Air damper

Abstract: An air damper (100) of the present invention is provided with: a cylinder (1) whose one end is closed and the other end is opened; a piston (2) which is movable along an axial direction of the cylinder within the cylinder in a state where an end of a string (3) is connected to the piston; a recess groove (7) formed in an peripheral surface of the piston; an O-ring (6) sealing between the cylinder (1) and the piston (2) and movably fitted to the recess groove (7); a coil spring (5) abutted against one of a pair of flanges (8) defining the recess groove (7) of the piston (2) for biasing the piston toward the one end of the cylinder (1); a hook (9) provided on the one of the pair of flanges (8), the end of the string (3) being attached to the hook (9); and opposed notches formed by notching portions (10) of the pair of flanges (8) of the piston (2) corresponding to opposite sides of the hook (9).

Description: The present invention relates to an air damper, and more particularly, although not exclusively, to a cylinder type air damper which can suitably be used for a glove box and the like of an automobile. As shown in Fig. 8, a conventional air damper 20 of this type comprises a cylindrical cylinder 21 whose opposite ends are opened, a piston 22 to which a base end of a string 23 is connected for moving within the cylinder 21, an end cap 26 having a valve 25 for opening and closing a communication hole 24 which is opened at one end opening of the cylinder 21, a guide cap 27 for guiding the movement of the string 23 at the other end opening side of the cylinder 21, and a compression coil spring 28 interposed between the guide cap 27 and the piston 22 in the cylinder 21. When this air damper is used for a glove box of an automobile, the cylinder 21 is fixed at the side of an instrument panel, and a tip end 23b of the string 23 extending from the guide cap 27 of the cylinder 21 to the outside is fixed to the side of the glove box. If a lid of the glove box is moved in its opening direction, the string 23 is gradually pulled out from the cylinder 21, and the piston 22 is moved in the same direction against the spring pressure of a compression coil spring 28. With this operation, a damper effect is obtained by a flowing resistance of air passing through an orifice (not shown) which is opened toward the piston 22, which ensures that the glove box is slowly moved toward its opening state. When the lid of the glove box is moved into its closing direction, the piston 22 together with the string 23 is forcibly pushed back into the cylinder 21 by the spring pressure of the compression coil spring 28, and air accumulated in the cylinder 21 is released to the outside from the end cap 26 through the communication hole 24 which is opened by the valve 25. Therefore, the piston 22 is swiftly moved within the cylinder 21, which facilitates the closing operation of the glove box. In the conventional air damper, however, if the air damper is checked in more detail, when the base end 23a of the string 23 is connected to the piston 22, as shown in Fig. 9, a side of the piston 22 which also serves as a mounting seat of the compression coil spring 28 is integrally formed with a connection cylinder 29, and the connection cylinder 29 is formed with a pair of resilient lock claws 30. On the other hand, a separate clip 31 formed with a slit 31a is mounted to the base end 23a of the string 23. The clip 31 is fitted into the connection cylinder 29, the resilient lock claws 30 are locked, thereby connecting the base end 23a of the string 23 to the piston 22. Therefore, in the case of the conventional air damper, it is needless to say that the number of parts about the clip body 31 is increased. Further, when the base end 23a of the string 23 is connected to the piston 22, the base 23a of the string 23 is mounted to the clip 31 through the slit 31a and then, the clip 31 must be locked to the connection cylinder 29 of the piston 22. Therefore, the connecting operation becomes a heavy work. EP-A-0 562 284 discloses an air damper according to the preamble of claim 1 hereinafter. It is desirable to solve the problem of the conventional air damper, and provide an air damper which reduces the number of parts, and effectively facilitates the assembling operation. The present invention provides an air damper comprising: a cylinder having a closed end and an open end; a piston which is movable along an axial direction of said cylinder within said cylinder, said piston having a pair of flanges defining a recess groove formed in a peripheral surface of said piston and a hook provided on one of said pair of flanges; a string having an end which is connected to said hook; and a coil spring abutted against said one of said pair of flanges for biasing said piston toward said closed end; characterised in that an O-ringis fitted for axial movement in said recess for sealing between said cylinder and said piston; and opposed notches are formed by notching portions of said pair of flanges corresponding to respective opposite sides of said hook. Other preferred aspects of the invention are defined in the accompanying claims. As will be appreciated from the embodiments described in more detail hereinafter, the embodiments enable an operator to inserts his or her finger, a jig or the like into the spaces of the notches to easily hook the end of the string to the hook, and he or she can mount the string to the piston. Therefore, no additional parts are required and excellent assembling operability is realized. Further, since the hook itself is small, it is possible to obtain an air damper having a small and rigid piston. If each of the notches is formed such that the notch spreads in a diametrical direction of the cylinder, it is preferable for the assembling operation. Further, if one of the flanges is provided with a wall rising therefrom for supporting a seat winding portion of the coil spring, the coil spring is reliably and easily mounted. Here, it is preferable that a plurality of such walls are provided such as to be opposed in a direction substantially perpendicular to a direction along which the opposed notches are provided such as to be located inside of the coil spring. According to such a structure, since the walls and the hook are disposed on one straight line while avoiding the notches, the assembling operability is reliably enhanced. In addition, since the width and the height of the wall can be increased, the coil spring can be mounted more reliably. An orifice may be provided in the recess groove of the piston in a diametrical direction of the piston. In such a case, if a recess is provided in an periphery of one of opposite ends of the orifice which is located outside in the diametrical direction of the cylinder, it is preferable because foreign matters such as fiber pieces and the like cased by contact with the string at the time of assembling can be restrained from attaching. Further, an orifice may be provided in the piston in a direction substantially parallel to the axial direction of the piston. In such a case, if a periphery around an opening of the orifice is recessed, foreign matters such as fiber pieces and the like cased by contact with the string at the time of assembling can be restrained from attaching. Further, in such a case, it is preferable that the orifice is located in a central portion of the one flange of the piston because a damping force is reliably generated with a simple structure. When the orifice is provided in a direction substantially parallel to the axial direction of the piston, it is preferable that the orifice is located at a position where a movable limit locus determined by a peripheral length of the end of the string does not interfere with the orifice, because foreign matters such as fiber pieces and the like cased by contact with the string at the time of assembling can be restrained from attaching. It is preferable that the hook includes a tip end which is inclined inwardly in a diametrical direction of the cylinder, because the string can reliably be mounted. Further, it is preferable that the one flange is provided with a wall supporting the seat winding portion of the coil spring in a standing manner, and a rib is provided between the hook and the wall, because the rigidity of the hook can be secured. Further, it is preferable that each of the pair of flanges defining the recess groove of the piston includes a reduced diameter portion, so that if a burr is generated during forming it does not deteriate operation of the piston. In order that the present invention may be well understood, three embodiments thereof, which are given by way of example only, will now be described with reference to the accompanying drawings, in which: Fig. 1 is an exploded perspective view of an air damper according to a first embodiment of the present invention; Fig. 2 is an enlarged perspective view showing a string and a piston of the embodiment before assembling; Fig. 3A is a front view of the piston of the embodiment, Fig. 3B is a sectional view of the piston taken along the line A-A in Fig. 3A, Fig. 3C is a plan view of the piston of the embodiment, and Fig. 3D is a bottom view of the piston of the embodiment; Fig. 4 is an enlarged perspective view showing the string and the piston of the embodiment at the time of assembling; Fig. 5 is a partial sectional view of the air damper of the embodiment; Fig. 6 is a partial sectional view of a piston in a cylinder of an air damper according to a second embodiment of the invention; Fig. 7 is a partially cut-away front view of a piston of an air damper according to a third embodiment of the invention; Fig. 8 is a partial sectional view of a conventional air damper; and Fig. 9 is an enlarged perspective view showing a string and a piston before the conventional air damper is assembled. Embodiments of the present invention will be explained in detail with reference to the drawings below. An air damper of a first embodiment of the present invention will be explained first. As shown in Figs. 1 to 5, an air damper 100 comprises a cylindrical cylinder 1 whose one end is closed and the other end is opened, a piston 2 which moves in the cylinder 1 and which is connected to an annular base end 3a of a string 3, a guide cap 4 for guiding the movement of the string 3 at the other end opening of the cylinder 1, and a compression coil spring 5 interposed between the guide cap 4 and the piston 2 for resiliently biasing the piston 2 toward the one end of the cylinder 1. As shown in Figs. 2, and 3A to 3D, the piston 2 is formed with a wide annular recess groove 7 around which an O-ring 6 is fitted for axial movement, and the recess groove 7 is defined by a pair of flange walls 8A and 8B. The flange wall 8A which also serves as a mounting seat of the compression coil spring 5 is integrally formed at its central portion with a reversed J-shaped hook 9 for hooking the annular base end 3a of the string 3. Portions of the hook 9 of the flange wall 8A located at opposite sides are notched into a fan-like shape such that the opposite sides open in a diametrical direction of the cylinder 1, and the recess groove 7 is formed at its bottom corresponding to the fan-like notched portions 10 with a pair of communication grooves 11. An orifice 12 is opened in a side surface of one of the communication grooves 11 in the diametrical direction of the cylinder 1. A guide piece 13 serving as a guide when the annular base end 3a of the string 3 is hooked to the hook 9 is continuously extended from an upper surface of the hook 9. Only an inner surface side of a tip end 9a of the hook 9 itself is swelled and inwardly inclined, and gaps L1 and L2 from a guide wall 14 which will be described later are set to establish a relation of L1<L2. With this design, during the most difficult operation that the annular base end 3a of the string 3 passes through the tip end 9a of the hook 9, a finger of an operator is automatically separated from the opposed guide walls 14, so that the annular base end 3a can smoothly pass through the tip end 9a. Therefore, the hooking operation is facilitated together with the help of the guide piece 13, and the base end 3a of the string 3 can be prevented from being disengaged from the hook 9. In addition, the pair of guide walls 14 for supporting a seat winding portion of the compression coil spring 5 rise such as to be opposed to each other at positions perpendicular to the notched portion 10 of the one flange wall 8A which also serves as the mounting seat of the compression coil spring 5, and each of the guide walls 14 and the hook 9 are disposed on one straight line while avoiding the notched portion. With this design, the hooking operability of the base end 3a of the string 3 with respect to the hook 9 is not deteriorated, and each of the guide walls 14 is set as wide and high as possible, and the seat winding portion of the compression coil spring 5 can be stably supported. Further, one of the guide walls 14 is connected to the hook 9 through a rib wall 15, even if the hook 9 is forced to bend by a force of the string 3, it is possible to effectively prevent the hook 9 from bending by the rib wall 15 and a fitting state of the compression coil spring 5 over the guide walls 14. Peripheral edges of the flange wall 8B which does not serve as the mounting seat of the compression coil spring 5 corresponding to the communication grooves 11 are cut to form cut portions 16, which reduce the diameter of the flange. Air accumulated in the cylinder 1 is straightly guided in the direction of the communication grooves 11 from the cut portions 16. Peripheral edges corresponding to the guide walls 14 are also cut so that even if a burr is generated in the cut portions 17 by parting, the burr is not brought into contact with an inner peripheral surface of the cylinder 1. The burr generated by the parting becomes significant issue at the side of the flange wall 8A which also serves as the mounting seat of the compression coil spring 5. Therefore, peripheral edges corresponding to the guide walls 14 are similarly cut to form cut portions 18. When the air damper having the above-described structure is assembled, the annular base end 3a of the string 3 is first hooked to the hook 9 of the piston 2. In this case, as described above, in the first embodiment, portions of the flange wall 8A located at the opposite sides of the hook 9 are notched. Therefore, as shown in Fig. 4, positively utilizing spaces generated at the opposite sides of the hook 9, by inserting a finger (or a jig) into the spaces to obtain a guide of the guide piece 13, and it is possible to extremely easily hook the annular base end 3a of the string 3 to the hook 9. That is, as compared with the conventional air damper, the connecting operation can largely be enhanced. Further, since each of the notched portions 10 of the flange wall 8A is cut into a fan-shape which spreads toward its outer periphery, the finger of the operator can easily enter, and should not be injured. Since the hooking operation becomes easier, the hook 9 itself can be made smaller, which makes it possible to reduce the piston 2 in size and to increase its rigidity. Thereafter, the tip end 3b of the string 3 hooked to the hook 9 passes through the inside of the compression coil spring 5, the seat winding portion of the compression coil spring 5 is supported by the pair of guide walls 14, and the piston 2 and the compression coil spring 5 are pushed into the cylinder 1 from the other end opening. Lastly, if the guide cap 4 is mounted to the other end opening of the cylinder 1, as shown in Fig. 5, the one-way type air damper can easily be assembled. When the air damper is actually used for the glove box, although it is not illustrated in the drawing, the cylinder 1 is fixed at the side of the instrument panel through the mounting piece 19 as in the conventional air damper, the tip end 3b of the string 3 extending from the guide cap 4 of the cylinder 1 to the outside is fixed at the side of the glove box. If the glove box side is moved in its opening direction, the string 3 is gradually pulled out from the cylinder 1, and the piston 2 is moved in the same direction against the spring pressure of the compression coil spring 5. With this operation, a damper effect is obtained by the flowing resistance of air passing through the orifice 12 which is opened in the communication grooves 11 of the piston 2, which ensures that the glove box is slowly moved toward its opening state. In this case, since the O-ring 6 moves in the recess groove 7, each of the communication grooves 11 is closed. If the glove box side is moved in its closing direction, the piston 2 together with the string 3 is forcibly pushed back into the cylinder 1 by the spring pressure of the compression coil spring 5. In accordance with this movement, the O-ring 6 is moved in the opposite direction within the recess groove 7 to open each of the communication grooves 11, thereby releasing the air accumulated in the cylinder 1 to the outside through the communication grooves 11 from the cut portions 16 of the flange wall 8B. With this operation, the piston 2 swiftly moves in the cylinder 1 to help the glove box to be closed. Further, in such a state, the air accumulated in the cylinder 1 straightly flows into each of the communication grooves 11 from the cut portions 16 of the flange wall 8B through the recess groove 7. Further, each of the communication grooves 11 is set smaller than the inner diameter of the compression coil spring 5. Therefore, the air should not collides against the compression spring 5 or should not flow outside and enter the gap between the cylinder 1 and the compression coil spring 5. Therefore, the air releasing efficiency is excellent, and a noise caused by collision of air can effectively be prevented. Next, an air damper according to a second embodiment will be explained. The second embodiment is basically following the first embodiment as it is. As shown in Fig. 6, differences are that an orifice 32 is opened in a central portion of the flange wall 8A which also serves as the mounting seat of the compression coil spring 5 in parallel to the axial direction of the cylinder 1, and a periphery around an opening of the orifice 32 is recessed by Δ toward the recess groove 7. In the second embodiment, an orifice 22 is provided on the axis of the cylinder 1. Only an outer wall of a portion of the cylinder 1 is illustrated. Therefore, even in the second embodiment, as in the first embodiment, positively utilizing spaces generated at the opposite sides of the hook 9, by inserting a finger into the spaces to obtain a guide of the guide piece 13, and it is possible to extremely easily hook the annular base end 3a of the string 3 to the hook 9. In addition, especially when the string 3 is hooked to the hook 9, the annular base end 3a of the string 3 does not come into contact with the opening edge of the orifice 32 directly due to the recess of Δ. Therefore, it is possible to effectively prevent a portion of the string 3 from being cut, and to prevent its fiber pieces from occluding the orifice 32. Lastly, an air damper of a third embodiment will be explained. The third embodiment is based on the second embodiment and is also basically following the first embodiment as it is. Features of the third embodiment are that an orifice 42 opened in the central portion of the flange wall 8A is located away from a movable limit locus X which is determined by a peripheral length of the annular base end 3a of the string 3 so as not to interface with the orifice 2. Although the opening of the orifice 42 is recessed toward the recess groove 7 in the drawing, in the third embodiment, since it is essential only that the opening of the orifice 42 is away from the movable limit locus X of the annular base end 3a of the string 3, the opening of the orifice 42 is not necessarily recessed. Therefore, even in the third embodiment, positively utilizing spaces generated at the opposite sides of the hook 9, by inserting a finger into the spaces to obtain a guide of the guide piece 13, and it is possible to extremely easily hook the annular base end 3a of the string 3 to the hook 9. In addition, especially when the string is hooked to the hook 9, since the opening of the orifice is located away from the movable limit locus X, the annular base end 3a of the string 3 should not come into contact with the orifice 42. Therefore, as in the second embodiment, a portion of the string 3 should not be cut, and its fiber pieces should not occlude the orifice 42.

Claims: An air damper (100) comprising: a cylinder (1) having a closed end and an open end; a piston (2) which is movable along an axial direction of said cylinder within said cylinder, said piston having a pair of flanges (8A,8B) defining a recess groove (7) formed in a peripheral surface of said piston and a hook (9) provided on one (8A) of said pair of flanges; a string (3) having an end which is connected to said hook; and a coil spring (5) abutted against said one of said pair of flanges for biasing said piston toward said closed end; characterised in that an O-ring (6) is fitted for axial movement in said recess for sealing between said cylinder and said piston; and opposed notches (10) are formed by notching portions of said pair of flanges corresponding to respective opposite sides of said hook. An air damper according to claim 1, wherein each of said notches (10) is formed such as to spread in a diametrical direction of said cylinder (1). An air damper according to claim 1 or 2, wherein a wall (14) rises from said one (8A) of said pair of flanges (8A, 8B) for supporting a seat winding portion of said coil spring (5) . An air damper according to claim 3, wherein a plurality of said walls (14) are provided such as to be opposed in a direction substantially perpendicular to a direction along which said opposed notches (10) are provided, and such as to be located inside of said coil spring (5). An air damper according to claim 1, wherein an orifice (12; 32; 42) is provided in said recess groove (7) of said piston (2) in a diametrical direction of said piston. An air damper according to claim 1, wherein an orifice (32; 42) is provided in said piston (2) in a direction substantially parallel to said axial direction of said piston. An air damper according to claim 5 or 6, wherein a periphery around an opening of said orifice (32; 42) is recessed. An air damper according to claim 7, wherein said orifice (32; 42) is located in a central portion of said one (8A) of said pair of flanges (8A, 8B) of said piston (2). An air damper according to claim 6, wherein said orifice (42) is located at a position where a movable limit locus determined by a peripheral length of said end of said string (3) does not interfere with said orifice. An air damper according to any one of the preceding claims, wherein said hook (9) includes a tip end which is inclined inwardly in a diametrical direction of said cylinder (1). An air damper according to any one of claims 3 to 10, wherein a rib (15) is provided between the hook (9) and the wall or walls (14) supporting the seat winding portion of said coil spring (5). An air damper according to any one of the preceding claims, wherein each of said pair of flanges (8A, 8B) defining said recess groove (7) of said piston (2) includes a reduced diameter portion (16).

Inventors: ITO KIICHIRO, ITO, KIICHIRO, Ito, Kiichiro, c/o Piolax Inc.
Applicants: PIOLAX INC, PIOLAX INC.
Application year: 1999
Main classification: B60R7
IPC codes: F16F9, B60R7, F16F7