Damper device

Abstract

To enable a seal member as a component of a damper device to make sliding contact with an inner wall of a cylinder body in the same manner as much as possible.SOLUTION: A piston body 2 comprises: a first holding part 2a which faces base parts 4a of a seal member 4 from one space 5 side; and a second holding part 2b located inside a lip part 4b of the seal member 4, and facing the base parts 4a from the other space 6 side. Between the base parts 4a constituting longitudinal portions 4c at two points which face a wider side face part 1c of a cylinder body 1 of the seal member 4, a regulation part 4f which is formed so as to make contact with the first holding part 2a on the side of a moving center axis x of the piston body 2 relative to the base part 4a when the piston body 2 moves to the one space 5 side, and which maintains postures of longitudinal portions 4c of the seal member 4 is provided.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to an improvement to a damper device that generates a braking force by movement or relative movement of a piston body. [Background technology]

[0002] Patent Document 1 shows an example of a damper device that includes a flat cylindrical cylinder, a piston movably housed within the cylinder, and a seal ring that is attached to the piston and surrounds it to provide a seal between the cylinder and the piston.

[0003] When a pressure difference occurs between the space formed on one side of the piston and the space formed on the other side thereof due to the movement of the piston, a force is applied to the seal ring to deform the seal ring.

[0004] However, since such a seal ring has a flattened ring shape following the cross-sectional shape of the cylinder, the major axis side, i.e., the portion of the seal ring that contacts the wide wall portion of the cylinder, is prone to deformation.

[0005] This type of damper device is typically used to make the movement of the object to be braked slow, elegant, moderate, or not sudden; if the deformation of the seal ring cannot be controlled, the braking force generated by the damper device will not be stable, resulting in problems such as the object to be braked being stopped suddenly or in multiple stages, or even a loss of braking force when it should be applied to the object to be braked. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6795688 Summary of the Invention [Problem to be solved by the invention]

[0007] The main problem that this invention seeks to solve is how to provide a structure in which the sealing members constituting this type of damper device always slide against the inner wall of the cylinder body in as uniform a manner as possible, so that the desired braking force can always be produced from the damper device. [Means for solving the problem]

[0008] In order to achieve the above object, the present invention provides a damper device comprising: a flat cylindrical cylinder body having a pair of wide side portions and a pair of narrow side portions, a piston body movably accommodated within the cylinder body, and a seal member for sealing between the cylinder body and the piston body, the damper device generating a braking force by movement or relative movement of the piston body, the sealing member has elasticity, is circumferential and surrounds the piston body, and has a base portion located on one side of the space inside the cylinder body divided by the piston body, and a lip portion extending from the base portion to the other side of the space inside the cylinder body, the lip portion being in sliding contact with an inner wall of the cylinder body, the piston body includes a first holding portion of the seal member facing the base portion of the seal member from the one space side, and a second holding portion of the seal member located inside the lip portion of the seal member and facing the base portion from the other space side, The sealing member is provided with a regulating portion between the base portion constituting two longitudinal portions facing the wide side portion of the cylinder body, the regulating portion being formed so as to contact the first retaining portion on the side of the central axis of movement of the piston body relative to the base portion when the piston body moves toward the one space side, thereby maintaining the posture of the longitudinal portion of the sealing member.

[0009] When a force is applied to the piston body in a direction that reduces one of the spaces or to cause relative movement, and the pressure in one of the spaces becomes high, a force is applied to the lip portion of the sealing member toward the central axis, and a force is applied to the base portion of the sealing member in a direction that moves it closer to the inner wall of the wide side portion of the cylinder body due to the force applied to the lip portion. If the regulating portion is not provided on the longitudinal portion of the sealing member, the longitudinal portion will be easily deformed by the force acting on the base portion as described above, and if the deformation of the longitudinal portion cannot be controlled, the braking force cannot be controlled either. On the other hand, according to the above configuration, the regulating portion can receive the force acting on the base portion when a force is applied to the lip portion as described above by pressing the regulating portion against the first retaining portion, thereby suppressing unexpected deformation of the longitudinal portion of the sealing member.

[0010] In one aspect of the present invention, the seal member has two longitudinal portions each having a protruding portion that protrudes toward the central axis of movement of the piston body and serves as the restricting portion.

[0011] In addition, one aspect of the present invention is that the protrusion portion has a first surface facing the first retaining portion and a second surface facing the second retaining portion, and is provided with an inclined surface between the first surface and the second surface such that the thickness of the protrusion portion gradually decreases as it approaches the second surface.

[0012] In one aspect of the present invention, a bridge portion serving as the restricting portion is formed between the two longitudinal portions of the seal member.

[0013] In addition, one aspect of the present invention is that the piston body is configured by combining a first part having the first retaining portion and a second part having the second retaining portion so as to sandwich the seal member between the first part and the second part. In this case, it is further considered as one aspect of the present invention to form a groove in either the first retaining portion in the first part of the piston body or the base portion of the sealing member, and to form a rib that fits into the groove on the other of them. Effect of the Invention

[0014] According to this invention, the regulating portion of the sealing member enables the sealing member to always slide against the inner wall of the cylinder body in as uniform a manner as possible, thereby enabling this type of damper device to always provide the desired braking force. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is an exploded perspective view of a damper device (first example) according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an exploded perspective view of the first example. [Diagram 3] FIG. 3 is a perspective view of the first example. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Diagram 5] FIG. 5 is a cross-sectional view taken along line BB in FIG. [Figure 6] FIG. 6 is an enlarged cross-sectional view of a main portion of FIG. 4, in which the piston body is moved in a direction to reduce one space. [Figure 7] FIG. 7 is an enlarged cross-sectional view of a main portion of FIG. 4, in which the piston body is moved in a direction to expand one space. [Figure 8] FIG. 8 is an enlarged cross-sectional view of a main portion of FIG. 5, where FIG. 8a shows the state of the orifice formation location when the piston body moves in a direction to reduce one of the spaces, and FIG. 8b shows the state of the orifice formation location when the piston body moves in a direction to expand one of the spaces. [Figure 9] FIG. 9 is a perspective view of the seal member constituting the first example. [Figure 10] FIG. 10 is a cross-sectional view taken along line CC in FIG. [Figure 11] FIG. 11 is a cross-sectional view taken along line DD in FIG. [Figure 12] FIG. 12 is a cross-sectional view taken along line EE in FIG. [Figure 13] FIG. 13 is a perspective view of the piston body and the seal member constituting the first example. [Figure 14] FIG. 14 is a perspective view of the piston body and the seal member assembled therewith. [Figure 15] FIG. 15 is a cross-sectional view taken along the line FF in FIG. [Figure 16] FIG. 16 is a cross-sectional view taken along line GG in FIG. [Figure 17] FIG. 17 is a side configuration diagram of a main part of a piston body constituting a damper device (second example) according to one embodiment of the present invention. [Figure 18] FIG. 18 is an exploded perspective view of the piston body of the second embodiment. [Figure 19] FIG. 19 is an exploded perspective view of the piston body of the second embodiment. [Figure 20] FIG. 20 is a cross-sectional view showing the main part of the second example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] A typical embodiment of the present invention will be described below with reference to Figures 1 to 20. The damper device according to this embodiment generates a damping force on the movement or relative movement of a piston body 2 constituting the damper device, and is typically combined with an article having a movable part or the like (not shown) to be braked, and is used to apply the damping force to the movement of the object to be braked, to make the movement of the object to be braked slow, luxurious, moderate, or not sudden.

[0017] Such a damper device is composed of a piston body 2 equipped with a rod body 3, and a cylinder body 1 that houses the piston body 2. Typically, such a damper device is combined with an article equipped with the object to be braked by directly or indirectly connecting one of the rod body 3 and the cylinder body 1 to the object to be braked and directly or indirectly connecting the other to a side that movably supports the object to be braked.

[0018] In the illustrated example, the cylinder body 1 is tubular with one end 1a open and the other end 1b closed. Although not shown, the cylinder body 1 may be a tubular body with both ends open, one end of which is closed by a separate part. Such a cylinder body 1 is tubular with a significantly reduced thickness. More specifically, the cylinder body 1 has two wide side portions 1c and two narrow side portions 1d. When the cylinder body 1 is cut in a cross section perpendicular to its central axis x (see Figs. 4 and 5; i.e., the central axis of movement of the piston body 2), the left and right narrow side portions 1d are curved so that the central axis x side is the curved inner side, and the cross-sectional inner shape of the cylinder body 1 is an ellipse (a shape consisting of two parallel lines of equal length and two semicircles). A connection portion 1e for the above-mentioned linkage is formed on the outside of the other closed end 1b of the cylinder body 1.

[0019] Also, an orifice 1f is formed in the closed other end 1b of the cylinder body 1. In the illustrated example, a braking force adjusting member 1g having a shaft 1h movably inserted into the orifice 1f is held by a holding portion 1i formed on the outside of the other end 1b of the cylinder body 1. In Figures 1, 2 and 8, reference symbol 1j denotes a coil spring that constantly biases the braking force adjusting member 1g in a direction to reduce the amount of insertion of the shaft 1h of the braking force adjusting member 1g into the orifice 1f.

[0020] In the illustrated example, the rod body 3 is formed with an elongated hole 3a aligned with the moving direction of the piston body 2. In the illustrated example, when at least the portions of the piston body 2 and the rod body 3 located on the piston body 2 side are housed within the cylinder body 1, a pin 1m is inserted through a through hole 1k and the elongated hole 3a formed in a pair of wide side surface portions 1c at the open end 2a side of the cylinder body 1, thereby maintaining the combined state of the cylinder body 1 and the piston body 2 side and guiding the movement of the piston body 2 side. The sealing member 4, which is combined with the piston body 2 and will be described later, is housed within the cylinder body 1 with the lip portion 4b, which will be described later, elastically deformed, so that the extending end 4e of this lip portion 4b is in contact with the inner wall 1n of the cylinder body 1 at any position around the central axis x. This seal member 4 divides the space inside the cylinder body 1 into one space 5 on the closed other end 2b side and another space 6 on the open one end 2a side.

[0021] The movement of the piston body 2 in the direction expanding the one space 5 (Figure 7) is permitted by the movement of fluid (gas in the illustrated example) from the outside to the one space 5 through the orifice 1f (Figure 8b).

[0022] On the other hand, in the illustrated example, when the piston body 2 moves in a direction to reduce the one space 5 (FIG. 6), the one space 5 side becomes high pressure, so that the seal member 4 is elastically deformed in a direction in which a lip portion 4b of the seal member 4 described later moves away from the inner wall 1n of the cylinder body 1, and the movement of the piston body 2 in this direction is permitted by the movement of fluid between the inner wall 1n of the cylinder body 1 and the lip portion 4b. In the illustrated example, when the piston body 2 moves in a direction to reduce the one space 5 (FIG. 6), the movement of fluid from the one space 5 side toward the other space 6 side is also permitted through a gap c formed between a base portion 4a of the seal member 4 described later and a first holding portion 2a of the piston body 2 described later, and a passage f provided at a portion forming a second holding portion 2b of the piston body 2 described later.

[0023] The rod body 3 includes a rod main body 3b and a rod head 3c which is integrated with the inner end of the rod main body 3b located within the cylinder body 1. The rod head 3c has an inner portion 3d and an outer portion 3e, whose cross-sectional outer shape in a direction perpendicular to the central axis x is an ellipse following the inner cross-sectional shape of the cylinder body 1. One end of the rod main body 3b is integrated with the center of the outer portion 3e of the rod head 3c. Also, a connecting portion 3f for the above-mentioned connection is formed at the outer end of the rod main body 3b located outside the cylinder body 1.

[0024] In the illustrated example, a fitted portion 3g for fitting the fitting portion 2c of the piston body 2 is formed in the center of the inner portion 3d side of the rod head portion 3c. In the illustrated example, the fitting portion 2c consists of a neck portion 2d and a fitting head 2e which is integrated through the neck portion 2d into the center of the back portion opposite the side facing the first retaining portion 2a of the second retaining portion 2b of the piston body 2 described below. On the other hand, the fitted portion 3g is composed of a notch 3h through which the neck portion 2d passes, and a fitting cavity 3i for the fitting head 2e formed between the inner portion 3d and the outer portion 3e. In the first example shown in Fig. 1 to Fig. 16, the piston body 2 is combined with a flat cylindrical seal member 4 as described below, and then the fitting head 2e is fitted into the fitting cavity 3i by utilizing the notch 3h of the rod head 3c, so that the piston body 2 and the rod body 3 are integrated.

[0025] The piston body 2 includes a first holding portion 2a, a second holding portion 2b, and an intermediate portion 2f connecting the first and second holding portions 2a and 2b. The piston body 2 has a long side facing the inner wall 1n of the cylinder body 1 at the wide side portion 1c, and a short side facing the inner wall 1n of the cylinder body 1 at the narrow side portion 1d.

[0026] The first retaining portion 2a and the second retaining portion 2b are each formed so that their outer contours are inscribed in a virtual ellipse (not shown) that conforms to the cross-sectional inner contour shape of the cylinder body 1. The intermediate portion 2f is formed around the entire circumference of the central axis x of the cylinder body 1 such that its outer contour is positioned closer to the central axis x than the outer contours of the first retaining portion 2a and the second retaining portion 2b, and the piston body 2 has a narrowed shape at the intermediate portion 2f.

[0027] The first retaining portion 2a faces a base portion 4a (described later) of the sealing member 4 from the one space 5 side. The first retaining portion 2a has an outer contour shape that is complementary to the cross-sectional inner contour shape of the cylinder body 1. In the illustrated example, the first retaining portion 2a has a plate shape with an elliptical contour shape. The first retaining portion 2a is configured to have a size between its outer edge and the inner wall 1n of the cylinder body 1 that allows the fluid (gas in this embodiment) to pass therethrough (see Figures 6 and 7) at any position around the central axis x.

[0028] The intermediate portion 2f has a convex portion 2g that is substantially positioned on a virtual ellipse (not shown) that is followed by the inner surface of the base portion 4a of the sealing member 4 described later, and a concave portion 2h that is positioned closer to the central axis x than the convex portion 2g. In the example shown in the figure, the short side of the intermediate portion 2f is the convex portion 2g, and the long side is the concave portion 2h.

[0029] The second retaining portion 2b is located inside a lip portion 4b (described later) of the seal member 4 and faces the base portion 4a from the other space 6 side. The outer contour of the second retaining portion 2b is located on the central axis x side of the cylinder body 1 relative to the outer contour of the first retaining portion 2a, all around the central axis x. In the illustrated example, the longitudinal side of the second retaining portion 2b is formed by a plurality of ribs 2i provided with gaps between adjacent ribs 2i, and recessed portions 2h of the intermediate portion 2f and the gaps between the ribs 2i function as the passages f.

[0030] The seal member 4 has elasticity and is formed in a circumferential shape surrounding the piston body 2. The seal member 4 is typically made of rubber or plastic having rubber-like elasticity. The seal member 4 has a flat ring shape and has two long side portions 4c and two short side portions 4d. The cross-sectional shape of the seal member 4 in the direction along the central axis x is substantially the same at any position around the central axis x, except for the position where the restricting portion 4f described below is formed. This restricting portion 4f protrudes from the inside portion 4aa of the base portion 4a to the central axis x side within a certain range, as described below, and in Fig. 15, the inside portion 4aa of the base portion 4a at a position where the restricting portion 4f is not formed is shown by a dotted line. The portion on the central axis x side from this dotted line is the restricting portion 4f.

[0031] The sealing member 4 has a base portion 4a located on one side of the space 5 within the cylinder body 1 divided by the piston body 2, and a lip portion 4b extending from the base portion 4a to the other side of the space 6 within the cylinder body 1, and is configured to be in sliding contact with the inner wall 1n of the cylinder body 1 at the lip portion 4b.

[0032] The base portion 4a has outer and inner surfaces that are shaped like an oval similar to the oval shape of the inner cross-sectional shape of the cylinder body 1, but smaller than this oval. That is, the base portion 4a has two long side portions 4c and two short side portions 4d.

[0033] The inner portion 4aa of the base portion 4a is configured to be positioned closer to the central axis x than the outer contour of the first retaining portion 2a and the outer contour of the second retaining portion 2b of the piston body 2, at any position around the central axis x. Therefore, the sealing member 4 is elastically deformed to allow the piston body 2 to pass inside it from either the first retaining portion 2a or the second retaining portion 2b, and then, with the middle portion 2f of the piston body 2 positioned inside the sealing member 4, this elastic deformation is released, thereby fitting the sealing member 4 into the narrowed portion of the piston body 2, i.e., the middle portion 2f. In the illustrated example, in the two short portions 4d of the sealing member 4, the sealing member 4 is fitted into the piston body 2 with the inner portion 4aa of its base portion 4a in contact with the convex portion 2g of the middle portion 2f of the piston body 2. On the other hand, in the two longitudinal portions 4c of the sealing member 4, a gap y (see Figure 15) is formed between the inner portion 4aa of the base portion 4a of the sealing member 4 and the inner back wall of the recessed portion 2h of the intermediate portion 2f of the piston body 2 to allow the regulating portion described below to protrude.

[0034] The outer portion 4ab of the base portion 4a is a surface facing the inner wall 1n of the cylinder body 1. The inner portion 4aa of the base portion 4a is a surface oriented substantially along the central axis x. The base portion 4a has a front end surface 4ac that is substantially perpendicular to the central axis x and extends between the outer portion 4ab and the inner portion 4aa on the one space 5 side, and a rear end surface 4ad that is substantially perpendicular to the central axis x and extends between the outer portion 4ab and the inner portion 4aa on the other space 6 side. The distance between the front end face 4ac and the rear end face 4ad is slightly smaller than the distance between the first holding portion 2a and the second holding portion 2b. The sealing member 4 fitted to the piston body 2 as described above is held by the piston body 2 with the front end face 4ac of the base portion 4a facing the first holding portion 2a and the rear end face 4ad of the base portion 4a facing the second holding portion 2b (see Figures 6 and 7).

[0035] The lip portion 4b is formed so as to protrude from a rear corner portion 4ae between an outer portion 4ab and a rear end face 4ad of the base portion 4a toward the other space 6, and is integral with the base portion 4a. The lip portion 4b is configured so that the cross-sectional shape in the direction along the central axis x is substantially the same at any position around the central axis x. The lip portion 4b has a lip outer surface that is continuous with the outer portion 4ab of the base portion 4a, and a lip inner surface between the lip portion 4b and the inner portion 4aa of the base portion 4a, the rear end surface 4ad of the base portion 4a being located between the lip portion 4b and the inner portion 4aa of the base portion 4a. The thickness of the lip portion 4b in the direction perpendicular to the central axis x is smaller than that of the base portion 4a, making the lip portion 4b more susceptible to elastic deformation than the base portion 4a.

[0036] The outer side 4ab of the base portion 4a is inclined in a direction in which the outer diameter of the base portion 4a increases as it approaches the rear corner portion 4ae. The lip portion 4b is formed in a manner inclined in the same manner as the outer side 4ab of the base portion 4a, so that the outer diameter of the seal member 4 gradually increases as it approaches the extending end 4e. The outer portion 4ab of the base portion 4a and the lip outer surface of the lip portion 4b are continuous with each other without creating any constriction between them. That is, the lip portion 4b has a skirt shape extending from the rear corner portion 4ae toward the other space 6 side. The sealing member 4 has its outer diameter largest at the extending end 4e of the lip portion 4b, and does not contact the inner wall 1n of the cylinder body 1 at the base portion 4a, but contacts the inner wall 1n of the cylinder body 1 on the extending end 4e side of the lip portion 4b.

[0037] In addition, the sealing member 4 is provided with a regulating portion 4f between the base portion 4a constituting two longitudinal portions 4c facing the wide side portion 1c of the cylinder body 1, the regulating portion 4f being formed so as to contact the first retaining portion 2a on the side closer to the central axis x of the movement of the piston body 2 than the base portion 4a when the piston body 2 moves toward the one space 5, thereby maintaining the posture of the longitudinal portion 4c of the sealing member 4.

[0038] In the first example shown in Figures 1 to 16, such a regulating portion 4f is formed by a protruding portion 4g formed on each of the two longitudinal portions 4c of the sealing member 4 and protruding toward the central axis x of movement of the piston body 2.

[0039] In the first example, the protruding portion 4g is a convex piece having a length and a width, that is, the protruding portion 4g has a length that continues along the longitudinal direction of the longitudinal portion 4c and a width that protrudes from the inner portion 4aa of the base portion 4a toward the central axis x. Further, the protruding portion 4g includes a first surface 4ga continuous with a front end surface 4ac of the base portion 4a, and a second surface 4gb continuous with a rear end surface 4ad of the base portion 4a. As a result, the protruding portion 4g has, on the central axis x side of the base portion 4a, a first surface 4ga facing the first holding portion 2a and a second surface 4gb facing the second holding portion 2b. In addition, the protrusion portion 4g is formed on the inner portion 4aa side of the base portion 4a that constitutes the long portion 4c, so that a gap z (see Figures 9 and 10) of approximately half the total length of the protrusion portion 4g is provided between one of the two short portions 4d and one end portion 4gc of the protrusion portion 4g facing the short portion 4d side, and between the other of the two short portions 4d and the other end portion 4gc of the protrusion portion 4g facing the short portion 4d side. In addition, a gap is formed between the tip end of the protruding portion 4g formed on one of the two longitudinal portions 4c, which is located on the side of the central axis x, and the tip end of the protruding portion 4g formed on the other of the two longitudinal portions 4c, which is located on the side of the central axis x, such that the recessed portion 2h of the intermediate portion 2f can be accommodated therein. In the illustrated example, one end 4gc and the other end 4gc of the overhanging portion 4g are each inclined in a direction such that the length of the overhanging portion 4g decreases as the end approaches the tip end 4gd of the overhanging portion 4g.

[0040] As shown in Fig. 6, when a force is applied to the piston body 2 to cause a movement in a direction to reduce the one-way space 5 or a relative movement, the rear end surface 4ad of the base portion 4a of the seal member 4 comes into contact with the second holding portion 2b, and a gap c is generated between the front end surface 4ac of the base portion 4a and the first holding portion 2a, and the movement of the fluid is permitted through the gap c and the recessed portion 2h of the intermediate portion 2f and the passage f between the rib 2i of the second holding portion 2b. At the same time, since the one-way space 5 side becomes high pressure, a force P1 toward the central axis x is applied to the lip portion 4b of the seal member 4, and the movement of the fluid is also permitted from between the lip portion 4b and the inner wall 1n of the cylinder body 1. This allows the piston body 2 to move in a direction to reduce the one-way space 5, and a certain braking force is generated along with this movement. At this time, a force P2 is applied to the base portion 4a of the seal member 4 in a direction approaching the inner wall 1n of the wide side surface portion 1c of the cylinder body 1 due to the force P1 applied to the lip portion 4b. If the regulating portion 4f is not provided in the longitudinal portion 4c of the sealing member 4, the longitudinal portion 4c is easily deformed by the force P2 acting on the base portion 4a as described above, and if the deformation of the longitudinal portion 4c cannot be controlled, the braking force cannot be controlled either. On the other hand, in this embodiment, the restricting portion 4f can receive the force P2 acting on the base portion 4a when the force P1 acts on the lip portion 4b as described above by pressing the restricting portion 4f against the first holding portion 2a, thereby suppressing unexpected deformation of the longitudinal portion 4c of the seal member 4. In other words, the function of the restricting portion 4f allows the posture of the longitudinal portion 4c of the seal member 4, which is easily deformed, to be stably maintained in a desired posture throughout the entire process of the movement of the piston body 2 or the relative movement.

[0041] 7, when a force is applied to the piston body 2 to cause a movement in a direction to expand the one-side space 5 or a relative movement, the front end surface 4ac of the base portion 4a of the seal member 4 comes into contact with the first holding portion 2a, and at the same time, the other-side space 6 side becomes high pressure, so that a force P3 is applied to the lip portion 4b of the seal member 4 in a direction to press it against the inner wall 1n of the cylinder body 1, and the movement of the fluid to the one-side space 5 is limited to that through the orifice 1f. As a result, a constant braking force larger than the braking force when the one-side space 5 is reduced by the movement of the piston body 2 in a direction to expand it is generated.

[0042] The restricting portion 4f is formed on the long portion 4c of the seal member 4, but not on the short portion 4d. As a result, when the seal member 4 is elastically deformed and fitted to the piston body 2 as described above, the short portion 4d of the seal member 4 serves as the deformation center to widen the distance between the two long portions 4c of the seal member 4, making it easier to receive the piston body 2 therebetween, and this fitting operation can be facilitated.

[0043] In the first example, the second surface 4gb of the protruding portion 4g is inclined so that the thickness of the protruding portion 4g gradually decreases as it approaches the tip end 4gd of the protruding portion 4g. In the illustrated example, the protrusion portion 4g has the first surface 4ga as a surface perpendicular to the central axis x, and the tip portion 4gd which is the protruding end of the protrusion 4g as a surface oriented along the central axis x, while the second surface 4gb is inclined as described above over the entire length of the protrusion portion 4g. Due to the inclination of this second surface 4gb, during the fitting operation of the sealing member 4 to the piston body 2, in which the middle portion 2f of the piston body 2 is received into the sealing member 4 from the second retaining portion 2b side of the piston body 2 while elastically deforming the sealing member 4, the elastic return of the sealing member 4 after the protruding portion 4g overcomes the second retaining portion 2b allows the protruding portion 4g to smoothly fit between the first retaining portion 2a and the second retaining portion 2b.

[0044] (Second example) 17 to 20 show a second example in which the piston body 2 is configured by combining a first part 7 having the first holding portion 2a and a second part 8 having the second holding portion 2b so as to sandwich the seal member 4 therebetween. The second part 8 is integrated with the inner end of the rod body 3. The remaining configuration of this second example is the same or substantially the same as that of the first example, so a description thereof will be omitted.

[0045] The first portion 7 is composed of a plate having an elliptical outline that is complementary to the inner cross-sectional shape of the cylinder body 1 in a direction perpendicular to the central axis x of the cylinder body 1 having a flattened cylindrical shape. The second portion 8 is formed by a surface portion located on the side of the one space 5 in the head portion of the rod. This surface portion also has an elliptical outline that is complementary to the inner circumferential shape of the cross section of the cylinder body 1. In the illustrated example, the first portion 7 is provided with legs 7a that protrude toward the other space 6 from a surface portion facing the other space 6. The legs 7a are provided on both sides of the first portion 7 at a position midway in the longitudinal direction. Further, the second portion 8 is formed with receiving portions 8a for receiving the leg bodies 7a on both sides of the middle position in the longitudinal direction. In addition, a claw portion 7b is formed at the tip of the leg body 7a, and an elastic piece 8b is formed inside the receiving portion 8a. The insertion of the leg body 7a into the receiving portion 8a is permitted by the elastic deformation of the elastic piece 8b, and when the leg body 7a is fully inserted into the receiving portion 8a, the elastic return of the elastic piece 8b causes the tip of the elastic piece 8b to engage with the claw portion 7b of the leg body 7a. In the illustrated example, the claw portion 7b is formed on the side of the leg 7a opposite to the central axis x. On the other hand, the elastic piece 8b has a base on the entrance side of the receiving portion 8a and extends so that the distance from the central axis x gradually decreases as it moves toward the back of the receiving portion 8a. When the leg 7a is introduced into the receiving portion 8a, the claw portion 7b comes into contact with the elastic piece 8b and the elastic piece 8b is deformed in a direction away from the central axis x, allowing the leg 7a to be introduced into the receiving portion 8a. When the leg 7a is fully inserted into the receiving portion 8a, the elastic piece 8b elastically returns in a direction approaching the central axis x, and the elastic piece 8b enters between the entrance of the receiving portion 8a and the claw portion 7b, preventing the leg 7a from slipping out of the receiving portion 8a.

[0046] The seal member 4 constituting the second example has a configuration in which a bridge portion 4h serving as the restricting portion 4f is formed between the two longitudinal portions 4c. The bridge portion 4h has a width spanning between the inner portions 4aa of the base portions 4a constituting the two longitudinal portions 4c, and is bridged between the two base portions 4a. In addition, the installation portion 4h has a length in a direction parallel to the length of the longitudinal portion 4c of the sealing member 4, and a gap z is formed between one end portion 4ha facing one side of the two short portions 4d of the sealing member 4 in the installation portion 4h and this one short portion 4d, and between the other end portion 4ha facing the other side of the two short portions 4d of the sealing member 4 in the installation portion 4h and this other short portion 4d, thereby blocking the remaining area between the two base portions 4a. In the illustrated example, the leg 7a can be introduced into the receiving portion 8a by utilizing the gap z between the bridge portion 4h and the short portion 4d, thereby making it possible to combine the first part 7 having the first retaining portion 2a and the second part 8 having the second retaining portion 2b with the sealing member 4 sandwiched between them.

[0047] By forming a groove in either the first retaining portion 2a in the first portion 7 of the piston body 2 or the base portion 4a of the sealing member 4, and forming a protrusion that fits into the groove on the other of them, the combined state of the sealing member 4 with the piston body 2 can be stabilized. In the illustrated example, a groove 9 and a protrusion 10 are formed in the first retaining portion 2a and the seal member 4, respectively. Each of the grooves 9 and the protrusions 10 is formed so as to go around the central axis x and to follow the oval. The first retaining portion 2a has a protrusion 10 on the inside, and a groove 9 adjacent to the outside. The seal member 4 has a groove 9 on the inside at the front end face 4ac of the base portion 4a, and a protrusion 10 adjacent to the inside. When the first portion 7 and the second portion 8 are combined with the seal member 4 sandwiched between them as described above, the protrusion 10 of the first retaining portion 2a fits into the groove 9 of the base portion 4a of the seal member 4, and the protrusion 10 of the base portion 4a of the seal member 4 fits into the groove 9 of the first retaining portion 2a.

[0048] Of course, the present invention is not limited to the above-described embodiment, but includes all embodiments that can achieve the object of the present invention. [Explanation of symbols]

[0049] 1 Cylinder body 1c Wide side section 2 Piston body 2a First holding part 2b Second holding part 4. Sealing material 4a Base 4b Lip part 4c Long section 4f Regulation Department x center axis

Claims

1. A damper device comprising a flat cylindrical cylinder body having a pair of wide side portions and a pair of narrow side portions, a piston body movably accommodated within the cylinder body, and a seal member for sealing between the cylinder body and the piston body, the damper device generating a braking force by movement or relative movement of the piston body, the sealing member has elasticity, is circumferential and surrounds the piston body, and has a base portion located on one side of the space inside the cylinder body divided by the piston body, and a lip portion extending from the base portion to the other side of the space inside the cylinder body, the lip portion being in sliding contact with an inner wall of the cylinder body, the piston body includes a first holding portion of the seal member facing the base portion of the seal member from the one space side, and a second holding portion of the seal member located inside the lip portion of the seal member and facing the base portion from the other space side, A damper device comprising a regulating portion formed between the base portion constituting two longitudinal portions of the sealing member facing the wide side portion of the cylinder body, the regulating portion being formed so as to contact the first retaining portion on the side of the central axis of movement of the piston body relative to the base portion when the piston body moves toward one space, thereby maintaining the posture of the longitudinal portion of the sealing member.

2. 2. The damper device according to claim 1, wherein the seal member has two longitudinal portions each having a protruding portion that protrudes toward the central axis of movement of the piston body and serves as the restricting portion.

3. The damper device according to claim 1, wherein the protrusion portion has a first surface facing the first retaining portion and a second surface facing the second retaining portion, and the second surface is inclined so that the thickness of the protrusion portion gradually decreases as it approaches the tip of the protrusion portion.

4. 2. The damper device according to claim 1, wherein a bridge portion serving as the restricting portion is formed between the two longitudinal portions of the seal member.

5. The damper device according to claim 1, wherein the piston body is configured by combining a first part having the first retaining portion and a second part having the second retaining portion so as to sandwich the sealing member between the first part and the second part.

6. 6. The damper device according to claim 5, wherein a groove is formed in one of the first retaining portion in the first portion of the piston body and the base portion of the sealing member, and a rib that fits into the groove is formed in the other of them.

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