JPS6318058Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of an electromagnetic plunger used as a key drive device for a player piano.

In general, this type of electromagnetic plunger used in player pianos, as shown in Fig. 1, includes a coil bobbin 2 that is fitted and fixed on the outer circumferential surface of a brass guide pipe 1, and a coil bobbin 2 that is wound around the outer circumferential surface of the coil bobbin 2. The rotated solenoid coil 3 and the movable iron core 4 passed through the guide pipe 1 with a slight gap maintained.
The yoke 5 is made of a magnetic material such as soft iron and has a cylindrical shape, for example, and forms a magnetic path by housing the solenoid coil 3 therein. And solenoid coil 3
When an electric signal obtained by reproducing an electric signal recorded in advance is applied to and excited, the movable iron core 4 rises and pushes up the key 6, so that the key 6 is operated as if by hand. It works as if it were.

In this case, the upper and lower end surfaces of the solenoid coil 3 constitute a part of the yoke 5, and the upper and lower end surfaces of the solenoid coil 3 are respectively connected to the coil bobbin 2.
By forming insertion holes 8A and 8B in the coil fixing parts 7a and 7b, which are fixed through the coil fixing parts 7a and 7b, respectively, and allowing the upper and lower ends of the movable core 4 to protrude outside the yoke 5, collision noise is suppressed when the movable core 4 is operated. Electromagnetic plungers of the leakage type (both ends open) are widely used.

Figures 2 a to e show the stroke and thrust (force that drives the movable core), key push-up amount and time, hammer travel amount and time, stroke and time of the movable core, and thrust and time in the conventional electromagnetic plunger described above. It is a figure which shows each relationship. Figure 2b
During the period when the key is held in the upward position, most of the impulse A between the hammer and the hammer shown in perspective in FIG. 2e is transmitted to the hammer as energy (amount of work). As is clear from these figures, it has been found that in the characteristics of the conventional electromagnetic plunger, the point where the string is struck by the hammer and the point of maximum thrust are deviated from each other. This means that the thrust of the electromagnetic plunger is not effectively and maximally utilized. As a result, the striking force of the hammer against the strings is small, resulting in poor performance expression.

For these reasons, it is necessary to develop an electromagnetic plunger in which the string-striking point and the maximum thrust point almost match, but in that case, if the key is supported at the maximum thrust point, the input power of the solenoid coil will be minimized and ineffective. Since the electromagnetic plunger has the great advantage of being able to reduce electric power and, as a result, minimize heat loss, there is a need for an electromagnetic plunger design that takes advantage of these advantages.

This idea was made in view of the above-mentioned points, and among the movable core insertion holes provided in the coil fixing part of the yoke, the output end side insertion hole of the movable core is provided with a magnetically connected wire to the yoke. It is extremely simple, by arranging a connected cylindrical sub-yoke to increase the circumferential cross-sectional area of the hole, and by arranging an armature at the end opposite to the output end of the movable iron core to pick up leakage magnetic flux from the yoke. This electromagnetic plunger for player pianos has a unique configuration that allows the string-striking point to almost match the maximum thrust point, increasing the impact force of the hammer and supporting the key at the maximum thrust point to minimize heat loss. It provides:

This invention will be described in detail below based on embodiments shown in the drawings.

FIG. 3 is a longitudinal sectional view showing an embodiment of the electromagnetic plunger for a player piano according to this invention. Components in the figure that are the same as those in FIG. 1 are designated by the same reference numerals, and their explanations will be omitted. As is clear from the figure, the gist of the electromagnetic plunger according to this invention is that the electromagnetic plunger is provided in the upper coil fixing part 7a in the figure, which constitutes a part of the yoke 5, and that the output end side of the movable iron core 4 passes through the insertion hole. The hole 8A is formed larger than the insertion hole 8B formed in the lower coil fixing part 7b, and is formed into a cylindrical shape from a magnetic material such as low carbon steel, and a flange 10a is integrally provided at the upper end. Tenaru sub yoke 10
The insertion hole 8 of the movable iron core 4 is fitted and fixed.
The armature 11, which is also made of low carbon steel or the like and shaped like a disk, is coaxially fixed to the lower end protruding from B.

In the sub-yoke 10, the plate thickness of the coil fixing portion 7a near the insertion hole 8A is substantially increased by the flange 10a, and the circumferential cross-sectional area of the insertion hole 8A is replaced by the circumferential cross-sectional area of the inner hole 12 of the sub-yoke 10. , the circumferential cross-sectional area of the output end side of the movable iron core serving as the yoke 5 is increased.
As a result, the magnetic flux from the yoke 5 is guided to the cylindrical portion of the sub-yoke 10 without being dispersed, and the magnetic gap between the movable core 4 and the cylindrical portion is always kept small regardless of the position of the movable core 4. . Therefore, the magnetic resistance near the insertion hole 8A is reduced and the number of magnetic fluxes is increased, so that the thrust of the electromagnetic plunger can be increased without increasing the coil current.

Similarly, the armature 11 also aims to increase thrust. That is, when the armature 11 rises together with the movable iron core 4 from the solid line position shown in the figure, as it approaches the coil fixing part 7b, the amount of leakage magnetic flux from the insertion hole 8B increases, so that it is strongly pulled toward the yoke 5 side. As a result, the rising speed of the movable iron core 4, in other words, the thrust force is increased.

The spring 13 is used to constantly bias the movable core 4 in the return direction, and is not necessarily required when the movable core 4 is returned by its own weight.

FIGS. 4a to 4c are diagrams showing the relationships between hammer movement amount and time, thrust force and time, and thrust force and stroke, respectively, in the electromagnetic plunger having the above configuration. As is clear from figure c, it is understood that the thrust-stroke characteristics are closer to flat than the conventional one, but this is due to the effect of providing the sub-yoke 10 and armature 11, and the output when the string is struck. can be kept large. In addition, the string-striking point and the maximum thrust point almost coincide, and the
If the key is supported using the range above, the holding current required to keep pushing the key up can be reduced. Therefore, reactive power is small and heat loss can be minimized. Furthermore, if the heat loss is small, an increase in the coil DC resistance can be suppressed, and therefore a decrease in thrust force can be prevented.

FIG. 5 is a sectional view of a main part showing another embodiment of this invention. In this embodiment, the inner hole 1 of the sub-yoke 10
2 is a tapered hole that widens toward the end, and the output end of the movable iron core 4 is formed in a tapered shape.
With such a configuration, the number of magnetic fluxes changes, so
The characteristics of the electromagnetic plunger can be changed.

In the above embodiment, the yoke 5 is composed of a pair of coil fixing parts 7a and 7b facing each other and a cylindrical wall part 7c connecting these coil fixing parts 7a and 7b, but this invention is different from this. Of course, the present invention is not limited to this, and can also be applied to an electromagnetic plunger in which a metal plate is bent into a substantially square shape and a part of the outer periphery of the solenoid coil 3 is surrounded by a flat wall portion 7c.

As explained above, according to the electromagnetic plunger for a player piano according to the present invention, in the leakage type, the electromagnetic plunger is magnetically coupled to the yoke through the insertion hole provided in the yoke and through which the output end side of the movable iron core passes. This configuration includes a cylindrical sub-yoke that provides a cylindrical sub-yoke, and an armature at the end opposite to the output end of the movable iron core, making it possible to almost match the string-striking point and the maximum thrust point, thereby increasing the thrust. can be used effectively and to the maximum extent. Therefore, the impact force of the hammer can be increased, and as a result, the output range of the piano can be expanded, and the performance expression can be enriched. On the other hand, when trying to obtain the same thrust as the conventional device, the solenoid coil can be made smaller. Furthermore, since the key is supported at the maximum thrust point, the input power of the solenoid coil is minimized, reducing reactive power, or in other words, heat loss, which has very practical effects such as preventing a drop in thrust force. It's large.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal cross-sectional view showing an example of a conventional electromagnetic plunger, Fig. 2 a to e are views showing the characteristics of the plunger, and Fig. 3 is a longitudinal cross-sectional view showing an embodiment of the electromagnetic plunger according to this invention. , FIGS. 4a to 4c are characteristic diagrams for explaining the effects of the plunger, and FIG. 5 is a sectional view of a main part showing another embodiment of this invention. 2...Coil bobbin, 3...Solenoid coil, 4...Movable iron core, 5...Yoke, 6...Key,
7a, 7b...Coil fixing part, 7c...Wall surface part,
8A, 8B...Insertion hole, 10...Sub yoke, 1
1... Armature.

Claims (1)

[Scope of utility model registration request] A solenoid coil arranged corresponding to the key,
A movable iron core is disposed through the center of the solenoid coil with a slight gap and drives the key as the solenoid coil is excited, and a pair of fixed coils are arranged in parallel to each other and both end surfaces of the solenoid coil are fixed. a yoke that connects the pair of coil fixing parts and has a wall part surrounding the entire or part of the outer periphery of the solenoid coil to form a magnetic path; Through-holes are formed at corresponding locations to allow the ends of the movable core to protrude outside the yoke, and a cylindrical tube magnetically coupled to the yoke is inserted into the output-end side through-hole of the movable core among the through-holes. An electromagnetic plunger for a player piano, characterized in that a sub-yoke is provided, and an armature is provided at an end opposite to the output end of the movable iron core.