JPS5947546B2 - electromagnetic drive device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electromagnetic drive device for driving various mechanical displacement mechanisms, and in particular, the power required for one drive is reduced, and the power supply of the control elements (transistors, etc.) used to drive it is reduced in capacity. This invention relates to an electromagnetic drive device that can reduce costs and drive accurately.

Figure 1 shows the configuration of a conventional electromagnetic drive control device.
To briefly explain Fig. 1, 1 is a core, 2 is a coil, and core 1 is magnetized by energizing coil 2.
Using such magnetization, the core 1 reciprocates between the permanent magnet 3 and the spring 4, which is an elastic member.

For example, Japanese Patent Application No. 50-63890 (Japanese Unexamined Patent Publication No. 51-14
No. 1029), the core 1 is attracted to the permanent magnet 3 when no current is applied to the coil 2, and when the current is applied to the core 2, the restoring force of the spring 4 and the core 2 The structure is such that the position of the core 2 is moved by the repulsive force obtained by the magnetization generated in the magnetization (so that it has the same polarity as the permanent magnet).

The above configuration requires a large amount of excitation power to cancel the magnetic flux generated by the permanent magnet that holds the displacement mechanism when displacing it, and is unsuitable for single drive with a small capacity power source. Accordingly, control driving using a small-capacity control element is also impossible, resulting in an increase in cost.

Furthermore, there is a problem in that the operation becomes uncertain when displacement is performed using a small-capacity power supply.

The present invention provides an improved electromagnetic drive device that eliminates such conventional drawbacks, and includes a movable member having a first excitation coil, an elastic member coupled to the movable member, and a magnetically equivalent a yoke that is part of a closed circuit and has a second excitation coil that attracts the movable member against the elastic force of the elastic member, and energizes the first excitation coil of the movable member. By moving the movable member, the movable member can be effectively operated by a small-capacity power source,
The result is an electromagnetic drive control device that can be controlled with small capacitance elements.

Note that it is also possible to release the holding of the displacement mechanism by discharging the electric charge accumulated in a capacitor connected in series with the excitation coil in a pulsed manner.

The present invention will be explained in detail below with reference to the drawings.

To simplify the explanation, an example of one movable member will be described.

FIG. 2 is a configuration diagram showing an embodiment of the electromagnetic drive device according to the present invention.

The figure shows an example in which an electromagnet is installed as a magnet that attracts a movable member, and 5 is an armature (movable member) made of magnetic material, and 6
7 is a yoke made of a magnetic material; 7 is a spring that biases the armature 5 toward the spring side; 8 is an excitation wire ring disposed on the yoke 6;
Reference numeral 9 denotes an excitation wire ring arranged on the armature 5.

To further explain the embodiment having the above configuration,
When a current is flowing through the excitation wire 8 and no current is flowing through the excitation wire 9, the armature 5 resists the spring 7 due to the magnetic flux from the attraction electromagnet A composed of the yoke 6 and the excitation wire 8. It is attracted to one end of the yoke 6.

An equivalent circuit of the device shown in FIG. 2 in this state is shown in FIG. 2A.

In the figure, RA is the armature, Ry is the yoke, and Rg
are the equivalent magnetic resistances of the gap between the armature and the yoke, and U2 means the magnetomotive force of the attraction electromagnet A.

In the circuit shown in the figure, if the magnetic flux by the attraction magnet A is Φ, and the contact area between the yoke and the armature is S, then the attraction force F1 between the armature and the yoke is expressed as follows.

Here, f is the tensile force exerted by the spring 7, and μ.

is the vacuum permeability, and the yoke and armature are assumed to be in the unsaturated region.

Next, power is supplied to the excitation wire ring 9, and the excitation wire ring 9 and the armature 5 are connected to each other.
FIG. 2B shows an equivalent circuit when applying a magnetomotive force in the opposite direction to the magnetic flux generated by electromagnet B, which is constructed of the following.

R'A, R'g, . . . are the magnetic resistances of the same portions in FIG. 2A, and dashes are added to represent the change in resistance value depending on the magnetic flux density.

Note that e is the magnetomotive force due to the excitation wire ring 9, J is the magnetic flux due to the attraction electromagnet, and d is the magnetic flux due to the excitation wire ring 9 (for release).

In the circuit shown in the figure, the attraction force F2 between the armature and yoke
The armature moves when F2<0.

Here, the magnetic flux is expressed as (a is the proportionality constant, N is the number of turns of the coil, and ■ is the current), and the magnetic resistance of the attraction magnet is smaller than when a permanent magnet is used as the attraction magnet, so the excitation If a small current ■ is applied to the coil 9, F2
It can be done.

For reference, the magnetic resistance when using a permanent magnet is rmζL
−(However, μ.

is μoS (vacuum permeability, materials such as ferrite, rare earth, magnet),
On the other hand, the magnetic resistance of the attracting electromagnet is RY=A, (where μ is the magnetic permeability at the yoke operating point), so r m >>
RY, the driving current for the electromagnet B is smaller than when an electromagnet is used instead of a permanent magnet for attraction.

Therefore, if the above-mentioned drive device is used, for example, to drive a hammer in a printer, the hammer drive current can be reduced.
The drive circuit can be integrated into an IC.

The present invention does not use a permanent magnet as an attraction magnet, but instead includes a movable member having a first excitation coil, an elastic member coupled to the movable member, and a part of a magnetic equivalent closed circuit.
and a yoke having a second excitation coil that attracts the movable member against the elastic force of the elastic member,
By energizing the first excitation coil of the movable member and moving the movable member, it is possible to reduce the electric power, and it is possible to release stability using a small-capacity control element with a small-capacity power supply, which means a significant cost reduction. Measure,
Moreover, since the drive (release) current is small, problems such as noise do not occur.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional electromagnetic drive device, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIGS. 2A and 2B are explanatory diagrams of its operation. 5 is the armature, 6 is the yoke.

Claims (1)

[Claims] 1 A movable member having a first excitation coil, an elastic member coupled to the movable member, the movable member being part of a magnetic equivalent closed circuit, and attracting the movable member against the elastic force of the elastic member. and a yoke having a second excitation coil, the electromagnetic drive device moving the movable member by energizing the first excitation coil of the movable member.