise generated in the electromagnet operating coil by the switching operation of the switching element by the drive circuit from being conducted to the power supply side is formed as a filter unit,
It is characterized in that the filter unit is detachably provided on the main body of the electromagnetic contactor. In the invention described in claim 3, the filter unit may be attached depending on the installation environment by forming the filter unit as an accessory of the electromagnetic contactor.

[0009]

According to the first aspect of the present invention, a noise filter is provided in which the switching element performs a switching operation in response to a pulse from the drive circuit, thereby preventing switching noise generated in the electromagnet operating coil. The noise filter is preferably formed by a capacitor that blocks normal mode noise and a common mode coil that blocks common mode noise.

Further, in order to achieve the second object, claim 3
In the invention described in 1), the noise filter is unitized as an accessory that can be attached to and detached from the electromagnetic contactor. Then, if necessary, the filter unit is attached to the electromagnetic contactor.

[0011]

An embodiment of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a circuit diagram showing an embodiment of the invention described in claim 1. In FIG. 1, the same parts as those of the conventional apparatus shown in FIG. 8 are designated by the same reference numerals, and the description thereof will be omitted. 1 is different from the conventional device shown in FIG. 8 in that it is a noise filter NF provided with power supply terminals T3 and T4 connected to coil terminals T1 and T2 of an electromagnetic contactor and to a single-phase AC power supply AC. That is the point. The noise filter NF is connected between the coil terminals T1 and T2, the capacitor C2, the coil connected between the coil terminal T1 and the power supply terminal T3, and between the coil terminal T2 and the power supply terminal T4. It consists of a common mode coil CC in which the coils are inductively coupled by an iron core, and a varistor BS connected between the power supply terminals T3 and T4. The capacitor C2 blocks the normal mode noise together with the noise absorbing capacitor C1 built into the electromagnetic contactor, the common mode coil CC blocks the common mode noise, and the varistor BS protects the surge voltage from the AC side of the single-phase AC power supply. Block.

Since the operation of the electromagnet device shown in FIG. 1 is the same as that of the conventional device shown in FIG. 8, the description thereof will be omitted, but the electromagnet operation is performed by the switching operation of the switching transistor (switching element) Tr by the drive circuit DS. Of the switching noise generated in the coil MC for
Normal mode noise is blocked by the noise absorbing capacitors C1 and C2, common mode noise is blocked by the common mode coil CC, and the switching noise is radiated through the power line of the single-phase AC power supply AC. To prevent.

FIG. 2 is a side view showing an external view of the electromagnetic contactor equipped with the filter unit obtained by unitizing the noise filter shown in FIG. 1, and FIG. 3 is a side sectional view of the filter unit shown in FIG. FIG. 4 is an exploded view of the filter unit, FIG. 5 is a front view of the filter unit at an assembly stage, FIG. 6 is an outline view of the filter unit shown in FIG. 3, (a) is its front view, and (b) is Side view, (c)
Shows a plan view and (d) shows a sectional view taken along line BB in (c). Note that FIG. 3 shows a cross section taken along the line AA of FIG.

In FIG. 2, 100 is an electromagnetic contactor,
This electromagnetic contactor 100 has the same structure as the electromagnetic contactor shown in FIG. The electromagnetic contactor 100 has main circuit terminals 101 and 101 at both ends thereof, and electric wires (shown by broken lines) on the power source side and the load side are connected to the main circuit terminals 101 and 101, respectively. Further, the electromagnetic contactor 100 is provided with a coil terminal 102, which is shown as the coil terminals T1 and T2 in the circuit diagram of FIG. 200 indicates the filter unit of the present invention.
The structure will be described in detail with reference to FIGS.
Coil terminals of filter unit 200 and magnetic contactor 100
It is connected to 102 with a lead wire 201. The filter unit 200 is screwed by a mounting screw 203 to a mounting plate (not shown) to which the electromagnetic contactor 100 is mounted. Note that 20
Reference numeral 2 is a power supply line connected to the single-phase AC power supply AC (see Fig. 1), and 300 is a safety cover indicated by a two-dot chain line.

The structure of the filter unit shown in FIG. 2 will be described below with reference to FIGS. 3 to 6. FIG. 3 shows a side cross-sectional view of the filter unit. In FIG. 3, 1 is a case made of a synthetic resin formed in a box shape with an opening on the front side, and 2 is a case 1 covered so as to cover the opening of the case 1. A cover made of synthetic resin, 3 is a terminal cover made of synthetic resin for covering the case 1 and the cover 2, 4 is a printed circuit board housed in the case 1, 5 is a capacitor, 6 is a common mode coil, 7 is a varistor, Each electronic component is mounted on the printed circuit board 4. Reference numeral 8 is an input terminal board mounted on the printed circuit board 4 and constituting the power supply terminal shown in FIG. 1, 9 is a lead wire mounted on the printed circuit board 4, 10 is a plate-shaped output terminal board fixed to the case 1, 11 , 1
2 is a terminal screw that is screwed into the output terminal board 10 and the input terminal board 8, 13 is a cured resin that seals the printed circuit board 4 housed in the case 1, and 101 is a partition wall formed in the case 1. 102 is a space formed by the partition wall 101.

As is apparent from FIG. 5 showing the state in which the cover 2 and the terminal cover 3 are removed, the case 1 has a rectangular outer shape, and the mounting seats 10 project at both ends on the mounting surface side.
5, the mounting seat 105 is formed with a mounting hole 106 into which a mounting screw is inserted. The structure of the case 1 can be easily understood from FIG. 4, which shows a cross section of only the case,
A partition wall 101 that rises toward the case opening side is formed, and a space 102 formed by this partition wall 101 communicates with the case back surface. A terminal mounting portion 103 communicating with the space 102 is formed on the back side of the case 1, and the output terminal plate 10 is press-fitted and fixed to the terminal mounting portion 103 from the space 102 side.
The terminal mounting part 103 has a terminal screw screwed to the output terminal board 10.
Insulating walls 104 are formed on both side surfaces of 11. The partition wall 012 and the terminal mounting portion 103 are provided at two positions on both ends of the case 1 for easy understanding from FIG.

As is apparent from FIG. 4, electronic components 5, 6 and 7 are mounted on the printed circuit board 4 housed in the case 1 and the input terminal board 8 facing the front side of the case 1 is mounted.
One end of each lead wire 9 that is drawn out to the back side of the case 1 is mounted. As is apparent from FIG. 5, the printed circuit board 4 is a quadrangle conforming to the shape of the case 1, and a portion corresponding to the partition wall 101 is cut out.

As shown in FIG. 4, a groove 201 into which the input terminal plate 8 is inserted is formed at two places on the upper end side of the cover 2 which covers the case 1 and is screwed into the input terminal plate 8. A recess 202 is formed so as to surround the terminal screw 12.
Engaging pieces 203 extending to the case 1 side are provided on both side surfaces of the cover 2.
The engaging pieces 203 are formed with engaging holes 204, 204, respectively. The terminal cover 3 includes cover portions 301 and 301 for covering the terminal screws 11 and 12, and the cover portions 301 and 301.
A flexible wall 303 is formed on the side wall adjacent to 301 by the notches 302, 302, an engaging hole 304 is provided in this flexible wall 303, and a part of the side wall aligned with the flexible wall 303 will be described later. Rib 30 that serves as a reference surface when the terminal cover 3 is attached
5 are formed. An insertion hole 306 into which a tool for tightening or loosening the terminal screws 11 and 12 is inserted is provided in a portion of the terminal cover 3 corresponding to the terminal screws 11 and 12.

Next, the assembly of the filter unit in this embodiment will be described. As shown in FIG. 4, the output terminal plate 10 is press-fitted and attached to the terminal attachment portion 103 of the case 1 from the space 102 side formed by the partition wall 101. Then, the printed circuit board 4 on which the electronic components 5, 6 and 7 are mounted and the input terminal board 8 and the lead wires 9 are mounted is the case 1
Insert it from the opening side. At that time, the positioning is achieved by engaging the input terminal plate 8 with the slit 107 formed on the inner wall of the case 1. After housing the printed circuit board 4 in the case 1, the other end of the lead wire 9 is connected to the output terminal board 10 arranged in the space 102 formed by the partition wall 101 of the case 1 by soldering. Next, in case 1,
The printed circuit board 4 is completely covered, but the amount of the cured resin 13 is filled such that the resin does not leak from the space formed by the partition wall 101 up to the height of the partition wall 101. When the filled hardened resin 13 hardens, the printed circuit board 4 is sealed with resin and fixed to the case 1. After the cured resin 13 is cured, the case 2 is covered with the cover 2. At this time, the engaging hole 204 provided in the engaging piece 203 of the cover 2 is engaged with the protrusion 108 (see FIG. 5 or 6) provided in the case 1 to integrate the both, and thus the case 1 is covered. Prevent 2 from falling off. After the case 1 and the cover 2 are integrated, terminal screws 11 and 12 are screwed to the output terminal plate 10 and the input terminal plate 8, respectively, and attached. The terminal cover 3 is attached by pressing the terminal cover 3 so that the inner surface of the cover portion 301 that covers the terminal screw 12 of the terminal cover 3 is brought into contact with the cover 2 and the rib 305 of the terminal cover 3 is brought into contact with the case 1.
The engaging hole 304 provided in the flexible wall 303 is engaged with the projection 109 (see FIG. 5 or 6) provided in the case 1. As a result, the terminal cover 3 is prevented from falling off, and the bare charging portions of the terminal screws 11 and 12 are covered by the cover portions 301 and 301 of the terminal cover 3.

In the above embodiment, the output terminal plate 10 is fixedly attached to the terminal mounting portion 103 of the case 1 and the lead wire 9 is connected to the output terminal plate 10. Partition the lead wire 9 without providing
Case 1 directly through the space 102 formed by 101
It can also be pulled out to the back side of.

[0021]

As described above, according to the first aspect of the present invention, the switching element performs the switching operation by the pulse supplied from the drive circuit, and the switching noise generated in the electromagnet operating coil by this switching operation is reduced. By providing the noise filter that blocks conduction to the power supply side, it is possible to reliably prevent switching noise from being conducted through the power supply line and radiated to the outside.

According to the third aspect of the invention, the noise filter is unitized to form a filter unit, which is detachably attached to the electromagnetic contactor, so that switching noise is prevented from being conducted through the power line and radiated to the outside. Only when desired, the filter unit may be attached to the electromagnetic contactor, and only one type of electromagnetic contactor may be manufactured as a standard product, and the number of types of electromagnetic contactor can be reduced. Also, if a filter unit is attached to an existing electromagnetic contactor, it is possible to prevent switching noise from being conducted through the wire and radiated to the outside.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an electromagnetic contactor including a noise filter according to an embodiment of the present invention.

FIG. 2 is a side view in which a filter unit showing an embodiment of the present invention is attached to an electromagnetic contactor.

FIG. 3 is a side sectional view of the filter unit shown in FIG.

FIG. 4 is an exploded view of the filter unit of FIG.

FIG. 5 is a front view of the filter unit of FIG. 3 in an assembling stage.

6 is an external view of the filter unit of FIG.
(a) is its front view, (b) is its side view, (c) is its plan view, (d) is an enlarged view of BB line in (c).

FIG. 7 is a side sectional view showing the structure of the electromagnetic contactor.

FIG. 8 is a circuit diagram of a conventional electromagnetic contactor.

9 is a time chart for explaining the operation of the circuit diagram of FIG.

[Explanation of symbols]

 C1 capacitor C2 capacitor DS Drive circuit Tr Switching transistor MC Electromagnetic operation coil CC Common mode coil BS Varistor NF Noise filter

Claims (3)

[Claims] 1. An electromagnetic contactor having a drive circuit, in which an electromagnet operating coil and a switching element are connected in series to a power source, and a continuous pulse is supplied to the switching element when the electromagnet is turned on and an intermittent pulse is supplied when the electromagnet is held. The electromagnetic contactor according to claim 1, further comprising a noise filter for preventing the switching noise generated in the electromagnet operating coil by the switching operation of the switching element by the drive circuit from being conducted to the power supply side. 2. The electromagnetic contactor according to claim 1, wherein the noise filter includes a capacitor that blocks normal mode noise and a common mode coil that blocks common mode noise. 3. An electromagnetic contactor having a drive circuit in which an electromagnet operating coil and a switching element are connected in series to a power supply, and a continuous pulse is supplied to the switching element when the electromagnet is turned on and an intermittent pulse is supplied when the electromagnet is held. In, a noise filter for preventing the switching noise generated in the electromagnet operating coil by the switching operation of the switching element by the drive circuit from being conducted to the power supply side is unitized into a filter unit, and this filter unit is used as the main body of the electromagnetic contactor. An electromagnetic contactor that is detachably installed.