JPH03174589A - Operator driving solenoid for automatic piano - Google Patents

Abstract

PURPOSE:To enable constant thrust to be generated at all the moving strokes of a plunger for a constant input voltage by providing an upper subyoke formed so as to reduce quantity equivalent to a confronting area to the plunger according to the inside in axial direction of a solenoid coil. CONSTITUTION:The upper subyoke 6 is provided between the upper part of the solenoid coil 1 and the plunger 5, and also, a wedge shape notch 7 is provided at the cylindrical part 6b of the subyoke 6, and the quantity equivalent to the area of the subyoke 6 confronting with the plunger 5 is set so as to decrease gradually as advancing the axial direction of the solenoid coil 1. Therefore, it is possible to always set a value of (flux density)<2>X(confronting area) so as to keep a constant value even when the position of the plunger 5 is located at any place on a moving stroke. Thereby, the thrust characteristic of the plunger 5 can be flattened.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention is directed to
lIf + - Suna ◆ Mesu oil m Seven handles ヱ Baku ni R-6su I-
This is related to J throat.

``Prior Art'' As a device for operating operators such as keys and pedals in a player piano, there are known devices described in, for example, Japanese Utility Model Publication No. 15838/1983 or Japanese Utility Model Publication No. 18058/1988.

The solenoid described in the former category has a thick part in the plunger insertion hole of the fixed yoke that supports the solenoid coil, and by increasing the circumferential cross-sectional area of this thick part, the magnetic flux in the plunger insertion hole is increased. This reduces the magnetic resistance and increases the thrust of the plunger without increasing the coil current.

Further, the solenoid described in the latter is provided with a cylindrical sub-yoke magnetically coupled to the fixed yoke in a plunger insertion hole through which the outward protruding portion of the plunger is inserted at one end of the fixed yoke, and a cylindrical sub-yoke magnetically coupled to the fixed yoke. An armature is provided at the end opposite to the protruding portion, and by making the string-striking point and the maximum thrust point substantially coincident, the thrust of the plunger can be effectively and maximally utilized.

"Problems to be Solved by the Invention" By the way, the conventional player piano operator drive solenoid described above has the following drawbacks.

That is, in the solenoid described in Japanese Utility Model Publication No. 62-15838, when the plunger suction starts due to coil excitation, there is an initial While the attraction force is weak, if magnetic flux acts on the thick portion as the plunger slides, the attraction force increases because the magnetic resistance of the thick portion is low.

On the other hand, in the solenoid disclosed in Japanese Utility Model Publication No. 63-18058, the initial attractive force is weak like the former, but in the final stage due to sliding of the plunger, the magnetic resistance decreases due to the sub-yoke and the armature causes leakage near the lower end of the coil. The attractive force increases because the magnetic flux passes through it.

In this way, in conventional technology, the plunger thrust has a strong tendency to gradually increase as the plunger approaches the fixed yoke, and under a constant input voltage, the thrust has a characteristic that changes as the plunger moves. There was a problem in that it was difficult to maintain the thrust characteristics of the plunger constant with respect to the stroke.

The present invention has been made in view of the above circumstances, and is a player piano that can always give a predetermined thrust to the plunger regardless of the movement stroke of the plunger under a constant input voltage, and can flatten the thrust characteristics. The purpose of the present invention is to provide an operator-driven solenoid.

"Means for Solving the Problem" In order to achieve the object, the configuration according to claim 1 of the present application includes a solenoid coil disposed corresponding to an operator of a player piano, and a solenoid coil that slides with the solenoid coil. a plunger that freely fits together and has one end protruding outward from the solenoid coil to transmit an operating force to the operator; a fixed yoke that holds the solenoid coil; a side of the solenoid coil from which the plunger protrudes; an upper sub-yoke interposed between the solenoid coil and the upper sub-yoke formed in a shape such that the equivalent area facing the plunger decreases toward the inside in the axial direction of the solenoid coil; and a location where the upper sub-yoke of the solenoid coil is arranged. and a center sub-yoke interposed between the opposite side of the solenoid coil and the plunger, and extending outward from the solenoid coil so as to cover the other end of the plunger even when the solenoid coil is not excited. It is characterized by:

In addition to the above-mentioned structure, the structure described in Item 2 of this ll1rIt is characterized in that a hollow portion is further provided in the vicinity of the axis of the plunger.

Furthermore, in the configuration according to claim 3 of this IQ, in addition to the configuration according to claim 1, there is further provided a center yoke extending from the fixed yoke to support the center sub-yoke, and a center yoke for returning the plunger of the center sub-yoke. a sub-solenoid coil disposed substantially coaxially with the solenoid coil on the side and slidably fitted with the plunger;
It is characterized by having the following.

"Operation" In the configuration according to claim 1 of the present application, when the solenoid coil is excited, a magnetic circuit is formed between the solenoid coil, the fixed yoke, the center sub-yoke, the plunger, and the upper sub-yoke. In this magnetic circuit, the upper sub-yoke is formed so that the area equivalent to the area facing the plunger decreases as it goes inside the solenoid coil in the axial direction, so it works to constantly generate the vertical force that causes the plunger to slide. By appropriately setting the shape of the upper sub-yoke, a substantially constant thrust can be applied to the plunger regardless of the movement of the plunger.

In addition, by providing a center sub-yoke at the end of the solenoid coil, it is possible to avoid the formation of a magnetic neck part (magnetic saturation part), and in this respect, the thrust characteristics of the plunger can also be flattened. At the same time, the thrust of the plunger can be increased.

Further, in the configuration according to claim 2 of the present application, by forming a hollow portion in the plunger, the weight of the plunger itself can be reduced, and the responsiveness of plunger sliding can be improved. Note that since the magnetic flux passes through the surface layer of the plunger, the thrust force of the plunger is hardly affected even if a hollow portion is bored near the plunger axis.

Furthermore, in the configuration according to claim 3 of the present application, since solenoid coils are provided on both sides of the center sub-yoke supported by the center yoke, differential control is possible by exciting both solenoid coils. becomes.

Therefore, it becomes possible to reduce the thrust force of the plunger or to apply a force to return the plunger in the return direction, thereby improving control accuracy.

"Example" Hereinafter, each embodiment of the invention will be described with reference to the drawings.

First Embodiment FIG. 1 shows a first embodiment of the present invention. Number 1 in the figure
are solenoid coils arranged corresponding to the keys 2, which are the operators of the player piano, and are wound around the outer circumferential surface of the coil pobbin 3, made of a magnetic material such as soft iron, and held in the fixed yoke 4. It is something that will be done. A plunger 5 is fitted into the solenoid coil 1 so as to be slidable along its axial direction. Upper end small diameter portion 5a of plunger 5
passes through the insertion hole 4b of the upper plate portion 4a of the fixed yoke 4 and projects outward, and when the plunger 5 is moved upward, the key 2
It acts to push up. Note that, for the purpose of reducing magnetic resistance as much as possible, the diameter of the plunger 5 is preferably made large enough to avoid contact with a sub-yoke 6.8, which will be described later.

An upper sub-yoke 6 is interposed at the end of the solenoid coil 1 on the plunger protruding side (the upper end in the figure) so as to be in magnetic contact with the fixed yoke 4 and spaced apart from the plunger 5 by a predetermined distance. . The upper sub-yoke 6 includes seven rung parts 6a that come into contact with the lower surface of the upper plate part 4a of the fixed yoke 4, and a cylindrical part 6 that is integrally formed coaxially with the seven rung parts 6a.
The cylindrical portion 6b has wedge-shaped notches 7 whose diameter expands downward and are formed at predetermined intervals in the circumferential direction. By forming the groove in the circumferential direction in this way, the upper sub-yoke 6 moves toward the plunger 5 in the axial direction of the solenoid coil l.
The area equivalent to the area facing the plunger 5 decreases, and as a result, the magnetic resistance gradually changes as the plunger 5 moves.

In addition, the above upper sub yoke 6 of the solenoid coil 1
A center sub-yoke 8 made of a ferromagnetic material is located on the opposite side of the fixed yoke 4 (lower end side in the figure).
The plunger 5 is placed in magnetic contact with the plunger 5 and is spaced apart from the plunger 5.

The center sub-yoke 8 can be used even when the twist/id coil l is not excited and the plunger 5 is not raised.
It is arranged to protrude outward from the lower end of the solenoid coil 1 and the lower plate portion 4b of the fixed yoke 4 so as to cover the lower end of the plunger 5.

Here, to explain the manufacturing method of the upper sub-yoke 6, for example, a plate material made of a high magnetic permeability material is punched out to form a member 9 having a shape of four fan-like shapes connected in a row as shown in FIG. 1(d). do.

Next, each fan-shaped portion 10 is bent from an arc σ at the intermediate portion, and then the bridge portion 11 connecting the fan-shaped portions 10 is bent by 90 degrees. As a result, the upper sub yoke 6 as shown in (b) and (c) in the same figure
can be obtained.

Next, the operation of the operator drive solenoid will be explained.

When the solenoid coil 1 is excited, a magnetic circuit is formed between the solenoid coil 11, the center sub-yoke 8, the plunger 5, and the upper sub-yoke 6, and the plunger 5
is sucked upward. At this time, the suction force (thrust force) of the plunger 5 is expressed by the following equation.

F=(10'/8K) 6b is provided with a wedge-shaped notch 7, so that the area corresponding to the area of the upper sub-yoke 6 facing the plunger 5 gradually decreases as it goes in the axial direction of the solenoid coil l, and the shape of the upper sub-yoke 6 can be adjusted as appropriate. By determining the plunger 5
No matter where the position of is on the movement stroke, B g
It is possible to set the value of 2·S to be always constant. Therefore, the thrust characteristics of the plunger 5 can be made flat.

Furthermore, by providing the center sub-yoke 8 at the end of the solenoid coil 1, the circumferential cross-sectional area of the plunger 5 insertion hole in the lower plate portion 4c of the fixed yoke 4 can be reduced by the center sub-yoke 8.
By replacing the magnetic flux with the circumferential cross-sectional area of the inner hole of Always keep it small.

Therefore, the magnetic resistance near the insertion hole of the lower plate part 4c of the fixed yoke 4 decreases, and the number of magnetic fluxes increases, so that the thrust of the plunger is increased without increasing the coil current, and the thrust characteristics of the plunger are improved by 7. Contribute to things.

FIG. 4 compares the plunger thrust characteristics of a conventional solenoid and a solenoid according to the present invention. The horizontal axis shows the moving stroke of the plunger, and the vertical axis shows the thrust force of the plunger. From this figure, it can be seen that the solenoid according to the first embodiment of the present invention has flat characteristics compared to the conventional solenoid.

FIG. 5 shows this example, and shows the solenoid coil l.
3 shows the thrust characteristics of the plunger 5 when different voltages are applied to the . From this figure, it can be seen that even if the supply voltage is changed, the characteristics are flat.

Second Embodiment FIG. 2 shows a second embodiment of the present invention. In this embodiment, the same components as those in the first embodiment are given the same reference numerals, and their explanations will be omitted.

In this embodiment the fixed yoke 4 has lids 20.2 at both ends.
1, the length is set longer than that of the brush jar 5, and a disk-shaped center yoke 2 extending inward is located at a location slightly lower than the center of the body.
2 is provided.

A center sub-yoke 8 that covers the lower end of the plunger 5 is supported by the center yoke 22 . In the direction in which the plunger 5 of the center yoke 22 returns, that is, below the center yoke 22 in the figure, a sub-solenoid coil 23 is wound around a coil bobbin 24.
It is arranged coaxially with the solenoid coil l and slidably relative to the plunger 5.

In this embodiment as well, an upper sub-yoke 6 is arranged at the upper end of the solenoid coil 1, but the upper sub-yoke 6 used here is formed so that the cylindrical part 6b becomes thinner as it goes downward. A tapered one is used. That is, in the first embodiment, the cylindrical portion 6
By providing a wedge-shaped notch 7 in b, the plunger 5
The relative amount of the opposing area is changed, but this is done here by changing the thickness of the cylindrical portion 6b.

Note that guide members 4d made of a non-magnetic material are provided in the plunger insertion holes of the upper plate portion 4a and lower plate portion 4b of the fixed yoke 4.
, 4d are interposed, and small diameter portions 5a and 5b extending vertically of the plunger 5 are inserted therethrough and guided so as to be freely slidable.

In this embodiment, since the center sub-yoke 6 is provided with the cylindrical portion 6b having a variable thickness, it is possible to make the thrust force characteristics of the plunger 5 flat as in the first embodiment. , t, upper and lower coils l,
By exciting the magnets 23 so as to generate magnetic fields in opposite directions, the plunger 5 can be differentially controlled, and the accuracy of M control of the plunger 5 can be improved. Therefore, when driving the keys of a player piano, it is possible to faithfully reproduce weak keystrokes and improve the performance of repeated hits, while reducing the supply voltage and realizing accurate key drive through feedback control.

FIG. 6 shows the plunger thrust characteristics of the solenoid of the second embodiment. As is clear from this figure and the above-mentioned FIG. 4, the plunger thrust characteristic is much flatter than that of the conventional plunger.

Further, the upper sub-yoke 6 is not limited to the above example, and an extremely thin tapered cylindrical portion 6b formed separately from the upper plate portion 6a as shown in FIG. 2(B) may be used. good.

Third Embodiment FIG. 3 shows a third embodiment of the present invention. In this example as well, the same components as in the first embodiment are designated by the same reference numerals, and their explanations will be omitted.

The plunger 5 of this embodiment has a structure having a hollow portion 30 with an open lower end near the axis.

The plunger 5 has a small diameter portion 5a extending vertically through the plunger 5, and is slidable vertically by being guided by a guide portion (not shown). Note that there are tapered cylindrical portions 6b above and below the solenoid coil l, respectively.
Upper support yoke 6 and center sub yoke 8 with
The arrangement of the upper sub-yoke 6 is the same as in the first and second embodiments, but here the upper sub-yoke 6 is the upper plate part 4 of the fixed yoke 4.
It is made integrally with a.

In this embodiment, since the tapered upper sub-yoke 6 and center sub-yoke 8 are provided, the thrust characteristics of the plunger 5 can be made flat (see Fig. 7), and in addition, the plunger 5 has a hollow structure. This has the advantage of reducing weight and improving responsiveness during coil excitation.

Even with the above-mentioned hollow structure, the magnetic flux has the highest density in the surface layer of the plunger 5, and in general use, it passes through a range close to the surface layer, so a hollow portion is bored in the close vicinity of the plunger 5. However, thrust is hardly affected. In each of the embodiments described above, the key is operated by the solenoid of the present invention, but the present invention is not limited to this, and the pedal can also be operated by the solenoid of the present invention.

"Effects of the Invention" In the invention set forth in Claim 11 of the present M, since the upper sub-yoke is formed so that the equivalent area facing the granger decreases along the inside of the solenoid coil in the axial direction, a constant input voltage can be maintained. On the other hand, by forming a magnetic circuit that generates a constant thrust force at all moving stroke positions of the plunger, the magnetic resistance can be kept low overall and the electromechanical energy conversion efficiency can be improved.

That is, irrespective of the moving stroke position of the plunger, a force component acting in the direction of attracting the plunger is effectively generated, and the absolute value of the thrust is kept large and a thrust with characteristics independent of the moving stroke is generated.

In addition, by providing a center sub-yoke at the end of the solenoid coil, it is possible to avoid the formation of a magnetic neck part (magnetic saturation part), and in this respect, the thrust characteristics of the plunger can be flattened. , the thrust of the plunger can be increased.

In the invention described in claim 2 of the present application, by providing a hollow portion in the plunger, the mass of the plunger can be reduced, and the responsiveness of plunger sliding can be improved. Moreover, since a hollow part is bored near the axis of the plunger,
The thrust has little effect on the plunger.

In the invention described in claim 3 of the present application, solenoid coils are provided on both sides of the center sub-yoke supported by the center yoke, and differential control by both solenoid coils is possible. Therefore, it becomes possible to reduce the thrust force of the plunger or to apply a force to return the plunger in the return direction, thereby further improving control accuracy.

As a result, when driving the operators of a player piano, accurate reproduction of keys and pedals can be achieved by faithfully reproducing weak keystrokes, improving repeatability, saving power supply, and feedback control.

[Brief explanation of the drawing]

FIG. 1 shows a first embodiment of the present invention, in which (A) is a vertical sectional view of the entire solenoid, (B) is a perspective view of the upper sub-yoke, and (C) is a perspective view of the upper sub-yoke. The side view (D) is an explanatory view showing an example of a method for manufacturing the upper sub-yoke. FIG. 2 shows a second embodiment of the present invention, in which FIG. 2A is a vertical cross-sectional view of the entire solenoid, and FIG. 2B is a cross-sectional view showing another example of the upper sub-yoke. FIG. 3 is a longitudinal sectional view showing a third embodiment of the present invention. FIG. 4 is an explanatory diagram comparing the plunger thrust characteristics of the solenoid of the present invention and a conventional solenoid, FIG. 5 is a plunger thrust characteristic diagram of the first embodiment of the present invention, and FIG. 6 is a diagram of the plunger thrust characteristic of the first embodiment of the present invention. FIG. 7 is a plunger thrust characteristic diagram of a third embodiment of the present invention. l...Solenoid coil 2...Key (operator) 4...Fixed yoke 5...Plunger 6...Upper sub-yoke 8. ... Center sub yoke 22 ... Center yoke 23 ... Sub solenoid coil 30 ...
・Hollow part

Claims (1)

[Scope of Claims] 1) A solenoid coil disposed corresponding to an operator of a player piano; and a solenoid coil slidably fitted to the solenoid coil, with one end protruding outward from the solenoid coil, and a solenoid coil disposed corresponding to an operator of the player piano. a fixed yoke that holds the solenoid coil; and a fixed yoke that is interposed between the plunger protruding side of the solenoid coil and the plunger, and that the plunger increases inward in the axial direction of the solenoid coil. an upper sub-yoke formed in a shape that reduces the amount equivalent to the facing area of the solenoid coil, and is interposed between the plunger and the opposite side of the solenoid coil where the upper sub-yoke is disposed, and the solenoid coil is energized. An operator drive solenoid for a player piano, comprising: a center sub-yoke extending outward from a solenoid coil so as to cover the other end of the plunger even when the plunger is not in use; 2) The operator drive solenoid for a player piano according to claim 1, characterized in that a hollow portion is bored near the axis of the plunger. 3) a center yoke extending from the fixed yoke to support the center sub-yoke; and a center yoke disposed approximately coaxially with the solenoid coil on the plunger return side of the center yoke and slidably fitted with the plunger. The operator driving solenoid for a player piano according to claim 1, further comprising: a sub-solenoid coil that performs the following steps.