| JP05305629 | MANUFACTURE OF POLYURETHANE FOAM MOLDED ARITCLE |
| WO/2008/106728 | METHOD AND APPARATUS FOR MOULDING CANNULAE |
| JP05042557 | HOLLOW MOLDING METHOD |
PHILIPS INTELLECTUAL PROPERTY & STANDARDS GMBH (Steindamm 94, Hamburg, 20099, DE)
MUELLER, Stefan (AA Eindhoven, NL-5656, NL)
CLAIMS:
1. Method of manufacturing a fluid damper (4) having an undercut portion (22) in a flexible part (8) of the damper (4), comprising the steps of: moulding the flexible part (8) of the damper (4) in a mould, comprising an outer mould part and a movable inner mould part, during which moulding the flexible part (8) is formed as a relieving wall part as seen in the direction of movement of the inner mould part, and a connecting bulge (21) in line with said direction of movement of the inner mould part, removing the formed flexible part (8) from the mould, and flattening the bulge (21) in a direction towards the relieving wall part such that at least a part of the bulge (21) and the relieving wall part is converted into the undercut portion (22) extending substantially perpendicular to the direction of movement of the inner mould part and maintaining the flattened bulge (21) in this position.
2. A fluid damper (4), comprising a base part (6), a central member having an outer surface and a centre line (5), said central member (7) and base part (6) fixed to each other, a flexible part (8) having a first end portion (12) fixed to the base part (6) and a second end portion (13) fixed to the central member (7) in a first connecting portion (14), and a fluid- filled cavity (15) which is enclosed by the base part (6), the central member (7) and the flexible part (8), the flexible part (8) being provided with an action portion (11) having an inner surface contacting the cavity (15) and facing the central member (7), which action portion (11) is movable with respect to the central member (7) in at least a first direction of movement parallel to the centre line (5) and a second direction of movement opposite thereto, and a first elastic portion (9) extending between the first connecting portion (14) of the central member (7) and the action portion (11), the first end portion (12) of the flexible part (8) lies beyond the inner surface (18) of the action portion (11) viewed from the centre line (5), wherein the first elastic portion (9) is adapted such that the fluid damper (4) has a ready- for-assembly condition (A) in which the first elastic portion (9) extends at least partly beyond the first connecting portion (14) viewed in the first direction of movement, and an assembled condition (B) in which at least a part of the first elastic portion (9) forms an undercut portion (22) extending in radial direction beyond the inner surface (18) of the action portion (11) viewed from the centre line (5), and the flexible part (8) has a contact surface contacting the cavity (15), which contact surface and the outer surface of the central member (7) are relieving surfaces in the second direction of movement in the ready- for-assemb Iy condition (A).
3. The fluid damper (4) according to claim 2, wherein in the ready- for-assembly condition (A) the first connecting portion (14) lies beyond the action portion (11) viewed in the first direction of movement, and at least a part of the first elastic portion (9) forms a bulge (21) beyond the first connecting portion (14) viewed in the first direction of movement.
4. The fluid damper (4) according to claim 2 or 3, wherein the flexible part (8) comprises a second elastic portion (10) extending between the action portion (11) and the first end portion (12) of the flexible part (8) which second elastic portion (10) has an S- shaped cross section in a plane which extends from the centre line (5) in radial direction.
5. The fluid damper (4) according to claim 4, wherein the first and second elastic portion (9, 10) and an upper and a lower side (19, 20) of the action portion (11), facing the first and second direction of movement, respectively, are adapted such, that in the assembled condition (B) the upper side (19) of the action portion (11) strikes against the first elastic portion (9) in the first direction of movement and the lower side (20) of the action portion (11) strikes against the second elastic portion (10) in the second direction of movement, respectively, at a predetermined distance from a predetermined reference position, so as to achieve a progressive spring factor characteristic when the action portion (11) is displaced beyond the predetermined distance viewed from the reference position.
6. The fluid damper (4) according to claim 5, wherein the upper and lower side (19, 20) of the action portion (11) comprise an elastic material.
7. The fluid damper (4) according to anyone of the claims 2 to 6, wherein the central member (7), the flexible part (8) and the base part (6) are concentrically orientated around the centre line (5) forming a circular fluid damper (4).
8. The fluid damper (4) according to anyone of the claims 2 to 7, wherein the first end portion (12) of the flexible part (8), the central member (7), the action portion (11), and the base part (6) are made from a non-elastic material.
9. The fluid damper (4) according to anyone of the claims 4 to 8, wherein the second elastic portion (10) is made from a different material than the first elastic portion (9), whereas its thickness is larger so as to achieve a predetermined spring factor characteristic.
10. The fluid damper (4) according to claims 4 - 9, wherein the thickness of the second elastic portion (10) varies over its length between the action portion (11) and the first end portion (12).
11. A fluid damper (4), comprising a base part (6), a central member (7) having a centre line (5), which base part (6) and central member (7) are fixed to each other, a flexible part (8) having a first end portion (12) fixed to the base part (6) and a second end portion (13) fixed to the central member (7), and a fluid- filled cavity (15) which is enclosed by the base part (6), the central member (7) and the flexible part (8), the flexible part (8) being provided with an action portion (11) which is movable with respect to the central member (7) in at least a first direction of movement parallel to the centre line (5) and a second direction of movement opposite thereto, the action portion (11) having an upper side (19) facing the first direction of movement and a lower side (20) facing the second direction of movement, the action portion (11) protruding into the fluid cavity (15) such that the fluid cavity (15) partly extends beyond the upper side (19) of the action portion (11) in the first direction of movement and beyond the lower side (20) of the action portion (11) in the second direction of movement, and a first elastic portion (9) connected to the central member (7) and the action portion (11), and a second elastic portion (10) connected to the first end portion (12) and the action portion (11), wherein the first and second elastic portion (9, 10) and the upper and lower side (19, 20) of the action portion (11) are adapted such, that the upper side (19) of the action portion (11) strikes against the first elastic portion (9) in the first direction of movement and the lower side (20) of the action portion (11) strikes against the second elastic portion (10) in the second direction of movement, respectively, at a predetermined distance from a predetermined reference position, so as to achieve a progressive spring factor characteristic when the action portion (11) is displaced beyond the predetermined distance viewed from the reference position.
12. The fluid damper (4) according to claim 11, wherein the upper and lower side (19, 20) of the action portion (11) are made from an elastic material.
13. An electronic device (1), in particular an optical disk player, provided with at least one fluid damper (4) for damping a vibrating part (2) which is mounted to a housing (3) of the electronic device (1) through the fluid damper (4) according to one of the claims 2 - 12. |
A method of manufacturing a fluid damper, a fluid damper and an electronic device
The present invention relates to a method of manufacturing a fluid damper for an electronic device, as well as to such a fluid damper and an electronic device provided with the fluid damper.
A fluid damper is known from the Japanese patent application JP 2004-21883. This prior art document discloses a fluid damper for damping of vibrations in a disk drive unit for disk media such as CD, DVD and the like. The known fluid damper is provided with an integrated spring member which comprises a flexible tubed part made of rubber- like elastic material. The flexible part comprises an attachment slot to which a vibrating part in the disk drive unit can be fixed. When the vibrating part displaces, the flexible part will move the fluid within the fluid damper, which has a damping effect. Furthermore, a displacement of the vibrating part in a certain direction results in a spring force generated by the flexible part on the vibrating part in opposite direction. A disadvantage of the fluid damper described in the prior art document is that it cannot be manufactured by a relatively low-cost moulding process.
It is an object of the present invention to provide a method for manufacturing the fluid damper in a simplified manner.
To obtain this object, the method of manufacturing a fluid damper having an undercut portion in a flexible part of the damper, comprises the steps of: moulding the flexible part of the damper in a mould, comprising an outer mould part and a movable inner mould part, during which moulding the flexible part is formed as a relieving wall part as seen in the direction of movement of the inner mould part, and a connecting bulge in line with said direction of movement of the inner mould part, removing the formed flexible part from the mould, and flattening the bulge in a direction towards the relieving wall part such that at least a part of the bulge and the relieving wall part is converted into the undercut portion
extending substantially perpendicular to the direction of movement of the inner mould part and maintaining the flattened bulge in this position.
Due to these features it is possible to manufacture the fluid damper in a moulding process. This lowers the costs of and simplifies the manufacturing process of the fluid damper.
The invention also relates to a fluid damper. The fluid damper according to the invention comprises a base part, a central member having an outer surface and a centre line, said central member and base part fixed to each other, a flexible part having a first end portion fixed to the base part and a second end portion fixed to the central member in a first connecting portion, and a fluid- filled cavity which is enclosed by the base part, the central member and the flexible part, the flexible part being provided with an action portion having an inner surface contacting the cavity and facing the central member, which action portion is movable with respect to the central member in at least a first direction of movement parallel to the centre line and a second direction of movement opposite thereto, and a first elastic portion extending between the first connecting portion of the central member and the action portion, the first end portion of the flexible part lies beyond the inner surface of the action portion viewed from the centre line, wherein the first elastic portion is adapted such that the fluid damper has a ready- for-assembly condition in which the first elastic portion extends at least partly beyond the first connecting portion viewed in the first direction of movement, and an assembled condition in which at least a part of the first elastic portion forms an undercut portion extending in radial direction beyond the inner surface of the action portion viewed from the centre line, and the flexible part has a contact surface contacting the cavity, which contact surface and the outer surface of the central member are relieving surfaces in the second direction of movement in the ready- for-assembly condition.
The advantage of this fluid damper is that its cost price is lowered because its features enable a low-cost and simple manufacturing method.
The advantage of the embodiment of claim 3 is that it enables a further simplified manufacturing method.
The embodiment of claim 4 has the advantage that it provides the opportunity to achieve a predetermined spring characteristic in the first and second direction of
movement, whereas it also provides a predetermined spring characteristic in a radial direction of the centre line.
The embodiment defined in claim 5 provides the benefit that a progressive spring factor characteristic avoids high amplitude vibrations hence enabling a reduced size of an electronic device which is provided with the fluid damper.
The features of claim 6 provide a simple construction to achieve a progressive spring factor characteristic.
Due to the features of claim 8 the central member and the base part provide a rigid basis for supporting the flexible part, whereas the action portion forms a rigid part to which a vibrating part are a housing of the electronic device can be fixed. A non-elastic material is defined herein as a material having a high elastic modulus.
The advantage of the embodiment defined in claim 9 is that the spring factor characteristic is determined by material and configuration choices which can be adjusted relatively simple in the manufacturing method of a fluid damper.
Claim 10 defines measures to achieve a further improved predetermined spring factor characteristic.
The embodiment of a fluid damper according to claim 11 has the advantage that vibrations of high amplitude are avoided by a simple construction.
The invention also relates to an electronic device. The electronic device according to the invention is defined in claim 13.
These and other aspects and advantages of the invention will be apparent from the following description with reference to the drawings. In the drawings:
Fig. 1 is a perspective plan view of an optical disk player provided with fluid dampers according to the invention.
Fig. 2 is a schematic cross sectional view of a fluid damper in assembled condition according to the invention.
Fig. 3a-3c are schematic cross sectional views of a part of the fluid damper of Fig. 2 at different displacement steps of the action portion in downward direction.
Fig. 4a-4c are schematic cross sectional views of a part of the fluid damper of Fig. 2 at different displacement steps of the action portion in upward direction.
Fig. 5 is a graph of spring force versus displacement of the action portion in different directions with respect to a reference position of the action portion of the fluid damper of Fig. 2.
Fig. 6 is a schematic cross sectional view of a part of the fluid damper in ready-for-assembly condition and assembled condition.
Fig. 1 shows an optical disk player 1 comprising a player part 2 and a housing 3. The player part 2 is resiliency attached to the housing 3 through fluid dampers 4 with integrated spring function. Springs and dampers are desired in optical disk players 1 or other electronic devices which operate under vibrational conditions in practical use such as in cars or when used as portable devices, for example. Using dampers with integrated spring function such as shown in Fig. 1 has the advantage that less components have to be assembled in comparison with using separate springs and dampers.
The fluid damper 4 according to the invention has a ready-for-assembly condition and an assembled condition. In the ready-for-assembly condition the fluid damper 4 has the configuration after manufacturing it, whereas in the assembled condition the shape of the fluid damper 4 is changed to obtain its desired characteristics of combined spring/damper function.
Fig. 2 shows a cross section of an embodiment of the fluid damper 4 in the assembled condition according to the invention. It has a circular shape with a centre line 5 and comprises a base part 6, a central member 7 and a flexible part 8. The flexible part 8 comprises a first elastic portion 9, a second elastic portion 10, an action portion 11, a first end portion 12 and a second end portion 13. The first end portion 12 is fixed to the base part 6 and the second end portion 13 is fixed to the central member 7 in a first connecting portion 14. The flexible part 8, the central member 7 and the base part 6 enclose a cavity 15, which is filled with a fluid, preferably oil. The action portion 11 is displaceable with respect to the base part 6 in X and +Y and -Y direction (as the embodiment of Fig. 2 is symmetrical in rotational direction only the X direction is indicated in Fig. 2).
The fluid damper 4 has an upper edge 16 which is aligned with the player part 2 of the disk player 1 in the assembled condition. Fixation of the damper 4 to the player part 2 can be achieved, for example, by inserting a screw through a through-hole 17 in +Y direction, and fixing it into the player part 2. The action portion 11 can be fixed to the housing 3 of the disk player 1, such as shown in Fig. 1. In order to obtain the shape of the
fluid damper 4 in the assembled condition such as shown in Fig. 2 the wall portion of the player part 2 to which the upper edge 16 is clamped preferably extends at least beyond an inner edge 18 of the action portion 11 viewed from the centre line 5 of the fluid damper 4 so as to form the first elastic portion 9 as a partly enclosure of a variable volume above the action portion 11 , which will be explained below.
In the embodiment of Fig. 2 the lower end of the second elastic portion 10 is fixed to the first end portion 12 and the upper end is fixed to the action portion 11. The second elastic portion 10 has an S-shaped cross section and is elastically de-formable in all directions, hence functioning as a spring in all directions of movement of the action portion 11 with respect to the base part 6. When displacing the action portion 11 in + Y direction a spring force is generated by elongating the second elastic portion 10. When displacing the action portion 11 in -Y direction a spring force is generated by a bending moment in the second elastic portion 10. A displacement of the action portion 11 in X direction leads to a spring force as a consequence of elongating the second elastic portion 10 at one side of the fluid damper 4 and a bending moment in the second elastic portion 10 at the opposite side with respect to the centre line 5.
In this embodiment, the spring force of the first elastic portion 9 on the action portion 11, when the latter is displaced in +Y and -Y direction, is negligable in comparison with that of the second elastic portion 10 as long as the action portion does not strike against the outer side of the first and second elastic portion 9, 10. Thus, within a predetermined range of displacement of the action portion 11 in +Y and -Y direction the spring force is mainly dependent on the characteristics of the second elastic portion 10. The spring factor can be influenced by the type of material and dimensions of the second elastic portion 10. Preferably, the spring factor within the predetermined range is constant and similar in +Y and -Y direction.
The damping effect is generated by fluid flow within the cavity 15 of the fluid damper 4. When the action portion 11 in Fig. 2 moves in upward direction the volume in a part of the fluid cavity 15 which is disposed above the action portion 11, is decreased and fluid will be pushed away downwards flowing to a part of the fluid cavity 15 that extends below the action portion 11 and which is enlarged due to the movement upwards of the action portion 11. The same effect happens in reversed direction when the action portion 11 moves in downward direction. The damping effect in horizontal direction is generated by fluid flow within the cavity 15 around the central member 7 in the same direction as the direction of movement of the action portion 11.
The embodiment of the fluid damper 4 of Fig. 2 has a progressive spring factor characteristic. The effect of these features is created by the shape of the first and second elastic portions 9, 10 in the assembled condition of the fluid damper 4 and the configuration of the action portion 11. This effect is illustrated in Figs. 3a-3c and 4a-4c. Fig. 3a shows the situation in which the action portion 11 is in a reference position. In this position there is no external force exerted on the action portion 11 of fluid damper 4. Fig. 3b shows a first step downwards of the action portion 11. The first elastic portion 9 is drawn downwards together with the action portion without exerting a substantial spring force on the action portion 11 , whereas the second elastic portion 10 is bent downwards exerting a back force on the action portion 11 in upward direction. Fig. 3c shows a next displacement step of the action portion 11 in downward direction. It can be seen that the action portion 11 strikes against the second elastic portion 10. A further displacement of the action portion 11 in downward direction leads to a progressively increased back force, because compression of the second elastic portion 10 requires a higher force than bending it during the first part of the movement in downward direction from the reference position.
The progressive spring factor can be further influenced by material properties of an upper side 19 and a lower side 20 of the action portion 11 which strike against the first and second elastic portion 9, 10, respectively. The upper and lower side 19, 20 can be made from an elastic material, as well. Preferably, the upper side 19 is of the same material as the first elastic portion 9, and the lower side 20 is of the same material as the second elastic portion 10. In that case the upper and lower side 19, 20 may be part of the first and second elastic portion 9, 10, such as shown in Fig. 2, which facilitates the manufacturing process.
Figs. 4a-c illustrate the same displacement steps of the action portion 11 as described above in opposite direction. The action portion 11 is moving upwards from its reference position. In the situation such as shown in Fig. 4b the second elastic portion 10 exerts a spring force on the action portion 11 in downward direction, whereas the back force of the deformed first elastic portion 9 is minimal. A further displacement of the action portion 11 in upward direction such as shown in Fig. 4c leads to compression of the first elastic portion 9 which is folded between the action portion 11 and the player part 2 of the disk player (not shown in Fig. 4) above the upper side 16.
The base part 6, the first end portion 12 and the action portion 11 are preferably made of a non-elastic PP (polypropylene). Non-elastic material is defined herein as material having a high elastic modulus. As standard PP is a relatively weak material the non-elastic PP parts 6, 11 and 12 can be re-inforced by GF (glass fibre). Other possible
materials are ABS, PA, PC and PVC. The first and second elastic portion 9, 10 can be made of a TPE (thermoplastic elastomer). In order to optimise the spring characteristics of the second elastic portion 10 it may have a different hardness and thickness in comparison with the first elastic portion 9. The thickness of the first elastic portion 9 may be 0.2 mm and the thickness of the second elastic portion 10 may be 0.3-0.35 mm, for example.
Fig 5. shows an example of spring force traces F exerted on the action portion 11 of the embodiment of Fig. 2 as a function of its displacement S with respect to its reference position. Trace I represents the spring force in X direction; trace II shows the spring force in +Y direction and trace III shows the spring force in -Y direction. Traces II and III clearly show the progressive spring force factor such as explained above. The material characteristics of the first and second elastic portion 9, 10 can be adjusted such that the spring force performance in +Y and -Y direction is more or less similar.
According to the invention the fluid damper 4 of which an embodiment is shown in Fig. 2 can be manufactured by a moulding process. This is advantageous in terms of production costs. A practical way of manufacturing a fluid damper such as shown in Fig. 2 is moulding the base part 6 as a first piece and the central member 7 and the flexible part 8 as a second piece and fixing both pieces together after moulding. The first piece can be moulded in a first moulding tool according to the following steps:
1. moulding the base part 6
2. ejecting the base part 6
The second piece can be moulded in a second moulding tool according to the following steps:
1. moulding the central member 7, the action portion 11 and the first end portion 12 of one material
2. moulding the first and second elastic portion 9, 10 of another material
3. ejecting the second piece (7, 9, 10, 11, 12)
In a next step the formed cavity 15 in the second piece can be filled with oil. In a final step the first and second piece are fixed to each other by ultrasonic welding or gluing.
A next step of the manufacturing method is to reshape the fluid damper such that it obtains the shape of Fig. 2. This part of the manufacturing method is illustrated in Fig. 6. It shows the contours of a part of the fluid damper 4 of Fig. 2 in the assembled condition B and in the ready- for-assembly condition A. In the ready- for-assembly condition A the first elastic portion 9 has the contours of a bulge 21 after the moulding process. The mould has an
outer mould and a movable inner mould (not shown), which is movable in +Y and -Y direction. In order to be able to relief the flexible part 8 from the mould the inner walls of the flexible part 8 and the outer wall of the central member 7 are relieving walls.
When the fluid damper 4 is in the ready- for-assembly condition A and it is assembled in an electronic device, for example, the bulge 21 is pressed against the player part 2 such that the bulge 21 is converted to an undercut 22, see Fig. 6. The undercut 22 creates the damping function of the fluid damper 4 together with the part of the cavity 15 which extends below the action portion 11.
From the foregoing it will be clear that the invention provides a fluid damper 4 with an integrated spring function including a progressive spring factor, which damper 4 can be manufactured by a moulding process.
The invention is not restricted to the above-described embodiments as shown in the drawings, which can be varied in several ways without departing from the scope of the claims. In general it is noted that, in this application, the expression "comprising" does not exclude other elements, and "a" or "an" does not exclude a plurality. Reference signs in the claims shall not be construed as limiting the scope thereof.
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