Vibration isolation device

Abstract

To provide a vibration isolator having a novel structure which can achieve both a soft spring characteristic in a state that a compression deformation amount of sideway stopper rubber is small and a hard spring characteristic in a state that the compression deformation amount of the sideway stopper rubber is large.SOLUTION: A vibration isolator 10 has a structure in which a first attachment member 12 and a second attachment member 14 are elastically connected to each other by a main body rubber elastic body 16. The first attachment member 12 comprises an attachment cylindrical part 18 which is opened at a sideway and extends. Sideway stopper rubber 30 protruding to a sideway intersecting with a center axis A of the cylindrical part 18 from an external peripheral face of the cylindrical part 18 toward an external periphery is arranged. The sideway stopper rubber 30 is formed into a shape tapered toward a protrusion tip. A recessed groove 38 extending in a circumferential direction of the sideway stopper rubber 30 is formed at a center portion deviated from a base end and a tip of the sideway stopper rubber 30 in a protrusion direction. A buffer protrusion 36 protruding from a protrusion tip face 32 of the sideway stopper rubber 30 is provided.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vibration damping device applied to, for example, automobile engine mounts and the like. [Background Art]

[0002] Conventionally, vibration damping devices applied to, for example, engine mounts for vibration-isolatingly coupling an engine to a vehicle body in automobiles have been known. For example, as disclosed in Japanese Translation of PCT International Publication No. 2006-505751 (Patent Document 1), the vibration damping device has a structure in which a first mounting member and a second mounting member are elastically connected by a main rubber elastic body. When the vibration damping device is used as an engine mount, for example, the first mounting member is attached to the engine side and the second mounting member is attached to the vehicle body side, thereby vibration-isolatingly coupling the engine and the vehicle body to each other.

[0003] Further, the vibration damping device of Patent Document 1 discloses a stopper mechanism that limits the amount of relative lateral displacement between the first mounting member and the second mounting member. The stopper mechanism limits the amount of relative displacement between the first mounting member and the second mounting member in the protruding direction of the lateral stopper rubber by the first mounting member abutting against the second mounting member side (such as a bracket attached to the second mounting member) via the lateral stopper rubber protruding outward from the cylindrical portion of the first mounting member toward the lateral outer peripheral side. [Prior Art Document] [Patent Document]

[0004] [Patent Document 1] Japanese Translation of PCT International Publication No. 2006-505751 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] Incidentally, the lateral stopper rubber is required to have stiff spring characteristics that can exhibit sufficient displacement restriction performance when the relative displacement between the first and second mounting members becomes large due to rapid acceleration or deceleration, but on the other hand, when it comes into contact with the second mounting member with a small amount of compressive deformation during gentle acceleration, etc., when strong displacement restriction performance is not required, soft spring characteristics are desirable from the viewpoint of preventing adverse effects on ride comfort.

[0006] However, with the lateral stopper rubber shown in Patent Document 1, even when the amount of compression deformation is small, a relatively stiff spring characteristic is exhibited, raising concerns about adverse effects on ride comfort and other performance aspects.

[0007] The problem to be solved by the present invention is to provide a novel vibration isolation device that can achieve both soft spring characteristics when the compressive deformation of the lateral stopper rubber is small and hard spring characteristics when the compressive deformation of the lateral stopper rubber is large. [Means for solving the problem]

[0008] The following describes preferred embodiments for understanding the present invention. However, each embodiment described below is illustrative and can be combined with others as appropriate. Furthermore, the multiple components described in each embodiment can be recognized and adopted as independently as possible, and can be combined with any component described in another embodiment as appropriate. Thus, the present invention is not limited to the embodiments described below, and various other embodiments can be realized.

[0009] The first embodiment is a vibration isolation device having a structure in which a first mounting member and a second mounting member are elastically connected by a main rubber elastic body, wherein the first mounting member has a cylindrical mounting portion that opens to the side and extends outward, and a lateral stopper rubber is provided that protrudes laterally from the outer circumferential surface of the cylindrical portion toward the outer circumferential surface, the lateral stopper rubber is tapered toward the protruding tip, and a groove extending in the circumferential direction of the lateral stopper rubber is formed in the intermediate portion of the lateral stopper rubber excluding the base and tip in the protruding direction, and a buffer projection is provided that protrudes from the protruding tip surface of the lateral stopper rubber. Furthermore, the groove is not formed on the base end side of the center in the protruding direction of the lateral stopper rubber, but is formed on the tip side of the center in the protruding direction of the lateral stopper rubber. They exist.

[0010] In a vibration isolation device with a structure according to this embodiment, the cross-sectional area in the direction perpendicular to the protruding direction of the lateral stopper rubber is reduced in the grooved portion, thereby enabling the lateral stopper rubber to have soft compression spring characteristics in the protruding direction. In particular, in a tapered lateral stopper rubber, since the groove is located in the middle portion of the lateral stopper rubber in the protruding direction, the effect of reducing the compression spring of the lateral stopper rubber due to the formation of the groove is effectively exerted when the amount of compression deformation of the lateral stopper rubber in the protruding direction is small.

[0011] Furthermore, the presence of a buffer projection on the protruding tip surface of the lateral stopper rubber reduces the initial contact area of ​​the lateral stopper rubber against the second mounting member, thereby reducing the impact upon contact. Since the protruding tip surface of the lateral stopper rubber contacts the second mounting member when the amount of compressive deformation in the protruding direction of the buffer projection is large, a sudden increase in spring tension due to contact between the protruding tip surface of the lateral stopper rubber and the second mounting member is avoided. In addition, when the buffer projection makes contact, the contact force is also applied to the lateral stopper rubber via the buffer projection, and the compression spring of the lateral stopper rubber itself, which forms the base of the buffer projection, is also reduced by the groove. This makes it possible to obtain an excellent impact reduction effect while maintaining the volume of the buffer projection. Furthermore, in a vibration isolation device with a structure according to this embodiment, the position where the groove is formed is located towards the tip of the tapered lateral stopper rubber rather than towards the center in the protruding direction. As a result, the compression spring reduction effect due to the formation of the groove is effectively exerted even when the amount of compression deformation in the protruding direction of the lateral stopper rubber is small. When the amount of compressive deformation in the protruding direction of the lateral stopper rubber increases, a stiff compression spring is exerted by the base portion of the lateral stopper rubber where no groove is formed. Therefore, when a large load is applied, the displacement restriction performance of the lateral stopper rubber is effectively utilized.

[0012] The second aspect is the vibration isolation device described in the first aspect, The aforementioned The lateral stopper rubber has a flattened shape in which the axial length of the cylindrical portion is greater than the width of the cylindrical portion perpendicular to the axial direction, and the buffer projection is partially provided in the center of the protruding tip surface of the lateral stopper rubber, and the buffer projection has a flattened shape in which the axial length of the cylindrical portion is greater than the width of the cylindrical portion perpendicular to the axial direction, and the buffer projection has a tapered shape in which the protruding height decreases from the center in the longitudinal direction toward both outer sides.

[0015] According to the vibration isolation device having a structure according to this embodiment, Since the lateral stopper rubber is longitudinal in the axial direction of the cylindrical part, and the cushioning projection is located in the central part of the protruding tip surface of the lateral stopper rubber, as the amount of compressive deformation of the lateral stopper rubber in the protruding direction increases, the contact area gradually expands from the central part where the cushioning projection is provided toward both outer sides in the axial direction of the cylindrical part. In this way, the protruding tip surface of the lateral stopper rubber does not contact the second mounting member side all at once, but rather the contact area gradually expands outward from the center in the axial direction of the cylindrical part as the amount of compressive deformation of the lateral stopper rubber increases, thereby preventing abrupt changes in the contact area and avoiding a sudden increase in spring tension.

[0016] The third embodiment is a vibration isolation device described in the first or second embodiment, wherein a pair of grooves are formed on both sides in the width direction of the lateral stopper rubber.

[0017] In the vibration isolation device according to this embodiment, the grooves open on both sides of the widthwise direction of the lateral stopper rubber and extend in the longitudinal direction of the lateral stopper rubber, thereby efficiently reducing the cross-sectional area of ​​the lateral stopper rubber perpendicular to the protruding direction in the grooved portion. Therefore, the grooved portion of the lateral stopper rubber deforms preferentially, resulting in soft compression spring characteristics. In particular, by forming grooves on both sides of the lateral stopper rubber, the cross-sectional area of ​​the lateral stopper rubber in the grooved portion can be set small even if the depth of the grooves is relatively small.

[0018] Depending on the direction of relative displacement (direction of load input) between the first and second mounting members, the lateral stopper rubber may deform in a swiveling manner at the groove formation portion, thereby exhibiting softer spring characteristics in the initial stages of contact.

[0019] The fourth aspect is a vibration isolation device described in the second or third aspect, wherein the grooves extend linearly on both sides of the lateral stopper rubber in the width direction, substantially parallel to the axial direction of the cylindrical portion, and the protruding height dimension of the lateral stopper rubber on the tip side of the grooves decreases toward the outside at both ends in the axial direction of the cylindrical portion.

[0020] In the vibration isolation device constructed according to this embodiment, the entire protruding tip surface of the lateral stopper rubber does not simultaneously contact the member on the second mounting member side in the axial direction of the cylindrical portion. Instead, the contact area expands gradually from the central portion outwards on both sides. This allows for a more advantageous realization of soft spring characteristics in the initial contact phase, and reduces the feeling of shock caused by a sudden rise in the spring.

[0021] The fifth aspect is a vibration isolation device described in the second or third aspect, wherein the buffer projection has a tapered shape, with the protruding height decreasing from the center in the width direction toward both outer sides.

[0022] According to the vibration damping device having a structure according to this aspect, since the buffer protrusion is tapered not only in the axial direction of the cylindrical portion but also in the circumferential direction, when the side stopper rubber provided with the buffer protrusion abuts against the second mounting member side, the buffering effect provided by the buffer protrusion can be obtained more effectively.

[0023] In a sixth aspect, in the vibration damping device according to the second or third aspect, the side stopper rubber is narrowed in width from the center in the length direction toward both outer sides.

[0024] According to the vibration damping device having a structure according to this aspect, when the contact area of the side stopper rubber with respect to the second mounting member side spreads from the central portion provided with the buffer protrusion toward both outer axial sides of the cylindrical portion, a rapid increase in the contact area of the side stopper rubber is suppressed. Therefore, a rapid increase in the compression spring constant of the side stopper rubber is prevented.

[0025] In a seventh aspect, in the vibration damping device according to any one of the first to sixth aspects, in a vehicle mounted state where the first mounting member and the second mounting member are mounted to a vehicle, a front stopper rubber protruding toward the front of the vehicle and a rear stopper rubber protruding toward the rear of the vehicle are provided, the rear stopper rubber is the side stopper rubber, the front stopper rubber has a protruding height dimension smaller than that of the rear stopper rubber, and neither the recessed groove on the outer circumferential surface nor the buffer protrusion on the protruding distal end surface is formed therein.

[0026] According to the vibration damping device having the structure according to the present embodiment, the front stopper rubber and the rear stopper rubber have mutually different spring characteristics set based on the presence or absence of the recessed groove and the buffer projection and the difference in the protruding height dimension, and when the amount of compressive deformation in the protruding direction is small, the rear stopper rubber is set with a softer spring characteristic than the front stopper rubber. And when the vibration damping device is mounted on a vehicle, the front stopper rubber is positioned on the vehicle front side. Thereby, for example, during gentle acceleration of the vehicle when the rear stopper rubber abuts against the second mounting member side with a small amount of compressive deformation, good riding comfort and the like are achieved by the relatively soft spring characteristic of the rear stopper rubber. On the other hand, during deceleration of the vehicle when the front stopper rubber abuts against the second mounting member side, good steering stability and the like during braking are achieved by the relatively hard spring characteristic of the front stopper rubber. Effects of the Invention

[0027] According to the present invention, both a soft spring characteristic in a state where the amount of compressive deformation of the side stopper rubber in the protruding direction is small and a hard spring characteristic in a state where the amount of compressive deformation of the side stopper rubber in the protruding direction is large can be achieved at the same time. And it becomes easy to increase the difference between the initial soft spring characteristic when the contact force is small and the hard spring characteristic after the contact force becomes sufficiently large, thereby easily setting a larger non-linear spring characteristic. Brief Description of the Drawings

[0028] [Figure 1] It is a partial cross-sectional view showing an engine mount as a first embodiment of the present invention, corresponding to the I-I cross-section in Fig. 3 [Figure 2] A perspective view showing a main part of the engine mount in Fig. 1 [Figure 3] A rear view of a main part of the engine mount shown in Fig. 2 [Figure 4] A plan view of a main part of the engine mount shown in Fig. 2 [Figure 5] A left side view of a main part of the engine mount shown in Fig. 2 [Figure 6] A left side view showing a main part of the engine mount in Fig. 2 in a state where an outer bracket is mounted [Figure 7] Figure 6, section VII-VII [Modes for carrying out the invention]

[0029] Embodiments of the present invention will be described below with reference to the drawings.

[0030] Figures 1 to 5 show an engine mount 10 for an automobile as a first embodiment of a vibration damping device with a structure according to the present invention. As shown in Figure 1, the engine mount 10 has a structure in which a first mounting member 12 and a second mounting member 14 are connected by a main rubber elastic body 16. In the following description, as a general rule, the vertical direction refers to the vertical direction in Figure 1, which is the width direction of the rear stopper rubber 30 and the cushioning projection 36 described later, the longitudinal direction refers to the vertical direction in Figure 4, which is the longitudinal direction of the vehicle, and the left-right direction refers to the left-right direction in Figure 4, which is the length direction of the rear stopper rubber 30 and the cushioning projection 36 described later.

[0031] The first mounting member 12 is a rigid member made of metal or the like, and integrally comprises a roughly rectangular cylindrical mounting portion 18 extending in the left-right direction, and a fixing portion 20 protruding downward from the lower edge of the cylindrical portion 18. The central axis A of the cylindrical portion 18 extends in the direction perpendicular to the plane of the paper in Figure 1.

[0032] The second mounting member 14 is a rigid member made of metal or the like, similar to the first mounting member 12, and is positioned below the first mounting member 12 at a distance. The shape of the second mounting member 14 is not particularly limited, but for example, it can be annular (cylindrical) or plate-shaped.

[0033] A main rubber elastic body 16 is positioned between the first mounting member 12 and the second mounting member 14. The main rubber elastic body 16 is roughly frustoconical in shape, with the first mounting member 12 fixed to its upper end, which is the smaller diameter end, and the second mounting member 14 fixed to its lower end, which is the larger diameter end.

[0034] A fitting rubber 22 is fixed to the inner circumferential surface of the first mounting member 12. The fitting rubber 22 is integrally formed with the main rubber elastic body 16 and is filled inside the fixing portion 20, which has an inverted hollow frustoconical shape, and is also formed in layers on the inner circumferential surface of the cylindrical portion 18. On the inner circumference of the cylindrical portion 18, a bracket mounting hole 24 with a square cross-section that penetrates in the left-right direction is formed by the fitting rubber 22.

[0035] An upper stopper rubber 26 is fixed to the outer circumferential surface of the cylindrical portion 18 of the first mounting member 12. The upper stopper rubber 26 is fixed to the upper surface of the upper edge portion of the cylindrical portion 18 and protrudes upward from the cylindrical portion 18. The upper stopper rubber 26 is integrally formed with the main rubber elastic body 16. The upper surface of the upper stopper rubber 26 has a wavy shape with repeated bumps and dips in the front-rear direction, which provides cushioning performance when it comes into contact with the outer bracket 40, which will be described later.

[0036] A front stopper rubber 28 is fixed to the outer circumferential surface of the cylindrical portion 18 of the first mounting member 12. The front stopper rubber 28 is fixed to the front surface of the front side portion of the cylindrical portion 18 and protrudes forward from the cylindrical portion 18. The front stopper rubber 28 is integrally formed with the main rubber elastic body 16. As shown in Figures 1 and 5, the front stopper rubber 28 gradually narrows in the vertical direction toward the protruding tip side (forward), and as shown in Figure 4, it also gradually narrows in the horizontal direction toward the protruding tip side. As shown in Figure 5, the front stopper rubber 28 has a curved surface at the protruding tip surface that curves convexly in the vertical direction, with the central part in the vertical direction protruding forward more than the ends. The front stopper rubber 28 does not have localized partial irregularities formed on its outer circumferential surface, and in particular, it does not have buffer protrusions (36) that protrude from the protruding tip surface or grooves (38) that open on the outer circumferential surface, such as the rear stopper rubber 30 described later.

[0037] A rear stopper rubber 30, which serves as a lateral stopper rubber, is fixed to the outer circumferential surface of the cylindrical portion 18 of the first mounting member 12. The rear stopper rubber 30 is fixed to the front surface of the rear side portion of the cylindrical portion 18 and protrudes rearward from the cylindrical portion 18. Therefore, the rear stopper rubber 30 protrudes in the front-rear direction perpendicular to the extension direction (axial direction) of the central axis A of the cylindrical portion 18, toward the opposite side from the front stopper rubber 28. The rear stopper rubber 30 is integrally formed with the main rubber elastic body 16.

[0038] The rear stopper rubber 30 has a flattened shape in which its outer dimensions (length) in the left-right direction are larger than its outer dimensions (width) in the up-down direction. In the left-right direction, which is the length direction, the vertical width dimension of the rear stopper rubber 30 gradually decreases from the center outwards, and in the rear view shown in Figure 3, it is approximately hexagonal. As shown in Figures 1 and 5, the rear stopper rubber 30 gradually narrows in the up-down direction toward the protruding tip side (rear), and as shown in Figure 4, it also gradually narrows in the left-right direction toward the protruding tip side, and has a tapered shape in which the cross-sectional area decreases from the base end of the protrusion to the tip of the protrusion.

[0039] As shown in Figure 4, the protruding tip surface (rear surface) of the rear stopper rubber 30 is a planar central orthogonal surface 32 that extends approximately perpendicular to the protruding direction (front-to-back direction) in the left and right central portions, and the left and right outer surfaces of the central orthogonal surface 32 are lateral inclined surfaces 34, 34 that slope forward toward the left and right outwards.

[0040] A cushioning projection 36 is formed protruding from the protruding tip surface of the rear stopper rubber 30. The cushioning projection 36 has a flattened shape in which the outer dimensions (length) in the left-right direction are larger than the outer dimensions (width) in the up-down direction when viewed from the rear, and in this embodiment it is a horizontally elongated, approximately rectangular shape. The cushioning projection 36 is partially provided in the central part of the protruding tip surface of the rear stopper rubber 30 in the up-down and left-right directions, and does not reach both the upper and lower ends and the left and right ends of the protruding tip surface of the rear stopper rubber 30. In this embodiment the cushioning projection 36 is provided on the central orthogonal surface 32 of the protruding tip surface of the rear stopper rubber 30, and does not reach both the left and right ends of the central orthogonal surface 32. In the short direction (up-down), the protruding height dimension of the cushioning projection 36 decreases from the center toward both sides toward the outside, and as a result it has a tapered shape that narrows toward the protruding tip. In the long direction (left-right), the protruding height dimension of the cushioning projection 36 decreases from the center toward both sides toward the outside, and as a result it has a tapered shape that narrows toward the protruding tip. In the central portion where the cushioning projection 36 is provided, the rear stopper rubber 30 protrudes furthest to the rear.

[0041] The protruding height dimension (front-to-back dimension) H1 of the rear stopper rubber 30 is greater than the protruding height dimension H2 of the front stopper rubber 28 (see Figure 5). Preferably, the protruding height dimension H1' of the portion of the rear stopper rubber 30 excluding the cushioning projection 36 is greater than the protruding height dimension H2 of the front stopper rubber 28. The protruding height dimension (H1-H1') of the cushioning projection 36 is smaller than the protruding height dimension H1' of the portion of the rear stopper rubber 30 excluding the cushioning projection 36, preferably 1 / 4 or less of H1'.

[0042] As shown in Figures 1 to 5, grooves 38, 38 are formed at both the upper and lower ends of the rear stopper rubber 30. The grooves 38 open to the upper and lower ends, which are the widthwise end faces of the rear stopper rubber 30, and extend continuously along the entire length in the front-to-back direction, which is the circumferential direction of the rear stopper rubber 30. As shown in Figure 4, the grooves 38 extend linearly in the left-to-right direction, which is the axial direction of the cylindrical portion 18, with a substantially constant groove width. As shown in Figure 1, the grooves 38 have a groove cross-sectional shape that widens in the front-to-back direction toward the openings on both the upper and lower sides. The cross-sectional shape of the grooves 38 is substantially constant in the groove length direction.

[0043] The groove 38 has a groove depth dimension that is approximately constant in the groove length direction and slopes downward or upward from the left-right center outward along the upper or lower surface of the rear stopper rubber 30. The groove depth dimension of the groove 38 is smaller than 1 / 4 of the vertical dimension of the rear stopper rubber 30, and more preferably smaller than 1 / 6. Furthermore, it is desirable that the depth dimension of the groove 38 be kept to such an extent that the area of ​​the cross-sectional surface of the rear stopper rubber 30 in the groove 38 formation portion is not smaller than the area of ​​the protruding tip surface of the rear stopper rubber 30. This effectively suppresses excessive concentration of strain and stress in the groove 38 formation portion and distorted, swaying deformation of the rear stopper rubber 30 on the protruding tip side of the groove 38.

[0044] The grooves 38, 38 on both the upper and lower sides are formed at the same positions relative to each other in the front-rear direction and are formed on opposing portions in the width direction (vertical direction) of the rear stopper rubber 30. In this embodiment, these grooves 38, 38 on both the upper and lower sides are a pair with a substantially symmetrical shape. As a result, in this embodiment, the rear stopper rubber 30 with grooves 38, 38, including the cushioning projection 36, has an overall symmetrical shape with respect to the vertical center.

[0045] Because the groove 38 extends approximately parallel to the axial direction (left-right direction) of the cylindrical portion 18, in the left-right central portion of the rear stopper rubber 30, where the tip surface is the central orthogonal surface 32, the protrusion height dimension toward the tip side of the groove 38 in the rear stopper rubber 30 is approximately constant in the left-right direction. Furthermore, in the left and right end portions of the rear stopper rubber 30, where the tip surface is the laterally inclined surface 34, the protrusion height dimension toward the tip side of the groove 38 in the rear stopper rubber 30 decreases toward the outside in the left-right direction, and the wall thickness is thinner in the front-rear direction toward the outside in the left-right direction.

[0046] The groove 38 is formed in the intermediate portion of the protruding direction of the rear stopper rubber 30, away from the base end and the tip end. The center of the groove 38 in the front-rear direction is located towards the tip end (rear) of the center B in the protruding direction of the rear stopper rubber 30, which is shown by the dashed line in Figure 1. Preferably, the entire groove 38 is located behind the center B in the protruding direction of the rear stopper rubber 30. In this embodiment, the groove 38 is located closer to the center B in the protruding direction of the rear stopper rubber 30 than the protruding tip surface (central orthogonal surface 32) of the rear stopper rubber 30. In this embodiment, the groove 38 is formed in only one place in the protruding direction of the rear stopper rubber 30, and no groove 38 is formed in front of the center B in the protruding direction of the rear stopper rubber 30 (towards the base end of the protruding part). In this embodiment, the outer circumferential surface of the rear stopper rubber 30 in front of the center B in the protruding direction is smooth and continuous in the circumferential direction without partial irregularities.

[0047] The engine mount 10, with this structure, is mounted to the vehicle by having a first mounting member 12 attached to the power unit side of the automobile via an inner bracket (not shown) fitted into a bracket mounting hole 24, and a second mounting member 14 attached to the vehicle body side via an outer bracket 40. The power unit and the vehicle body are then vibration-damping connected to each other via the engine mount 10 mounted to the vehicle. When the engine mount 10 is mounted to the vehicle, the front stopper rubber 28 protrudes toward the front of the vehicle, and the rear stopper rubber 30 protrudes toward the rear of the vehicle.

[0048] As shown in Figures 6 and 7, the outer bracket 40 is positioned to surround both the front and rear sides and the top of the first mounting member 12, and is positioned opposite the outer circumference of the cylindrical portion 18. In particular, the front wall portion 44 and the rear wall portion 46 of the outer bracket 40 are positioned at a predetermined stopper clearance distance from the front and rear stopper rubbers 28 and 30 to the front and rear outward. In Figure 6, the upper stopper rubber 26 is in contact with the upper wall portion 42 of the outer bracket 40, but when the engine mount 10 is mounted on the vehicle, the first mounting member 12 moves downward relative to the outer bracket 40 due to the support load borne by the power unit, so the upper stopper rubber 26 moves downward relative to the upper wall portion 42 of the outer bracket 40.

[0049] When the engine mount 10 is mounted on a vehicle, if the relative displacement between the power unit and the vehicle body becomes excessively large when the power unit and the vehicle body are displaced relative to each other, there is a risk that the power unit may interfere with other components or the main rubber elastic body 16 may be damaged. Therefore, the engine mount 10 is equipped with a stopper mechanism to limit the relative displacement between the first mounting member 12 and the second mounting member 14.

[0050] The engine mount 10 is equipped with an upper stopper mechanism that limits the relative upward displacement of the first mounting member 12 relative to the second mounting member 14. The upper stopper mechanism is formed by the upper edge portion of the cylindrical portion 18 of the first mounting member 12 and the upper wall portion 42 of the outer bracket 40 coming into contact via an upper stopper rubber 26. Specifically, for example, when the power unit attempts to be displaced significantly upward relative to the vehicle body due to driving over steps or bumps, the relative displacement between the power unit and the vehicle body is limited by the upper stopper mechanism, preventing excessive vertical tensile force from acting on the main rubber elastic body 16.

[0051] Furthermore, the engine mount 10 is equipped with a forward stopper mechanism that limits the relative forward displacement of the first mounting member 12 with respect to the second mounting member 14. The forward stopper mechanism is constructed by the front side wall portion of the cylindrical portion 18 of the first mounting member 12 and the front wall portion 44 of the outer bracket 40, which is a member on the second mounting member 14 side, contacting each other via a forward stopper rubber 28. Specifically, for example, when the power unit attempts to displace significantly forward relative to the vehicle body due to sudden deceleration of the vehicle, the relative displacement between the power unit and the vehicle body is limited by the forward stopper mechanism. This improves, for example, steering stability by limiting the displacement of the large-mass power unit and improves durability by preventing excessive deformation of the main rubber elastic body 16.

[0052] The front stopper rubber 28 does not have cushioning protrusions or grooves like the rear stopper rubber 30. Furthermore, the protruding height dimension of the front stopper rubber 28 is smaller than that of the rear stopper rubber 30, and the maximum cross-sectional area of ​​the front stopper rubber 28 in the orthogonal cross-section (cross-sectional area at the base end) is approximately the same as the maximum cross-sectional area of ​​the rear stopper rubber 30 in the orthogonal cross-section (cross-sectional area at the base end). As a result, the compression spring in the protruding direction of the front stopper rubber 28 is set to be stiffer than the compression spring in the protruding direction of the rear stopper rubber 30, and the front stopper mechanism has excellent displacement restriction performance against power unit displacement during rapid deceleration.

[0053] Furthermore, the engine mount 10 is equipped with a rear stopper mechanism that limits the amount of rearward relative displacement of the first mounting member 12 with respect to the second mounting member 14. The rear stopper mechanism is constructed by the rear side wall portion of the cylindrical portion 18 of the first mounting member 12 and the rear wall portion 46 of the outer bracket 40 coming into contact via a rear stopper rubber 30. Specifically, for example, when the power unit attempts to be displaced significantly rearward relative to the vehicle body due to sudden acceleration of the vehicle, the amount of relative displacement between the power unit and the vehicle body is limited by the rear stopper mechanism. This improves, for example, steering stability by limiting the displacement of the large mass power unit and improves durability by preventing excessive deformation of the main rubber elastic body 16.

[0054] Incidentally, the rear stopper rubber 30, which constitutes the rear stopper mechanism, contacts the rear wall portion 46 of the outer bracket 40 not only during rapid acceleration, but also, for example, during gradual acceleration. Therefore, even during gradual acceleration, the amount of relative rearward displacement of the power unit with respect to the vehicle body is limited by the rear stopper mechanism.

[0055] In this state of contact between the rear stopper rubber 30 and the outer bracket 40 due to gentle acceleration, loads in other directions such as left and right may also be applied due to steering wheel operation, etc. Therefore, it is important from the viewpoint of ride comfort performance to avoid the spring becoming too stiff due to the contact of the rear stopper rubber 30. Furthermore, when the rear stopper rubber 30 contacts the outer bracket 40 due to gentle acceleration, the amount of compression deformation is small, and the tip portion with a small cross-sectional area undergoes compression deformation, while the base portion with a large cross-sectional area is less prone to compression deformation. Therefore, a soft spring characteristic is required for the protruding tip portion. In this regard, the rear stopper rubber 30 has a tapered shape that narrows in the vertical and left and right directions toward the protruding tip, so the cross-sectional area of ​​the front-to-back orthogonal cross-section of the protruding tip portion is small, and the protruding tip portion deforms preferentially to the base portion, thereby achieving a soft spring characteristic with a small amount of compression deformation.

[0056] The rear stopper rubber 30 is equipped with a cushioning projection 36 on its protruding tip surface. The cushioning projection 36 has a cross-sectional area perpendicular to the front-rear surface that is smaller than the protruding tip surface of the rear stopper rubber 30, and has soft compression spring characteristics, and also protrudes further rearward from the protruding tip surface of the rear stopper rubber 30. Therefore, the cushioning projection 36 preferentially contacts the outer bracket 40, and soft spring characteristics can be obtained. Moreover, the cushioning projection 36 tapers toward the protruding tip side, and as the amount of compression deformation in the front-rear direction increases, the compression spring gradually hardens. As a result, the rise in spring characteristics in the initial stages of contact is kept small, and the shock sensation caused by the rapid increase in compression spring in response to the increase in the amount of compression deformation is suppressed, resulting in good ride comfort performance. In particular, the cushioning projection 36 of this embodiment has a larger left-right dimension than its up-down dimension when viewed from the rear. Therefore, it is efficiently formed on the protruding tip surface of the rear stopper rubber 30, which has a larger left-right dimension than its up-down dimension when viewed from the rear. The large left-right dimension makes it easier to obtain the characteristic that the compression spring becomes stiffer as the compression deformation of the cushioning projection 36 progresses.

[0057] The rear stopper rubber 30 gradually decreases in vertical width from the left-right center outwards on both sides. Since the contact area of ​​the rear stopper rubber 30 with respect to the outer bracket 40 expands from the central part where the cushioning protrusion 36 is provided outwards on both sides, if the vertical width of the rear stopper rubber 30 is narrowed outwards on both sides, the rate of increase in the contact area associated with the expansion of the contact area of ​​the rear stopper rubber 30 outwards on both sides can be suppressed. Therefore, the change in the compression spring associated with the increase in the amount of compression deformation of the rear stopper rubber 30 becomes more gradual, and adverse effects on ride comfort due to abrupt changes in the compression spring can be prevented.

[0058] The rear stopper rubber 30 has upper and lower grooves 38, 38 formed therein. The cross-sectional area of ​​the front-to-rear perpendicular cross-section of the rear stopper rubber 30 is reduced in the portion where the grooves 38, 38 are formed. As a result, when the rear stopper rubber 30 is compressed in the front-to-rear direction, the compression spring of the rear stopper rubber 30 is reduced, and a soft spring characteristic is achieved, especially when the amount of compression deformation of the rear stopper rubber 30 is small.

[0059] Since the grooves 38, 38 are located on the tip side of the center B in the protruding direction of the rear stopper rubber 30, the deformation amount of the grooves 38, 38 is ensured even when the amount of compressive deformation of the rear stopper rubber 30 is small, and the soft spring characteristics due to the formation of the grooves 38, 38 are quickly exhibited. Moreover, by forming the grooves 38, 38 at the tapered tip portion of the rear stopper rubber 30, the cross-sectional area of ​​the rear stopper rubber 30 in the groove portion can be sufficiently reduced without making the grooves 38, 38 excessively deep. Furthermore, since the grooves 38, 38 are not formed on the base side of the center B in the protruding direction of the rear stopper rubber 30, excellent displacement control performance is exhibited when a large load is applied, resulting in a large amount of compressive deformation of the rear stopper rubber 30, due to the hard compressive spring characteristics of the base portion of the rear stopper rubber 30.

[0060] The upper and lower grooves 38, 38 are formed at approximately the same position in the protruding direction of the rear stopper rubber 30 and open to the upper and lower opposing portions of the rear stopper rubber 30. Therefore, without making the depth of the upper and lower grooves 38, 38 excessively large, the area of ​​the front-to-back orthogonal cross-section of the rear stopper rubber 30 in the portion where the grooves 38, 38 are formed is reduced, thereby realizing the soft compression spring characteristics of the rear stopper rubber 30. In this embodiment, since the upper and lower grooves 38, 38 are approximately the same shape and size, when a compressive force in the protruding direction acts on the rear stopper rubber 30, it is less likely that the rear stopper rubber 30 will undergo distorted deformation due to the formation of the grooves 38, 38, or that the protruding tip side of the grooves 38, 38 will undergo a swaying tilt deformation.

[0061] The front-to-rear separation distance (stopper clearance) between the rear stopper rubber 30, including the buffer projection 36, and the rear wall portion 46 of the outer bracket 40 is smaller than the front-to-rear separation distance between the front stopper rubber 28 and the front wall portion 44 of the outer bracket 40. As a result, the rear stopper rubber 30 contacts the outer bracket 40 when a relatively small load is applied, exhibiting soft spring characteristics, and as the input load increases, the compression spring gradually hardens, and the stopper action that restricts the displacement of the power unit gradually becomes stronger. In short, the rear stopper rubber 30 is set to have a larger compression deformation stroke than the front stopper rubber 28, and is designed to gradually transition from soft spring characteristics to hard spring characteristics. Therefore, the engine mount 10 provides a good ride comfort during normal acceleration and ensures handling stability and durability by limiting the amount of displacement of the power unit during rapid acceleration.

[0062] Although embodiments of the present invention have been described in detail above, the present invention is not limited by its specific description. For example, if a plurality of grooves are formed in the lateral stopper rubber, these grooves may be arranged at mutually different positions in the protruding direction of the lateral stopper rubber.

[0063] The groove may extend continuously around the entire circumference of the lateral stopper rubber, or it may be provided only on a part of the circumference. As can be seen from this, the groove is not limited to opening on the upper and lower surfaces of the lateral stopper rubber as shown in the above embodiment, but may also be formed opening on the left or right surface. Specifically, for example, grooves that open on both or one of the left and right surfaces of the lateral stopper rubber, grooves that extend in a hook shape continuously from the upper and left surfaces of the lateral stopper rubber, grooves that extend in a U shape continuously from the upper, left, and lower surfaces of the lateral stopper rubber, and so on can all be adopted.

[0064] The groove may have at least one of its width, depth, or cross-sectional shape varying along its length. The width, depth, and cross-sectional shape of the groove shown in the above embodiment are merely illustrative and should not be interpreted restrictively. At least a portion of the groove may extend inclined with respect to the circumferential direction of the lateral stopper rubber. The groove as a whole only needs to extend in the circumferential direction of the lateral stopper rubber, and may have a portion that extends in the direction of protrusion of the lateral stopper rubber.

[0065] The lateral stopper rubber is not limited to a substantially hexagonal shape as shown in the above embodiment when viewed in the protruding direction, but may also be other polygons such as quadrilaterals, or a circular or irregular shape including an ellipse.

[0066] The lateral stopper rubber only needs to have a tapered shape in which the area of ​​the protruding tip surface is smaller than the cross-sectional area of ​​the protruding base end, and the inclined surface on the outer circumference that gradually narrows toward the protruding tip may be partial in the direction of protrusion. In this case, the position where the groove is formed in the lateral stopper rubber is such that the cross-sectional area of ​​the lateral stopper rubber at the groove formation site is smaller than the cross-sectional area of ​​the protruding base end of the lateral stopper rubber and larger than the area of ​​the protruding tip surface.

[0067] The cross-sectional shape perpendicular to the direction of protrusion of the buffer projection is not necessarily limited to a flat shape, but may be square or circular, for example. Multiple buffer projections may be provided on the tip surface of the lateral stopper rubber.

[0068] In the above embodiment, an example was shown in which only the rear stopper rubber located on the rear side of the vehicle was made of the lateral stopper rubber according to the present invention. However, the front stopper rubber located on the front side of the vehicle can also be made of the lateral stopper rubber according to the present invention. In short, the arrangement (protrusion direction) of the lateral stopper rubber according to the present invention is not particularly limited. Therefore, for example, the lateral stopper rubber can be provided to protrude in the left-right direction of the vehicle.

[0069] The vibration isolation device may also be a fluid-filled vibration isolation device that has a liquid chamber inside and exhibits a vibration isolation effect based on the flow action of the liquid. Furthermore, the present invention originally encompasses all of the inventions described in (i) to (vii) below, and its structure and effects are noted below. The present invention (i) A vibration isolation device having a structure in which a first mounting member and a second mounting member are elastically connected by a main rubber elastic body, wherein the first mounting member is provided with a cylindrical mounting portion that opens to the side and extends outward, and a lateral stopper rubber is provided that protrudes laterally from the outer circumferential surface of the cylindrical portion toward the outer circumferential direction perpendicular to the axial direction of the cylindrical portion, and the lateral stopper rubber is tapered toward the protruding tip, and a groove extending in the circumferential direction of the lateral stopper rubber is formed in the intermediate portion of the lateral stopper rubber away from the base and tip in the protruding direction, and a buffer projection is provided that protrudes from the protruding tip surface of the lateral stopper rubber, (ii) The groove is not formed on the base end side of the center in the protruding direction of the lateral stopper rubber, but is formed on the tip side of the center in the protruding direction of the lateral stopper rubber, the lateral stopper rubber has a flattened shape in which the length dimension in the axial direction of the cylindrical portion is greater than the width dimension perpendicular to the axial direction of the cylindrical portion, the cushioning projection is partially provided in the center of the protruding tip surface of the lateral stopper rubber, the cushioning projection has a flattened shape in which the length dimension in the axial direction of the cylindrical portion is greater than the width dimension perpendicular to the axial direction of the cylindrical portion, and the cushioning projection has a tapered shape in which the protruding height dimension decreases from the center in the longitudinal direction toward both outer sides, as described in (i). (iii) The vibration isolation device according to (i) or (ii), wherein a pair of grooves are formed on both sides in the width direction of the lateral stopper rubber, (iv) The vibration isolation device according to (ii) or (iii), wherein the groove extends linearly on both sides of the lateral stopper rubber in the width direction, substantially parallel to the axial direction of the cylindrical portion, and the protruding height dimension of the lateral stopper rubber on the tip side of the groove decreases toward the outside at both ends in the axial direction of the cylindrical portion, (v) The shock-absorbing protrusions are tapered in shape, with the height of the protrusion decreasing from the center in the width direction toward both outer sides, as described in (ii) or (iii), (vi) The vibration isolation device according to (ii) or (iii), wherein the lateral stopper rubber is narrowed from the center in the longitudinal direction toward both outer sides, (vii) The vibration damping device according to (i) to (vi), wherein, in a vehicle-mounted state in which the first mounting member and the second mounting member are attached to the vehicle, a front stopper rubber protruding toward the front of the vehicle and a rear stopper rubber protruding toward the rear of the vehicle are provided, the rear stopper rubber is the lateral stopper rubber, the protruding height dimension of the front stopper rubber is smaller than that of the rear stopper rubber, and neither the groove on the outer peripheral surface nor the buffer projection on the protruding tip surface is formed thereon. This includes inventions relating to the present invention. In the invention described in (i) above, since the cross-sectional area in the direction perpendicular to the protruding direction of the lateral stopper rubber is reduced in the grooved portion, a soft compression spring characteristic can be set for the lateral stopper rubber in the protruding direction. In particular, in the case of a tapered lateral stopper rubber, since the groove is located in the middle portion of the protruding direction of the lateral stopper rubber, the effect of reducing the compression spring of the lateral stopper rubber due to the formation of the groove is effectively exerted when the amount of compression deformation of the lateral stopper rubber in the protruding direction is small. Furthermore, since a buffer projection is provided on the protruding tip surface of the lateral stopper rubber, the initial contact area with the second mounting member side of the lateral stopper rubber is reduced, thereby reducing the impact at the time of contact. When the amount of compression deformation of the buffer projection in the protruding direction is large, the protruding tip surface of the lateral stopper rubber comes into contact with the second mounting member side, thus avoiding a sudden increase in spring due to the contact of the protruding tip surface of the lateral stopper rubber with the second mounting member side. In addition, when the cushioning protrusion makes contact, the contact force is also applied to the lateral stopper rubber via the cushioning protrusion. As a result, the compression spring of the lateral stopper rubber itself, which forms the base of the cushioning protrusion, is reduced by the groove. This makes it possible to obtain an excellent impact reduction effect while maintaining the volume of the cushioning protrusion. In the invention described in (ii) above, the position where the groove is formed is towards the tip side of the protruding center of the tapered lateral stopper rubber, so that the compression spring reduction effect due to the formation of the groove is effectively exerted even when the amount of compressive deformation of the lateral stopper rubber in the protruding direction is small. When the amount of compressive deformation of the lateral stopper rubber in the protruding direction becomes large, a hard compression spring is exerted by the base end portion of the lateral stopper rubber where the groove is not formed, so that the displacement restriction performance of the lateral stopper rubber is effectively exerted when a large load is applied. Since the lateral stopper rubber is longitudinal in the axial direction of the cylindrical portion, and the buffer projection is located in the central part of the protruding tip surface of the lateral stopper rubber, as the amount of compressive deformation of the lateral stopper rubber in the protruding direction increases, the contact area gradually widens from the central portion where the buffer projection is provided toward both outer sides in the axial direction of the cylindrical portion. In this way, the protruding tip surface of the lateral stopper rubber does not contact the second mounting member side all at once, but rather, as the amount of compression deformation of the lateral stopper rubber increases, it gradually expands outward from the center in the axial direction of the cylindrical part, thereby preventing abrupt changes in the contact area and avoiding a sudden increase in spring tension. In the invention described in (iii) above, the grooves open on both sides of the widthwise side of the lateral stopper rubber and extend in the longitudinal direction of the lateral stopper rubber, thereby efficiently reducing the cross-sectional area of ​​the lateral stopper rubber perpendicular to the protruding direction in the grooved portion. Therefore, the grooved portion of the lateral stopper rubber deforms preferentially, resulting in soft compression spring characteristics. In particular, by forming grooves on both sides of the lateral stopper rubber, the cross-sectional area of ​​the lateral stopper rubber in the grooved portion can be set to be small even if the groove depth is relatively small. Depending on the direction of relative displacement (load input direction) between the first and second mounting members, the lateral stopper rubber may deform in a swiveling manner in the grooved portion, resulting in softer spring characteristics in the initial contact phase. In the invention described in (iv) above, the entire protruding tip surface of the lateral stopper rubber does not simultaneously contact the member on the second mounting member side in the axial direction of the cylindrical portion. Instead, the contact area expands gradually from the central portion toward both outer sides. This allows for a more advantageous realization of soft spring characteristics in the initial contact phase, while also reducing the feeling of shock caused by a sudden rise in the spring. In the invention described in (v) above, since the cushioning projection is tapered not only in the axial direction of the cylindrical portion but also in the circumferential direction, the cushioning effect of the cushioning projection can be obtained more effectively when the lateral stopper rubber equipped with the cushioning projection comes into contact with the second mounting member. In the invention described in (vi) above, as the contact area of ​​the lateral stopper rubber with respect to the second mounting member expands from the central portion where the buffer projection is provided toward both axial outward directions of the cylindrical portion, a rapid increase in the contact area of ​​the lateral stopper rubber is suppressed. Therefore, a rapid increase in the compression spring of the lateral stopper rubber is prevented. In the invention described in (vii) above, the front stopper rubber and the rear stopper rubber have different spring characteristics due to the presence or absence of grooves and cushioning protrusions and differences in the protrusion height dimension. When the amount of compression deformation in the protrusion direction is small, the rear stopper rubber has a softer spring characteristic than the front stopper rubber. When the vibration damping device is mounted on a vehicle, the front stopper rubber is located in front of the vehicle. As a result, for example, during gentle acceleration of the vehicle when the rear stopper rubber contacts the second mounting member with a small amount of compression deformation, the relatively soft spring characteristics of the rear stopper rubber provide good ride comfort. On the other hand, when the vehicle decelerates and the front stopper rubber contacts the second mounting member, the relatively stiff spring characteristics of the front stopper rubber provide good handling stability during braking. [Explanation of Symbols]

[0070] 10. Engine mount (First embodiment: Vibration isolation device) 12 First mounting member 14 Second mounting member 16 Main body rubber elastic body 18. Cylindrical part 20 Fixing part 22 Fitting rubber 24 bracket mounting holes 26 Upper stopper rubber 28 Front stopper rubber 30 Rear stopper rubber (side stopper rubber) 32. Central orthogonal plane (projecting tip surface) 34 Lateral inclined surface (protruding tip surface) 36 Buffer protrusion 38 grooves 40 Outer Bracket 42 Upper wall 44 Front wall 46 Rear wall A. Central axis of the cylindrical part B. Center of the rear stopper rubber in the direction of protrusion

Claims

1. In a vibration isolation device having a structure in which a first mounting member and a second mounting member are elastically connected by a main rubber elastic body, The first mounting member is provided with a cylindrical mounting portion that extends outwards to the side, A lateral stopper rubber is provided that protrudes laterally from the outer surface of the cylindrical portion toward the outer circumference, perpendicular to the axial direction of the cylindrical portion. The lateral stopper rubber is tapered towards the protruding tip. In the lateral stopper rubber, a groove extending in the circumferential direction is formed in the intermediate portion excluding the base end and tip in the protruding direction. A cushioning projection is provided that protrudes from the protruding tip surface of the lateral stopper rubber. The groove is not formed on the proximal end side of the center in the protruding direction of the lateral stopper rubber, but is formed on the tip side of the center in the protruding direction of the lateral stopper rubber.

2. The lateral stopper rubber has a flattened shape in which the length dimension in the axial direction of the cylindrical portion is greater than the width dimension perpendicular to the axial direction of the cylindrical portion. The aforementioned buffer projection is partially provided at the center of the protruding tip surface of the lateral stopper rubber, The buffer projection has a flattened shape in which the length dimension in the axial direction of the cylindrical portion is greater than the width dimension perpendicular to the axial direction of the cylindrical portion. The vibration isolation device according to claim 1, wherein the buffering protrusion has a tapered shape, with the protruding height decreasing from the center in the longitudinal direction toward both outer sides.

3. The vibration damping device according to claim 2, wherein a pair of grooves are formed on both sides in the width direction of the lateral stopper rubber.

4. On both sides of the lateral stopper rubber in the width direction, the grooves extend linearly in a manner substantially parallel to the axial direction of the cylindrical portion. The vibration damping device according to claim 2 or 3, wherein the protruding height dimension of the lateral stopper rubber on the tip side of the groove is smaller toward the outside at both ends in the axial direction of the cylindrical portion.

5. The vibration isolation device according to claim 2 or 3, wherein the buffer protrusion has a tapered shape, with the protruding height decreasing from the center in the width direction toward both outer sides.

6. The vibration isolation device according to claim 2 or 3, wherein the lateral stopper rubber is narrowed from the center in the longitudinal direction toward both outer sides.

7. In the vehicle-mounted state in which the first mounting member and the second mounting member are attached to the vehicle, a front stopper rubber protruding toward the front of the vehicle and a rear stopper rubber protruding toward the rear of the vehicle are provided. The rear stopper rubber is the same as the lateral stopper rubber. The vibration damping device according to claim 1 or 2, wherein the front stopper rubber has a protruding height dimension smaller than that of the rear stopper rubber, and neither the groove on the outer circumferential surface nor the buffer projection on the protruding tip surface is formed thereon.

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