FR2718877A1 - Hydraulic device for tensioning a membrane applied to a support. - Google Patents

Abstract

Use of an expansible member for varying the tension of a membrane. The membrane (2) is held by a rigid structure (4) and applied over the support (1). The expansible member (3) is wedged between the membrane (2) and the dimensionally stable structure (5). The support (1) and the structure (5) are stationary. When the volume of the expansible member is altered, the membrane (2) is deformed and its tension is also altered. The measurement of the pressure in the expansible member (3) corresponds to the tension of the membrane (2). The tensioning device is especially suitable for adjusting the tension of percussion instruments and especially kettledrums. It is highly responsive to adjustment and provides a precise and reliable indication of the tuning note.

Description

-1- 1 The present invention relates to a device for tensioning and

  to vary the tension of a membrane applied to a support. One of the fields of application of this invention is

  instruments with skins, and more specifically timpani which require a system allowing to modify the tension of the skin during the execution of a musical work.

  Current systems for varying the tension of timpani skins use metal rods which, associated with references, centralize the point of tightening of the skin. A lever system controlled by a pedal allows adjustment of the tension. These systems have the drawbacks of mechanical transmission, that is to say essentially play, and friction which can be the source of parasitic noise. In order to obtain the most regular tension possible, the rigid structure of the instrument base is very bulky and sometimes includes up to eight

flying arches.

  A mechanical system makes it possible to identify the different notes that can be obtained. This system is supported on the tightening circle or on the lever actuated by the pedal. This system has reliability flaws due to the multiplicity of moving parts and the inaccuracy of the

positioning of these.

  The invention presented is the use of an expandable member like a flexible hose which under the effect of its expansion comes to stretch the skin of the instrument. Several tension systems can be designed from this expandable member. However, direct contact of the skin with the expandable organ will lead to better sensitivity of the tension system. In fact, however small a variation in the pressure in the expandable organ, iM li affects the tension of the skin. Also the measurement of the pressure in the expandable organ using a manometer will allow

  know precisely the fundamental note emitted by the timpani.

  Such a hydraulic control device has the advantage of not having the play inherent in mechanical transmissions and offers excellent adjustment sensitivity. If the expandable organ is located over the entire periphery of the skin, it ensures equal tension at all points thereof, and

  the note emitted as its harmonics will only be purer.

  This expandable member being compact it is no longer necessary to have a heavy and bulky structure to support the barrel of the timpani. It is possible to think of a stand as a column that supports one or even two timpani. This foot makes it possible to fix on its upper part any other accessory useful to the percussionist, starting with the door support

wand or music stand.

  The connection ensured by an inextensible flexible hose between the tension circle and the pump

  foot, ensures quick and easy disassembly of the component parts of the instrument.

  The timpani is made up of the following parts: * a foot supporting a barrel of suitable profile having the qualities of resonator -2- 1 To a membrane which produces sound vibrations

  a tightening circle allowing the membrane applied to the fat to be kept in tension.

  With an expandable organ located on the entire periphery of the skin and ensuring the placing qualities

in tension of the skin.

  S. a foot-operated pump for pressurizing the liquid in the expandable member in order to regulate the tension of the membrane. A flexible hose makes the

  junction between the pump and the expandable member.

  If the skin tensioning system is external to the timpani, it does not change

  nothing its sound characteristics nor its design.

  The permnnet system can adapt tanks of different shapes or skins with different sound characteristics without the need to invest in a new set of instruments. The hydraulic system gives freedom as well on the positioning of the pressure gauges

  informing notes that agree on pedal systems for adjusting the tension.

  It is for example interesting to gather the information of the manometers on the lower part of the musician's desk. This allows you to know the chord notes without losing sight of the score, which is very significant. This device can very easily be done by a liquid crystal or other type display, reproducing a musical staff with the notes.

  agree with the different timpani used.

  It is also wise for the execution of certain works to be able to place the different pedal systems in the immediate vicinity of the timpani driver's seat. It is planned to produce a seat, the base of which can support the pedals of the adjustment mechanisms, possibly with the example of an organ crankset. In addition, the timpani adjustment lever mechanism can have the following characteristics:

  constant contact pressure throughout the lever stroke.

  To control the pedal travel according to the agreement.

  The ease of removing the skin makes it easy to access the inside of the barrel.

  timpani. It is therefore planned to make a mute reducing the sound qualities of the instrument.

  This mute can for example be produced by a solid disc covered with a foam having a relief studied to dampen the sound vibrations. The diameter of the disc defines the height of the disc in the barrel of the instrument. This mute allows the musician to do instrumental technique work without having to endure too much sound intensity.

  important, and facilitates the practice of the instrument in urban housing.

-3-

  1 Figures 1 to 3 show different embodiments of a tension system using the expandable member.

  Figures 4 to 10 show the details of an embodiment of a timpani with the advantages of

  new tension system shown in Figure 3.

  Figure 1 shows a tension system on which the expandable member, a flexible material pipe (3), is located between the barrel of the instrument (1) and the skin of the timpani (2). This system is particularly well suited to skins which coat the barrel of the instrument. The skin can be kept stretched by a strapping system (4) or a system of laces. It requires a particular profile of the barrel of the instrument in order to adapt to the shape of the expandable member maintained

  in position by the tightening circle (5).

  Figure 2 shows a tension system on which rorgane expandable (3), a material pipe

  flexible, is located between the barrel of the instrument (1) and the support circle (6) of the skin of the instrument. This embodiment introduces an additional part, the support circle (6). The discontinuity between the support circle (6) and the barrel of the instrument (1) disturbs the transmission of waves from the skin to the barrel of the instrument.

  Figure 3 shows a system on which the support of the expandable member (3) is made directly on the upper part of the skin of the instrument (2). The expandable member is located between the skin (2) and the

  tightening circle acting at all points according to the principle of the traditional instrument (5).

  The circle must respect the following profile: À The inside diameter of the tightening circle (dl) must be the diameter of the timpani (dO)

  increased by a few millimeters (2 to 3).

  Intérieur The inside diameter of the tightening circle (d3) must be the diameter of the strapping of the

  skin (d2) increased by a few millimeters (2 to 3).

  * The height H depends on the volume of the expandable member and the height of the strapping of the

  skin (4). In practice, the height should be a few centimeters (H> 3 cm.).

  The thickness of the tightening circle depends on the material in which it is made. It is essential that there is no deformation of the upper part of the circle of

  tightening (5) under the effect of the pressure which is a few bars.

  Respecting these dimensions makes it possible to ensure that the expandable and possibly extensible clamping member does not leave the area (A), otherwise the effect of placing under

tension would get out of hand.

  Figure 4 shows the parts ensuring the junction between the upper circle (5) and the drum of the timpani (1). These parts (7 8 9 10 1l) allow easy mounting of the skin, placing under -4-

  1 preliminary tension and by the reversible profile of the part (9) an adaptation to skins of different depths.

  On the outside timpani drum, the part (10) is fixed opposite the part (11) which is located in the timpani drum. For ease of storing timpani drums, it is advisable to nest them in one another. The part (11) then serves to support the part (10)

  a timpani drum of smaller diameter when storing it.

  The part (9) serves as a support for the bolt (8) which is screwed into the part (7). The upper part of the part (9) can be the side (9a) or the side (9b) depending on how it is engaged in the part (10). When the assembly is such that the side (9a) is in the high position (opposite position of the figure) the circle (5) can descend lower before touching the part (9). This assembly is more suitable for skins whose hoop (4) has a significant difference in height by

  relative to the surface of the skin (2).

  The part (7) fixed on the sides of the circle (5) consists of a vertical threaded groove. This thread receives the bolt (8) which will hold the tank to the tightening circle (5). In its lower part, the bolt (8) ends with a butterfly (8a) which ensures the pre-tension of the skin. In its upper section, the bolt (8) has a hexagonal recess allowing it to be maneuvered using a hexagon wrench. This keeps an extra adjustment of the tension very accessible to the timpanist. The pieces (7, 8, 9, 10, 11) are six or eight in number

  according to the diameter of the tank and distributed regularly over the circumference of the timpani.

  Figure 5 shows a vertical section of the coupling of the expandable member (3) to the hydraulic part (12) supplying the circuit. The part (12) is a rigid pipe which makes the connection between the pipe coming from the adjustment mechanism and the two ends of the expandable member (3). The tight connection between these two parts is made by a clamp (13). A supply of the expandable member by its two ends ensures better dynamic performance thanks to

  a good distribution of the pressure which causes the rapid and homogeneous displacement of the skin.

  The oversizing of the main feed section (12) allows rapid variations in

  tension, necessary in the contemporary repertoire.

  Figure 6 shows a top view of the coupling of the expandable member to the hydraulic part supplying the system. In order to have pressure on the entire circumference of the hooping of the skin

  equal, the two tubes of the part (12) entering the circle (5) are placed contiguously.

  In dotted lines is shown the expandable member (3). Hose clamps (13) provide sealing

between parts (3) and (12).

  FIG. 7 shows an embodiment of the system for pressurizing the liquid sent into the expandable member. This system consists of a jack (piston, cylinder) articulated at point C and a lever articulated at point D which can be actuated by the musician's foot. This system is distinguished by a non-fixed connection of the lever piston parts symbolized in the figure by the position of point B. Thus the mobility of the three lever elements, piston, and cylinder governed by the following relationships allows all the adaptations of strokes and pressures. .5 Angle 0 is defined as the angle between the horizontal and the pedal lever. The length of the lever L / ever is defined as the distance between points A and D. The length of the Lvein cylinder is defined as the distance between points B and C.

  The function fl gives the relationship between the angle 0 and the length of the cylinder Lvrin.

  Lvé, rin = f 1 (o) The function f2 gives the relationship between the angle 0 and the force exerted vertically at the end of the lever Flevier À Fv / er = f 2 (0) The function f3 gives the relationship between the length of the Lv.rn cylinder and the force exerted in its

Fvrin end.

  F = f3 (L Fverin véf3 (Lvrin) Let D be the pivot point of the lever having in the coordinate system (C, i, j) the coordinates (xD 'YD),' we have the relation: Llevier C s () Flevier = lxD. sin (a) + yD.cos (cx) cylinder oa is the angle made by the cylinder of the cylinder with the horizontal axis For any angle 0, we can thus determine the angle a which verifies the previous relation and have

  in the reference (C, i, j) the position of point B end of the jack.

  FIG. 8 shows a possible embodiment of the system shown schematically in FIG. 7. The point C is the point of articulation of the jack. Point D is the point of articulation of the

lever (13).

  In the slot (14) is housed a pin fixed to the end of the cylinder body (E) of the jack.

  When the lever (13) moves, the slot (14) forces the cylinder to take the desired angle. In the slot (15) is housed the end B of the piston of the cylinder. When the lever (13) moves, the slot (15) forces the cylinder to take the desired length Lvdri / n The cylinder being positioned in the right direction by the slot (14), there is no lateral force which

  come and exercise on the piston arm.

  -6- 1 The part (16) is an axis articulated in F which allows by a blocking system to maintain in a given position the jack of the jack. A quick coupling attached to the base of the cylinder allows

  6possibly to separate the hose which connects the cylinder of the jack to the expandable member.

  Figure 9 shows the mounting of the timpani on its support foot.

  S The part (17) is a pin which allows you to adjust the height of the part (18) which supports the tightening circle (5). This part (18) has hinges d6saxed relative to each other which allow to engage the end (19) of the tightening circle. The presence of the two hinges on the part (18) and the two off-center sockets (19) on the tightening circle (5) makes it possible to achieve

  the assembly shown in Figure 10.

  Figure 10 shows how the use of two hinges and two shanks at different heights makes it possible to support two timpani in the same horizontal plane In order to ensure a better seat of the instrument, one can establish two or three support points thus produced (17, 18, 19, 20) on the periphery of the instrument -7-

Claims (9)

Claims   1) Device for tensioning and varying the tension of a membrane, such as a timpani skin, for ensuring uniform tension over the entire periphery of a circular membrane, characterized in that it comprises a organ capable of being dilated by a liquid under pressure.   2) Device according to claim 1, characterized in that the expandable member is brought directly into contact with a membrane of any shape to vary the tension thereof. The expandable member (3) being trapped between the membrane (2) and a non-deformable structure (5) while the membrane is initially held on a rigid structure   (4) or may be integral with the non-deformable structure (5).   3) Device according to claims 1 and 2, characterized in that it comprises a pressure gauge   with needle or digital display placed either on the instrument or on any other support, for example the musician's desk. The pressure measurement in the expandable member obtained by the pressure gauge, being transformed into music note information, displayed by crystals   liquids or by a needle indicator.   4) Device according to any one of claims 1 to 3, characterized in that it   comprises a supply system for the expandable member intended to modify the volume of this expandable member. This feeding system is characterized by the junction of the two ends of the expandable member with the feeding member outside the tightening circle. The tight connection between the expandable member (3) and the supply system (12) can be   provided by a clamp (13) outside the clamping circle (5).   ) Device according to any one of claims 1 to 4, characterized in that it   includes a pump system actuated by a lever and consisting of a cylinder. The point of connection between these two parts along a path defined by guiding the slots (14) and (15), which makes it possible to obtain, for a given inclination of the lever, the desired chord note by exerting the desired force in end of the lever. An angle at between the cylinder of the jack and the horizontal axis being determined by the following equation: LL -co lever = xD sin (a) + YD. cos (a) cylinder   O being the angle between the horizontal and the pedal lever. -8-   6) Device according to any one of claims 1 to 5, characterized in that it   includes a secondary tuning system consisting for example of a second small cylinder which allows very precise adjustment of the skin tension. This system can   be operated manually and for example be integral with the non-deformable structure (5).   7) Device according to any one of claims 1 to 6, characterized in that the   non-deformable structure (5) supports the bowl (1) of the timpani via the parts (7, 8, 9, 10, 11), the element (9) by its reversible design allowing it to be adapted according to the   direction in which it is engaged with skins of different depths.   8) Device according to any one of claims 1 to 7, characterized in that the   elements (10) fits into the element (11) of a timpani tank of larger diameter, this principle of nesting the tanks one inside the other ensuring a   minimum space required for the storage and transport of instruments.   9) Device according to any one of claims 1 to 8, characterized in that it   includes a mute consisting of a piece absorbing sound waves and placed in the instrument.   ) Device according to any one of claims 1 to 9, characterized in that it   comprises a ring (18) having offset hinges at several heights which engage   in hinges (19) integral with the tightening circle.   11) Device according to any one of claims 1 to 10, characterized in that it   includes a foot to support one or more timpani, as well as to adjust the   height and tilt of the instruments.