US3859885A

US3859885A - Bushing structure for use in piano action

Info

Publication number: US3859885A
Application number: US362711A
Authority: US
Inventors: Hajime Hayashida
Original assignee: Nippon Gakki Co Ltd
Current assignee: Nippon Gakki Co Ltd
Priority date: 1972-05-22
Filing date: 1973-05-22
Publication date: 1975-01-14
Anticipated expiration: 1992-01-14
Also published as: JPS4913544A

Abstract

A bushing for use in a piano action is integrally molded of a synthetic resin and comprises an inner and an outer ring defining an annular space therebetween. The inner ring includes two different portions, one portion being larger in inner diameter and integrally connecting the inner and outer rings, and the other portion being smaller in inner diameter and spaced apart from the outer ring through the annular space. A pin, which is to be inserted through a bore defined by the inner ring, is supported by the other portion of the inner ring so as to cushion the radial thrust imparted to the pin.

Description

-United States Patent 1191 Hayashida Jan. 14, 1975 BUSHING STRUCTURE FOR USE IN PIANO 2,948,180 8/1960 Wood 84/251 ACTION 3,186,287 6/1965 3,372,960. 3/1968 Inventor: Haiime Hayashida, Hamamatsu, 3,730,963 5/1973 Imagawa 84/251 Japan 73 Assignee: Nippon Gakki seam Kabushiki Primary Examiner-l-awrenee Franklin Kaisha, Hamamatswshi Japan Attorney, Agent, or FirmKenneth S. Goldfarb [22] F1led. May 22, 1973 ABSTRACT [21] Appl' 3627ll A bushing for use in a piano action is integrally molded of a synthetic resin and comprises an inner [30] Foreign Application Priority Data and an outer ring defining an annular space therebe- May 22, 1972 Japan....; 47-50445 twee" The inner ring includes different Portions one portion being larger in inner diameter and inte- 52 US. (:1. 84/251, 308/238 grally eenneeting the inner and Outer rings andlhe 51 1m. 01 G100 3/18 other Portion being Smaller in inner diameter and [58] Field of Search 84/236, 251, 452, 434, Spaced from the Outer ring threugh the annular 84/435; 308/26, 238 space. Apin, which is to be inserted through a bore defined by the inner ring, is supported by the other 5 R f c Cited portion of the inner ring so as to cushion the radial UNITED STATES PATENTS imparted to the 1,670,915 5/1928 Volare 84/251 x 4 Claims, 6 Drawing Figures PATENTED JAN 1 41975 38 5 SHEEI 2 OF 2 FIG. 5'

BACKGROUND OF THE INVENTION This invention relates generally to musical instru-' ments, to pianos, and to an improved bushing structure for use in piano action. More specifically, the bushing structure of the invention is adapted for swingably supporting a hammer butt which conveys the thrust of a piano key to a hammer head to cause the same to strike a string corresponding thereto.

In upright piano action, for example, each of the keys conveys the thrust to the corresponding hammer head through a hammer butt fixedly supporting the same. The butt is usually swingably supported by means of a pin projecting therefrom to have its ends-revolvably received in aligned bores formed through the bifurcated end of a support member the other end of which is affixed to the main rail of the piano.

Since, in this manner, the pin is subject to radial thrust each time the key is depressed, there has easily 8 been caused relative displacement between thepin and the support member which results in the production of noise. Conventionally, this defect has been circumvented by means of felt or like fabrics shaped into tubular form to be fitted into each of the bores to cushion the thrust imparted to the pin.

However, such fabric-made bushings readily absorb or desorb moisture depending upon ambient humidity and thus affect the mating condition of the pin and the support ,member. Moreover, the fabric-made bushings have very'short service life and are highly difficult to manufacture uniformly in large numbers.

Although bushings of similar structure have more recently been made of plastics to overcome the deficiencies of the fabric-made bushings, the plastic bushings have also proved to be unsatisfactory in their shockabsorbing property because of their shape. Thus, as far as I am aware, there have been known to truly satisfactory means for swingably supporting the hammer butt of the piano action so as to minimize the production of noise.

SUMMARY OF THE INVENTION In view of the listed disadvantages of the prior art, it is an object of this invention to provide an improved bushing structure for use in swingably supporting a hammer butt which conveys the thrust of a piano key to a hammer head to cause the same to strike the corresponding string, in such a manner that the possibility of noise production is substantially eliminated.

Another object of the invention is to provide a bushing structure of the class described, which is easily manufacturable in great quantities, highly endurable, and practically unaffected by ambient humidity and other conditions.

With these objects in view and the other objects hereinafter made apparent, this invention provides a bushing structure to be securely fitted in each of the bores formed through the bifurcated end of a stationary support member to revolvably receive a pin projecting from a hammer butt which is adapted to convey the thrust of each piano key to a hammer head mounted thereon to cause the same to strike the corresponding string. The bushing-structure according to the invention is broadly composed of an inner and an outer ring disposed coaxially relative to each other to define an annular space-therebetween. The inner ring extends from the outer ring, having two different diameter portions, one portion being larger in inner diameter and integrally connecting the inner and outer rings, and the other portion being smaller in inner diameter and spaced apart from the outer ring through the annular space. The angle of extension of the inner ring relative to the axis of the bushing is variable in accordance with the degree to which the thrust imparted to the pin passing therethrough is to be cushioned. The entire bushing structure can be molded integrally of a suitable synthetic resin to resist the effects of ambient humidity and to permit the pin to revolve slidingly relative to the bushing.

The features which are believed to be novel and characteristic of this invention are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and mode of operation, together with the further objects and advantages thereof, will be best understood from the following description taken in connection with the accompanying drawings which illustrate, by way of example only, some preferred embodiments of the invention and in which like reference characters donote like parts throughout the several views.

BRIEF DESCRIPTION OF THE DRAWINGS shown in FIG. 2;

FIG. 4 is a fragmentary axial sectional view showing the bushing structure of FIG. 2 as actually fitted in a bore of a support member for revolvably receiving a pin therethrough;

FIG. 5 is a view similar to FIG. 2 showing another preferred embodiment of the invention, and

FIG. 6 is a view similar to FIG. 4 showing still another preferred embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, and first of all to FIG. 1, which illustrates by way of example the configuration of an upright piano action to which is applicable the present invention, the reference numeral 10 designates one of the keys of the upright piano. The key 10 is pivoted at its pivot point 11 and has an arm 12 mounted uprightly on its rear end seen to the left in the drawing. A hammer butt 13 supporting a hammer head 14 is felted at 15 to receive the upward thrust of the arm 12 each time the key 10 is depressed. Although not clearly seen in the drawing, it is assumed that the butt 13 has a pin 16 projecting from both sides of its lower end to be received in-aligned bores formed through the bifurcated upper end of a support member 17, the lower end of which is affixed in a suitable manner to the main rail 18 of the piano.

In the upright piano action of the above explained configuration, the key 10 raises the arm 12 to turn the butt l3 counterclockwise, as seen in FIG. 1, on the pin 16 through the felt 15, thereby causing the hammer head 14 to strike the string, not shown, corresponding thereto. In this instance, however, the impact upon the key is conveyed to the pin 16 as radial thrust which can give rise to relative displacement between the butt l3 and pin 16 and hence to the production of noise, as previously pointed out.

According to this invention, in order to overcome this defect of the prior art, the pin 16 is inserted into each of the bores at the bifurcated end of the support member 17 through a bushing 20 shown in further detail in FIGS. 2 and 3.

Referring specifically to FIG. 2, the bushing 20 according to the invention is-broadly composed of inner ring 21 and outer ring 22 which are disposed coaxially relative to each other to define an annular space 23 therebetween. The inner and outer rings 21 and 22are interconnected at least at one end 24 of the bushing. End 24 and outer ring 22 are relatively rigid and provide only minimal flecture. 1

, As a further feature of the invention, the inner ring 21 is provided with a sloping step or portion 25 adapted for the purpose of shockabsorption, so that the inner ring has two

portions

26 and 27 of different inner diameters formed on both sides of the step 25, the portion 26 being larger in inner diameter than the portion 27. The larger diameter portion 26 of the inner ring 21 is connected to the outer ring 22 at 24. The smaller diameter portion 27 is spaced apart from the outer ring 22 through the annular space 23, so that the portion 27 I can produce acushioning effect. As is seen from FIG. 3, the inner ring 21 is made continuous along the circumference thereof.

The bushing 20 of the foregoing structure is preferably molded in one piece of a suitable synthetic resin 1 member 17 and preferably is securely retained therein as by means of an adhesive. The pin 16 for' turnably supporting the butt 13 as shown in FIG. 1 is then neatly but revolvably fitted into the axial opening of the bushing 20. In this instance,it will be noted that the pin 16 is supported only by the smaller diameter portion 27 of the inner ring 21.

In this manner, the radial thrust imparted to the pin 16 upon depression of the key 1 0 can be cushioned by the flection of the step 25 of the bushing inner ring 21. Since the degree to which the thrust is cushioned is dependent largely upon the angle between the step 25 and the axis of the bushing 20 and upon the width of its annular space 23, the angle may be made as acute as possible, and the width as large as possible, in order to ensure maximum shock absorption. On the other hand, if the minimum degree of shock absorption is to be expected, the step 25 may be formed at right angles with the axis of the bushing 20 as illustrated in FIG. 5.

FIG. 6 illustrates a further preferred embodiment of the invention, in which the bushing 20a is formed integral with the support member 17a. Thesupport member 17a in this case is of course made of the same material as the bushings 20 of FIGS. 1 to 5, andthe pin 16 is supported substantially in the same way as in the preceding embodiments.

While the various objects of the invention, either explicitly, stated or otherwise pointed out, are believed to be fully accomplished by the preferred embodiments disclosed herein, it will be understood that all matter described herein or shown in the accompanying drawings is by way of example only and is in no way restrictive of the invention, as various modifications may occur to those skilled in the art on the basis of this disclosure. It is therefore appropriate that the invention be construed broadly and in a manner consistent with the proper scope or fair meaning of the appended claims.

smaller diameter portion, said sloping portion.

forming an acute angle with the axis common'to said inner and outer rings; and

a relatively rigid member connecting said outer ring to the other end of said. larger diameter portion,

said rigid member and said rings defining an annula r space between said rings, whereby a pin smoothly fitted into said smaller diameter portion of said inner ring may be rotated therein and may undergo small radial and axial movement provided substantially exclusively by flexure of said sloping portion.

2. A bushing as in claim 1 wherein said bushing is molded integrally of a's'ynthetic resin. I v

3. In a piano action of the'type comprising a hammer buttfor supporting'a hammer head, said butt being s'wingableupon depressions of a keyto cause said hammer head to strike a string, and a stationary support member for swingably supporting said butt, said support member being-bored to receive a pin projecting from said butt, an integrally molded bushingsecurely held by said support member to revolvably receive said pin therethrough, said bushing comprising a relatively rigid outer ring for insertion into said bore, a relatively flexible inner ring mounted-coaxially with said outer ring and consisting of a larger diameter portion, a sloptively rigid member connecting said outer ring to the other, end of said larger diameter portion, said rigid member and said rings defining an annular space between said rings, whereby said pinmay be rotated therein and may undergo small radial'and axial movement provided substantially exclusively by flexure of said sloping portion.

4. The improvement as recited in claim 3 wherein saidbushing molded integrally with said support member, said support member and said bushing being formed of a synthetic resin.

Claims

1. A bushing for use in a piano comprising: a relatively rigid outer ring; a relatively flexible inner ring mounted coaxially with said outer ring and consisting of a larger diameter portion, a sloping portion, and a smaller diameter portion, said sloping portion connecting one end of said larger diameter portion to one end of said smaller diameter portion, said sloping portion forming an acute angle With the axis common to said inner and outer rings; and a relatively rigid member connecting said outer ring to the other end of said larger diameter portion, said rigid member and said rings defining an annular space between said rings, whereby a pin smoothly fitted into said smaller diameter portion of said inner ring may be rotated therein and may undergo small radial and axial movement provided substantially exclusively by flexure of said sloping portion.

2. A bushing as in claim 1 wherein said bushing is molded integrally of a synthetic resin.

3. In a piano action of the type comprising a hammer butt for supporting a hammer head, said butt being swingable upon depressions of a key to cause said hammer head to strike a string, and a stationary support member for swingably supporting said butt, said support member being bored to receive a pin projecting from said butt, an integrally molded bushing securely held by said support member to revolvably receive said pin therethrough, said bushing comprising a relatively rigid outer ring for insertion into said bore, a relatively flexible inner ring mounted coaxially with said outer ring and consisting of a larger diameter portion, a sloping portion, and a smaller diameter portion, said sloping portion connecting one end of said larger diameter portion to one end of said smaller diameter portion, said sloping portion forming an acute angle with the axis common to said inner and outer rings, and a relatively rigid member connecting said outer ring to the other end of said larger diameter portion, said rigid member and said rings defining an annular space between said rings, whereby said pin may be rotated therein and may undergo small radial and axial movement provided substantially exclusively by flexure of said sloping portion.

4. The improvement as recited in claim 3 wherein said bushing molded integrally with said support member, said support member and said bushing being formed of a synthetic resin.