JP2019124283A - Cylindrical vibration controller - Google Patents

Abstract

To provide a cylindrical vibration controller of a novel structure capable of tuning a spring characteristic at large degree of freedom, and capable of attaining excellent durability.SOLUTION: An elastic connector 16 elastically connecting an inner shaft member 14 and an outer cylinder member 22 to each other over the whole circumference is formed of foam polyurethane resin. The elastic connector 16 is disposed between the inner shaft member 14 and the outer cylinder member 22 in a state of being compressed in a direction orthogonal to an axis. Annular recess grooves 20, 20 extending circumferentially are each formed on both end surfaces of the elastic connector 16. In the elastic connector 16 in a molding state of being not compressed between the inner shaft member 14 and the outer cylinder member 22, the recess grooves 20, 20 are opened to an axial end surface of the elastic connector 16.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a cylindrical vibration damping device having a structure in which an inner shaft member and an outer cylindrical member are elastically connected to each other by an elastic connecting member.

  2. Description of the Related Art Conventionally, a cylindrical vibration damping device applied to a suspension bush or the like of an automobile is known. The cylindrical vibration isolation device is, for example, an inner cylinder and an outer cylinder that are thick-walled cylindrical rubber-like elastic bodies, such as a vibration isolation bush disclosed in JP-A-2004-205049 (Patent Document 1). It has a resiliently coupled structure.

  By the way, in the conventional cylindrical vibration-damping device, when softer spring characteristics are required, a structure is also generally known in which a burr hole penetrating in the axial direction is formed with respect to the rubber-like elastic body. For example, as disclosed in Patent Document 1, the spring characteristics in the radial direction are adjusted by forming a pair of blind holes on both sides in the radial direction across the inner cylinder.

  However, in the structure in which the flat hole is formed as in Patent Document 1, stress concentration may occur on the inner peripheral surface of the flat hole during elastic deformation of the rubber-like elastic body, and the durability of the rubber-like elastic body may be reduced. was there. In addition, when the rubber-like elastic body is largely deformed and crushed until the burr hole is substantially eliminated, the dynamic spring of the rubber-like elastic body may be rapidly enlarged, which may cause a deterioration in ride comfort and the like.

JP 2004-205049 A

  The present invention has been made in the background of the above-mentioned circumstances, and the problem to be solved is that the spring characteristics can be tuned with a large degree of freedom, and excellent durability can also be realized. An object of the present invention is to provide a cylindrical vibration damping device having a structure.

  The following describes aspects of the present invention made to solve such problems. In addition, the component employ | adopted in each aspect described below can be employ | adopted as much as possible in arbitrary combination.

  The present inventors examined forming an elastic connecting body which elastically connects an inner shaft member and an outer cylinder member with foaming polyurethane resin, in order to realize a soft spring characteristic in a cylindrical vibration isolation device. However, if it is attempted to obtain the spring characteristics required for a cylindrical vibration damping device such as a suspension bush with an elastic connection body made of foamed polyurethane resin, the spring characteristics may be too soft, in which case the inner shaft member It is necessary to adjust the spring by greatly compressing the resilient connection between the and the outer tubular member.

  However, since the size, shape, arrangement, etc. of the bubbles are not uniform, and the density is uneven, the elastic connector made of the foamed polyurethane resin is unlikely to be uniform in deformation rigidity, and the density is small when trying to compress largely. There has been a new problem that it is difficult to compress the part to a target deformation mode stably by causing a large local deformation. Accordingly, as a result of conducting a number of studies and experiments to solve such problems, the present inventors have also solved the above new problems caused by employing an elastic connector made of a foamed polyurethane resin. The present invention has been made possible.

  That is, according to the first aspect of the present invention, in the cylindrical vibration-damping device in which the inner shaft member and the outer cylindrical member are elastically connected to each other over the entire circumference by the elastic connection body, the elastic connection body is a polyurethane foam resin. The elastic connector is disposed between the inner shaft member and the outer cylindrical member in a state of being compressed in a direction perpendicular to the axial direction, and an annular concave groove extending in the circumferential direction is the elastic connector The concave groove is formed in the end face in the axial direction of the elastic connector in the elastic connector in a molded state not formed between the inner shaft member and the outer cylindrical member, which are respectively formed on both end surfaces of the It is characterized by

  According to the cylindrical vibration-damping device having the structure according to the first aspect, softer spring characteristics can be easily realized by forming the elastic connector from the foamed polyurethane resin. Therefore, it is possible to obtain a sufficiently soft spring characteristic without providing a through hole (surrounding hole) or the like formed in the elastic connector in order to obtain a soft spring characteristic, and a through hole or the like in the elastic connector It is also possible to avoid stress concentration due to the formation of

  Furthermore, since the elastic connector is compressed in the direction perpendicular to the axis between the inner shaft member and the outer cylinder member, the spring characteristics of the elastic connector can be increased by adjusting the amount of compressive deformation of the elastic connector. Can be tuned.

  Moreover, even when the elastic connector is greatly compressed, the deformation of the axial ends of the elastic connector can be particularly stabilized by the annular recessed grooves opened at both axial end surfaces of the elastic connector. It is possible to prevent the occurrence of distortion such as buckling at the axial end face of the elastic connector. Therefore, the amount of compressive deformation in the direction perpendicular to the axis of the elastic connector can be set with a large degree of freedom, and the spring characteristics of the elastic connector can be easily tuned.

  A second aspect of the present invention is the cylindrical vibration damping device described in the first aspect, wherein the elastic connector is compressed in a direction perpendicular to the axis between the inner shaft member and the outer cylindrical member. In the state, the concave groove is crushed and substantially closed.

  According to the second aspect, in the state where the elastic connector is compressed in the direction perpendicular to the axis between the inner shaft member and the outer cylinder member, vibration is input by the concave groove being substantially crushed and closed. In the state of use of the cylindrical vibration isolation device, the recessed groove hardly affects the vibration isolation characteristics. Furthermore, in the use state of the cylindrical vibration damping device, concentration of stress on the formation portion of the concave groove is prevented, and durability is ensured.

  According to a third aspect of the present invention, in the cylindrical vibration-damping device described in the first or second aspect, the inner shaft member is provided with a convex portion projecting to the outer periphery, and the deep groove in the concave groove The portion having the largest dimension is located on the outer peripheral side of the projection.

  According to the third aspect, it is possible to adjust the rate of compressive deformation and the like of the elastic connector also by the convex portion of the inner shaft member, and to tune the spring characteristics of the elastic connector with a greater degree of freedom It becomes possible.

  Furthermore, by providing the recessed groove of the elastic connection body on the outer periphery than the convex portion of the inner shaft member, the strain deformation of the outer peripheral portion of the elastic connection body which is not restrained by the convex portion when the elastic connection body is compressed is concaved. By means of the groove, the deformation of the elastic connection is stabilized.

  According to a fourth aspect of the present invention, in the cylindrical vibration damping device described in any one of the first to third aspects, the molded state which is not compressed between the inner shaft member and the outer cylindrical member An outer diameter dimension in a direction perpendicular to the axis of the elastic connection body is larger than an inner diameter dimension in a direction perpendicular to the axis of the outer cylindrical member.

  According to the fourth aspect, by arranging the elastic connecting body on the inner periphery of the outer cylindrical member, the outer diameter dimension of the elastic connecting body is reduced by the outer cylindrical member, and the elastic connecting body is compressed in the direction perpendicular to the axis Ru. The outer cylindrical member may be previously formed to have an inner diameter smaller than the outer diameter of the elastic connector in the molded state, or the diameter may be reduced in the state of being externally inserted into the elastic connector in the molded state. By being processed, the inner diameter may be smaller than the outer diameter of the elastic connection body in a molded state.

  According to a fifth aspect of the present invention, in the cylindrical vibration damping device described in any one of the first to fourth aspects, the elastic connector has an outer diameter dimension in a direction perpendicular to the axis of the elastic connector. By being compressed in a direction perpendicular to the axis between the inner shaft member and the outer cylindrical member, it is 25 to 70% smaller than the molded state.

  According to the fifth aspect, the proportion of the compressive deformation in the direction perpendicular to the axis of the elastic connector is set within the above range, whereby spring characteristics suitable for practical use can be obtained while forming the elastic connector from the foamed polyurethane resin. The cylindrical vibration-damping device can be obtained.

  According to the present invention, since the elastic connector is formed of the foamed polyurethane resin, it is possible to easily realize softer spring characteristics, and it is necessary to specially provide spring reduction means such as through holes. It is also possible to avoid concentration of stress due to formation of through holes and the like. Furthermore, since the elastic connector is compressed in the direction perpendicular to the axis between the inner shaft member and the outer cylindrical member, the spring characteristics of the elastic connector can be made largely free by adjusting the ratio of the compressive deformation of the elastic connector. Can be tuned in degrees. Moreover, even when the elastic connector is greatly compressed, the deformation of the axial ends of the elastic connector can be particularly stabilized by the annular recessed grooves opened at both axial end surfaces of the elastic connector. It is possible to prevent the occurrence of distortion such as buckling at the axial end face of the elastic connector.

BRIEF DESCRIPTION OF THE DRAWINGS The front view which shows the suspension bush as 1st embodiment of this invention. II-II sectional drawing of FIG. III-III sectional drawing of FIG. The front view of the bush main body which comprises the suspension bush shown in FIG. FIG. 5 is a cross-sectional view taken along line V-V of FIG. 4. The front view which shows the suspension bush as 2nd embodiment of this invention. VII-VII sectional drawing of FIG. The front view of the bush main body which comprises the suspension bush shown in FIG. IX-IX sectional drawing of FIG. The front view which shows the suspension bush as 3rd embodiment of this invention. XI-XI sectional drawing of FIG. The front view of the bush main body which comprises the suspension bush shown in FIG. XIII-XIII sectional drawing of FIG. FIG. 16 is a cross-sectional view showing a suspension bush as another embodiment of the present invention, the view corresponding to the XIV-XIV cross section of FIG. 15. XV-XV sectional drawing of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 to 3 show a suspension bush 10 for a car as a first embodiment of a cylindrical vibration-damping device constructed according to the present invention. The suspension bush 10 includes a bush main body 12, and the bush main body 12 has a structure in which an elastic connecting member 16 is fixed to an inner shaft member 14. In the following description, in principle, the vertical direction means the vertical direction in FIG. 1, the longitudinal direction means the vertical direction in FIG. 2 which is the axial direction, and the horizontal direction means the horizontal direction in FIG. . In the following description, the vertical direction, the horizontal direction, and the front-rear direction do not necessarily coincide with the vertical direction, the horizontal direction, or the front-rear direction of the vehicle when the suspension bush 10 is mounted on the vehicle.

  More specifically, the inner shaft member 14 is a hard member formed of metal or the like, and has a thick, small diameter, substantially cylindrical shape extending linearly in the front-rear direction as a whole. Furthermore, the inner shaft member 14 is provided with convex portions 18 and 18 which project to the left and right sides in the central portion in the axial direction. The convex portion 18 of the present embodiment is integrally formed with the inner shaft member 14 as shown in FIGS. 2 and 3 and the like, and the surface of the base end portion is a portion of the inner shaft member 14 outside the convex portion 18. While being smoothly continuous with the outer peripheral surface, the surface of the projecting tip portion is constituted by a smooth curved surface without corners or partial irregularities.

  The elastic connector 16 has a toroidal shape or a cylindrical shape as a whole, and the front and rear surfaces are inclined surfaces which gradually incline inward in the axial direction toward the outer periphery, and the thickness dimension in the front-rear direction is the outer periphery It is getting smaller and smaller.

  Furthermore, the elastic connector 16 is formed of a porous polyurethane foam resin (hereinafter, urethane foam). The composition of the foamed urethane forming the elastic connector 16 is not particularly limited. For example, a polyester-based polyol composed of a condensation polymer of ethylene glycol, butanediol and adipic acid etc. is used as a polyol component, and diphenylmethane diisocyanate ( Foamed urethane made of a urethane material having MDI), 1,5-naphthalene diisocyanate (NDI) or the like as an isocyanate component is preferably employed. In addition to the above-mentioned polyol component and isocyanate component, urethane raw materials also include foaming agents such as water, chain extenders such as ethylene glycol, catalysts, foam stabilizers, hydrolysis inhibitors, flame retardants, viscosity reducing agents, Stabilizers, fillers, crosslinking agents, colorants, etc. are blended as needed. Further, the foaming ratio of the foamed urethane is not particularly limited, but for example, it is desirable to be about 25 to 70%.

  Furthermore, the elastic connecting member 16 is in the form of a continuous ring or tube around the entire circumference, and no axially penetrating hole is formed. The elastic connector 16 may include an axially penetrating continuous bubble unless it has a predetermined axially penetrating hole, but preferably has no axially penetrating bubble, For example, it is formed of closed-cell urethane foam.

  Furthermore, in the elastic connection body 16, concave grooves 20, 20 extending in the circumferential direction are formed. As shown in FIGS. 4 and 5, the recessed groove 20 is formed into an annular shape extending continuously along the entire circumference, and the shaft is provided at the radially intermediate portion of the resilient connecting member 16 in a molded state which is not radially compressed. It opens in each one of the front and rear surfaces which are the direction both end surfaces. The concave groove 20 of this embodiment has a groove cross-sectional shape in which the groove width dimension gradually increases toward the opening, and the inner surface of the groove is formed of a smoothly continuous surface without partial unevenness and corners. There is. The depth d of the recessed groove 20 shown in FIG. 5 is preferably 25% or less with respect to the front-rear thickness t of the elastic connector 16 at the same position in the radial direction.

  In the present embodiment, the concave groove 20 opening in the front surface of the elastic connector 16 and the concave groove 20 opening in the rear surface have substantially the same shape and are formed at substantially the same positions in the radial direction with respect to the elastic connector 16 It is done. As a result, the elastic connector 16 of the present embodiment has a substantially plane-symmetrical shape with respect to a plane extending in the direction perpendicular to the axis through the axial center.

  The inner peripheral surface of the elastic connecting member 16 is fixed to the outer peripheral surface of the inner shaft member 14 to constitute the bush main body 12. The means for fixing the inner shaft member 14 and the elastic connector 16 to each other is not particularly limited, but in the present embodiment, they are adhered by an adhesive.

  In the bonded state of the inner shaft member 14 and the elastic connector 16, the convex portions 18 and 18 of the inner shaft member 14 are fixed to the elastic connector 16 in a buried state, and the front and back of the inner peripheral surface of the elastic connector 16 Both end portions are fixed to the outer peripheral surface of the inner shaft member 14 at the front and rear outside of the convex portions 18, 18. Further, at least a portion where the depth dimension of the concave portions 20 and 20 of the elastic connection body 16 is maximum is disposed on the outer peripheral side of the convex portions 18 and 18 of the inner shaft member 14, and in the present embodiment, As shown in FIG. 4, the entire recessed grooves 20, 20 are separated radially outward without overlapping with the projections 18, 18 in axial projection.

  Further, the outer cylindrical member 22 is attached to the bush main body 12. The outer cylindrical member 22 is a hard member formed of metal or the like, and has a thin, large-diameter, substantially cylindrical shape that linearly extends in the front-rear direction. Furthermore, the axial dimension of the outer cylindrical member 22 is made smaller than the axial dimension of the inner shaft member 14 and made larger than the maximum dimension of the convex portions 18, 18 in the inner shaft member 14 in the same direction. There is. The outer cylindrical member 22 of the present embodiment has an inner diameter dimension substantially the same as the outer diameter dimension of the elastic connecting member 16 in a state before the diameter reducing process described later is performed.

  Then, the outer cylindrical member 22 is extrapolated to the elastic connection body 16 of the bush main body 12 as virtually shown by a two-dot chain line in FIG. 5. In the present embodiment, the outer cylindrical member 22 is externally inserted in the front-rear central portion of the bush main body 12, and the entire convex portions 18, 18 of the inner shaft member 14 overlap the outer cylindrical member 22 in the left-right direction projection. At the same time, the axially opposite end portions of the outer cylindrical member 22 located axially outward of the projections 18, 18 project axially outward beyond the outer peripheral surface of the elastic connector 16. In the present embodiment, the compression in the radial direction of the elastic connector 16 due to the extrapolation of the outer cylindrical member 22 does not substantially occur.

  Further, as shown in FIGS. 1 to 3, the diameter of the outer cylindrical member 22 extrapolated to the elastic connection body 16 is reduced by diameter reduction processing such as an eight-way drawing. Thus, the outer cylindrical member 22 is non-adhesively attached to the outer peripheral portion of the elastic connecting member 16 in the bush main body 12, and the inner shaft member 14 and the outer cylindrical member 22 are elastically connected to each other by the elastic connecting member 16.

  The inner shaft member 14 and the outer cylindrical member 22 are formed by the elastic connecting member 16 because the elastic connecting member 16 does not have a hole or the like penetrating in the axial direction but has a shape continuous over the entire circumference. It is elastically connected mutually in the radial direction over the entire circumference. However, it is also possible to form a recess intended for adjustment of the spring characteristics, a hole penetrating in the axial direction, etc. in the elastic connecting member 16, in which case the recess or the hole corresponds to that of the elastic connecting member 16. It may be crushed and eliminated substantially by pre-compression, or may remain in an open state after pre-compression of the elastic connector 16. Further, for example, a cylindrical or plate-like intermediate member extending in the circumferential direction may be fixed to a radially intermediate portion of the elastic connector 16 to adjust the spring characteristics. In the case where a recess or a through hole is provided in the elastic connection body 16 or the intermediate member is fixed, the recess, the through hole, the intermediate member or the like is provided out of the recessed grooves 20, 20.

  In this embodiment, as can be seen from the fact that the inner diameter of the outer cylindrical member 22 before diameter reduction processing and the outer diameter of the elastic connector 16 in the molded state are substantially the same, the elastic connector 16 in the molded state is The outer diameter dimension is made larger than the inner diameter dimension of the outer cylindrical member 22 after diameter reduction processing. Therefore, by reducing the diameter of the outer cylindrical member 22 in a state where the outer cylindrical member 22 is externally inserted into the elastic connecting body 16, the elastic connecting body 16 is radially compressed between the inner shaft member 14 and the outer cylindrical member 22 in the radial direction. There is.

  In addition, since the elastic connecting body 16 is formed of porous urethane foam, in order to obtain the spring characteristics required for a suspension bush for automobiles and the like, the diameter is smaller than that of a general solid rubber. It is greatly compressed in the direction. In particular, the elastic connector 16 is compressed at a larger ratio than the vertical direction in the left-right direction in which the protrusions 18 of the inner shaft member 14 project, for example, with the protrusions 18 of the inner shaft member 14 and It is disposed in a state of being compressed at a high ratio of 25 to 70% with respect to the outer diameter dimension of the elastic connecting member 16 before compression between the outer cylindrical member 22 and the radial direction. However, the amount of compressive deformation of the elastic connector 16 is appropriately set in consideration of the required spring characteristics, the expansion ratio of the elastic connector 16 and the like.

  Here, the concave grooves 20, 20 provided on the front surface and the rear surface of the elastic connector 16 in the compressed state shown in FIGS. 1 and 2 by the elastic connector 16 being compressed and deformed in the radial direction. Crushed in the direction is substantially closed. Thus, in the portion where the recessed grooves 20, 20 are formed, the elastic connector 16 is easily deformed such that the recessed grooves 20, 20 close in the groove width direction. In particular, even if the elastic connector 16 is made of urethane foam and requires a large compression, the axial end of the elastic connector 16 is stabilized by being guided to the recessed grooves 20 and 20 particularly at both axial ends. It is possible to prevent distorted deformation in the part.

  Since the elastic connector 16 is formed of urethane foam, it has a sufficiently small Poisson's ratio and has compressibility. Therefore, when the elastic connector 16 is pre-compressed in the radial direction, the elastic connector 16 has small or little axial expansion, and has an Poisson's ratio of about 0.5 in the axial direction like a rubber or elastomer. Unlike the fact that the bottom surface of the recessed groove is raised by swelling and the depth is reduced, the recessed groove 20 is closed so that both inner surfaces in the groove width direction overlap with each other. As described above, the recessed groove 20 is simply closed in the groove width direction and both inner surfaces in the groove width direction overlap with each other, so that the elastic connector is formed of rubber or elastomer. The fact that the groove depth is reduced due to the axial expansion to make the groove shallow and disappears is different in the mechanism of deformation and structurally different. In the present embodiment, in consideration of the deformation mode of the elastic connecting member 16 made of foamed urethane, the groove cross-sectional shape of the groove 20 is gradually narrowed toward the bottom in the present embodiment. The inner surfaces in the groove width direction come into contact with each other from the bottom side by pre-compression of the elastic connection body 16 so as to gradually become shallow and disappear.

  The respective recessed grooves 20 do not have to be strictly closed entirely by the compression of the elastic connection body 16 and may be substantially closed. That is, the concave groove 20 can be considered to be substantially closed if 2/3 or more of the groove depth dimension is crushed and closed by the compression of the elastic connection body 16. For example, in the present embodiment, as shown in FIGS. 1 and 2, although a slight dent remains at the open end of the recessed groove 20, substantially the entire inner surface of the groove of the recessed groove 20 adheres to each other in the radial direction. And the recessed groove 20 is substantially closed.

  According to the suspension bush 10 having the structure according to the present embodiment, since the elastic connection body 16 is formed of urethane foam, soft spring characteristics (low motion without forming an axial through hole, etc. Spring characteristics) can be realized. Therefore, in the use condition where vibration is input, stress is not concentrated on the formation portion of the through hole, and durability can be improved.

  Furthermore, the elastic connection body 16 is compressed between the inner shaft member 14 and the outer cylindrical member 22, so that the spring characteristics of the elastic connection body 16 can be adjusted with a large degree of freedom. In particular, if the elastic connector 16 is compressed more than the conventional rubber bush, the spring characteristic realized by providing the through hole in the conventional rubber bush can be realized simply and with excellent durability. . In particular, the spring of the elastic connector 16 can be adjusted to a practically suitable hardness by setting the change ratio of the outer diameter of the elastic connector 16 due to radial compression to 25% or more and 70% or less. it can.

  Further, by forming the concave grooves 20, 20 opened in the front surface and the rear surface of the elastic connecting member 16, when the elastic connecting member 16 is largely compressed, deformation of the axial end portion of the elastic connecting member 16 occurs. It is guided by the recessed grooves 20 and 20, and it is possible to avoid a defect such as the occurrence of a buckling-like distorted breakage at the axial end face of the elastic connection body 16. Therefore, while the spring characteristics of the elastic connector 16 can be adjusted with a large degree of freedom, the deformation of the elastic connector 16 can be stabilized and the compression operation of the elastic connector 16 can be facilitated.

  Furthermore, the concave grooves 20, 20 are substantially collapsed and closed in a state in which the elastic connector 16 is radially compressed between the inner shaft member 14 and the outer cylindrical member 22. As a result, in the suspension bush 10 in use, the recessed grooves 20 do not easily affect the spring characteristics of the elastic connecting member 16, and the concentration of stress on the portion where the recessed grooves 20 are formed is also avoided.

  Further, in the present embodiment, since the convex portions 18 and 18 projecting to the left and right sides in the inner shaft member 14 are partially provided in the circumferential direction, the length of the elastic connecting member 16 in the left and right direction is The height dimension is made shorter than the vertical length dimension. Therefore, when the diameter of the outer cylindrical member 22 is reduced by a fixed amount over the entire circumference, the elastic connector 16 has a rate of deformation due to compression in the left-right direction greater than a rate of deformation due to compression in the vertical direction. The left and right springs are harder than the vertical springs. Thus, the spring characteristics of the elastic connector 16 can also be adjusted by forming the projections 18 and 18 on the inner shaft member 14.

  In addition, the concave grooves 20 and 20 are disposed on the outer periphery than the convex portions 18 and 18, so stabilization of the deformation mode of the elastic connecting member 16 by the concave grooves 20 and 20 is deformed by the convex portions 18 and 18. It is effectively exhibited at the outer peripheral portion of the elastic connector 16 which is not restrained.

  6 and 7 show a suspension bush 30 for a car as a second embodiment of a cylindrical vibration-damping device constructed according to the present invention. The suspension bush 30 includes a bush main body 32. The bush main body 32 has a structure in which an elastic connection body 34 made of urethane foam is fixed to the inner shaft member 14. In the following description, parts substantially the same as those of the first embodiment are denoted by the same reference numerals in the drawings, and the description thereof is omitted.

  As shown in FIGS. 8 and 9, in the elastic connection body 34, inner circumferential grooves 36, 36 and outer circumferential grooves 38, 38 are formed as the grooves of the present embodiment. The inner circumferential groove 36 and the outer circumferential groove 38 respectively open in the front and rear surfaces of the elastic connecting member 34 and extend circumferentially annularly, and the outer circumferential groove 38 separates from the inner circumferential groove 36 toward the outer circumferential side Is provided. Further, in the present embodiment, the groove bottom surface of the inner peripheral groove 36 and the groove bottom surface of the outer peripheral groove 38 are disposed at substantially the same position in the front-rear direction, and the groove depth dimension of the inner peripheral groove 36 is the outer peripheral groove. It is made larger than the 38 groove depth dimension. Each of the inner circumferential groove 36 and the outer circumferential groove 38 is located on the outer periphery than the projections 18 and 18 of the inner shaft member 14.

  Then, the outer cylindrical member 22 is externally inserted into the bush main body 32 in which the elastic connecting body 34 and the inner shaft member 14 are fixed, and the diameter of the outer cylindrical member 22 is reduced, whereby the elastic connecting body 34 is inner shaft It is radially pre-compressed between the member 14 and the outer cylindrical member 22. In the elastic connector 34 in such a pre-compressed state, the inner circumferential grooves 36, 36 and the outer circumferential grooves 38, 38 are all radially closed and substantially closed.

  Also in the suspension bush 30 having the structure according to the present embodiment, since the elastic connecting body 34 is made of urethane foam, the spring characteristics are adjusted by adjusting the amount of compression of the elastic connecting body 34 in the radial direction. You can easily tune with great freedom.

  Further, in the suspension bush 30 according to the present embodiment, since the inner peripheral groove 36 and the outer peripheral groove 38 extending annularly at different positions in the radial direction are formed on both the front and rear surfaces of the elastic connector 34, the elastic connector is When pre-compressing 34 greatly in the radial direction, strain deformation is less likely to occur at both axial ends of the elastic connector 34, and the deformation mode of the elastic connector 34 can be stabilized. Moreover, since the inner circumferential grooves 36, 36 and the outer circumferential grooves 38, 38 are substantially closed in the pre-compression state of the elastic connector 34, vibration is input when the suspension bush 30 is in use. In such a case, the inner peripheral grooves 36, 36 and the outer peripheral grooves 38, 38 hardly affect the anti-vibration performance, and the decrease in durability due to the concentration of stress does not easily become a problem.

  As described above, the concave grooves formed in the elastic connector are not limited to one each in the front and rear direction, and a plurality of concave grooves may be formed on the front surface and the rear surface of the elastic connector. In addition, three or more concave grooves can also be formed on any of the front surface and the rear surface of the elastic connector.

  10 and 11 show a suspension bush 40 for a car as a third embodiment of a cylindrical vibration-damping device constructed according to the present invention. The suspension bush 40 includes a bush main body 42, and the bush main body 42 has a structure in which an elastic connecting body 44 is fixed to the inner shaft member 14.

  More specifically, the elastic connector 44 is formed of the same urethane foam as that of the first embodiment, and as shown in FIGS. An outer peripheral thin portion 48 with a small dimension is integrally provided.

  The inner circumferential thick portion 46 has a thick, substantially cylindrical shape, and has an axial dimension smaller than the inner shaft member 14 and substantially the same as the outer cylindrical member 22. The elastic connecting member 44 is fixed to the inner shaft member 14 by the inner peripheral surface of the inner peripheral thick portion 46 being fixed to the outer peripheral surface of the inner shaft member 14, and the bush main body 42 is configured.

  The outer peripheral thin portion 48 is provided with a substantially constant cross-sectional shape over the entire periphery so as to project from the outer peripheral surface of the inner peripheral thick portion 46 to the outer periphery, and the thickness dimension becomes smaller gradually toward the outer periphery In addition, the front and rear thickness dimension of the inner peripheral end is made smaller than the front and rear thickness dimension of the inner peripheral thick portion 46. Thus, the axial end surface of the inner circumferential thick portion 46 and the axial end surface of the outer circumferential thin portion 48 are continuous via the step 50 formed by the outer circumferential surface of the inner circumferential thick portion 46.

  Then, the elastic connecting body 44 having such a structure has an inner peripheral surface fixed to the inner shaft member 14 and is inserted into the outer cylindrical member 22, and the outer cylinder is externally inserted into the elastic connecting body 44. By reducing the diameter of the member 22, it is radially compressed between the inner shaft member 14 and the outer cylindrical member 22. In the state where the elastic connecting member 44 shown in FIG. 11 is pre-compressed, the outer peripheral thin portion 48 remains without being completely crushed, and the outer peripheral surface (step 50) of the inner peripheral thick portion 46 is the outer cylindrical member. It is separated to the outer periphery with respect to the inner peripheral surface of 22.

  In the present embodiment, the recessed grooves 20 are formed in the outer peripheral thin portion 48 of the elastic connection body 44. As a result, the recessed groove 20 in the outer peripheral thin portion 48 in which the deformation mode is difficult to be stabilized at the time of compression of the elastic connector 44 as compared with the inner circumferential thick portion 46 which has a large axial dimension and is fixed to the inner shaft member 14. , 20 stabilize the deformation mode.

  As shown in the present embodiment, the specific shape of the elastic connector is not particularly limited, and may be appropriately set according to the required characteristics and the like.

  Although the embodiments of the present invention have been described above in detail, the present invention is not limited by the specific description. For example, the convex portions 18 and 18 provided on the inner shaft member 14 in the embodiment are not essential. For example, like the inner shaft member 62 constituting the suspension bush 60 shown in FIGS. A structure without a can also be adopted. Further, the convex portions do not necessarily have to be a pair protruding in both radial directions, and may have convex portions having a substantially constant cross-sectional shape over the entire circumference, and the protruding height changes in the circumferential direction The convex portion may be provided over the entire circumference. Furthermore, the convex portion may be formed separately from the inner shaft member and provided by being fixed to the inner shaft member.

  Moreover, if the ditch | groove formed in an elastic connection body is continuous in the circumferential direction, it is also possible to change cross-sectional shape in the circumferential direction. That is, by changing the groove width dimension, the groove depth dimension, the groove cross-sectional area, and the like in the circumferential direction, it becomes possible to set different spring characteristics in mutually different radial directions. Furthermore, spring characteristics can be made different in different radial directions by adding a groove that extends partially in the circumferential direction on the inner peripheral side or the outer peripheral side of the recessed groove formed over the entire circumference.

  In the above embodiment, after the outer cylindrical member 22 is extrapolated to the elastic connection body 16 in the formed state, the diameter reduction process of the outer cylindrical member 22 is performed, whereby the elastic connection body 16 is precompressed in the radial direction. As described above, for example, an outer cylindrical member having a diameter smaller than that of the elastic connection body in a molded state is prepared, and the elastic connection body is preliminarily inserted by pressing the elastic connection body into the outer cylindrical member while reducing the diameter. It can also be compressed. In addition, after the elastic connecting body is pre-compressed to a certain extent by the insertion into the outer cylindrical member, the diameter of the outer cylindrical member may be reduced to pre-compress the elastic connecting body.

  Furthermore, the outer diameter dimension of the inner shaft member is made larger than the inner diameter dimension of the elastic connection body in the molded state, and the elastic connection body is radially pretensioned by the inner shaft member being pushed into the central hole of the elastic connection body. It can also be compressed. Furthermore, radial compression can be exerted on the elastic connector by reducing the diameter of the outer cylindrical member bonded to the outer peripheral surface of the elastic connector.

  Further, since the elastic connector is formed of urethane foam, it has a sufficiently small Poisson's ratio and has compressibility. Therefore, when the concave groove deforms so as to be crushed, local stress concentration is less likely to be a problem, and for example, a concave groove having an angular groove cross-sectional shape such as a rectangular cross-section can be adopted. However, from the viewpoint of reducing stress concentration and improving durability, the groove cross-sectional shape of the recessed groove is preferably a shape having a smoothly curved inner surface without corners. More preferably, the groove has a cross-sectional shape that gradually narrows in the groove width direction from the opening to the bottom as in the above embodiment, whereby stress is particularly concentrated in the deformed deformation of the groove. Further stress concentration reduction can be achieved at the deepest portion of the easy groove.

  The inner shaft member and the outer cylindrical member are not limited to the cylindrical shape, and may be, for example, an elongated cylindrical shape. In addition, the shape of the elastic coupling body may be appropriately changed according to the shapes of the inner shaft member and the outer cylindrical member.

10, 30, 40, 60: Suspension bush (cylindrical vibration damping device) 14, 62: Inner shaft member, 16, 34, 44: Elastic connection body, 18: convex portion, 20: concave groove, 22: outer cylinder Member, 36: inner circumferential concave groove (concave groove), 38: outer circumferential concave groove (concave groove)

Claims (5)

In a cylindrical vibration damping device in which an inner shaft member and an outer cylindrical member are elastically connected to each other over the entire circumference by an elastic connecting member,
The elastic connecting body is formed of a foamed polyurethane resin, and the elastic connecting body is disposed between the inner shaft member and the outer cylindrical member in a state of being compressed in a direction perpendicular to the axial direction,
Annular concave grooves extending in the circumferential direction are respectively formed on both end faces of the elastic connector, and the recesses are formed in the elastic connector in a non-compressed state between the inner shaft member and the outer cylindrical member. A groove is opened at an axial end face of the elastic coupling body.   The cylindrical vibration-damping device according to claim 1, wherein the recessed groove is crushed and substantially closed in a state in which the elastic coupling body is compressed in a direction perpendicular to the axis between the inner shaft member and the outer cylindrical member.   The said inner-shaft member is provided with the convex part which protrudes on outer periphery, The part which the depth dimension in the said concave part becomes the largest is located in the outer peripheral side rather than this convex part. Cylindrical vibration control device.   The outer diameter dimension in the direction perpendicular to the axis of the elastic connecting member in a molded state not being compressed between the inner shaft member and the outer cylinder member is larger than the inner diameter dimension in the direction perpendicular to the axis of the outer cylinder member The cylindrical vibration-damping device according to any one of claims 1 to 3.   The outer diameter dimension of the elastic connector in the direction perpendicular to the axis is 25 to 70% of the molded state by the elastic connector being compressed in the direction perpendicular to the axis between the inner shaft member and the outer cylindrical member The cylindrical vibration-damping device according to any one of claims 1 to 4, which is smaller.

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