JPH0411799Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a plunger type solenoid equipped with a printing hammer and used in static type impact printers and the like.

[Conventional technology]

Generally, as a type impact printer, a so-called daisy foil type printer in which groups of type are arranged in a petal-like manner is known.

In this type of printer, the daisy wheel rotates at high speed in response to a print selection signal, and when the desired type is in the printing position, the arm end of the type is struck by a hammer of a plunger type solenoid, and the type is transferred through the ink ribbon. Printing is done by hitting the paper on a platen.

FIG. 2 is a longitudinal cross-sectional view of a conventional plunger type solenoid, and this will be explained based on the same figure.The solenoid 1 is equipped with a cylindrical yoke 2 having an annular groove 2a on its inner peripheral surface. 2a has a built-in electromagnet 4 connected to a power source (not shown) through a lead wire 3. The lower open end of the yoke 2 is connected to a lid 5 having a spring chamber 5a and a bearing 5b.
Further, a cylindrical bearing 6 made of synthetic resin or the like is press-fitted into a stepped portion formed at the upper open end. Reference numeral 7 denotes a hollow plunger having a hammer 8, which is slidably fitted into the yoke 2 and is configured to be moved by the excitation force of the electromagnet 4. 9 is a compression coil spring that is loaded on the same axis as the plunger 7 and gives it a return behavior;
is a cap-shaped stopper which has a through hole 10a in the center and is fixed to the open end of the yoke 2 on the side opposite to the spring with a bolt 11. Further, a buffer damper 12 is attached to the stopper 10 so as to face the plunger 7, and a spacer 1 is provided between the yoke 2 and the stopper 10 to prevent the bearing 6 from coming off.
3 is fitted.

With this configuration, when the electromagnet 4 is excited, the plunger 7 with the hammer 8
The stopper 1 resists the stepped force of the compression coil spring 9.
It slides in the direction away from 0, and the hammer 8 strikes the type arm. When the electromagnet 4 is demagnetized from this state, the plunger 7 is activated by the compression coil spring 9.
The plunger 7 moves rapidly in the direction of the stopper 10 due to the elastic force of
It is stopped by colliding with the stopper 10 via.

However, in such a conventional plunger type solenoid, the plunger 7 is connected to the damper 1.
When it collides with the hammer 8, the repulsive force acts directly on the hammer 8, and after the printing operation, it bounces a lot and the hammer 8
There was a problem in that the daisy wheel collided again with the daisy wheel (not shown) and the daisy wheel was damaged. However, the damper 12 should be installed so as not to be damaged.
If you set the thickness to be large, it will be difficult to print continuously or
When operating in a high-temperature atmosphere, there is a drawback that the damping performance is reduced and the rebound of the hammer 8 becomes even larger.

Therefore, the present applicant has developed and proposed a plunger type solenoid, whose vertical cross-sectional view is shown in FIG. 3, as a solution to the above-mentioned drawback. 2b
is formed, and the stopper 1 shown in FIG.
Stopper 1 with flange 14a instead of 0
4, and a damper 15 having a through hole 15a in the center is inserted between the inner surface thereof and the upper end surface of the plunger 7. Reference numeral 16 denotes another damper formed in an annular shape from an elastic material such as rubber or plastic, and includes a wide flange 16a at the center and narrow flanges 16a and 16c at the top and bottom. Wide flange 1
6a is interposed between the cap 14 and the yoke 2, and the narrow flanges 16b, 16c are connected to the flanges 2b, 1.
4a and is compressed by elastic deformation. Since the other parts are the same as those shown in FIG. 2, they will be given the same reference numerals and the explanation will be omitted.

With this configuration, after printing is performed in the same manner as described above, when the electromagnet 4 is demagnetized and the plunger 7 collides with the damper 15 due to the elastic force of the compression coil spring 9, the stopper 14 is moved separately. Since the damper 16 moves in the axial direction due to the vibration, the impact is alleviated together with the damping action of the damper 15.

[Problem that the invention attempts to solve]

However, in all of these conventional plunger type solenoids, in order to ensure the stroke, the plunger 7 must be made long so that the plunger 7 does not come off the bearing 6 when the hammer 8 protrudes. The problem was that it was difficult to downsize. That is, when the electromagnet 4 is energized, the plunger 7 can move up to the chain line position in the figure, but an extra length is required for the part of the yoke 2 that forms the air gap, and the plunger 7 itself is large. become In order to solve this problem, the bearing 6 can be press-fitted to the electromagnet 4 side, but if such a design is adopted, the bearing 6 will be provided approximately at the diameter of the magnetic flux shown by the reference numeral 17 in the figure, and the bearing 6 requires non-magnetism, which results in poor magnetic permeability and a large magnetomotive force. For this reason, in the conventional device, the air gap shown by the symbol g in the figure has a magnetic flux of 1.
7, so if the stroke is considered constant, the bearing 6 becomes longer by the distance from the bobbin end face 18. Furthermore, the wall thickness of the bearing 6 is adjusted to the air gap.
However, it is currently difficult to provide a resin layer directly on the inner hole surface of the yoke 2 from the viewpoint of production technology, and also poses a problem from the viewpoint of cost reduction.

[Means for solving problems]

In order to solve such problems, in the present invention, the bearing that is attached to the yoke and slidably supports the plunger is made of a metal cylinder with resin fixed to the inner hole surface, and the upper part of the inner hole of the cylindrical yoke is made of metal. formed continuously between the electromagnet and the open end of the cylindrical yoke,
It was press-fitted into the yoke, which serves as a path for the magnetic flux of the electromagnet.

[Effect]

When the electromagnet is energized, magnetic flux flows and the plunger slides along the bearing inner hole. At this time, the resin part of the bearing becomes the bearing surface, and the thickness of the resin becomes an air gap on the path of the magnetic flux.

〔Example〕

FIG. 1 is a longitudinal sectional view showing an embodiment of a plunger type solenoid according to the present invention. In the figure, components having the same configuration as those in FIG. 3 are given the same reference numerals, and a detailed explanation thereof will be omitted, and a brief explanation will be given below. Electromagnet 4
A narrow flange 16c of a resin damper 16 is press-fitted onto the flange 2a of the yoke 2 that incorporates the yoke 2, and an upper narrow-width flange 16c of the damper 16 is press-fitted onto the flange 20a of the stopper 20.
The stopper 20 does not have a concave portion as shown in FIGS. 2 and 3, but is formed in the shape of a disc without a concave portion, and a resin damper 21 is inserted into the concave hole on the lower surface. It is worn. Further, a wide flange 16a of the damper 16 is inserted between the stopper 20 and the yoke 2. A resin bearing 5b is fitted into the lower end opening of the spring chamber 5a, which is joined to the lower end surface of the yoke 2 and houses the compression coil spring 9 inside. A bearing 22, which will be described later, is fitted. A plunger 7 having a hammer 8 is slidably supported on both bearings 22 and 5b and is urged toward the damper 21 by a compression coil spring 9.

At the upper part of the inner hole of the yoke 2, there is a tapered hole 2b as an annular space that becomes larger in diameter toward the opening end;
A bearing hole 2c having the same diameter as the small diameter portion is continuously formed between the open end and the electromagnet 4, and the bearing 22 is inserted from the open end of the tapered hole 2b and passes through the tapered hole 2b. It is press-fitted into the hole 2c. This bearing 22 is formed into a cylindrical shape made of steel, and has a resin 2 formed in a cylindrical shape made of fluororesin or the like with approximately the same thickness as the air gap in its inner hole.
2a is fixed. Note that this bearing 22 is
For example, commercially available composites are made by impregnating a porous layer of sintered bronze powder on a steel backing with a mixture of a fluororesin base, added with a lubricant such as lead, and a wear-resistant resin. It may also be a body bearing or the like.

The operation of the plunger type solenoid configured as above will be explained. When the electromagnet 4 is excited in the illustrated state, the plunger 7 with the hammer 8 slides away from the stopper 20 against the elastic force of the compression coil spring 9, and the hammer 8 strikes the arm of the type. . When the electromagnet 4 is demagnetized immediately after striking, the plunger 7 rapidly moves toward the stopper 20 due to the elastic force of the compression coil spring 9, and the end surface of the plunger 7 on the side opposite to the hammer collides with the stopper 20 via the damper 21. Stop by doing. At this time, both dampers 21 and 16 made of rubber or resin
The impact of a collision is alleviated by this.

The magnetic flux generated by excitation of the electromagnet 4 is:
It flows across the bearing 22 without an air gap, but since the main part of this bearing 22 is made of metal,
Good permeability of magnetic flux. Moreover, by having the resin 2a, it functions as a bearing. Furthermore, since the fitting position of the bearing 22 has been moved in the direction in which the hammer 8 protrudes, the plunger 7 does not come off the bearing 22 and the same stroke as before can be ensured, and there is no need to provide a recess in the stopper 20. Therefore, the thickness of the stopper 20 becomes thinner, and the entire solenoid becomes smaller.

[Effect of idea]

As is clear from the above explanation, in the plunger type solenoid according to the present invention, the bearing that is fitted into the yoke and slidably supports the plunger is made of a metal cylinder with resin fixed to the inner hole surface. The electromagnet is formed continuously between the electromagnet and the open end of the cylindrical yoke at the upper part of the inner hole of the cylindrical yoke, and is press-fitted into the yoke, which serves as a path for the magnetic flux of the electromagnet, thereby reducing magnetic flux due to excitation of the electromagnet. Since the flow passes through the bearing whose main part is metal, good magnetic permeability can be ensured, and since the plunger fits into the resin part of the bearing, sliding is performed smoothly. In addition, by moving the bearing position in the hammer protruding direction, the thickness of the stopper can be reduced without extending the electromagnet's magnetic flux path, making it possible to make the entire solenoid smaller and lighter. Miniaturization and cost savings can be achieved without reducing magnetomotive force.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of a plunger type solenoid according to the present invention, and FIGS. 2 and 3 are longitudinal sectional views of conventional plunger type solenoid. 2... Yoke, 2b... Tapered hole, 2c... Bearing hole, 4... Electromagnet, 5b... Bearing, 7... Plunger, 8... Hammer, 9... Compression coil spring,
16, 21...Damper, 20...Stopper, 22
... Bearing, 22a ... Resin.

Claims (1)

[Scope of utility model registration request] In a plunger type solenoid comprising a plunger with a hammer that is slidably supported via a bearing on a cylindrical yoke containing an electromagnet and is moved by the excitation of the electromagnet, the bearing is fixed to the inner hole surface by a resin. The cylindrical metal tube is formed continuously between the electromagnet and the open end of the cylindrical yoke at the upper part of the inner hole of the cylindrical yoke, and is press-fitted into the yoke to serve as a path for the magnetic flux of the electromagnet. A plunger type solenoid characterized by: