CN215868594U - Linkage device of upright piano action and keyboard - Google Patents

Abstract

A linkage device of a string striking machine and a keyboard of an upright piano comprises the string striking machine, the keyboard and a middle disc, wherein the keyboard is arranged on the middle disc, a top post is arranged on the keyboard, the linkage device also comprises an upper gear and a lower gear, the upper gear and the lower gear are arranged on a side plate of the upright piano, and the mounting height of the upper gear is higher than that of the lower gear; an upper shaft bracket is arranged on the upper gear from top to bottom, an upper connecting rod is hinged on the upper shaft bracket, and the lower part of one end of the upper connecting rod is connected with the top column in a jacking way; the lower gear is upward provided with a lower shaft bracket, the lower shaft bracket is articulated with a lower connecting rod, one end of the lower connecting rod is provided with a top shaft, the top shaft is connected with the bottom of a linkage rod of the string striking machine in a propping manner, and the other end of the lower connecting rod and the end of the upper connecting rod far away from the top column are articulated with a pull rod. The linkage device of the upright piano action and the keyboard can reduce the installation height of the upright piano action, has good rebound force and high sensitivity, and is convenient for the adjustment and the maintenance of the action.

Description

Linkage device of upright piano action and keyboard

Technical Field

The utility model relates to the technical field of piano parts, in particular to a linkage device of a vertical piano action and a keyboard.

Background

Because the piano has unique wide range, beautiful timbre and unique performance, it is very popular with the music enthusiasts. With the development of society, the market demand of upright pianos is more and more. The action is the core playing mechanism of each piano to produce action. The player gives the piano different melodies by playing the keyboard connected to the action. A piano with high quality must be provided with a highly accurate action. The publications also report some action machines, such as:

1. chinese patent: action of upright piano, application No.: 201180040404.8, filing date: 2011.07.07, patentee: rattan piano services limited, address day: the inventor of the western county sammochun city western county city of deer island number 15,11: rattan well luck, abstract: the utility model provides a string striking machine of an upright piano, which can show abundant tone variation and improve the continuous striking performance of the same key. Specifically, the action (1) of the upright piano is provided with: a guide member (67) fixed to the center rail (14) and continuous in the left-right direction; and a guided member (73) that slides along the guide member (67), fixes the hammer inner back rail (19) with which the hammer shank (45) abuts to the hammer back rail (18), fixes the butt pedestal (41) to the guided member (73), connects the guided member (73) to the pedal (77) via the pedal stick (81) and the pedal lever (79), and slides the guided member (73) in either right or left direction in accordance with the force with which the player depresses the pedal (77).

2. Chinese patent: piano action, application No.: 201410287066.3, filing date: 2014.06.24, patentee: address of the institute for making a musical instrument of the japan society: jinggang county, japan, the inventors: temple well health log, abstract: a piano action is obtained which can ensure excellent performance reproducibility even in the case of a performance with rapid successive strokes of a keyboard. The piano action has: a plurality of hammers (31) for striking strings; a hammer shank (32) that supports the hammers in a freely rotatable manner; a hammer stopper rail (1) that restricts rotation of the hammer shank (32) after the hammer strikes a string; and a hammer pad (buffering member) (100) that is placed on the hammer block rail, absorbs kinetic energy generated at the time of collision of the hammer shank (32), wherein the hammer pad (buffering member) (100) is configured to have an angle not parallel to an abutting surface with the hammer shank (32).

3. Chinese patent: upright piano action, application number: 201120074064.8, filing date: 2011.03.21, patentee: yichang jinbao musical instrument manufacturing company, address: 443000 Kyoho No. 1 in economic development area of Yichang city, Hubei province, the inventor: wutianyan, abstract: a vertical piano string striking machine, the plastic linkage rod is installed on the plastic clutch pedestal, one end of the plastic linkage rod is hinged with one end of the plastic ejector rod, the other end of the plastic ejector rod is matched with the plastic rotary striker cam installed on the plastic rotary striker pedestal, the hammer head component is installed on the plastic rotary striker cam; the left, middle and right of the total gear are provided with brackets, and the brackets are provided with back gears and support bars. By adopting the structure and manufacturing part of parts by adopting plastic synthetic materials, the utility model has simple process, and the manufactured parts have good lubricity and small resistance; the strength and the durability of the action are greatly improved; the produced parts have high precision, and the adjustment is less and the time is saved when the string striking machine is assembled, so the production efficiency is high; due to the fact that the plasticizing part is properly selected, the control performance is good during playing, and the weather resistance is excellent.

4. Chinese patent: a wooden electric piano keyboard of connecting rod formula structure, application number: 201320404208.0, filing date: 2013.07.09, patentee: beijing institute for musical instruments, address: 100122 West Lu Jia No. 6, south Xinyuan of the rising area, Beijing, patentee: grandfather, Chen jin Wu, Tang Jian, Korea fragrance, inventor: grandfather, Chen jin Wu, Tang Jian, Korea fragrance, abstract: a wooden electrical piano keyboard with a connecting rod type structure is characterized in that on the basis of a traditional upright piano string striking machine, the wooden electrical piano keyboard further comprises an upper gear and a lower gear, wherein the upper gear and the lower gear are respectively arranged on a bracket so as to limit the motion positions of a counterweight hammer handle and a counterweight hammer within the range below the upper gear and above the lower gear; the upper rail and the lower rail are both composed of metal corner beam members and felt pads, the metal corner beam members are fixedly connected to the support, and the felt pads are fixed on the metal corner beam members; the included angle between the hoe handle and the counterweight hammer handle is reduced to be less than or equal to 60 degrees, preferably 45 degrees; the hammer of the string hammering machine is transformed into a counterweight hammer and a counterweight hammer structure with adjustable weight is designed, namely 1, 2 or a plurality of iron or copper pins are arranged on the counterweight hammer to adjust the weight of the counterweight hammer. The wood electric piano keyboard with the connecting rod type structure effectively simplifies the assembling process of a traditional upright piano string striking machine and saves the material consumption, so that the electric piano has the playing touch effect of the traditional piano.

5. Chinese patent: piano action, application No.: 201621417025.2, filing date: 2016.12.22, patentee: yichang jinbao musical instrument manufacturing company, address: 443005 Kyoho No. 1 in economic development area of Yichang city, Hubei province, the inventor: luoyang, bear south, liujie jade, abstract: the utility model provides a piano string striking machine, a string hammer is fixedly connected with a rotary striking device, the rotary striking device is hinged with a rotary striking device shaft frame through a fourth Shenda needle, a damper is hinged with a damper shaft frame through a first Shenda needle, the rotary striking device shaft frame is fixedly connected with the top of a connecting rod, the damper shaft frame is fixedly connected with the rear side part of the top of the connecting rod, the bottom of the connecting rod is fixedly connected with a linkage device shaft frame, the linkage device shaft frame is hinged with a linkage device through a second Shenda needle, the linkage device is hinged with a mandril through a third Shenda needle, and the mandril is propped against the bottom of the rotary striking device; the first Shendao needle, the second Shendao needle, the third Shendao needle and the fourth Shendao needle are made of carbon fiber materials. Through improving the material of the extension needle, the corrosion resistance of the hinged position is improved, and the problem of rusting or deformation cannot occur in the long-term playing process, so that the flexibility of the action machine can be kept for a long time.

6. Chinese patent: upright piano mobile type string hitting keyboard system, application number: 201820546756.X, application date: 2018.04.17, patentee: mendelson piano (Jiangsu) ltd, address: 214105 Wu Tou 59, the inventor: jinyou brocade, abstract: the utility model discloses a mobile type string striking keyboard system of an upright piano, which comprises a string striking mechanism, a keyboard mechanism, pedal mechanisms related to the keyboard mechanism and strings corresponding to hammers, wherein the string striking mechanism is arranged on the keyboard mechanism; the string striking mechanism comprises a linkage rod component, a rotary striking device component, a sound stopper component, a round back baffle, a main baffle and a bracket; the keyboard mechanism comprises black keys, white keys and a keyboard frame; the linkage rod assembly and the rotary beater assembly are assembled on the main gear, and the main gear and the round back gear are respectively arranged on the bracket; the sound stopping device component and the main gear are of a separated structure; the trace subassembly includes trace support piece, and the butt subassembly includes butt support piece, and the trace subassembly is under black key, white key receive the effect of external force for the string is strikeed under the condition that its longitudinal axis angle produced continuous variation to the hammer, arouses the vibrations of string and produces sound. The string striking mechanism and the keyboard mechanism can integrally move rightwards for a proper amount under the action of the pedal mechanism so as to reduce the number of strings struck by the hammers and realize the decrement and weakness of the volume.

Researches show that the height of the middle disc of the upright piano has a design standard, and the currently used string striking machine is arranged above the keyboard, so that the piano is high and is not suitable for short players to play, and the middle disc of the upright piano needs to be integrally disassembled and assembled during disassembly and assembly, and is inconvenient to adjust and maintain.

Disclosure of Invention

The utility model aims to provide a linkage device of a string striking machine and a keyboard of an upright piano, which can reduce the installation height of the string striking machine of the upright piano, has good rebound force and high sensitivity, and is convenient for adjustment and maintenance of the string striking machine.

In order to achieve the purpose, the utility model adopts the following technical scheme:

a linkage device of a string striking machine and a keyboard of an upright piano comprises the string striking machine, the keyboard and a middle disc, wherein the keyboard is arranged on the middle disc, a top post is arranged on the keyboard, the linkage device also comprises an upper gear and a lower gear, the upper gear and the lower gear are arranged on a side plate of the upright piano, and the mounting height of the upper gear is higher than that of the lower gear; an upper shaft bracket is arranged on the upper gear from top to bottom, an upper connecting rod is hinged on the upper shaft bracket, and the lower part of one end of the upper connecting rod is connected with the top column in a jacking way; the lower gear is upward provided with a lower shaft bracket, the lower shaft bracket is articulated with a lower connecting rod, one end of the lower connecting rod is provided with a top shaft, the top shaft is connected with the bottom of a linkage rod of the string striking machine in a propping manner, and the other end of the lower connecting rod and the end of the upper connecting rod far away from the top column are articulated with a pull rod.

Further preferred is: and a silencing felt is arranged at the joint of the lower part of the upper connecting rod and the top of the top column.

Further preferred is: the pull rod comprises an upper pull rod and a lower pull rod, the upper end of the upper pull rod is hinged to the upper connecting rod, the lower end of the lower pull rod is hinged to the lower connecting rod, a threaded connecting sleeve is in threaded connection between the lower end of the upper pull rod and the upper end of the lower connecting rod, and the length of the pull rod is adjusted by adjusting the connection length of the threaded connecting sleeve, the upper pull rod and the lower pull rod.

Further preferred is: the string-striking machine comprises a string-striking machine main gear, the front part of the string-striking machine main gear is hinged with a damper rod through a damper shaft bracket, the top of the damper rod is provided with a damper lead screw, the top of the damper lead screw is provided with a damper head with a damper felt through a damper head button, the rear side of the damper lead screw is provided with a damper gear, and the damper rod is provided with a damper spring; a rotary beater cam is hinged above the rear part of the main gear of the string beating machine through a rotary beater shaft bracket; the top of the rotary beater cam is connected with a hammer handle, the top of the hammer handle is provided with a hammer core forward, the hammer core is provided with a hammer felt, the rear side of the hammer handle is provided with a back rail, and the back rail is provided with back rail wool; a hook spring is arranged on the front side of the rotary beater cam, and a hook rope is connected to the hook spring; the rear side of the rotary beater cam is connected with a brake handle, brake wood is mounted on the brake handle, and brake wood leather is arranged on the brake wood; the lower part of the rear side of the rotary beater cam is provided with a rotary beater felt and a rotary beater felt skin; the bottom of a main gear of the string striking machine is hinged with a linkage rod through a linkage device shaft bracket, a spoon nail used for knocking and pushing a damper rod is arranged above the front part of the linkage rod, a climbing belt hook and a wood supporting rod are arranged above the rear part of the linkage rod, the upper part of the climbing belt hook is connected with a brake through a climbing belt, a wood support with a wood supporting felt is arranged at the top of the wood supporting rod, and the wood supporting felt is used for knocking brake leather; an L-shaped ejector rod is hinged to the linkage rod through an ejector rod shaft frame, the long end of the L-shaped ejector rod is connected with the butt-joint of the butt-joint felt and the butt-joint felt, an ejector rod spring is installed between the short end of the L-shaped ejector rod and the linkage rod, a tuning gear is arranged above the short end of the L-shaped ejector rod, a tuning button is installed on the tuning gear downwards through a regulating screw, and a bottom felt used for being connected with the short end of the L-shaped ejector rod in a butt-joint mode is installed at the bottom of the tuning button. The sound making bar, the string striking machine main bar, the sound adjusting bar and the back bar are all arranged on the side plate of the upright piano.

This vertical piano action and linkage of keyboard's advantage does:

1. the linkage device can reduce the mounting height of the string striking machine on the premise of not influencing the mounting height of the middle disc, thereby reducing the height of the piano and preventing short players from feeling oppressed during playing.

2. The keyboard has the advantages that the keyboard has good rebound force, high sensitivity and good playing hand feeling due to the self weight of the keyboard in a linkage mode of the upper connecting rod, the pull rod and the lower connecting rod.

3. The linkage device can ensure that the string striking machine is arranged at the front side of the keyboard and is linked through the upper connecting rod, the pull rod and the lower connecting rod, when the string striking machine is adjusted and maintained, the middle disc and the like do not need to be integrally disassembled, and the adjustment and the maintenance are inconvenient.

Drawings

FIG. 1 is a schematic view showing the installation relationship of the present upright piano action with the linkage of the keyboard;

FIG. 2 is a schematic view showing the structure of a tension rod in embodiment 2;

the names corresponding to the sequence numbers in the figure are:

1. a sound making felt; 2. a damper head; 3. a sound head button; 4. a damper screw rod; 5. a sound making file; 6. a damper lever; 7. a damper spring; 8. a damper shaft bracket; 9. a main gear of the action; 10. a butt shaft bracket; 11. spoon and nail; 12. a linkage shaft bracket; 13. a linkage rod; 14. a mandril shaft frame; 15. a push rod spring; 16. climbing with a hook; 17. a wood supporting rod; 18. a bottom felt; 19. a tuning button; 20. adjusting a tone file; 21. adjusting screws; 22. climbing a belt; 23. carrying out wood supporting; 24. supporting a wood felt; 25. braking the wood leather; 26. braking wood; 27. a brake lever; 28. an L-shaped ejector rod; 29. a butt felt; 30. felt skin of the rotary beater; 31. a butt cam; 32. hooking a rope; 33. a hook spring; 34. hammer shanks; 35. back stop wool; 36. a back rail; 37. a hammer core; 38. hammer felt; 39. uploading a file; 40. an upper shaft bracket; 41. an upper connecting rod; 42. silencing felt, 43, top column; 44. keyboard, 45, middle panel; 46. a pull rod; 47. a lower connecting rod; 48. a lower shaft bracket; 49. down shifting; 50. a top shaft; 51. an upper pull rod; 52. a threaded connecting sleeve; 53. and a pull rod is pulled down.

Detailed Description

In order that the above objects, features and advantages of the present invention can be more clearly understood, the present invention will be further described with reference to the accompanying drawings and examples. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.

Example 1

A linkage device of an upright piano string striking machine and a keyboard comprises the string striking machine, the keyboard 44 and a middle disc 45, wherein the keyboard 44 is installed on the middle disc 45, a top pillar 43 is installed on the keyboard 44, the linkage device also comprises an upper rail 39 and a lower rail 49, the upper rail 39 and the lower rail 49 are installed on a side plate of the upright piano, and the installation height of the upper rail 39 is higher than that of the lower rail 49; an upper shaft bracket 40 is arranged on the upper stop 39 from top to bottom, an upper connecting rod 41 is hinged on the upper shaft bracket 40, and the lower part of one end of the upper connecting rod 41 is connected with a top column 43 in a jacking way; the lower rail 49 is provided with a lower shaft bracket 48 upwards, the lower shaft bracket 48 is hinged with a lower connecting rod 47, one end of the lower connecting rod 47 is provided with a top shaft 50, the top shaft 50 is connected with the bottom of the linkage rod 13 of the string striking machine in a propping way, and the other end of the lower connecting rod 47 is hinged with the end of the upper connecting rod 41 far away from the top column 43 and provided with a pull rod 46.

Example 2

A linkage device of an upright piano string striking machine and a keyboard comprises the string striking machine, the keyboard 44 and a middle disc 45, wherein the keyboard 44 is installed on the middle disc 45, a top pillar 43 is installed on the keyboard 44, the linkage device also comprises an upper rail 39 and a lower rail 49, the upper rail 39 and the lower rail 49 are installed on a side plate of the upright piano, and the installation height of the upper rail 39 is higher than that of the lower rail 49; an upper shaft bracket 40 is arranged on the upper stop 39 from top to bottom, an upper connecting rod 41 is hinged on the upper shaft bracket 40, the lower part of one end of the upper connecting rod 41 is connected with a top column 43 in a propping manner, and a silencing felt 42 is arranged at the joint of the lower part of the upper connecting rod 41 and the top column 43 in a propping manner; the lower rail 49 is provided with a lower shaft bracket 48 upwards, the lower shaft bracket 48 is hinged with a lower connecting rod 47, one end of the lower connecting rod 47 is provided with a top shaft 50, the top shaft 50 is connected with the bottom of the linkage rod 13 of the string striking machine in a propping way, and the other end of the lower connecting rod 47 is hinged with the end of the upper connecting rod 41 far away from the top column 43 and provided with a pull rod 46.

The pull rod 46 comprises an upper pull rod 51 and a lower pull rod 53, the upper end of the upper pull rod 51 is hinged to the upper connecting rod 41, the lower end of the lower pull rod 53 is hinged to the lower connecting rod 47, a threaded connecting sleeve 52 is in threaded connection between the lower end of the upper pull rod 51 and the upper end of the lower connecting rod 47, and the length of the pull rod 46 is adjusted by adjusting the connection length of the threaded connecting sleeve 52, the upper pull rod 51 and the lower pull rod 53.

The string-striking machine comprises a string-striking machine main gear 9, the front part of the string-striking machine main gear 9 is hinged with a damper rod 6 through a damper shaft bracket 8, the top of the damper rod 6 is provided with a damper lead screw 4, the top of the damper lead screw 4 is provided with a damper head 2 with a damper felt 1 through a damper head button 3, the rear side of the damper lead screw 4 is provided with a damper gear 5, and the damper rod 6 is provided with a damper spring 7; a rotary beater cam 31 is hinged above the rear part of the main gear 9 of the string beating machine through a rotary beater shaft bracket 10; the top of the butt cam 31 is connected with a hammer handle 34, the top of the hammer handle 34 is provided with a hammer core 37 forward, the hammer core 37 is provided with a hammer felt 38, the rear side of the hammer handle 34 is provided with a back rail 36, and the back rail 36 is provided with a back rail woolen 35; a hook spring 33 is arranged at the front side of the butt cam 31, and a hook rope 32 is connected to the hook spring 33; the rear side of the butt cam 31 is connected with a brake handle 27, a brake wood 26 is arranged on the brake handle 27, and a brake wood leather 25 is arranged on the brake wood 26; a butt felt 29 and a butt felt skin 30 are arranged at the lower part of the rear side of the butt cam 31; the bottom of a main gear 9 of the string-striking machine is hinged with a linkage rod 13 through a linkage device shaft bracket 12, a spoon nail 11 used for knocking and pushing a damper rod 6 is installed above the front part of the linkage rod 13, a climbing belt hook 16 and a wood supporting rod 17 are installed above the rear part of the linkage rod 13, the upper part of the climbing belt hook 16 is connected with a brake wood 26 through a climbing belt 22, a wood support 23 with a wood support felt 24 is installed at the top of the wood support rod 17, and the wood support felt 24 is used for knocking brake wood leather 25; an L-shaped ejector rod 28 is hinged to the linkage rod 13 through an ejector rod shaft bracket 14, the long end of the L-shaped ejector rod 28 is connected with a butt felt 29 and a butt felt 30 in a propping mode, an ejector rod spring 15 is installed between the short end of the L-shaped ejector rod 28 and the linkage rod 13, a tuning gear 20 is arranged above the short end of the L-shaped ejector rod 28, a tuning button 19 is installed on the tuning gear 20 downwards through a regulating screw 21, and a bottom felt 18 used for being connected with the short end of the L-shaped ejector rod 28 in a propping mode is installed at the bottom of the tuning button 19.

The above description is only a preferred embodiment of the present invention, and not intended to limit the present invention in other forms, and any person skilled in the art may apply the above modifications or changes to the equivalent embodiments with equivalent changes, without departing from the technical spirit of the present invention, and any simple modification, equivalent change and change made to the above embodiments according to the technical spirit of the present invention still belong to the protection scope of the technical spirit of the present invention.

Claims (4)

1. The utility model provides an aggregate unit of upright piano action machine and keyboard, includes action machine, keyboard (44) and well dish (45), and install on well dish (45) keyboard (44), installs fore-set (43) on keyboard (44), its characterized in that: the vertical piano also comprises an upper rail (39) and a lower rail (49), wherein the upper rail (39) and the lower rail (49) are arranged on a side plate of the vertical piano, and the mounting height of the upper rail (39) is higher than that of the lower rail (49); an upper shaft bracket (40) is arranged on the upper gear (39) from top to bottom, an upper connecting rod (41) is hinged on the upper shaft bracket (40), and the lower part of one end of the upper connecting rod (41) is connected with a top column (43) in a jacking way; a lower shaft bracket (48) is arranged on the lower gear (49) in an upward direction, a lower connecting rod (47) is hinged on the lower shaft bracket (48), a top shaft (50) is arranged at one end of the lower connecting rod (47), the top shaft (50) is connected with the bottom of a linkage rod (13) of the string striking machine in a jacking mode, and a pull rod (46) is hinged between the other end of the lower connecting rod (47) and the end, far away from the top column (43), of the upper connecting rod (41).

2. The upright piano action and keyboard linkage according to claim 1, wherein: and a silencing felt (42) is arranged at the joint of the lower part of the upper connecting rod (41) and the top of the top column (43).

3. The upright piano action and keyboard linkage according to claim 1, wherein: pull rod (46) including last pull rod (51) and lower link (53), the upper end and the last connecting rod (41) of going up pull rod (51) are articulated, the lower extreme and the lower connecting rod (47) of lower link (53) are articulated, threaded connection has threaded connection cover (52) between the lower extreme of going up pull rod (51) and the upper end of lower connecting rod (47), through adjusting the connection length of threaded connection cover (52) and last pull rod (51) and lower link (53), realize the length adjustment of pull rod (46).

4. The upright piano action and keyboard linkage according to claim 1, wherein: the string-striking machine comprises a string-striking machine main gear (9), the front part of the string-striking machine main gear (9) is hinged with a damper rod (6) through a damper shaft bracket (8), the top of the damper rod (6) is provided with a damper lead screw (4), the top of the damper lead screw (4) is provided with a damper head (2) with a damper felt (1) through a damper head button (3), the rear side of the damper lead screw (4) is provided with a damper gear (5), and the damper rod (6) is provided with a damper spring (7); a rotary beater cam (31) is hinged above the rear part of the string beating machine main gear (9) through a rotary beater shaft bracket (10); the top of the butt cam (31) is connected with a hammer handle (34), the top of the hammer handle (34) is provided with a hammer core (37) towards the front, a hammer felt (38) is arranged on the hammer core (37), the rear side of the hammer handle (34) is provided with a back rail (36), and the back rail (36) is provided with a back rail woolen (35); a hook spring (33) is arranged on the front side of the butt cam (31), and a hook rope (32) is connected to the hook spring (33); the rear side of the butt cam (31) is connected with a brake handle (27), a brake wood (26) is installed on the brake handle (27), and brake wood leather (25) is arranged on the brake wood (26); a butt felt (29) and a butt felt (30) are arranged at the lower part of the rear side of the butt cam (31); the bottom of a main gear (9) of the string-striking machine is hinged with a linkage rod (13) through a linkage device shaft bracket (12), a spoon nail (11) used for knocking and pushing a damper rod (6) is installed above the front part of the linkage rod (13), a climbing belt hook (16) and a wood supporting rod (17) are installed above the rear part of the linkage rod (13), the upper part of the climbing belt hook (16) is connected with a brake block (26) through a climbing belt (22), a wood support (23) with a wood support felt (24) is installed at the top of the wood supporting rod (17), and the wood support felt (24) is used for knocking brake block leather (25); an L-shaped ejector rod (28) is hinged to the linkage rod (13) through an ejector rod shaft bracket (14), the long end of the L-shaped ejector rod (28) is connected with a butt felt (29) and a butt felt (30) in a propping mode, an ejector rod spring (15) is installed between the short end of the L-shaped ejector rod (28) and the linkage rod (13), a tuning gear (20) is arranged above the short end of the L-shaped ejector rod (28), a tuning button (19) is installed on the tuning gear (20) downwards through a regulating screw (21), and a bottom felt (18) used for being connected with the short end of the L-shaped ejector rod (28) in a propping mode is installed at the bottom of the tuning button (19).

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