US1765112A - Pneumatic striker unit for player pianos - Google Patents

Description

June 17, 1930. w. B. TUNSTALL PNEUMATIC STRIKER UNIT FOR PLAYER PIANOS Original Filed July 11, 1927 2 Sheets-Sheet l June 1 7, 1930. w. B. TLJNSTALL 1,765,112

PNEUMATIO S TRIKER UNIT FOR PLAYER PIANOS Original Filed July 11, 1927 2.Sheets-Sheet 2 Patented June 17, 1930 @FFEQ WILLIAM B. TUNS'IALL, OF WORCESTER, MASSACHUSETTS PNEUMATIC STRIKER UNIT FOR PLAYER PIANOS Original application filed Ju1y 11, 1927, Serial No. 204,873. Divided. and this application filed July 9,

structure that is particularly adapted for production in large quantities at low cost.

Each striker unit is a duplicate of the others and the internal construction of each unit is such that the width of a unit is so reduced that a large number can be arranged in a single row extending across the piano with the unitsin substantial alinement with the corresponding keys of the instrument. Each .unit is further characterized by an improved arrangement of valves therein whereby when a note is struck by the collapse of the power pouch, the valve controlling this action opens in the direction of the induced flow of air thereby resulting in very rapid and positive action of the note striking means.

The above and other advantageous features of my invention will hereinafter more fullyappear, reference being had to the accompanying drawings in which Fig. 1 is a View partially in section and partially in end elevation of a portion of an upright piano provided with my improved striker units.

Fig. 2 is a view in front elevation of a number of keys with the striker units controlling the same.

Fig. 3 is a perspective view of one of my improved striker units removed from the piano.

Fig. i is a perspective view of the unit shown in Fig. 3 with the power pouch removed.

Fig. 5 is a perspective view similar to Fig.

4 looking at the other side of the unit.

Fig. 6 is a sectional view through the unit along the line 6, 6 of Fig. 13.

Serial No. 291,312.

Fig. 7 is a sectional view along the line 7, 7 of Fig. 5.

Fig. 8 is a sectional view similar to Fig. 6 showing the striker unit in collapsed condition to strike a note.

Fig. 9 is a fragmentary view showing a portion of Fig. 7 on an enlarged scale.

Like reference characters refer to like parts in the diflerent'figures.

Referring first to Fig. 1, one of my improved striker units is shown in connect-ion with the usual parts of a player piano and also in connection with the parts of the improved pneumatic action which forms the subject matter of my aforesaid original application Serial No. 204,878, itbeing obvious that striker units of the present invention may be as well employed with other types of pneumatic actions. The spool box 1 is of any usual construction with a tracker bar 2,

take-up spool 3 and tubes 4 leading from the tracker bar 2 to my improved striker units, one of which is generally designated by the reference numeral 5. As shown in Fig. 2, the units 5 are of such width that a single row of them extending across the piano is sumcient to provide for the playing of all of the notes of the key board which can be manually operated by keys 6.

As set forth in detail in my original application Serial No. 204,873, the striker units 5 form part of a pneumatic action located entirely above the keys 6, the component parts of this action comprising a main channel board 7 having a bellows section or chamber 8 and an action section or wind chest 9 extending behind the row of striker units 5. Rigidly secured to the channel board 7 and in communication with the bellows chamber 8 are mounted the feeders or eXhausters 10 and the reservoir 11. The movable leaf 10 of each feeder 10 is connected by means of a link 12 to any suitable pedal mechanism not shown, suitable valves 13 and 14 being provided to regulate the fiow of air from the bellows chamber 8 1 0 the reservoir 11.

During the operation of the mechanism, the bellows section 8 is adapted to be connected to the wind chest 9 by suitable valves not shown and the wind chest 9 provides spaced ducts each adapted to su ply vacuum from the wind chest to one of the striker units 5. Eachstriker unit 5 provides what will be hereinafter termed a power pneumatic which consists of two movable leaves 16 and 17 connected by flexible material 18, the outer leaf 16 carrying a striking lever 16 extending in the direction of the piano action. Normally the pouch is expanded and a note is adapted to be struck by collapse of the pouch and upward movement of the lever 16*, in response to operation of the pneumatic unit which will now be described in detail with reference to Figs. 3 to 8 inclusive.

As best shown in Fig. 3 each pneumatic unit 5 consists of an L-shaped block, preferably of wood and fabric, the elongated portion 5 of which provides a beveled projection 19 to which the center leaf 17 of the pouch is hinged by means of a piece of fabric 20 attached to the center leaf 17, the rejection 19 and to the end of the outside ea'f 16 respectively. The center leaf 17 provides a passage 17 to the space between the pouch material 18 and the'outer leaf 16, the two leaves 16 and 17 in combination giving added power to the action of the unit as compared to a single leaf pneumatic unit.

A rubber tube 4 leading from the tracker bar 2 is connected to the unit block 5 by means of a nipple 21 which opens into a longitudinal passage 22 rovided in the elongated block portion 5. his channel 22 leads into a chamber 23 forming part of an annular recess 23 provided on one face of the block 5 and the channel 22 is also in communication with a tube 24 received in an opening 25 extendin transverse across the block, see Figs. and 9. T e tube 24 in passing through the block bridges a slot 26 extending verticall downwardly from the to surface of the lock to the center thereo ,this slot 26 being in communication with the power pneumatic as clearly shown in Fig. 6. The tube 24 makes a ti ht fit in the hole 25 so that there is no possi ility of anyleakage of atmospheric pressure from the tube 24 into the slot 26. V

vThe end of the tube 24 opposite to the tracker bar channel 22 is partially blocked by, a closure 27 which provides a small vent hole 28 so that the channel'22 is in restricted communication with a small circular recess 29 provided in the face ofthe block in the form of a shallow bore. 'The'recess 29 is in turn in communication with similar recesses 29 and 29. both of which open into a deeper recess 30 as best shown in Fig. 5, it being possible to make all of the recesses by means of different sized boring tools. The recess a 29" is in communication with a slot 31 extend- 7 ing vertically through the rear of the block,

which slot -may be conveniently made by means of a circular saw. The slot 31 is 65 adapted to register with a duct 15 extending from the wind chest 9 as shown in Fig. 1, so that the vent 28 in the tube 24 is in direct communication with the wind chest 9 and the tube 24 is subjected to a limited amount of vacuum effect.

As previously pointed out, the recesses 29 and 29" are in communication with the doc recess 30 and this recess 30 adjoins a sma ler concentric opening 32 located substantially at the center of the block, into which opening 32 extends the slot 26 from the power pouch previously referred to. A valve spindle 33 is supported within the central opening 32 by means of a guide 34 and this spindle 33 carries at op osite ends thereof valvedisks 35 and 36. Ks shown in Fig. 6 the valve disk 36 is normally seated in engagement with the shoulder 32" separating the recess 30 from the central opening 32, so that the central opening 32 is shut off from the suction normally existent within the recess 30.

The other valve disk 35 is carried by a diaphragm 37 which is anchored around its periphery to a shoulder 38 provided in the recess 23 by means of a ring 39. The side of the diaphragm 37 opposite to the valve 35 carries a disk 40 which bears a ainst the side wall 41 of the block when the d iaphragm 37 is in the position shown in Fi 6. It is apparent that the diaphragm 37 ivides-the recess 23 into two chambers, the outer chamber 23 between the side wall 41 and the diaphragm 37 being always in full communication with a tracker bar tube 4 through the passage 22, and in restricted communication withthe recess 30 through the'vent 28. The inner chamber 23 formed in the recess 23 is always in communication with the atmosphere through a duct 42 provided by a circular saw cut extending from the bottom of the block as clearly shown in Fig. 3 and when the valve 35 is separated from its seat 35 as shown in Fig. 6 the central opening 32 is also opened to the atmosphere.

Referring now particularly to the operation of the several parts shown in Fig. 1, it is obvious that when the movable leaves 10' of the cxhausters 10. are moved downwardly air is exhausted from the wind chest 9 to the reservoir 11, the vacuum thus created being locked against atmospheric pressure by means of the'valve-14, all asdescribed in my aforesaidv original application Serial No. 204,873. The vacuum in the wind chest 9 is transmitted through the registering slots 15 and 31 to the chamber or recess 30 of each unit and the vacuum is also transmitted through the commu nicating recesses 29, 29 to the vent 28. The vacuum of the vent 28 is transmitted to the outside of the diaphragm 37 by means of the tube 24, so long as the opening in the traiike r bar 2 is covered bythe note sheet, so that the diaphragm 37 will tend to hold the valve '35 open and the valve 36 closed due to the atmospheric pressure admitted to the inside of the diaphragm 37 by meansoi the slot 42.

The above described condition of affairs 15 illustrated in Fig. 6 from which it is apparent that atmospheric pressure entering the slot 4-2 and acting on the diaphragm 37 is the active force which tends to hold the valve 35 away from its seat Whiie at the same time maintaining the valve 36 in close engagement with the shoulder-32 thus keeping suction away from the central opening i l 3th this Condition, air at atmospheric pressure ad mitted to'the interior of the power pouch by means of'the slot 26 leading from the cen tral'opening -32, sov that the pneumatic remains in an expanded condition as long as the tracker bar opening is covered by the note sheet.

When, however, an opening in the tracker bar 2 is exposed, atmospheric pressure enters the corresponding tube 4: and passing through thechannel 22, overcomes the limited vacuum maintained in this channel through the vent 28 and ad vi air at atmospheric pressure to the outer chamber portion 23" of the recess 23. The result is that 'air at atmospheric pressure is then acting on both sides of the diaphragm37 thereby neutralizing the force previously acting on the diaphragm 37 and immediately causing thevalve disk to be drawn-away from its seat 32 by the suction effect on the side of this valve exposed to the recess 30, as shown in Fig. 3. the valve 36 opens the valve 35 closes, thereoy cutting off the central chamber 32 from the atmosphere and admitting suction to the central chamber 32 and the slot 26 leading therefrom," i i The interior of the power pouch thus being enhausted, atmospheric pressure surrounding the pouch forces it to collapse with the result that a note is striick by the lever 16 carried, by, the outer leaf 16. The lever 16 extends "beneath the end of a wippen 43 as shown in Fig. 1, so that when the pneumatic collapses the free end of the lever 16 moves upwardly thus strikingthe note in the usual manner. t is obvious'that the action of the powerpneumatic is quick and positive owing to'the direct connection of the lever 16 to the leaf 16 with no motion lost in transmitting the action. Furthermore it is apparent from Fig. 2 that each striker unit 5 practically lines up with the corresponding note, so that the levers 16 extend rearwardly from the single row of units without interference, each lever16 permitting a small amount of lateral bending'to bring, it directly below the corresponding wippen 43.

As previously pointed out my improved striker.v unit is particularly characterized by itsvery quick action in striking a note in re sponse to the uncovering of an opening in I the tracker bar 2. This very quick action results to a large extent from the fact that the valve 36 which controls the admission of suction to the central chamber 32 to collapse the power pouch, opens in the direction of the induced flow of air. That is to say there is always, as long as the exhausters are operating, a tendency to draw air out of the recess 30 and of course the vent 28 always permits a limited amount of air to be exhausted from this recess 30. But it is perfectly obvious that with the parts in the position shown in Fig. 6 atmospheric pressure within the central chamber 32 exerts a tendency to push the valve 36 away from its seat 32 to admit atmosphere to the recess 30. However this tendency for the valve 36 to open is counteracted and overcome by the greater force exerted by atmosphere pressing on the under side of the other valve and on the diaphragm 37 itself. Obviously the combined areas of the valve 35 and of the diaphragm 37 exposed to atmosphere are much-greater than the area of the valve 36 exposed to atmosphere, and since there is a suction effect on the outside 01" the diaphragm 37, the forces tending to move the spindle 33 to the right are preponderantand suiiicientto hold the valve 36 tightly closed on its seat 32. However, as soon as an opening in the tracker bar 2 is exposed to the atmosphere the rush of air at atmospheric pressure through the tube 4 almost instantaneously overcomes the limited, although heretofore suilicient, vacuum effect in the outside chamber 23 of the recess 23 and conditions within the unit are immediately reversed in so tar as results on the valve 36 are concerned. As soon as atmosphere is admitted to the chamber 23, the force previously exerted on the diaphragm 27 and valve 35 is eliminated so there is a sudden and immediate pressure exerted on the inside of the valve 36. As previously pointed out this opening pressure on the valve 36 had been in existence before so that as soon as there is neutralization 01 the forces acting on the diaphragm 37, the valve 36 starts to open and once started the movement is almost instantaneous due to the rush oi air past the valve 36. In other words once the forces acting on the diaphragm 37 are counterbalanced, there is no force whatsoever tending to hold the valve 36 closed and it opens in the direction of the induced flow of air.

It should be particularly noted that the various ducts 26, 31 and 42 are shown as being made by the use of small circular saws of the proper diameter while the v rious recesses such as 23, 29, 29 and 29 are shown,

as being made by the use o1 boring tools oi the proper diameter. By this manner of forming it is possible to produce standardized units properly recessed and slotted in very large quantities with relatively small expenditure of time and labor and with absolute accuracy. It is to be understood, howmy invention I have provide ever, that the principle of my improved pneumatic unit is not dependent upon the exact form of the various ducts and recesses which can be made in other ways than as shown to obtain the same results.

From the foregoing it is ap out that by F dn improved pneumatic striker unit for player pianos that can be quickly and cheaply manufactured operates in" an extremely effective manner in striking a note. 7 The unit is further characterized by its very compact form due in (part to the manner of forming the slots an recesses and to the disposal of the valves in vertical planes. This construction results in a very narrow unit which lends itself to the arrangement of all of the units in a single row above the key board of the piano with each unit in substantial alinement with the key, the note of which is controlled by the striker unit. v

I claim,

1. In a valve action for striker pneumatics,

a diaphragm chamber, normally under exhaust, and covered by a diaphragm, a valve chamber and a valve mounted therein, said valve chamber being normally filled with air below atmospheric pressure, a passage be tween the valve chamber and diaphragm, means providing communication between said passage and. the atmosphere, and means for providing communication between said assage and the proper pneumatic, said rst named means being closed by movement of the diaphragm when atmospheric premure is admitted to the diaphragm chamber.

2. In a valve action for striker neumatics, a diaphragm chamber, a diaphragm covering said chamber, a valve chamber normally in an exhausted condition, a passage between the valve chamber and the diaphragm, a valve in the valve chamber and adapted to close one end of'said-passage, a second valve on the diaphragm and adapted to close the other end of said passage, means providing communication between said passage and the power pneumatic, and means placing the one side of the diaphragm constantly in communication with the atmosphere;

3. In a valve action for striker pneumatics,

a diaphragm having a chamber on each side thereof, a valve chamber spaced from the diaphragm, a valve in said chamber adapted to be operated by the diaphragm, means connecting the chamber on one side of the diaphragm with a tracker bar, means providi communication between the atmosphere an the chamber 011- the other side of said diaphragm means providing a passage between said last named chamber and the valve chamber, and means providin communication between said passage and t e power pneumatic,

with said valve chamber being constantly subject to exhaust tension,

- 4. In a pneumatic striker unit for musical a diaphragm, and thereby forming an open air chamber on one side, and grooved and recessed on the other side, to provide a v uum chamber and valve sod, a valve fortaaid seat, a vent to conduct alimi'ted flow of vac, uum on one side of the diaphragm and means for connecting this same side of the diaphragm to the opening in the tracker bar, a port connecting the outside air chamber and the vacuum chamber havi a groove therefrom to the interior :5 the power pneumatic, an outside air valve on the diaphra for seating against said port, and means or retaining the said valves in proper relations to their respective seats.

5. In a pneumatic striker unit for musical instruments, in combination, a block chamfered to present a surface to contact with one face of a wind chest, and leaving a rtion to extend past said face of the wind 0 est, said extended portion forming the fixed leaf of the power pneumatic, a tube and channel inlaid extended portion to convey air from the tracker bar to the primary diaphragm in the said block, a groove and recess provided on one side of the block to receive said diap and thus form an'atmospheric air chamber, a valve secured to said diaphragm, said valve cooperating with a valve seat and port leading to a vacuum chamber on the oppote side of said block, a valve in said vacuum chamber and operatively secured to said diaphragm in said atmospheric chamber, a vent in said vacuum chamber to conduct a limited amount of vaccum to one side of said die hragm, whereby said diaphragm is forced y atmospheric pressure away from the said valve'seat in the atmospheric chamber, and at the some time draws the valve in the vacuum chamber tight against its seat when the note is normally idle,-and whereby, when an opening is exposed in the tracker bar, atmospheric pressure will overcome the vent and both valves will move in the direction of the induced flow of air to strike a. given note. I 6. Ina pneumatic striker unit for musical instruments, a block recessed to form a vacuum chamber and an atmospheric chamber grooves in said block to supply air to chambers, and ports connecting said chambers together and both chambers with the interior of the power pneumatic, a. (lia phragm and valve co-operating with the port in the atmospheric chambenand a valve cooperating with 5PM inxthe-vacnnm= t chamber, both valves being operatively connected with the diaphragm, a vent-in the vacuum chamber for mind i a'limited supply of vacuum to the-side of the diaphragm opposite the atmospheric chamber chamber closed, and when an opening is exposed in the tracker bar, allowing the valve in the vacuum chamber to open and the valve in the atmospheric chamber to close, thus causing the power pneumatic to collapse.

7. An automatic mechanism for player pianos, comprising a collapsible power pneumatic, a tracker bar having air ports controlled by a perforated note sheet, a casing intermediate the power pneumatic and the tracker bar, subdivided to form a vacuum chamber communicating with suction apparatus, and an open chamber communicating with the atmosphere, a power conduit connecting the interior of the power pneumatic with both chambers, and co-operative means whereby, when a tracker bar port is closed, the power pneumatic is connected with the open chamber, and disconnected from the vacuum chamber, and when said port is opened, the power pneumatic is disconnected from the open chamber, and connected with the vacuum chamber to cause an induced flow of air from the power pneumatic to the vacuum chamber, and the collapse of the power pneumatic by external atmospheric pressure, said co-operative means including a valve and valve seat for controlling the passage of air from said power conduit to the vacuum chamber, the said valve seat being between the valve and the power conduit whereby said valve, to open, moves in the direction of said induced flow of air, the entire mechanism for striking the note being contained in one unitary structure.

8. In an automatic mechanism for player pianos, a vacuum chamber, a power pneumatic, a power pneumatic conduit, and means for bringing about the induction of a flow of air through said conduit to the vacuum chamber to cause the collapse of the power pneumatic by external atmospheric pressure, said means including a valve and valve seat for controlling the passage of air from said power pneumatic conduit to the vacuum chamber, the said valve seat being between the valve and the power pneumatic conduit, whereby said valve, to open, moves in the direction of the induced flow of air, the entire mechanism for striking the note being contained in one unitary structure.

WILLIAM B. TUNSTALL.

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