WO1995028698A1

WO1995028698A1 - Hydraulic device for tensioning a membrane applied over a support

Info

Publication number: WO1995028698A1
Application number: PCT/FR1995/000470
Authority: WO
Inventors: Raphaël MARTIN
Original assignee: Martin Raphael
Priority date: 1994-04-13
Filing date: 1995-04-12
Publication date: 1995-10-26
Also published as: FR2718877A1; FR2718877B1

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

Hydraulic device for tensioning a membrane applied to a support

The present invention relates to a device for tensioning and varying the tension of a membrane applied to a support. One of the fields of application of this invention is the instruments with skins, and more specifically the timpani which require a system making it possible to modify the tension of the skin during the performance of a musical work.

The current systems allowing to faine vary the tension of PE? timpani, use metal rods which, associated with references, centralize the point of tightening of the skin. A lever system controlled by a pedal allows tension adjustment. 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 base of the instrument is very voluminous 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 their positioning.

The invention presented is the use of an expandable member as a flexible hose which under the effect of its expansion comes to tighten the skin of the rinstrumenLPlusieurs 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. Indeed, however small the variation in the pressure in the expandable organ, immediately affects the tension of the skin. Also the measurement of the pressure in the expandable organ using a manometer will allow to 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 on the entire periphery of the skin, it ensures an equal tension in all the points of the latter, 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 stick holder or the music stand.

The connection ensured by an inextensible flexible hose between the tension circle and the foot pump, ensures quick and easy disassembly of the component parts of the instrument The timpani consists of the following parts: • a support leg

• an adapted profile drum having the qualities of a resonator

SUBSTITUTE SHEET (RULE 26) • a membrane that produces sound vibrations

• a tightening circle to keep the membrane applied to the barrel in tension

• an expandable member located over the entire periphery of the skin and ensuring the tensioning qualities of the skin. • a foot-operated pump for pressurizing the liquid in the expandable member in order to regulate the tension of the membrane. A flexible hose connects the pump to the expandable member.

If the skin tensioning system is external to the timpani drum, it does not change its sound characteristics or its design. The system makes it possible to adapt tanks of different shapes or skins of 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 of the chord notes as on the pedal systems for the adjustment of the tension.

π 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 chord notes of the various 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. • control of the pedal travel according to the agreement.

The ease of removing the skin allows easy access to the inside of the timpani drum. 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 foam having a relief studied to dampen 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 excessive sound intensity, and facilitates the practice of the instrument in urban housing. Figures 1 to 3 show different embodiments of a tension system using the expandable member.

FIGS. 4 to 10 present the details of an embodiment of a timpani comprising the advantages of the new tension system presented in FIG. 3.

FIG. 1 shows a tension system on which the expandable member, a hose made of flexible material (3), is situated 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 taut 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 held in position by the tightening circle (5).

FIG. 2 shows a tension system on which the expandable member (3), a hose made of flexible material, 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: "The inside diameter of the tightening circle (dl) must be the diameter of the timpani (dO) increased by a few millimeters (2 to 3).

• The inside diameter of the tightening circle (d3) must be the diameter of the skin hoop (d2) increased by a few millimeters (2 to 3).

• The height H depends on the volume of the expandable member and on the height of the hooping 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, π is essential that there is no deformation of the upper part of the tightening circle (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 tensioning effect would become uncontrollable.

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 11) allow easy mounting of the skin, placing under prior 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 easy storage of timpani drums, it is a good idea to nest them one inside the other. The part (11) is then used to suppoπer the part (10) of 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 level with 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 depending on 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 organ 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 power section (12) allows rapid voltage variations, 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 an equal pressure over the entire circumference of the hooping of the skin, the two tubes of the part (12) penetrating into 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 cylinder (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 characterized 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 adaptations of strokes and pressures . The angle θ is defined as the angle between the horizontal and the pedal lever. The length of the lever L.. is defined as the distance between points A and D.

The length of the cylinder L *. is defined as the distance between points B and C.

The function f 1 gives the relationship between the angle θ and the length of the cylinder L. . .

The function f2 gives the relationship between the angle θ and the force exerted vertically at the end of the lever lever

"lever = fW

The function f3 gives the relationship between the length of the cylinder L. . and the force exerted at its end F _yMn . ^F veain ^{= f3 (L} jack

Let D be the pivot point of the lever having in the coordinate system (C, i, j) the coordinates (x _D , y ~), we have the relation:

where α is the angle made by the cylinder of the cylinder with the horizontal axis.

For any angle θ, we can thus determine the angle α which verifies the previous relationship and have in the coordinate system (C, i, j) the position of point B end of the jack.

FIG. 8 shows a possible embodiment of the system shown diagrammatically 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 α. 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 jack to take the desired length L. . .

The cylinder being positioned in the right direction by the slot (14), there is no lateral force which comes to act on the piston arm. The part (16) is an axis articulated in F which allows by a blocking system to maintain in a given position the lever of the jack. A quick connector fixed on the base of the cylinder can optionally separate the hose which connects the cylinder of the cylinder to the expandable member.

FIG. 9 shows the mounting of the timpani on its support foot The part (17) is a pin which makes it possible to adjust the height of the part (18) which supports the tightening circle (5). This part (18) has off-center hinges relative to each other which make it possible to engage the end (19) of the tightening circle. The presence of the two hinges on the part (18) and the two sockets (19) offset on the tightening circle (5) allows the assembly presented in FIG. 10 to be carried out.

Figure 10 shows how the use of two hinges and two shanks at different heights can support two timpani in the same horizontal plane. In order to ensure better seating of the instrument, two or three support points thus produced (17, 18, 19, 20) can be established on the periphery of the instrument.

Claims

1) Device making it possible to tension and vary the tension of a membrane, such as a timpani skin, making it possible to ensure uniform tension over the entire periphery of a circular membrane, comprising a member capable of being expanded by a pressurized liquid, characterized in that the expandable member is brought into direct contact with the membrane of any shape, the expandable member (3) being trapped between the membrane (2) and a non-deformable structure (5).

2) Device according to claim 1, characterized in that it comprises a needle pressure gauge 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 musical note information, displayed by liquid crystal or by a pointer indicator.

3) Device according to any one of claims 1 to 2, characterized in that it comprises a supply system for the expandable member intended to modify the volume of this expandable member, this supply system being made by the junction of the two ends of the expandable member with the supply member external to the tightening circle, the tight junction between the expandable member (3) and the supply system (12), being provided for example by a collar clamp (13) outside the clamping circle (5).

4) Device according to any one of claims 1 to 3, characterized in that it comprises 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 α between the cylinder of the cylinder and the horizontal axis being determined by the following equation:

'lever ^' → ^ levi r _{= sin (α) + os (α)} | cylinder

θ being the angle between the horizontal and the pedal lever 5) Device according to any one of claims 1 to 4, characterized in that it comprises a secondary tuning system constituted for example by a second small cylinder which allows a very precise adjustment of the tension of the skin, this system being manually operated and can be integral with the non-deformable structure (5).

6) Device according to any one of claims 1 to 5, characterized in that the non-deformable structure (5) supports the tank (1) of the timpani through the parts (7, 8, 9, 10, 11) , the element (9) by its reversible design making it possible to adapt in the direction in which it is engaged to skins of different depths.

7) Device according to any one of claims 1 to 6, characterized in that the element (10) fits into the element (11) of a timpani tank of larger diameter, this principle of interlocking of the tanks one inside the other ensuring minimal space for the storage and transport of the instruments.

8) Device according to any one of claims 1 to 7, characterized in that it comprises a mute constituted by a part absorbing the sound waves, placed in the barrel of the instrument, without being in direct contact with the vibrating membrane .

9) Device according to any one of claims 1 to 8, characterized in that it comprises a ring (18) having offset hinges at several heights which engage in hinges (19) integral with the tightening circle.

10) Device according to any one of claims 1 to 9, characterized in that it comprises a foot making it possible to support one or more timpani, as well as to adjust the height and the inclination of the instruments.