JP4579734B2 - Shock absorber - Google Patents

Description

  The present invention relates to a shock absorber having a piston and cylinder structure.

2. Description of the Related Art Conventionally, some open / close bodies that open / close with respect to a main body use a shock absorber in order to relax the impact force in the opening / closing operation and to give a high-class feeling due to a gentle operation. Such a shock absorber has a piston and cylinder structure, and the cylinder is filled with a viscous fluid such as silicone oil, and an orifice is provided in the piston, and the shock absorbing performance is exhibited by the resistance of the viscous fluid passing through the orifice by the movement of the piston. There is something like this (for example, see Patent Document 1).
Japanese Patent No. 3465978

  On the other hand, there is one provided with a slidable drawer on a desk or cabinet. By supporting such a drawer by the main body via the slide rail, the support rigidity of the drawer can be increased, so that the load resistance of the drawer can be increased. In such a drawer structure using slide rails, when the drawer is returned to the main body, the drawer can be positioned by contacting a part of the drawer with the stopper at the storage position of the main body. When the drawer with the increased weight of the contained item is slid and hit against the stopper, a large impact force is generated because the weight of the entire container is large. In order to reduce such an impact force, it is conceivable to use the above-described shock absorber.

  On the other hand, a device provided with a drawer is not limited to being used at room temperature where normal human activities are possible, and may be used in a low temperature environment in a cold region, for example. In this case, the temperature is considered to be -30 degrees in the extremely cold region as well as near 0 degrees. When selecting a viscous fluid considering only that it will be used at room temperature, select a fluid with a relatively high viscosity, and when placing importance on use at low temperatures, select a fluid with a low viscosity. It is normal. However, there is a problem that preparing a shock absorber having a changed viscosity for a specification place is complicated in assembly. Therefore, a shock absorber that can exhibit performance without any problems at both normal temperature and low temperature is desired.

In order to solve such a problem and realize a shock absorber that does not deteriorate the buffer performance in both low temperature and normal temperature environments, in the present invention, the cylinder in which the viscous fluid is sealed is axially arranged. In the shock absorber that splits into two in the axial direction by a piston having a communicating orifice, and generates a braking force by the resistance of the viscous fluid passing through the orifice when the piston moves in the cylinder in the axial direction, the viscous fluid to, the use of which resistance against shear even if the temperature difference between the low and normal temperature containing the vicinity of at least 0 ° becomes substantially equal, the piston and piston rod that is adapted to move integrally with the infested annular sealing member for preventing leakage of the viscous fluid in the axial end portion of the cylinder is provided with said piston, said piston rod An inner member provided integrally with the outer member, and an outer member that is loosely fitted to the inner member with a gap between the inner member and the inner peripheral surface of the cylinder. A compression coil spring that urges the inner member and the outer member in an axial direction is provided between the outer member and the inner member and the outer member to the inside of the outer member. It is assumed that the gap is formed in a stepwise manner when the amount of the inner member entering increases .

  In particular, the viscosity of the viscous fluid is preferably 1000 CST or less, and more preferably 200 to 350 CST. In addition, a cap is provided at the axial end portion of the cylinder, and the cap is provided with a seal member holding portion provided on the immersive side of the piston rod so as to hold the annular seal member coaxially, and the piston rod It is preferable to integrally have a piston rod shaft support portion that is provided on the protruding side of the piston rod and is elongated in the moving direction of the piston rod so as to support the cylinder coaxially and movably. In addition, it is preferable that a plurality of inner peripheral side annular protrusions that are spaced apart in the axial direction and project inward in the radial direction are formed on the inner peripheral surface of the annular seal member. The outer peripheral surface is preferably provided with an outer peripheral annular protrusion that protrudes outward in the radial direction. Moreover, it is good to use for the relief | moderation of the impact force at the time of a slide stop of a slide-type movable body.

  As described above, according to the present invention, in the shock absorber of the piston and cylinder structure, the viscous fluid sealed in the cylinder has a resistance to shearing at a low temperature of at least near 0 ° C. or at a normal temperature. By using an equivalent one, it is possible to prevent a difference in buffer performance from the temperature change between the low temperature and the normal temperature. In terms of resistance to shearing, high resistance means that shearing deterioration at high speeds and high loads is unlikely to occur. In particular, by using a viscous fluid having a viscosity of 1000 CST or less and a viscosity of 200 to 350 CST, the resistance to shearing can be substantially the same regardless of whether the resistance is low or normal temperature. It should be noted that the low temperature is not limited to around 0 ° C., and −30 ° C. can also be included.

  In particular, the annular seal member is held by a cap provided at the end of the cylinder in the axial direction, and the piston rod is pivotally supported to ensure the coaxiality of the moving piston rod and the annular seal member. It is possible to easily provide a shock absorber having a long piston stroke without any problem even if the length is long. In addition, for viscous fluids that are selected considering the low temperature, a fluid with a lower viscosity than that selected only for normal temperatures is selected. There is a possibility that a viscous fluid having a low viscosity leaks from a protruding portion with respect to the cylinder. By forming a plurality of inner peripheral annular protrusions that are spaced apart in the axial direction and project radially inwardly on the inner peripheral surface of the annular seal member provided in that portion, the shaft can be Since the piston rod can be blocked at multiple locations in the direction, even if there is a gap between the outer peripheral surface of the piston rod and the inner peripheral annular projection at the location where the outer peripheral surface of the piston rod is rough, the sliding contact state at other locations is ensured. As a result, sealing performance as a sealing member is ensured, and there is no problem even if a low-viscosity viscous fluid is used. Furthermore, by providing an outer peripheral side annular protrusion that protrudes radially outward on the outer peripheral surface of the annular seal member, for example, a seal member holding portion is formed in a cylindrical shape, and the annular seal member is held therein. In this case, since the outer peripheral annular protrusion can be resiliently brought into contact with the inner peripheral surface of the seal member holding portion, the sealability of that portion can be suitably ensured. As a result, even if the outer peripheral portion of the seal member is deformed so as to be drawn inward in the radial direction due to the movement of the piston rod, the seal performance can be ensured by the outer peripheral annular projection, and higher seal performance can be exhibited. .

  The shock absorber according to the present invention may be used to reduce the impact force when the sliding movable body is stopped. In a sliding movable body used for drawer of a cabinet or the like, the sliding direction is linear, and an impact force can be suitably reduced by a piston that moves in the axial direction of the cylinder. Since it is not necessary to use a shock absorber in which a different viscous fluid is sealed for each use environment, complexity in the manufacturing process can be eliminated. Further, it is only necessary to prepare the same one, and the component cost can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partial perspective view showing a main part of the appearance of a cabinet 2 in which a damper 1 as a shock absorber according to the present invention is used. As shown in the figure, the cabinet 2 is provided with a drawer 3 that can slide forward. Further, base rails 4 are fixed to the left and right side walls of the cabinet 2 in a substantially horizontal state, and the slide rails 5 are supported by the base rails 4 so that the slide rails 5 can be slid toward and away from the front surface of the cabinet 2. ing. The drawer 3 is supported by the slide rail 5.

  In the illustrated example, the damper 1 is fixed at an appropriate position on the inner surface of the main body of the cabinet 2 in order to reduce the impact force when the drawer 3 is stored in the cabinet 2 when the slide stops at the end of the slide. A damper actuating striker 6 is provided at an appropriate position of the drawer 3 so that it can strike a piston rod, which will be described later, when the drawer 3 is stored.

  FIG. 2 shows a side cross section of the damper 1 according to the present invention. The damper 1 is designed with a long piston stroke, and the cylinder and the piston rod are partially cut away in the figure.

  The cylinder 11 is formed in a bottomed cylindrical shape having one end in the axial direction as a closed bottom surface and the other end in the axial direction as an open surface. In the cylinder 11, a small-diameter portion 11a on the bottom surface formed in a small-diameter cylindrical shape and a large-diameter portion 11b on the opening surface side formed in a cylindrical shape larger in diameter than the small-diameter portion 11a are coaxially adjacent to each other. Each is provided with a predetermined axial length. A piston 12 that slides on the inner peripheral surface of the small-diameter portion 11 a is coaxially disposed, and an end portion of the piston rod 13 in the immersion direction is connected to the piston 12. Note that the protruding direction side of the piston rod 13 extends outward from the opening surface of the cylinder 11. A cap 14 that closes the opening surface is attached to the axial end of the opening surface side of the cylinder 11, and silicone oil is sealed in the cylinder 11 as a viscous fluid.

  An accumulator 15 made of a cylindrical foam material surrounding the piston rod 13 is provided at the large diameter portion of the cylinder 11. Between the inner peripheral surface of the accumulator 15 and the outer peripheral surface of the piston rod 13. A certain amount of space is provided. The accumulator 15 is formed in a cylindrical shape with a foaming synthetic resin material that has an appropriate resilience and shrinks when a predetermined pressure is applied. The accumulator 15 is formed on the inner peripheral surface of the large diameter portion 11b via a retainer 16. Is retained.

  The piston 12 is loosely fitted to the inner member 12a with a predetermined gap G between an inner member 12a that is substantially integrated with the end portion of the piston rod 13 in the immersion direction, and an outer peripheral surface of the inner member 12a, and a small diameter of the cylinder 11 A compression coil spring 17 is mounted between the inner member 12a and the outer member 12b. The compression coil spring 17 elastically urges the outer member 12b to be separated from each other in the axial direction. ing. Here, the outer diameter of the inner member 12a is changed stepwise so that the protruding side of the piston rod 13 becomes larger, and the inner member 12a enters the outer member 12b against the elastic biasing force of the compression coil spring 17. The gap G between the inner member 12a and the outer member 12b is narrowed when the amount of the inner member 12a is increased. The outer member 12b has a bottomed cylindrical shape, and an orifice 18 having an appropriate diameter for allowing a viscous fluid to flow through is formed on the bottom wall.

  For viscous fluids, even if this cabinet 2 is used in various environments, it has extremely high resistance to shearing so that the damper 1 can cope with any problems. Silicone oils that are less likely to occur and have the property of maintaining a long life span are suitable. In addition, the environment to be used is assumed to be a low temperature of about 30 degrees from normal temperature. First, from those that can obtain appropriate (as designed) viscous resistance at room temperature, select those that can obtain viscous resistance equivalent to normal temperature even at a low temperature of about 30 degrees. In the case of a viscous fluid that satisfies such conditions, the viscosity should be 1000 CST or less.

  In particular, the viscosity is preferably 200 to 350 CST. Since the silicone oil has high resistance to shearing, it can exhibit predetermined impact force relaxation performance regardless of the temperature difference between a low temperature including −30 degrees and a normal temperature.

  However, the viscosity of the 200-350 CST viscous fluid mentioned above is usually low. When the viscosity is low, it is important to take measures against leakage from the seal portion. The seal structure is shown below.

  Inside the cylinder 11 of the cap 14, a cylindrical portion 14 a having an inner peripheral surface that surrounds the piston rod 13 with a predetermined gap is formed as a seal member holding portion so as to protrude in the axial direction. In the cylindrical portion 14a, an annular oil seal 19 is mounted as a seal member that is in sliding contact with the outer peripheral surface of the piston rod 13. The cross-sectional shape of the oil seal 19 is formed in an X shape. Since both leg portions of the oil seal 19 on the inner peripheral side of the X-shape are in sliding contact with the piston rod 13 at two positions spaced in the axial direction, the oil adhering to the outer peripheral surface of the piston rod 13 at the two positions is removed. Can be scraped off. For example, in the case of an oil seal having a transverse V-shaped cross section, one of the expanded projecting ends is in sliding contact with the piston rod, so that the piston rod is cut off at only one location. When the outer peripheral surface of the rod is rough, air may enter when it floats. On the other hand, by using an oil seal that is slidably contacted with the piston rod 13 at two or more locations such as an X-shape, even if one location is floating, the other is in slidable contact Air entry and oil leakage can be prevented. As described above, since the sealing performance stronger than that of the V-shaped oil seal can be exhibited, the leakage can be prevented even when a viscous fluid having a low viscosity is used.

  A boss portion 14b that protrudes in the protruding direction of the piston rod 13 is formed on the cylinder outer side of the cap 14 as a piston rod shaft supporting portion. A shaft support hole 14c is formed through the end plate portion of the cap 14 and the central portion of the boss portion 14b so as to support the piston rod 13 coaxially and movably in the axial direction. The axial length of the shaft support hole 14c is increased to some extent in the moving direction of the piston rod 13. Thus, by increasing the length of the shaft support hole 14c, it is possible to suppress the deflection of the piston rod 13 in the direction intersecting with the axis. Thereby, since the piston rod 13 can be lengthened, that is, the piston stroke of the damper 1 can be lengthened, the impact force can be reduced over a long movement distance of the piston rod 13, and the damper applicable to a larger impact force. 1 can be provided.

  Next, the operating procedure of the damper 1 will be described.

  When the drawer 3 is pulled out largely, the piston rod 13 is pulled out from the cylinder 11 as shown in FIG. This is possible by pulling out the drawer 3 so that the piston rod 13 is pulled out. For example, the engaging member 13a is fixed to the end of the piston rod 13 in the protruding direction, and engages with the engaging member 13a in the pulling direction, but can be freely displaced with respect to the engaging member 13a in the retracting direction. A member may be provided on the slide rail 6.

  When the drawer 3 is pushed in the retracted direction from the state shown in FIG. 2, the damper actuating striker 6 comes into contact with the end of the piston rod 13 in the middle of the slide, and when the drawer 3 is pushed further, The piston rod 13 is immersed. At this time, the silicone oil on the bottom surface side of the cylinder 11 moves to the accumulator 15 side through the orifice 18 of the outer member 12b of the piston 12 and the gap G between the outer member 12b and the inner member 12a. The energy applied to the piston rod 13 is attenuated by the resistance.

  When the piston 12 moves while the outer member 12b and the inner member 12a are separated from each other by the elastic force of the compression coil spring 17, the gap G between the outer member 12b and the inner member 12a is formed. Since it is widely held, the braking force is kept in a low range. When the drawer 3 of the cabinet 2 is moved relatively slowly, a large impact force is not generated when the end of the slide is reached. It is effective to use the piston structure because it is not necessary to provide a large buffer until a large impact force is not generated by such a gentle movement. Further, when the immersion length of the piston rod 13 into the cylinder 11 is increased, the internal volume of the cylinder 11 is reduced correspondingly and the sealing pressure of the silicone oil is increased. This is an accumulator formed of a foamable synthetic resin material. It is absorbed by 15 compression deformations.

  As described above, the damper 1 configured in this way exhibits substantially the same buffering capacity even at room temperature, even at a low temperature that is at least near 0 degree and further includes −30 degrees. Therefore, the trouble of replacing the damper 1 for the specification area can be saved. Further, when a plurality of types of dampers are prepared, the assembly work is complicated in order to prevent wrong assembly, whereas only one type of damper 1 needs to be handled. Efficiency can be improved.

  Since the flow resistance of the silicone oil increases progressively with respect to the piston speed, for example, the compression coil spring 17 is set to be contracted by the resistance of the silicone oil applied to the outer member 12b when the piston 12 moves above a certain speed. If this is done, the outer member 12b becomes difficult to move above a certain speed, so that the compression coil spring 17 contracts, and the inner member 12a enters the outer member 12b as shown in FIG. Then, since the gap G between the inner member 12a and the outer member 12b becomes narrow, the braking force due to the flow resistance of the silicone oil increases. In this way, since a large impact force can be suitably reduced, it is possible to prevent the generation of a large impact force at the end of the slide when storing at a high moving speed.

  In this way, the compression coil spring 17 is used for detecting the speed at which the braking force is switched by the variable orifice, so that the change in the switching speed due to the change in the ambient temperature can be made relatively small. This also exhibits substantially the same buffering capacity against the temperature difference between the normal temperature use state and the low temperature use state.

  Moreover, in the annular seal member based on this invention, the cross-sectional shape of the said illustration example is not restricted to a X-shaped thing, It shows below with reference to FIG. 4 as another example. In addition, the same code | symbol is attached | subjected about the part similar to the said example of illustration, and the detailed description is abbreviate | omitted.

  In the annular seal member 21 shown in FIG. 4, the overall shape of the cross-sectional shape is Y-shaped along the axial direction as shown in the figure. The inner peripheral arm on the piston rod 13 side of the two Y-shaped arms is formed as an inner peripheral annular protrusion 21a that protrudes inward and obliquely in the radial direction, and the other outer peripheral arm 21b is Y-shaped. The outer peripheral surface of the annular seal member 21 is formed together with the portion serving as the shaft. Furthermore, a second inner peripheral side annular protrusion 21c that protrudes inward in the radial direction is formed on the inner peripheral surface of the portion that becomes the Y-shaped shaft. In this way, both the inner peripheral side annular projections 21a and 21c are arranged apart from each other in the axial direction. In addition, an outer peripheral annular protrusion 21 d that protrudes outward in the radial direction is formed on the outer peripheral surface of the annular seal member 21. The annular protrusions 21a, 21c, and 21d are formed over the entire circumference of the annular seal member 21.

  The annular seal member 21 formed as described above is attached to the cylindrical portion 14a with its outer peripheral surface being in close contact with the inner peripheral surface of the cylindrical portion 14a. In the mounted state, the outer peripheral annular protrusion 21d is pushed inward in the radial direction as indicated by a two-dot chain line in the figure, and therefore the protruding end (edge) of the outer peripheral annular protrusion 21d is generated by the elastic restoring force of the outer arm 21b. ) Elastically contacts the inner peripheral surface of the cylindrical portion 14a.

  Further, in the shape of the inner peripheral side of the annular seal member 21, the inner peripheral surface of the Y-shaped shaft portion faces the outer peripheral surface of the piston rod 13 with a gap therebetween, so that each inner peripheral side The annular protrusions 21a and 21c are elastically slidably contacted with the outer peripheral surface of the piston rod 13 as indicated by a two-dot chain line in the figure. As a result, the projecting ends (edges) of the inner circumferential annular projections 21a and 21c are elastically slidably contacted at two locations spaced in the axial direction with respect to the outer circumferential surface of the piston rod 13. As a result, even when the outer peripheral surface of the piston rod 13 is rough and one of them floats as in the case of the oil seal 19, the other is in sliding contact, thereby preventing air intrusion and oil leakage due to axial movement of the piston rod 13. can do.

  Further, even when the entire annular seal member 21 is dragged in the moving direction due to the axial movement of the piston rod 13 and the outer peripheral arm 21b is deformed inward in the radial direction, the outer peripheral ring with respect to the inner peripheral surface of the cylindrical portion 14a. Since the elastic contact state of the protrusion 21d is maintained, the sealing performance of the portion is ensured, and therefore oil leakage can be reliably prevented without using an adhesive or the like.

  The shock absorber according to the present invention is capable of exhibiting substantially the same shock absorbing capacity with respect to a temperature change between a low temperature and a normal temperature, and the shock absorber is attached to a product used in an environment where such a temperature change is possible. Useful when

It is a principal part perspective view of the cabinet to which this invention was applied. It is side sectional drawing which shows the damper based on this invention. It is a figure corresponding to Drawing 2 showing a damper at the time of high-speed operation. It is an expanded sectional side view which shows the other example of a sealing member.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Damper 11 Cylinder 12 Piston 13 Piston rod 14 Cap, 14a Cylindrical part, 14b Boss part, 14c Shaft support hole 19 * 21 Oil seal

Claims (7)

A cylinder filled with a viscous fluid is divided into two axially by a piston having an orifice communicating in the axial direction, and by the resistance of the viscous fluid passing through the orifice when the piston moves in the axial direction in the cylinder In a shock absorber that generates a braking force,
Said viscous fluid, the use of which resistance against shear even if the temperature difference between the low and normal temperature containing the vicinity of at least 0 ° becomes substantially equal,
An annular seal member for preventing leakage of the viscous fluid is provided at an axial end portion of the cylinder where a piston rod adapted to move integrally with the piston is projected and retracted ,
The piston includes an inner member provided integrally with the piston rod, and an outer member that is loosely fitted to the inner member with a gap between the outer circumferential surface and the inner member that slides on the inner circumferential surface of the cylinder. Have
Between the inner member and the outer member, there is provided a compression coil spring that urges the inner member and the outer member in a direction to separate them in the axial direction, and the inner member and the outer member are The shock absorber is characterized in that the gap is formed in a stepwise manner as the amount of the inner member entering the outer member increases .   The shock absorber according to claim 1, wherein the viscosity of the viscous fluid is 1000 CST or less.   The shock absorber according to claim 1, wherein the viscosity of the viscous fluid is 200 to 350 CST. A cap is provided at the axial end of the cylinder;
The cap is configured to support a seal member holding portion provided on the immersion side of the piston rod so as to hold the annular seal member coaxially, and to support the piston rod so as to be movable coaxially with respect to the cylinder. The shock absorber according to any one of claims 1 to 3, further comprising a piston rod shaft support portion provided on a protruding side of the piston rod and elongated in a moving direction of the piston rod. .   The inner peripheral surface of the annular seal member is formed with a plurality of inner peripheral annular protrusions that are spaced apart in the axial direction and project inward in the radial direction. 4. The shock absorber according to any one of 4 above.   The shock absorber according to claim 5, wherein an outer peripheral side annular protrusion that protrudes outward in a radial direction is provided on an outer peripheral surface of the annular seal member.   The shock absorber according to any one of claims 1 to 6, wherein the shock absorber is used for alleviating an impact force when the sliding of the sliding movable body is stopped.

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