US3820433A

US3820433A - Bushing structure for use in pivotally supporting the keys of keyboard musical instruments

Info

Publication number: US3820433A
Application number: US00367715A
Authority: US
Inventors: H Hayashida
Original assignee: Nippon Gakki Co Ltd
Current assignee: Nippon Gakki Co Ltd
Priority date: 1973-06-07
Filing date: 1973-06-07
Publication date: 1974-06-28
Anticipated expiration: 1991-06-28

Abstract

Each of the keys of a keyboard musical instrument such as a piano is pivotally supported by a stationary pivot pin inserted with clearance into a slot formed therein. The upper end of the pivot pin projecting from the slot is caught in a slotted plate through a bushing according to the invention. Preferably integrally molded of a synthetic resin, the bushing comprises a hollow body with cross sectional shape conforming to the shape of the slot formed in the plate, and a flange formed on the upper end thereof. The hollow body is composed of a pair of parallel walls interconnected through arcuate walls at both ends thereof, and at least the middle portions of the parallel walls are made thinner than the other wall portions of the hollow body by forming recesses on the external surfaces of the parallel walls. The flange is also cut open above the recesses so that the pivot pin, having a diameter greater than the spacing between the parallel walls is securely caught between the middle portions of the parallel walls by causing the same to bulge without correspondingly deforming the flange.

Description

United States Patent [191 Hayashida June 28, 1974 [73] Assignee: Nippon Gakki Seizo Kabushiki Kaisha, Hamamatsu-shi, Shizuoka-ken. Japan [22] Filed: June 7, 1973 [21] Appl. No.: 367,715

Primary Examiner-Lawrence R. Franklin Attorney, Agent, or Firm-Kenneth S. Goldfarb [5 7 ABSTRACT Each of the keys of a keyboard musical instrument such as a piano is pivotally supported by a stationary pivot pin inserted with clearance into a slot formed therein. The upper end of the pivot pin projecting from the slot is caught in a slotted plate through a bushing according to the invention. Preferably integrally molded of a synthetic resin, the bushing comprises a hollow body with cross sectional shape conforming to the shape of the slot formed in the plate, and a flange formed on the upper end thereof. The hollow body is composed of a pair of parallel walls interconnected through arcuate walls at both ends thereof, and at least the middle portions of the parallel walls are made thinner than the other wall portions of the hollow body by forming recesses on the external surfaces of the parallel walls. The flange is also cut open above the recesses so that the pivot pin, having a diameter greater than the spacing between the parallel walls is securely caught between the middle portions of the parallel walls by causing the same to bulge without correspondingly deforming the flange.

6 Claims, 5 Drawing Figures mmmwm m4 1820.433

SHEET 1 OF 2 FIG. 1

BUSHING STRUCTURE FORv USE IN PIVOTALLY SUPPORTING THE KEYS OF KEYBOARD MUSICAL INSTRUMENTS BACKGROUND OF THE INVENTION This invention relates generally to musical instruments, to keyboard musical instruments, and to the novel and improved structure of a bushing for particular use in pivotally supporting each of the keys of a keyboard musical instrument such as a piano.

Each key of a keyboard musical instrument, for example, of a piano, is pivotally supported by a pivot pin mounted vertically and inserted with required clearance into a slot formed in the key. The upper end of the pivot pin projecting from the slot of the key is fitted in a slot formed centrally of a rectangular plate adapted to turnably retain the key in position. Heretofore, a piece of suitable cloth has been bonded or otherwise attached to the internal surface of the rectangular plate defining the slot, and-the projecting upper end of the pin has been received therein through the cloth.

However, since the cloth easily absorbs or desorbs moisture depending upon ambient humidity and thus affects the mating condition of the pivot pin and the plate, clattering or squeaking sounds tend to be produced as the key is depressed. Moreover, it involves a highly troublesome and time-consuming operation to uniformly attach such pieces of cloth to a number of the slotted plates required for the respective keys of a musical instrument.

SUMMARY OF THE INVENTION In view of the noted deficiencies of the prior art, it is an object of this invention to provide a novel and improved bushing for use in pivotally supporting each of the keys of a piano or like keyboard musical instrument, in such a manner that the impact delivered as upon depression of the keys is appropriately cushioned, and the possibility of noise production is substantially eliminated.

Another object of the invention is to provide a bushing of the class described, which is easily manufacturable in large quantities, highly endurable, and can readily be installed in working position.

A further object of the invention is to provide a bushing of the class described, which is molded of a suitable synthetic resin to resist the effects of ambient humidity and other conditions and to offer little frictional resistance to the keys of a keyboard musical instrument as they are played upon.

With these objects in view and the other objects hereinafter made apparent, this invention provides a bushing which, in its perhaps broadest aspects, comprises a hollow body having a cross sectional shape corresponding to the shape of a slot formed in a plate adapted for engaging one end of a stationary pivot pin projecting from a slot formed in each of the keys of a keyboard musical instrument. This hollow body is composed of a pair of parallel walls interconnected through arcuate walls at both ends thereof.

At least the middle portion of each of the parallel walls is made thinner, and therefore more resilient, than the other wall portions of thehollow body so as to define a vertical upper portion and a lower portion which flares out, the vertical upper portion being formed by making a recess on the external surface of each parallel wall. The spacing between the vertical upper portions of the parallel walls is made smaller than the diameter of the pivot pin so that the said one end of the pin can be caught resiliently but securely between the vertical upper portions by causing the same to swell out.

In more specific aspects of the invention, a flange is formed on the upper end of the aforesaid hollow body. This flange is cut open above the recesses formed as above stated on the external surfaces of the parallel walls, so that the vertical upper portions of the parallel walls are permitted to swell without causing any deformation in .the flange.

The features which are believed to be novel and characteristic of this invention are set forth with particularly 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, a preferred embodiment of the invention and in which like reference characters denote like parts throughout the several views.

BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings:

FIG. 1 is a schematic side elevational view showing by way of example the configuration of upright piano action for which is adaptable the bushing of this invention;

FIG. 2 is an enlarged perspective view of a slotted plate used for pivotally supporting the key shown in FIG. 1;

FIG. 3 is a perspective view of a bushing constructed by way of a preferred embodiment of the invention;

FIG. 4 is a fragmentary, enlarged top plan view of an explanatory nature showing the bushing of FIG. 3 as actually installed in the slotted plate of FIG. 2; and

FIG. 5 is a view partly in side elevation and partly taken along the planes of line 55 in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, and first of all to FIG. 1 thereof; which illustrates by way of example the known configuration of upright piano action to which is applicable the present invention, the reference numeral l0 designates one of the keys of the upright piano-The key 10 is slotted at 11 to receive a pivot pin 12 with the required clearance, the pivot pin 12 extending upwardly from a balance rail 13 secured on a key mount 14. The key 10 is further bored at 15 adjacent its front end, seen to the right in the drawing, to receive a guide pin 16 extending upwardly from the key mount 14. An arm 17 is mounted uprightly on the rear end of the key 10. A hammer butt 18 pivotally supported at 19 is felted at 20 to receive the upward thrust of the arm 17 and carries a hammer head 21 for striking a string, not shown, corresponding thereto.

When, in the upright piano action of the above explained configuration, the key 10 is depressed as guided by the guide pin 16, the key turns on the pivot pin 12 to raise the arm 17. Thereupon the butt 18 is turned counterclockwise, as viewed in FIG. 1, to cause the hammer head 21 to strike the string.

As will be seen from FIGS. 1 and 2, the upper end of the pivot pin 12 projecting from the slot 11 of the key is fitted in a slot 22 of a rectangular plate 23 to turnably retain the key in position. Conventionally, the projecting upper end of the pivot pin 12 has been received in the slot 22 of the plate 23 through a suitable cloth adherently attached to the internal surface of the plate defining the slot as previously stated. The difficulties arising from this conventional practice are also as set forth already. I

According to this invention, such difficulties of the prior art are successfully overcome by use of the bushing shown in FIGS. 3 to 5 by way of a preferred embodiment of the invention. Preferably, the bushing 30 according to the invention is integrally molded of a suitable synthetic resin such as polyformaldehydes (known in the United States as Delrin) and, as will be seen from FIG. 3 in particular, is broadly comprised of a hollow body portion 31 of cross sectional shape conforming to the shape of the slot 22 formed in the plate 23, and a flange portion 32 formed on the upper end of the body portion 31. This body portion includes a pair of substantially fiat, parallel walls 33 interconnected through arcuate walls 34 at both ends thereof as seen in FIGS. 3 and 4.

At least the middle portions of the parallel walls 33 are made thinner and therefore more resilient than the other wall portions to resiliently but securely hold the pivot pin 12 therebetween as shown in FIG. 4. Each of the arcuate walls 34 may be about 0.9 millimeters in thickness, and each of the parallel walls 33 about 0.4 millimeters in thickness. Generally, the thickness of each parallel wall 33 may be made less than half the thickness of each arcuate wall 34 for the best results. These thinner portions of the parallel walls 33 each include a vertical upper portion 35 and a lower portion 36 flares out as best shown in FIG. 5. The vertical upper portion 35 is formed by recessing the external surface of each parallel wall 33 as indicated by the numeral 37 in FIG. 5, whereas the flaring lower portion 36 is formed by recessing both the external and internal surfaces of each parallel wall 33 at the required angle.

Further according to this invention, the flange portion 32 is cut open at 38 above the recesses 37 of the parallel walls 33 to permit outward flection or bulging of their vertical upper portions 35. It will be apparent that the vertical upper portions 35 of the parallel walls 33 are thinner than the other wall portions but that their internal surfaces are flush with those of the other wall portions. The flaring lower portions 36 of the parallel walls 33, which also are made thinner than the other wall portions, are formed to facilitate the insertion of the pivot pin 12 into the bushing.

As best illustrated in FIGS. 3 and 5, the external surfaces of the arcuate walls 34 may be appropriately knurled as indicated by the numeral 39 to prevent easy detachment of the bushing from within the slot 22 of the rectangular plate 23. Additionally, a taper 40 can be formed at the lower end portion of the bushing 30 to facilitate its insertion into the slot 22 of the plate 23.

For use, the bushing 30 of the above described construction is first pressed into the slot 22 of the plate 23 until its flange portion 32 rests securely on the upper surface of the plate as shown in FIG. 5. The bushing will then be firmly retained in position due to the knurled external surfaces of its arcuate walls 34. With the bushing 30 thus held in position in the slot 22 of the plate 23, a required spacing S exists as indicated in FIG. 5 between the ,extemal surface of each of the vertical upper portions 35 of the parallel walls 33 and the corresponding internal surface of the plate 23 defining the slot 22.

The plate-bushing combination is then placed in position on the key 10, FIG. 1, to receive the projecting upper end portion of the pivot pin 12 into and through the bushing 30 and thus to securely retain the plate 23 on the key. The pivot pin 12 is now caught between the vertical upper portions 35 of the parallel walls 33 of the bushing 30. Since the distance between the internal surfaces of these vertical upper portions 35 is made smaller than the diameter of the pivot pin 12, and since the spacings S are provided between the external surfaces of the vertical upper portions 35 and the internal surfaces of the plate 23, the pivot pin 12 causes the vertical upper portions to bulge as indicated by the dotand-dash lines in FIG. 4.

Upon depression of the key 10, therefore, the key turns as aforesaid on the pivot pin 12 to raise the arm 17 and thus to turn the hammer butt 18 counterclockwise as viewed in FIG. 1, thereby causing the hammer head 21 to strike the string. The impact delivered to the key 10 as above can be appropriately cushioned due to the resiliency of the vertical upper portions 35 of the bushing walls 33 which are made thinner than the other wall portions of the bushing.

While in the foregoing disclosure the bushing according to the invention is used to tumably retain the key 10 by receiving the upper end of the pivot pin 12 projecting therethrough, the utility of the bushing is not limited to this application. The bushing can also be used, for example, to receive the guide pin 16 in the slot or bore 15 of the key 10.

While it is believed that the various objects of this invention, either explicitly stated or otherwise pointed out, are fully accomplished by the preferred embodiment disclosed herein, it will nevertheless be easy for those skilled in the art to devise many modifications thereof on the basis of this disclosure, without departing from the spirit and scope of the invention.

For instance, the bushing 30 may easily be secured to the plate 23 by means other than disclosed herein, and

if desired the bushing and the plate can be molded integrally of one and the same synthetic resin. Further, although in the embodiment shown in the drawings the distance between the vertical upper portions 35 of the parallel walls 33 is made smaller than the distance between the lower portions 36, the former distance can be made larger than the latter distance, so that the pivot pin will be resiliently but securely held by the lower portions of the parallel walls. All such and other modifications or changes are intended in the foregoing disclosure. It is therefore appropriate that the invention be constructed broadly and in a manner consistent with the fair meaning or proper scope of the appended claims.

I claim:

1. A bushing for use in a piano or like musical instrument, comprising a pair of parallel walls spaced apart from each other, a pair of connecting walls integrally connecting said parallel walls at both ends thereof, one of said connecting walls connecting one end of one of said parallel walls with one end of the other of said parallel walls, the other of said connecting walls connecting the other end of said one of said parallel walls with the other end of said the other of said parallel walls, said parallel and connecting walls defining a hollow space therebetween, each of said parallel walls being made thinner and more resilient at least at the intermediate thereof than each of said connecting walls, each of said parallel walls including a first portion and a second portion each extending from one of said connecting walls to the other of said connecting walls, the distance between the first portions of said parallel walls being made smaller than the distance between the second portions of said parallel walls, a flange formed integrally with at least said connecting walls, said flange extending perpendicular to said parallel and connecting walls, said flange extending around said parallel and connecting walls, and an elongated opening formed between each of said parallel walls and said flange.

2. A bushing as recited in claim 1, wherein each of said connecting walls is of arcuate cross section.

3. A bushing as recited in claim 1, wherein said first portions of said parallel walls are located nearer said flange than said second portions thereof, and said second portions flare out from said first portions, respectively.

4. A bushing as recited in claim 1, wherein each of said parallel walls has a thickness less than half that of each of said connecting walls.

5. A bushing as recited in claim 1, wherein at least part of the external surfaces of said arcuate walls is knurled.

6. A bushing as recited in claim 1, wherein said parallel and connecting walls are formed into an integral one-piece member of synthetic resin material.