JPH0212672Y2 - - Google Patents

Description

[Detailed Description of the Invention] A. Field of the Invention The present invention relates to an AC relay that uses an electrostrictive element as a drive source for contacts.

B. Conventional technology and its problems In recent years, with the aim of reducing power consumption and reducing heat generation,
For the purpose of reducing noise, various relays using electrostrictive elements as drive sources for contacts have been proposed.

However, when the displacement of the electrostrictive element is used as a drive source for the contact, the displacement force and amount are small, so
When a large current is switched on and off, the contacts are worn out, making it impossible to maintain contact pressure, which ultimately leads to poor contact. This is because the AC load current phase when the contacts open is random, so they often open near the peak of the AC load current phase, and the arc that occurs between the contacts when they open will wear out the contacts. It is.

C. Purpose of the invention The present invention was developed in view of these drawbacks, and its purpose is to apply a magnetic attraction force between the iron core and the movable iron piece using an alternating current load current, thereby preventing the contacts from opening. By performing this operation when the phase of the AC load current is close to zero, contact wear can be greatly reduced, and even if an electrostrictive element with small displacement force and amount is used as the contact drive source, the initial characteristics will remain the same. The object of the present invention is to provide an alternating current relay that can maintain semipermanently and control large currents.

D. Description of Embodiments The present invention will be described below with reference to the accompanying drawings, which are one embodiment.

1 has electrostrictive elements 1A on both sides of the center electrode 1C,
It is an electro-mechanical transducer consisting of an electrostrictive element bonded together with electrodes 1B, which is cantilever-supported by a support part 2A electrically connected to the terminal 2 and an electrically insulated support part 2B, and the center electrode 1C and the terminal 3 is connected via a discharge resistor 4, and operates by being connected to an input signal source (power supply) 5.

The iron core 8 is a thin plate having a substantially U-shape. The movable iron piece 10 is supported by a hinge at one end of the iron core 8 (hinge point A), and the insulating material (resin material) 11 attached to the rear end is the insulating material (resin material) attached to the free end of the electro-mechanical conversion element 1. 7 is engaged.

The movable contact piece 12 has a movable contact 13 at its tip,
It is connected to the movable iron piece 10 via an insulating material (resin material) 14, and its rear end is electrically and mechanically connected to the AC load terminal 16, and the movable iron piece 10 is connected to the above-mentioned hinge point A.
is used as a fulcrum and is constantly biased upward. The fixed contact 15 is fixed to another AC load terminal 17, and the movable contact 13 can be connected and separated.

AC load terminals 16 and 17 are vertically orthogonal to the base of the iron core 8, and an AC power source 18 and a load 19 are connected in series.

In the above configuration, when the switch 6 is turned off and no voltage is applied to the electro-mechanical conversion element 1, the electro-mechanical conversion element 1 extends in the horizontal direction,
The movable iron piece 10 is rotated clockwise in FIG. 3 about the hinge point A as a fulcrum by the spring force of the movable contact piece 12 itself, and the movable contact 13 is separated from the fixed contact 15.

Here, when the switch 6 is turned on and a constant voltage is applied from the power source 5, the free end of the electro-mechanical conversion element 1 is displaced upward, and based on this displacement, the movable iron piece 10 and the movable contact piece 12 are moved. The movable iron piece 10 rotates counterclockwise in FIG. 3 using the hinge point A as a fulcrum, and the tip of the movable iron piece 10 comes into contact with the other end of the iron core 8.
The movable contact 13 closes the fixed contact 15, AC load terminals 16, 17, power supply 18, load 19, contact 1
3, 15, and an alternating current flows through a closed circuit including the movable contact piece 12. At the same time, a magnetic flux is generated in the closed loop magnetic circuit formed by the iron core 8 and the movable iron piece 10, and this magnetic flux acts as an attractive force that holds the movable iron piece 10 on the iron core 8 (see FIG. 4d).

Next, when the switch 6 is turned off and the voltage application is cut off, the charge in the electro-mechanical transducer 1 is discharged via the discharge resistor 4, and the free end of the electro-mechanical transducer 1 is caused by its own elasticity. Returning downward, the movable iron piece 10 attempts to separate from the other end of the iron core 8 due to the return force of the movable contact piece 12. However, if the phase of the AC load current flowing through the current path is near the peak at that time, the attractive force of the magnetic flux generated in the magnetic circuit acts to prevent the return rotation of the movable iron piece 10, and the contact 13 , 15 maintain the closed state. As the AC load current decreases in a sine curve, the attractive force of the magnetic circuit also decreases, and when the phase of the AC load current approaches zero (the attractive force becomes Fr in Figure 4 d).
), the return force of the movable contact piece 12 exceeds this suction force, and the movable iron piece 10 rotates (returns) in the clockwise direction in FIG. Separate from 15. When the contacts are opened, the AC load current is almost zero, so no arc occurs between the contacts 13 and 15. Therefore, even if a large current is switched on and off, the contacts 13 and 15 will not wear out, and the initially set contact pressure and contact follow will hardly change during use. That is, even if an electro-mechanical transducer with a small displacement force and amount of displacement is used as a drive source, the initial characteristics can be maintained and the input/output ratio can be said to be very excellent. Further, the power consumed by the electro-mechanical conversion element 1 itself is very small, and the power is only consumed by the discharge resistor 4, so the power consumption is very small.

On the other hand, the return force of the movable iron piece 10 needs to be set approximately equal to the attraction force when the phase of the AC load current is near zero, and in this embodiment, the return force shown in FIG.
is made equal to Fr. Note that the return force may be applied by the movable contact piece 12 or by the electro-mechanical conversion element 1, and depending on the case, a separate return means may be provided.

Further, the attractive force due to the AC load current can be arbitrarily changed by changing the magnitude of the load current itself and the number of turns of the current path to the iron core 8.

In addition, the AC relay according to the present invention can be modified in various ways within the scope of its gist. For example, a part of the AC load terminals 16 and 17 may be formed of lead wires, or the movable contact piece 12 and the AC load terminal 16 may be formed integrally.

As is clear from the above explanation, according to the present invention, by using an electrostrictive element, it is possible not only to reduce power consumption, heat generation, and noise, but also to improve the timing of the return of the electro-mechanical transducer. Regardless,
Since the contacts open when the phase of the AC load current approaches zero, there is no arcing and wear and tear on the contacts is greatly reduced, resulting in an electro-mechanical transducer with small displacement force and amount. can be used as a driving source to open and close large currents, and can maintain initial setting characteristics such as contact pressure and contact follow well.

[Brief explanation of the drawing]

The drawings show one embodiment of the AC relay according to the present invention, in which Fig. 1 is an overall perspective view, Fig. 2 is a perspective view with a part replaced with an electric circuit, and Fig. 3 is a front view of Fig. 2. FIG. 4 is a time chart of the operation. 1...Electro-mechanical conversion element consisting of an electrostrictive element,
4...discharge resistance, 5...power supply, 8...iron core, 10
... Movable iron piece, 12 ... Movable contact piece, 13 ... Movable contact, 15 ... Fixed contact, 16, 17 ... AC load terminal, 18 ... AC power supply, 19 ... Load.

Claims (1)

[Scope of utility model registration request] It is connected to the power supply via a discharge resistor, and
An electrostrictive element supported at a cantilever, an iron core having a substantially U-shape, and a restoring force is applied to one end of the iron core to be rotatably supported, and the electrostrictive element responds to the displacement of the electrostrictive element when a voltage is applied. a movable iron piece that rotates and contacts the other end of the iron core to form a magnetic closed circuit; a movable contact piece that has a movable contact and is attached to the movable iron piece; and when the movable iron piece rotates, A fixed contact that the movable contact contacts, and an AC load terminal that is orthogonal to the magnetic circuit and electrically connected to the movable contact and the fixed contact, and the return force of the movable iron piece is applied when the phase of the AC load current is zero. An AC relay characterized by having an attraction force that is almost equal to the attraction force when it is nearby.