WO1996028807A1

WO1996028807A1 - Drum instrument, hydraulic system for such a drum instrument, and method for manufacturing such a drum instrument

Info

Publication number: WO1996028807A1
Application number: PCT/NL1996/000112
Authority: WO
Inventors: Willem Herman Masseling; Leendert Willem Cornelis De Jong
Original assignee: Applied Power Inc.
Priority date: 1995-03-14
Filing date: 1996-03-13
Publication date: 1996-09-19
Also published as: AU4850996A; NL9500507A

Abstract

Drum instrument comprising a frame (1) with a first rigid ring element which rests against the drumhead (20), and a second rigid ring element (23) which is situated around the first ring element and is in engagement with the drumhead (20). For regulation of the tension of the drumhead (20), one ring element (23) is movable relative to the other by means of a hydraulic system (10). This system (10) comprises a hydraulic actuator which acts upon the movable ring element (23) and which has a working chamber (11a) forming part of a volume for hydraulic fluid formed by the hydraulic system (10), so that the tension of the drumhead (20) can be regulated depending on the pressure in the working chamber (11a). The system (10) comprises setting means (12) for setting a basic pressure in the working chamber, and foot-operated means (13) for varying by foot the pressure in the working chamber (11a) of the hydraulic actuator, in such a way that the setting of the basic pressure achieved by means of the setting means (12) is retained. The hydraulic actuator (10) preferably acts upon the second ring element (23).

Description

Short title: Drum instrument, hydraulic system for such a drum instrument, and method for manufacturing such a drum instrument.

The present invention relates to a drum instrument according to the preamble of claims 1 and 7. The invention also relates to a hydraulic system for such a drum instrument and a method for manufacturing such a drum instrument.

DE 27 54 048 discloses a drum instrument, in this case a kettledrum, according to the preamble of claims 1 and 7. In the case of the known kettledrum the hydraulic actuator is a hose which can expand under the influence of the fluid pressure in the hose; in particular the cross- section of the hose can change. The hose lies between the frame and the first ring element of the kettledrum, which first ring element rests against the bottom-side of the drumhead. A piston-cylinder assembly is provided for setting the liquid pressure in the hose. The working chamber of this cylinder is connected by way of a line to the working chamber in the expandable hose. In the closed hydraulic system formed in this way a basic pressure can be set by fixing the piston at a particular position in the cylinder. In the case of the known kettledrum this is achieved by operating a rotary knob by hand. In this way the kettledrum can be tuned by the kettledrummer, of course before the start of the musical performance. The kettledrummer can read the pressure in the closed hydraulic volume on a pressure gauge.

The known kettledrum has a number of disadvantages.

First, the hydraulic system of the known kettledrum in practice does not allow the tension of the drumhead to be varied during playing of the kettledrum. On the one hand, the kettledrummer does not have a hand free to operate the rotary knob and, on the other hand, in the case of the known system no variation of the pressure is possible in a manner which in the process retains the basic pressure setting which has been carefully set during the tuning of the kettledrum.

Secondly, it is found that the positioning of the hydraulic actuator proposed according to DE 27 54 048 adversely affects the purity of sound of the instrument.

The object of the present invention is to eliminate the abovementioned disadvantages and in particular to provide a drum instrument with a hydraulic system for regulating the tension of the drumhead which can be operated without any problems, which is durable, and which guarantees a high sound quality.

This object is achieved according to a first aspect of the invention by providing a drum instrument according to the preamble of claim 1, which is characterized in that the hydraulic system also has foot-operated means for varying by foot the pressure in the working chamber of the hydraulic actuator, in such a way that the setting of the basic pressure achieved by means of the setting means is retained. Through foot-operated control of the pressure in the hydraulic system, the musician can now regulate the tension of the drumhead while playing. Due to the fact that the foot-operated means leave the basic pressure setting achieved during tuning of the instrument undisturbed, it is ensured that if the foot-operated means are not operated, the pressure in the closed volume of the hydraulic system assumes the value of the basic pressure.

Further advantageous embodiments of the drum instrument with variable pressure in the hydraulic system are described in subclaims 2 - 6.

In order to achieve a higher sound quality than that with the drum instrument according to DE 27 54 048, according to a second aspect of the present invention, provision is made in the drum instrument according to the preamble of claim 7 for the hydraulic actuator to act upon the second ring element.

This second aspect of the present invention is based on the realization that placing a hydraulic actuator between the first ring element situated below the drumhead and the frame, as in the case of DE 27 54 048, produces an undesirable damping of the vibrations of the drumhead and adversely affects the sound quality.

Further advantageous embodiments of this second aspect of the invention are described in subclai s 8 - 12. It will be clear that a very practical drum instrument is obtained if the measures according to both aspects of the present invention are used in combination, but this is not absolutely essential.

The exclusive right applied for also relates to a hydraulic system for a drum instrument according to the present invention. Provision is made for the hydraulic system to be supplied as a fully assembled system filled with hydraulic fluid to the producer of the drum instru¬ ment, who then only has to fit the hydraulic system in the drum instrument which he has manufactured. This is also advantageous in the event of any repairs having to be made to the drum instrument. The invention will be explained in greater detail below with reference to the drawing, in which:

Fig. 1 shows a diagrammatic view in perspective of the hydraulic system of a kettledrum according to the invention; Fig. 2 shows in section a detail of a preferred embodiment of the drum instrument according to the invention;

Fig. 3 is an illustration corresponding to Fig. 2, in which the tension in the drumhead is higher; Fig. 4 shows in longitudinal section a preferred embodiment of the piston-cylinder assembly for setting the basic pressure in the hydraulic system;

Fig. 5 shows in longitudinal section a preferred embodiment of the piston-cylinder assembly operated by foot pedal in Fig. 1; and

Fig. 6 shows a top view of the annular support, composed of two parts hingedly connected to each other, of the kettledrum according to Figs. 2 and 3.

Fig. 1 shows a part of a kettledrum according to the invention, namely frame 1 with three legs 2, which are connected to each other at the top side by a ring 4, and kettle 3, which rests by means of a ring 5 fixed thereto on the ring 4 (see Figs. 2 and 3). Fig. 1 also shows a hydraulic system 10 according to the invention, which serves to regulate the tension of the drumhead (not shown in Figure 1) of the kettledrum.

The hydraulic system 10 comprises a hose element 11 whose internal cavity 11a in the context of the present invention is described as a working chamber. The hose element 11 is expandable under the influence of the fluid pressure prevailing in the working chamber lla, as a result of which the hose element 11 serves as a hydraulic actuator by means of which the tension in the drumhead can be regulated. The way in which the hydraulic actuator is accommodated in the kettledrum, so that through regulation of the pressure in the hydraulic system the tension in the drumhead - and consequently the pitch - can be regulated, will be explained with reference to Figs. 2 and 3. The hydraulic system 10 also comprises a first piston-cylinder assembly 12, by means of which a basic pressure of the fluid in the hydraulic system can be set, and a second piston-cylinder assembly 13, by means of which the pressure in the hydraulic system can be varied. This variation of the pressure can occur during playing of the kettledrum, through the fact that a foot pedal 14 is provided. The pressure in the closed hydraulic system can be read from the top on a pressure gauge 15, for example an analogue pressure gauge. The second piston-cylinder assembly 13 and the foot pedal 14 are fixed on a common support 16, and the foot pedal 14 is mechanically connected to the piston of the second piston-cylinder assembly 13. A flexible line 17 connects to the second piston-cylinder assembly 13, so that the support 16 can be placed at any desired point on the ground. This gives the kettledrummer considerably more possibilities than if the foot pedal 14 were immovably connected to the kettledrum.

For use of the kettledrum according to Fig. 1, the kettledrummer proceeds as follows. After the kettledrum has been set up, the instrument can be tuned by turning rotary knob 18 by hand. Turning said knob 18 results in a movement of the piston in the cylinder of assembly 12. Since the hydraulic system is a closed system, i.e. the system forms an essentially invariable volume for the hydraulic fluid present therein, fluid can be forced into the hose 11, which expands as a result. This expansion is counteracted, inter alia, through the then increasing tension in the head of the drum, and an increase in the pressure in the system results. If the kettledrum has been tuned as desired, a pressure prevails in the system which in the context of the present invention is described as basic pressure.

During the musical performance it is possible to change the pitch of the kettledrum by varying the pressure in the hydraulic system by means of the foot pedal 14. This can be performed in a continuously variable manner by moving the piston of the assembly 13 in its cylinder. The use of the second piston-cylinder assembly 13 means that the setting of the basic pressure, which is obtained with the first assembly 12, is retained unchanged, and it cannot be changed accidentally either. Moreover, with very little effort it is possible to obtain a pressure in the system which results in high tension on the head of the kettledrum. Further advantages are that the hydraulic system requires no external energy supply (for example an electrical connection) , that the system functions com¬ pletely noiselessly, and that even after a long period of use it remains noiseless. Known mechanical systems for adjusting the tension of a head of a drum instrument also require considerably more maintenance, for example regular lubrication, in order to ensure noiseless and smooth movement of the moving parts. Such maintenance is not necessary in the case of the instrument according to the invention.

Figures 2 and 3 show in greater detail the way in which the tension in the head of the kettledrum according to the invention can be regulated by expansion of the hose 11. In Figs. 2 and 3 drumhead 20 is provided with a relatively flexible edge element 21 on its outer periphery. The head 20 lies over the bent-over top edge of the kettle 3 of the kettledrum, which top edge in the context of the present invention forms the first rigid ring element. The flexible edge element 21 is connected to a second ring element 23, which is made of metal and runs around the kettle 3 of the kettledrum. As can be seen from the section in Figs. 2 and 3, the second ring element 23 has a wall part which rests against the inside of the hose 11, a connecting piece - situated on the inner periphery of that wall part - for the edge element 21 fitted on the head of the kettledrum, and a wall part which extends on the outer periphery of that wall part and lies below the hose 11. At its top side the hose 11 is supported by an annular support 25, which is made of metal and lies around the drum 3. A top view of the support 25 is shown in Fig. 6. The annular support 25 is approximately C-shaped in cross-section, while the top part of the wall has a radius which corresponds approximately to the radius of the hose when it is not under pressure. The part of the wall of the annular support 25 connecting thereto lies against the outside of the hose 11. The bottom part of the wall of the third ring element lies under the edge 5 of the kettle 3. In order to permit fitting of the annular support 25 and to be able to replace the head 20 of the kettledrum, the third annular element 25 is in the form of a split element. It can be seen in Fig. 6 that the annular support 25 consists of two halves, which at their one end are connected to a hinge 26 and at their other end can be pulled towards each other by means of a clamping bolt 27.

It can also be seen in Figs. 2 and 3 that the edge 5 of the kettle 3 is provided with a vertical annular wall 30, which guides the edge element 21 fixed to the head 20 on the inner periphery thereof. In order to reduce the friction, the annular wall 30 is provided on its outer periphery with a sliding layer 31 of plastic.

As appears from a comparison of Figs. 2 and 3, the pressure of the fluid in the working chamber 11a of the hose 11 in the situation in Fig. 3 is greater than that in Fig. 2. The result of increasing the fluid pressure in the working chamber 11a is that the hose 11 expands. Since expansion in the peripheral direction is virtually impossible, due to the lateral enclosure of the hose 11 between the second ring element 23 and the annular support 25, the hose 11 will expand virtually exclusively in the vertical direction, and will change from the circular cross-section in Fig. 2 to the more oval cross-section in Fig. 3. The result of this is that the second ring element 23 is pressed uniformly downwards over its entire periphery relative to the annular support 25, and thus also relative to the top edge (the first ring element) of the kettle 3 (see the height difference "h" in Figs. 2 and 3) . This results in an increase in the tension in the head 20. Due to the fact that the head 20 is under tension all the way round, a very advantageous and regular tension pattern is produced in the head 20. If the pressure in the hydraulic system is lowered again, the head 20 pulls the ring 23 back up again and compresses the hose 11. Fig. 4 shows a preferred embodiment of the first piston-cylinder assembly of the hydraulic system of the kettledrum according to the invention, which serves to set the basic pressure in the hydraulic system. This embodiment differs from the embodiment shown in Fig. 1. The piston-cylinder assembly comprises a cylinder

40, which consists of two parts which are connected to each other to form a seal by means of a clamping ring 41. The cylinder 40 has a cylinder space 42, of which a part 44, shut off by a flexible rolling membrane 43, is connected by way of connection 45 to the remainder of the hydraulic system. The rolling membrane 43 is clamped between the two parts of the cylinder 40 and in this way also provides the fluid seal. The volume of part 44 of the cylinder space 42 can be changed by moving piston 46, which has a clearly smaller diameter than the diameter of the cylinder space 42. For movement of the piston 46, piston rod 47 is provided with external screw thread and is screwed into a corresponding threaded hole of the wall of the cylinder 40. Piston 46 can be moved by turning the piston rod 47 by means of manual knob 48. The piston rod 47 projects in a freely rotatable manner into the piston 46. In order to prevent transmission of torsion to the rolling membrane 43, a ball 49 is placed between the free end of the piston rod 47 and the bottom of the blind hole formed in the piston 46. The furthest inward rotated position of the piston 47 is indicated by dashed lines in Fig. 4. An analogue pressure gauge 50 is also screwed onto the cylinder 40, which pressure gauge is in communication with the space 44, and in this way can indicate the pressure in the hydraulic system of the kettledrum.

Fig. 5 shows a preferred embodiment of the second piston-cylinder assembly of the hydraulic system of the kettledrum according to the invention. The second piston-cylinder assembly comprises a cylinder 60, consisting of two parts which are connected to one another to form a seal by way of a clamping ring 61. The cylinder 60 has a cylinder space 62, of which a part 64 which is shut off by a flexible rolling membrane 63 is connected by way of connection 65 to the remainder of the hydraulic system. The volume of part 64 of the cylinder space 62 can be changed by moving piston 66. For this purpose, piston rod 67 is guided in a sliding manner in a corresponding bore of the cylinder 60. The piston can be moved inwards by moving end 68 of the piston rod 67 by means of a foot pedal (not shown) connected mechanically to that end. The piston rod 67 is screwed down in the piston 66. The position of the piston rod 67 pressed furthest inward is indicated by dashed lines in Fig. 5. Water is preferably used as the fluid for the hydraulic system, in particular water with glycol added.

A major advantage of using piston-cylinder assemblies with a membrane construction, as shown in Figs. 4 and 5, is that the volume of the hydraulic system is completely closed as a result, i.e. it is impossible for fluid to leak out of said volume. In the case of conventional piston-cylinder assemblies, where the piston slides in the cylinder, thereby forming a seal, there is a considerable chance of fluid leaking out along the piston. In the case of a drum instrument this would lead to the pitch which was set during the tuning being lost. The mem¬ brane construction has the further advantage that the cylinders do not have to meet such high standards as conventional cylinders where the piston moves to and fro therein, forming a seal.

If water is used as the hydraulic fluid, the rolling membranes of the piston-cylinder assemblies shown in Figs. 4 and 5 also have the advantage that smooth move- ent of the pistons is guaranteed. In a construction in which the piston slides in the cylinder and forms a seal, water would not have sufficient lubricating effect. The hose 11 is preferably made of rubber or polyurethane. Rubber or felt parts are preferably placed between the edge 5 provided on the kettle 3 and the edge 4 of the frame. These parts are indicated by 33 in Figs. 2 and 3.

In an embodiment which is not shown, the hydraulic system for regulating the tension of the head of the drum instrument can comprise only the piston-cylinder assembly connected to the foot-operated mechanism, instead of two piston-cylinder assemblies as described above. In that case the basic pressure in the hydraulic system can be achieved by detaining the piston of that piston-cylinder assembly, by means of an adjustable stop, in the position in which the volume of the working chamber of that piston-cylinder assembly is greatest. However, for practical use this embodiment is less advantageous than the embodiment described above, because in the above case the manual knob for tuning the drum instrument can be placed in a position above the ground which is easy to reach.

Claims

C L A I M S

1. Drum instrument with a drumhead, comprising a frame (1) with a first rigid ring element (3) which rests against the drumhead (20) , and a second rigid ring element (23) which is situated around the first ring element (3) and is in engagement with the drumhead, while for regulation of the tension of the drumhead one of the two ring elements (23) is movable relative to the other ring element (3) by means of a hydraulic system (10) , which hydraulic system comprises a hydraulic actuator (11) which acts upon the movable ring element (23) , and which has a working chamber (11a) forming part of a volume for hydraulic fluid formed by the hydraulic system, so that the tension of the drumhead can be regulated depending on the pressure in the working chamber, the hydraulic system having setting means (12, 18) for setting a basic pressure in the working chamber, characterized in that the hydraulic system (10) also comprises foot-operated means (13, 14) for varying by foot the pressure in the working chamber (11a) of the hydraulic actuator (11), such that the setting of the basic pressure achieved by means of the setting means (12) is retained.

2. Drum instrument according to claim 1, in which the setting means (12, 18) for the basic pressure comprise a first piston-cylinder assembly (12), and the foot-operated means comprise a second piston-cylinder assembly (13) and a foot pedal (14) for varying the position of the piston of the second piston-cylinder assembly (13).

3. Drum instrument according to claim 2, in which the second piston-cylinder assembly (13) and the foot pedal (14) are fixed on a common support (16) , and the foot pedal is connected mechanically to the piston-cylinder assembly (13) .

4. Drum instrument according to one or more of the preceding claims, in which the hydraulic actuator comprises a hose element (11) which is expandable under the influence of the pressure in the hydraulic system (10) , which hose element is placed between the frame (25) and the movable ring element (23) .

5. Drum instrument according to one or more of the preceding claims, in which a flexible line (17) connects to the second piston-cylinder assembly (13) .

6. Drum instrument according to one or more of the preceding claims, in which the hydraulic actuator (11) acts upon the second ring element (23) .

7. Drum instrument with a drumhead, comprising a frame (1) with a first rigid ring element (3) which rests against the drumhead (20) , and a second rigid ring element (23) which is situated around the first ring element (3) and is in engagement with the drumhead, while for regulation of the tension of the drumhead one of the two ring elements (23) is movable relative to the other ring element (3) by means of a hydraulic system (10) , which hydraulic system comprises a hydraulic actuator (11) which acts upon the movable ring element (23) , and which has a working chamber (11a) forming part of a volume for hydraulic fluid formed by the hydraulic system, so that the tension of the drumhead can be regulated depending on the pressure in the working chamber, the hydraulic system having setting means (12, 18) for setting a basic pressure in the working chamber, characterized in that the hydraulic actuator (11) acts upon the second ring element (23) .

8. Drum instrument according to claim 7, in which the hydraulic actuator comprises a hose (11) which is expandable, in particular as regards its cross-section, under the influence of the pressure in the working chamber (11a) formed by the hose.

9. Drum instrument according to claim 8, in which the frame is provided with an annular support (25) which has essentially the same annular dimensions as the second ring element (23), while the hose (11) is placed between the second ring element (23) and the annular support (25) .

10. Drum instrument according to claim 9, in which the annular support (25) rests against the outer periphery of the hose (11) .

11. Drum instrument according to claim 8 or 9, in which the annular support (25) is detachable, for replacement of the drumhead.

12. Drum instrument according to one or more of the preceding claims, in which a flexible fixing element (21) is fitted around the outer periphery of the drumhead (20) , while the second ring element (23) is equipped for connecting to the fixing element (21) .

13. Hydraulic system (10) for a drum instrument according to one or more of the preceding claims.

14. Kettledrum according to one or more of the preceding claims.

15. Method for manufacturing a drum instrument according to one or more of the preceding claims, in which the hydraulic system is combined to a fully assembled unit filled with hydraulic fluid, and this unit is subsequently built into the drum instrument.