JPH0223965B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to the improvement of self-holding magnetic contactors, and in particular, to extremely suppressing the discharge that occurs when the B contact is opened, and providing a long-life self-holding magnetic contactor. This is what we provide.

(Prior art) Conventionally, there have been two types of electromagnetic contactors: so-called AC electromagnetic contactors, which use alternating current electromagnets to open and close contacts when opening and closing electric circuits, and those that use permanent magnets instead of alternating current electromagnets. Self-holding electromagnetic contactors are used, but the former requires constant AC current to maintain the closed state of the contact, and while the latter is energy-saving, the drive power is DC. Therefore, there are problems such as the need for a switch to change the polarity of the rectifier circuit power supply.

Therefore, the present inventor first solved the above-mentioned drawbacks and proposed a self-holding electromagnetic contactor that maintains the closed state of the contactor by the attraction force of a permanent magnet and also enables the contactor to be opened and closed by alternating current energization. (Japanese Patent Publication No. 59-40429).

This self-holding type electromagnetic contactor uses a high coercive force magnet such as a rare earth permanent magnet that is magnetized in a predetermined direction as a permanent magnet, and attracts the mover connected to the contactor.
At the time of attraction and release, the configuration is such that alternating current is simply applied to an excitation coil wound around the outer periphery of the mover without changing the magnetization direction of the permanent magnet. A circuit shown in FIG. 5 is provided to prevent malfunctions caused by vibrations caused by AC energization to the excitation coil.

That is, in FIG. 5, the mover (not shown)
When the switch 1 is turned on to attract and attract the movable element to the stator (not shown), an alternating current is applied to the excitation coil 5, the movable element approaches the stator, and furthermore, the movable element approaches the stator and is further attracted only by the attraction force of the permanent magnet (not shown). Therefore, when the movable element reaches a state where it can be sufficiently attracted to the stator, the contact 3 changes from closed to open, cutting off the current to the excitation coil 5. Thereafter, the movable element is attracted to the stator by the attraction force of the permanent magnet, and the electrical circuit switching contact, that is, the main contact (not shown) connected to the movable element moves from open circuit to closed circuit. maintain the condition. Contact 4 similarly transitions from open to closed. In other words, when the excitation coil 5 is energized with alternating current and the direction of the alternating magnetic field is applied in the same direction as the magnetic field of the permanent magnet, the attraction force generated on the mover is equal to the combined attraction force of the excitation coil and the permanent magnet. The resultant attraction force is stronger than the spring force of the coil spring (not shown) that acts in the direction of pushing the mover upward, so the mover approaches the stator and is essentially attracted by the permanent magnet. It is attracted to the stator only by force.

Next, when the switch 2 is turned on to release the mover, since the contact 4 is in a closed state, an alternating current is applied to the excitation coil 5 via the electric resistance 6, canceling the attractive force of the permanent magnet and the repulsive force of the coil spring 23. The mover is released. By making the magnetomotive force of the excitation coil smaller than the magnetomotive force when attracting the movable element through the electric resistance 6, irreversible demagnetization of the permanent magnet is prevented, and the above-mentioned release and attraction are carried out smoothly. This will allow you to do it continuously.

That is, when the switch 2 is turned on and an alternating current weaker than that during attraction is applied to the excitation coil 5 via the resistor 6, the direction of the alternating magnetic field and the direction of the magnetic field by the permanent magnet are applied in opposite directions (cancelling directions). , the combined attraction force of the permanent magnet and excitation coil generated in the mover becomes weaker than the spring force of the coil spring, and a gap is created between the mover and stator, and the mutual attraction force is rapidly attenuated, causing release. It becomes a state.

In this case, if the magnetomotive force of the excitation coil at the time of release is the same as the magnetomotive force at the time of attracting the mover, then the mover, which is about to shift to the release state, will be able to change the direction of the magnetic field of the excitation coil and the magnetic field of the permanent magnet. When they are in the same direction, they are attracted again by the permanent magnet and cause chattering, making it impossible to release them reliably.
Note that although the figure shows a case in which attraction and attraction and release are performed using a single excitation coil, the same effect can be obtained by using a pair of excitation coils having mutually different magnetomotive forces. In the figure, 7 indicates an AC power source.

As the movable element is released, the main contactor and the contact 4 transition from a closed circuit to an open circuit. Similarly, contact 3 transitions from open to closed.

In this specification, the contact 4 which performs the same opening and closing operation as the main contact when the excitation coil 5 is energized is referred to as the A contact, and the contact 3 which performs the opposite opening and closing operation to the main contact is referred to as the B contact.

(Problems to be Solved by the Invention) When the A contact 4 and the B contact 3 are opened, a discharge occurs and sparks are generated, and especially when the B contact 3 is opened, a large discharge occurs. That is, when comparing the current to the exciting coil when contact 4 (A contact) and contact 3 (B contact) are opened in Fig. 5,
The contact 3 changes from a closed circuit to an open circuit in a state in which the movable element and the stator are in contact with each other and can be attracted, that is, in a state in which a large amount of current is flowing through the excitation coil, and a large discharge occurs. On the other hand, when the contact 4 is open, compared to the contact 3, the amount of current flowing to the excitation coil through the resistor 6 is smaller, and the amount of discharge is also inevitably smaller.
For this reason, the B contact 3 is significantly worn out, causing a shortened lifespan of the electromagnetic contactor.

The object of the present invention is to improve this and propose a self-holding electromagnetic contactor using alternating current current, which has extremely high industrial value and suppresses large discharge when the B contact is opened as much as possible.

(Means for Solving the Problem) As a result of various studies such as the opening/closing operation of the main contact, A contact, and B contact as the movable element moves, and the amount of current to the excitation coil, the inventor determined the opening timing of the B contact. It has been discovered that the discharge at the B contact point can be significantly reduced by appropriately delaying the time compared to conventional electromagnetic contactors. In other words, it has been confirmed that even when the amount of current to the excitation coil is slightly reduced from the maximum value, attraction and attraction between the mover and stator, which are brought close to each other, can be substantially achieved by the attraction and attraction force of the permanent magnets. Therefore, the discharge at the B contact can be greatly reduced by slightly delaying the opening timing of the B contact from the timing when the amount of current to the excitation coil reaches its maximum, and opening it when the amount of current to the excitation coil decreases. was successful.

In order to achieve this without making major changes to the configuration and arrangement of each part of conventionally used electromagnetic contactors, it is necessary to It was determined that this could be achieved by making the distance between the contacts smaller than the facing distance between the fixed contact and the movable contact forming the main contact and the A contact in the open state, that is, the distance between the respective contacts.

The present invention is based on the above knowledge, and includes a permanent magnet that is magnetized in the moving direction of the mover, stator, and mover, and an excitation coil on the outer periphery of the permanent magnet, and is fixed to the mover side by applying alternating current to the excitation coil. In a self-holding electromagnetic contactor that opens and closes the main contact, A contact, and B contact configured between the child sides, the distance between the fixed contact and the movable contact when the B contact is open is the main contact. The gist of the present invention is a self-holding electromagnetic contactor in which the distance between the fixed contact and the movable contact is smaller than the distance between the fixed contact and the movable contact when the child and A contacts are in the open state. The permanent magnet used in this electromagnetic contactor is preferably a high coercive force magnet such as a rare earth permanent magnet that is not demagnetized by the magnetic field of the excitation coil generated when the mover is released. The excitation coil wound around the outer periphery of the central magnetic pole of the mover and stator is usually wound using a non-magnetic bobbin, etc., as long as it does not interfere with the smooth movement of the mover. A single coil may be used (FIG. 5), or a pair of coils may be used independently, and this can be selected as appropriate depending on the current to be applied, the space for arrangement, etc.

Shading coils are installed on each leg of the mover and stator to completely prevent vibrations caused by alternating current, but at least one opposing section is installed in consideration of the carrying current capacity, size and shape of the opposing sections of the legs, etc. installation is required.

Although various mechanisms for adjusting the distance between the fixed contact and the movable contact in the open state of the B contact of the present invention can be considered, it is possible to configure it without majorly changing the normally used contact structure. . Note that the optimum dimension for setting the distance between the contacts is determined according to the current capacity of the excitation coil.

Further explanation will be given below based on drawings listed as examples.

(Example) FIG. 1 is a longitudinal sectional view of an example of a self-holding electromagnetic contactor, in which 10 indicates a magnetic circuit section and 11 indicates a contactor section.

The magnetic circuit section 10 has a central magnetic pole section 12a and a pair of leg sections 12b and 12c, and is an E-shaped stator in which a rare earth permanent magnet 13 magnetized in the vertical direction is placed below the central magnetic pole section 12a as shown in the figure. 12 and an E-shaped mover 14 having a central magnetic pole part 14a and a pair of legs 14b, 14c are disposed facing each other, and an excitation coil 16 is connected to the outer periphery of each central magnetic pole part 12a, 14a via a non-magnetic bobbin 15. It is wrapped in 1
7a is a shading coil provided on a surface of the stator 12 facing one leg 12b, and 17b is a shading coil provided on a surface of the movable element 14 facing one leg 14c.

18 is a non-magnetic case, and the above-mentioned magnetic circuit section 1
The fixed contact 19 of the main contact and the A contact not only surrounds the
A, 20a and a fixed contact 21a of the B contact are fixed.

Movable contacts 19b, 20b, 21b arranged opposite to the fixed contacts 19a, 20a, 21a are connected to the movable element 14 side via a non-magnetic support member 22.
A and movable contacts 19b, 20b, and 21b constitute a contact portion 11.

In the figure, 23 is a coil spring, which is disposed between the lower surface of the non-magnetic support member 22 and the upper surface of the non-magnetic bobbin 15, and acts in a direction to push the movable element 14 upward.

Among the above configurations, movable contacts 19b, 20b,
The details of the arrangement of 21b are shown in FIG. 1 in the diagram
9b is the main contact (usually 3 pieces), 20b is the A contact,
21b is each movable contact forming the B contact;
It is attached to a non-magnetic support member 22 above the movable element 14.

That is, the non-magnetic support member 22 is provided with a plurality of guide windows 25 (five in the figure) having guides 24 so that the movable contact can move in the vertical direction.

Further, pedestals 26, 2 are provided at the upper and lower ends of the guide window 25.
A pair of guide fittings 27, 27, which are movable in the vertical direction along the guide, are attached to the base by a compression spring 28.
They are placed opposite each other by the spring force. Further, each movable contact is arranged as shown in the figure to the guide fitting 27.
It is inserted and supported between the base 26 and the base 26. However, B
The upper end of the guide window 25 in which the movable contact 21b of the contact point is arranged has a configuration for obtaining the effects of the present invention, that is, B
In order to make the distance between the contacts in the open state of the contacts smaller than the distance between the contacts in the open states of the main contact and the A contact, the pedestal 26 is not provided. Next, its effect will be explained.

(Function) Figure 3 shows the B contact and the A contact (the main contact shows the same operation as the A contact, so hereafter A
FIG. 4 is an explanatory diagram of the opening/closing operation of the A contact including the contact and the main contact.

FIG. 3A shows the electric circuit in an open state, that is, the mover 1
4 (Fig. 1) is in the open state, and the fixed contact 20a and the movable contact 20b of the A contact are L ₁
B is in the open state with a distance between the contacts of
The fixed contact 21a and the movable contact 21b are maintained in a closed state by a contact force corresponding to the spring force of the compression spring 28 (force extending in the vertical direction in the figure).
Here, the configuration of the present invention is that the guide window 2 in which the B contact is arranged is
5 does not have the pedestal 26 at the lower end thereof, it has a larger gap 29 than in the conventional structure.

FIG. 3B shows that when AC current is applied to the excitation coil 16 (FIG. 1) to close the electric circuit, the mover 14 (FIG. 1) moves the excitation coil 16 and the permanent magnet 13 (FIG. 1). A non-magnetic support member 22 that moves downward by an attractive force and is connected to the movable element 14.
also indicates a downward movement. At this time, in the configuration of the present invention, the distance between the fixed contact 20a and the movable contact 20b of the A contact becomes smaller.
The fixed contact 21a and the movable contact 21b of the B contact maintain the closed state. In the conventional configuration, the B contact has already shifted from the closed state to the open state at this point, as shown by the two-dot chain line in the figure.

FIG. 3C shows a state in which the mover 14 (FIG. 1) has moved further downward and is attracted to the stator 12 (FIG. 1), and as shown in the same figure, the A contact has shifted to the closed state,
The B contact transitions to the open state. At this time, the fixed contact 21a and the movable contact 21b of the B contact have an inter-contact distance of _L2 . In the case of a conventional configuration, the distance between the contacts is _L3 , as shown by the two-dot chain line in the figure, and the relationship between the present invention and the conventional product is _L1 = _L3 > _L2 .

As shown above, in the present invention, the movable contact 21b of the B contact provided on the non-magnetic support member 22
Since there is no pedestal above the guide window 25 (Fig. 2) where the contact is placed, the distance between the contacts in the open state is
L ₂ is smaller than the distance between the contacts L ₃ when a conventional pedestal is provided (Fig. 3 C), and when transitioning from Fig. 3 A to Fig. 3 B and Fig. 3 C, that is, the distance between the movers The opening timing of the B contact during suction is later than in conventional electromagnetic contactors. For this reason, the generation of sparks due to discharge at the contact can be extremely suppressed.

FIG. 4 shows another embodiment of the mechanism for adjusting the distance between the B contacts in the present invention.
When a pedestal 26 is provided above the guide window 25 where the movable contact 21b of the contact is arranged, as in the conventional case, the tip portion of the fixed contact 21a is curved downward, and the distance L ₂ between the contacts is changed from the conventional (Fig. By making the inter-contact distance L3 (indicated by the dashed line in the center) smaller than _L3 , the same effect as the configuration shown in FIG. 3 can be obtained.

(Effects of the Invention) As shown above, the present invention minimizes the discharge that occurs when the B contact opens by making a slight change in the mechanism.
This product extends the lifespan of the AC self-holding electromagnetic contactor, which allows the main contact to be opened and closed by AC current, and increases the scope of use of the AC self-holding electromagnetic contactor.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of the self-holding electromagnetic contactor of the present invention. FIG. 2 is a detailed view of the movable contact portion of the self-holding electromagnetic contactor of the present invention. 3A, B, and C are explanatory diagrams of the operation of the A contact and the B contact in the present invention. Fourth
The figure is a diagram showing another embodiment of the adjustment mechanism for the distance between B contacts in the present invention. FIG. 5 is a circuit diagram illustrating the operation of the A contact and the B contact of the AC self-holding electromagnetic contactor. 1, 2: Switch, 3: B contact, 4: A contact,
5, 16: Excitation coil, 6: Electrical resistance, 7: AC power supply, 10: Magnetic circuit section, 11: Contact section, 12
a, 14a: central magnetic pole part, 12b, 12c, 14
b, 14c: Leg, 13: Permanent magnet, 14: Mover, 15: Non-magnetic bobbin, 17a, 17b: Shading coil, 18: Non-magnetic case, 19a: Fixed contact of main contact, 19b: Main contact child movable contact, 20a: fixed contact of A contact, 20b: movable contact of A contact, 21a: fixed contact of B contact,
21b: Movable contact of B contact, 22: Non-magnetic support member, 23, 28: Coil spring, 24: Guide, 2
5: Guide window, 26: Pedestal, 27: Guide metal fittings, 2
9: Gap.

Claims (1)

[Claims] 1 Equipped with a permanent magnet magnetized in the moving direction of the mover, stator, and mover, and an excitation coil around the outer periphery,
In a self-holding electromagnetic contactor that opens and closes the main contact, A contact, and B contact configured between the mover side and the stator side by applying alternating current to the excitation coil, the fixed contact when the B contact is open. A self-holding electromagnetic contactor characterized in that the distance between the fixed contact and the movable contact is smaller than the distance between the fixed contact and the movable contact when the main contact and the A contact are open.