US1292362A - Pneumatic action for musical instruments. - Google Patents

Description

1. A. OBST PNEUMATIC ACTION FOR MUSICAL INSTRUMENTS.

Patented Jan. 21, 1919.

APPLKCATION HLED SEPT. 10. 1914.

il i 7165,6635

JOSEPH A. OBST,

OF PAWTUCKET, RHODE ISLAND.

PNEUMATIC ACTION FOB MUSICAL INSTRUMENTS.

Application flied September 10, 18141.

T 0 all whom, it may concern:

Be it known that I, Josnrn A. Onsr, a citizen of the United States, residing at Pawtucket, in the county of Providence and State of Rhode Island, have invented new and useful Improvement in Pneumatic Actions for Musical Instruments, of which the following, taken in connection with the accompanying drawings, is a specification.

The present invention relates to improvements in the construction and operation of pneumatic actions for musical instruments. The present construction particularly adapts itself to the employment of a single valve control for the motor pneumatic, in contradistinction to the double valve control orc inarily employed, and embodying primary and secondary valves, but it is to be understood that while the invention is shown and described as a single valve act-ion, the prin ciples of the same are equally applicable to the double valve action.

The object of my invention is to simplify the construction and lessen the cost of devices of this character, and in particular, to increase the responsiveness of such devices by improvements directed to the control of the bleed devices thereof. Other and further objects will appear from the following description taken in connection with the accompanying drawings, in which Figure 1 is a sectional view of a device embodying my invention.

Fig. 2 is a similar view showing the parts in different positions.

Fig. 3 is a fragmentary sectional view showing the parts in the positions which they assume at one stage in the operation of the device, and

Fig. 1 is a cross section on the plane of the broken line 4 1, Fig. 1.

Like parts are indicated by like reference characters in the different figures.

The drawing illustrates a single motor pneumatic 1, the movable leaf of which carries an arm 2 which is adapted to actuate the corresponding abstract, not shown, of a keyboard operated instrument in a manner well understood and common to instruments of this class. The stationary leaf of the pneumatic 1 is supported beneath a valve box 3, which has a channel 1, communicating by means of a tube 5 with a corresponding aperture in the tracker board of the instrument, not shown.

Each valve box 3 has a vacuum chamber 6,

Specification of Letters Patent.

Patented Jan. 21, 1919.

Serial No. 861,141.

in' constant communication, through a common passage 7, with an exhausting device, not shown, in the manner common to devices of this class. The vacuum chamber 6 of each valve box communicates with the channel 1 of said box by means of a restricted passage 8, commonly known as a bleed passage for the purpose of exhausting the air from channel 1 into the vacuum chamber 6. Below the vacuum chamber 6 and separated therefrom by a flexible diaphragm 9, is a recess 10 with which the channel 4 communicates.

The box 3 is formed with a chamber 11, which is in constant communication, by means of a channel 12 with the interior of the motor pneumatic 1. Said chamber 11 has a port 13 leading to the vacuum chamber 6, and a port 14 leading to the atmosphere. A double faced valve 15 is contained within the chamber 11 and adapted to control the two ports 13 and 11 thereof. The valve 15 has a stem 16 extending through said port 18 and preferably carrying on its end a disk 17, preferably disposed somewhat above the upper surface of the diaphragm 9 in the normal collapsed pos'tion of the latter, as shown in Fig. 1.

The saidfivalve 15, in the position shown in Fig. 1, wherein it rests by gravity on the bottom of chamber 11, closes the port 13 between said chamber and the vacuum chamher 6, and leaves open the port 141, to establish communication between the interior of the motor pneumatic l and the atmosphere. In the position of the valve shown in Fig. 2, wherein it is shown as elevated by an air pressure beneath the diaphragm 9, the valve shuts off the motor pneumatic from the atmosphere, and connects it with the vacuum chamber 6.

My present invention relates to the bleed device by which the initial air pressure is sustained beneath the diaphragm 9, during the elevation of the valve 15, and by which the air pressure beneath the diaphragm is quickly reduced at the proper time to permit the fall of the valve 15 after the motor pneumatic 1 has collapsed, and the chief object of my invention is to render the apparatus more quickly responsive in its action.

The operation of my improved device is as 'follows:The normal position of valve 15 is shown in Fig. 1, but when a perforation of the traveling note sheet registers with the tracker-board aperture with which the tube 5 is connected, the resulting impulse of air through the channel 4 fills the chamber 10 and lifts the diaphragm 9, .carrying it into contact with the material surrounding the opening 18, and by its continued movement to lift the valve '15 to close the port 1i and open the port 13, as shown in Fig. 2, with the result that the diaphragm will substantially close the end of the bleed passage 8 and restrict the flow of air through the bleed passage so the normal air pressure admitted to the recess 10 will be effective to raise the valve 15 into the position shown in Fig. 2. The interior of the motor pneumatic l is thereby cut off from the outer air and connected with the vacuum chamber 6, resulting in the collapse of the :movable leaf of the motor pneumatic and the operation of the corresponding (albstract the usual manner.

The closing of the bleed passage 8 -is not complete as a slight leakage ofiair will occur around the opening 18, for the reason that 'the contact of the diaphragm 9 with the material surrounding the opening :18 is not sufficiently intimate to wholly prevent .a slight leakage of air into the vacuum chamber 6. So long as the opening in .the trackerboard is uncovered *by the note sheet, this leakage is negligible, but when the opening in the tracker-board is closed, the air pressure in channel i and recess 10 becomes reduced sufiiciently to allow the diaphragm 9 and valve 15 to'drop, thereby instantly openingthe .full :area of the bleed passage 8 to the vacuum chamber.

The responsiveness of the apparatus is greatly increased as the slackness of the dia phragm 9 substantially closes the bleed pas-p sage in advance of the lifting of the valve 15, restricting the bleeding effect to :the slight leakage around the openinglS due to the imperfect contact of the diaphragm withthe material around theopening I18, al-

though the .area 20, Fig. .4, .is preferablyslightly rounded in order to reduce theleakage to a minimum which, however, will be sufficient, 'due to the .pull of :the vacuum chamber 6, to slightly reduce the pressure'in the recess 10, While the :perforation in rthe tracker-board is closed. The closing :of Til-116 perforation in the tracker-board will therefore be followed by the depression :of the diaphragm and the consequent rapid i equalizationof the air pressure in tllGIBCGSSIlOxfl-Ild the vacuum chainber6 vdue'to the complete openingof the channels 4 and 8 which are of sufficient size to cause the pressure in the recess 10 to be instantly reduced to that of the chamber -6, rendering the apparatus extremely responsive to the opening and closing of the perforations in the tracker-board by the note sheet. In other Words, the bleed aperture in my improved device is variable. The passages i and 8 are of suflicient area in cross section to efiect an instantaneous change in the air pressure of recess 10, while the passages 41: and 8 are restricted by the initial upward movement of the diaphragm so long .as the aperture in the tracker-board is open. When the valve 15 is in its lowest position some space exists between the diaphragm 9-,and .thedisk 17, and theinitial elevation .ofxthe diaphragm .9 carries it into the positionshown'in Fig. 3, closing the opening 18,before the-valve 15 is raised. In the positionshown in Fig. 3,, the air pressure in the recess 10 is substantially the normal air pressure so long as the corresponding perforation is .open, and :air is supplied wfreely through :the flexible tube 5. Then the ,perforation in theitracker-Eboard is closed by the note sheet, the leakage from .the opening 18 reduces thegair pressure in the recess 10 sufficiently "to allow the *weight of the valve and the normal .air pressure upon its upper surface :to :peel the diaphragm from the surface 20, and fully open the passage to the vacuum chamber.

:Lclaim,

In a pneumatic action for musical instruments,:a vacuum chamber, an airchamber, a flexible-diaphragmseparating said chainbers, an air channel forsupplying airto said air chamber,,a bleed passage normally open between said air'channel and said vacuum chamber and entering said vacuum chamber through a wall-of the vacuum chamber opposed to said diaphragm and lying in its path :as :said diaphragm is actuated by the difference in air pressure on its opposite sides, a valve having its stein in the path of said diaphragm with normally aspace be tween ;the walve stem and the diaphragm, whereby the movement of the valve as actuated by theidiaphragm will occur subsequent to the covering of the .bleed passage by the diaphragm, .and th reverse :movement of the Valve will occursubsequent to'iihe uncoveringiof the ibleed passage.

JOSEPH A. 01381. Witnesses:

GEORGE W. MILLER, vJosr-rn iB'OWLAND.

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