Cylindrical vibration control device for motor mount

Abstract

To provide a cylindrical vibration control device for a motor mount having a novel structure which can secure durability and attain greater freedom in characteristics tuning while reducing deterioration of vibration control performance by surging of rubber legs.SOLUTION: In a cylindrical vibration control device 10 for a motor mount, an inner shaft member 12 and an outer cylinder member 14 are connected by two rubber legs 16, 16 extending between opposed surfaces of the inner shaft member 12 and the outer cylinder member 14. The two rubber legs 16, 16 are both disposed on the lower side of the inner shaft member 12, which is the compression side when a main load is input, and extend in a vertical direction at positions separated from each other in a lateral direction. The two rubber legs 16, 16 have connection rubber parts 26, 26 which are continuous in the vertical direction and directly connect the opposed surfaces of the inner shaft member 12 and the outer cylinder member 14. The two rubber legs 16, 16 are each provided with a rubber projection 28 projecting in an axial direction. The rubber projection 28 is disposed fitted in the inner side of the connection rubber part 26 in the lateral direction relative to left and right outer edges of the connection rubber part 26.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a cylindrical vibration isolation device for a motor mount used as a motor mount that connects an electric motor to a vehicle body in an electrically powered vehicle such as an electric vehicle (BEV) or a hybrid car in a vibration-proof manner. [Background technology]

[0002] Recently, with the electrification of vehicles, motor mounts that connect electric motors to vehicle bodies in a vibration-proof manner have been developed. For example, a cylindrical vibration-proof device in which an inner shaft member and an outer cylindrical member are connected to each other by rubber legs extending in the radial direction is used as a motor mount. A four-leg structure having two rubber legs on both the upper and lower sides of the inner shaft member is used as a cylindrical vibration-proof device for a motor mount, but a structure in which two elastic legs (rubber legs) are provided below the inner tube (inner shaft member), as in JP 2008-267443 A (Patent Document 1), is also being considered for application to a motor mount. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-267443 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in motor mounts that provide vibration isolation for electric motors, which have smaller vibrations than internal combustion engines, the deterioration of vibration conditions in the high frequency range caused by surging of the rubber legs is likely to become a problem. Therefore, Patent Document 1 discloses that a mass protrusion that protrudes in the axial direction is provided on the elastic legs, and the surging of the elastic legs is suppressed by the resonance of the mass protrusion.

[0005] However, in the cylindrical vibration isolation device of Patent Document 1, the fixing surface of the elastic leg to the inner cylinder and the fixing surface to the outer cylinder (outer cylindrical member) are separated from each other when projected in the up-down direction, which is the main vibration input direction, and the elastic leg undergoes shear deformation over a wide range when vibration is input, which may limit the degree of freedom in tuning the spring characteristics of the elastic leg. In addition, in addition to the fact that the shear deformation becomes dominant and the deformation amount of the elastic leg tends to increase, distortion tends to concentrate around the mass protrusion when the elastic leg deforms, and in order to ensure durability, the formation position of the mass protrusion is significantly limited, as specified in Patent Document 1.

[0006] The problem to be solved by the present invention is to provide a cylindrical vibration isolation device for motor mounts of a new structure which ensures durability while suppressing the deterioration of vibration isolation performance due to surging of the rubber feet, and further allows for great freedom in tuning the characteristics. [Means for solving the problem]

[0007] The following describes preferred embodiments for understanding the present invention, but the embodiments described below are merely illustrative and may be combined with one another as appropriate, and the multiple components described in each embodiment may be recognized and used independently as far as possible, and may also be combined with any of the components described in another embodiment as appropriate. As a result, the present invention is not limited to the embodiments described below, and various other embodiments may be realized.

[0008] The first aspect is a cylindrical vibration-damping device for a motor mount in which an inner shaft member and an outer cylindrical member are connected by two rubber legs extending between the opposing surfaces of the inner shaft member and the outer cylindrical member, and the two rubber legs are both positioned below the inner shaft member which is compressed when the main load is input, and extend in the vertical direction at positions spaced apart from each other in the left-right direction, and the two rubber legs are connected in the vertical direction and have a connecting rubber part that directly connects the opposing surfaces of the inner shaft member and the outer cylindrical member, and the two rubber legs are each provided with a rubber protrusion that protrudes in the axial direction, and are arranged in a state in which the rubber protrusions are located left-right inward of the left and right outer ends of the connecting rubber part.

[0009] According to the cylindrical vibration isolation device for motor mounts constructed according to this embodiment, the two rubber legs are only on the underside of the inner shaft member, so it is easier to ensure the free length and volume of the two rubber legs compared to when rubber legs are on both the top and bottom of the inner shaft member, improving durability, for example. Also, the two rubber legs are provided with connecting rubber parts that directly connect the opposing surfaces of the inner shaft member and the outer cylindrical member in a continuous vertical direction, and a compression spring component is advantageously ensured when the main load is input, so the spring characteristics can be set with a greater degree of freedom in tuning, and further durability can be improved by suppressing the deformation of the connecting rubber parts.

[0010] By providing each rubber leg with a rubber protrusion, the mass damping action of the rubber protrusion can prevent deterioration of the vibration state due to bending resonance (surging) of the rubber leg. Because each rubber protrusion protrudes in the axial direction, for example, when the rubber leg deforms due to the input of vibration, the rubber protrusion is less likely to interfere with other members such as the outer cylindrical member.

[0011] The rubber protrusions are arranged in a state where they are contained on the left and right inner side of the left and right outer ends of the connecting rubber part, which is the compression region of the rubber leg arranged below the inner shaft member (the region where a compressive load is directly or predominantly applied when a vertical load is input by directly connecting the opposing vertical surfaces of the inner shaft member and the outer cylindrical member) of the rubber leg. Therefore, compared to a case where the rubber protrusions are provided in a shear deformation region on the left and right outer side of the left and right outer ends of the connecting rubber part (the region where shear deformation is large when a vertical load is input because there is no direct connection between the opposing vertical surfaces of the inner shaft member and the outer cylindrical member), distortion around the rubber protrusions is reduced when the rubber leg elastically deforms due to vibration input, improving durability.

[0012] The second aspect is a cylindrical vibration isolation device for a motor mount described in the first aspect, in which 90% or more of the rubber protrusions are positioned on the connecting rubber part, such that the rubber protrusions are essentially only provided on the connecting rubber part.

[0013] With a cylindrical vibration isolation device for a motor mount constructed in accordance with this embodiment, the rubber protrusions are essentially provided only on the connecting rubber parts, which are the compression areas of the rubber legs, so that distortion around the rubber protrusions is more effectively reduced when the rubber legs deform.

[0014] The third aspect is a cylindrical vibration isolation device for a motor mount described in the first or second aspect, wherein the inner shaft member has a pair of rubber fixing portions protruding on both the left and right sides, the two rubber feet are fixed to the pair of rubber fixing portions, and a stopper protrusion is provided between the pair of rubber fixing portions on the inner shaft member, protruding downward between the two rubber feet.

[0015] In a cylindrical vibration-damping device for a motor mount constructed in accordance with this embodiment, the inner shaft member has a pair of rubber fixing portions protruding on both the left and right sides, making it easier to position the two rubber legs on the underside of the inner shaft member and ensuring the cross-sectional area of ​​the connecting rubber portion to obtain a large compression spring component.

[0016] In addition, by fixing one of the two rubber legs to a pair of rubber fixing parts protruding on both the left and right sides, a space is secured between the left and right of the two rubber legs, and the inner shaft member is provided with a stopper protrusion protruding downward by utilizing this space. This makes it possible to configure a stopper mechanism that limits the amount of relative displacement between the inner shaft member and the outer cylindrical member in the up-down direction by the abutment of the stopper protrusion with the outer cylindrical member.

[0017] A fourth aspect is a cylindrical vibration-damping device for a motor mount described in any one of the first to third aspects, in which a stopper rubber is provided between the two rubber legs, protruding in the vertical direction between the inner shaft member and the outer cylindrical member.

[0018] According to a cylindrical vibration isolation device for a motor mount constructed in accordance with this embodiment, a stopper mechanism can be provided, utilizing the space between the two rubber legs, that limits the amount of downward relative displacement of the inner shaft member with respect to the outer cylindrical member by indirect abutment between the inner shaft member and the outer cylindrical member via the stopper rubber.

[0019] A fifth aspect is a cylindrical vibration-damping device for a motor mount described in any one of the first to fourth aspects, wherein the width dimension of the connecting rubber part is made 20% or more of the width dimension of the rubber foot, so that the compression spring component in the rubber foot against a downward input is made larger than the shear spring component.

[0020] With a cylindrical vibration isolation device for a motor mount constructed in accordance with this embodiment, the compression spring component is dominant in the rubber foot on which the rubber protrusion is provided, and therefore distortion around the rubber protrusion is reduced compared to when the rubber protrusion is provided on the rubber foot where the shear spring component is dominant.

[0021] Furthermore, by setting the width dimension of the connecting rubber portion to a sufficiently large ratio to the width dimension of the rubber legs, the arrangement of the rubber protrusions on the axial end faces of the rubber legs can be set with a large degree of freedom. Effect of the Invention

[0022] According to the present invention, in a cylindrical vibration isolation device for a motor mount, it is possible to ensure durability while suppressing deterioration of vibration isolation performance due to surging of the rubber legs, and further to provide a large degree of freedom in tuning the characteristics. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a perspective view showing a motor mount according to a first embodiment of the present invention; [Diagram 2] Front view of the motor mount shown in Figure 1 [Diagram 3] III-III cross section of Figure 2 [Figure 4] A graph showing the spring characteristics of the motor mount shown in Figure 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0025] 1 and 2 show a motor mount 10 for a vehicle as a first embodiment of a cylindrical vibration isolator for a motor mount according to the present invention. The motor mount 10 has a structure in which an inner shaft member 12 and an outer cylindrical member 14 are connected to each other by two rubber legs 16, 16. In the following description, the up-down direction basically refers to the up-down direction in FIG. 2, the left-right direction refers to the left-right direction in FIG. 2, and the front-rear direction refers to the axial direction in FIG. 2, which is perpendicular to the paper. Note that the up-down direction in the following description refers to the input direction of a main load to the motor mount 10, and does not necessarily coincide with the up-down direction of the vehicle when the motor mount 10 is mounted on the vehicle, which will be described later. Similarly, the left-right direction and the front-rear direction in the following description do not necessarily coincide with the left-right direction and the front-rear direction of the vehicle.

[0026] The inner shaft member 12 is a highly rigid member made of, for example, a metal such as iron or an aluminum alloy, or a fiber-reinforced synthetic resin. The inner shaft member 12 is generally columnar and extends linearly with a substantially constant cross-sectional shape, so that it can be easily manufactured by, for example, extrusion processing. A mounting hole 18 is formed in the center of the inner shaft member 12, penetrating it in the axial direction.

[0027] The inner shaft member 12 of this embodiment has rubber fixing parts 20, 20 protruding to both the left and right sides. The upper surface of the rubber fixing part 20 spreads outwardly in the vertical direction, and the lower surface is inclined upward toward the left and right outward, narrowing in the vertical direction toward the protruding tip. The protruding tip surface of the rubber fixing part 20 is curved in the axial direction and smoothly continues to both the upper and lower surfaces. The rubber fixing parts 20, 20 on both the left and right sides are symmetrical with respect to the horizontal orthogonal plane. The rubber fixing part 20 of this embodiment is provided continuously over the entire axial length of the inner shaft member 12, but may be shorter in the axial length than other parts of the inner shaft member 12, for example.

[0028] The inner shaft member 12 is provided with a stopper projection 22 that projects downward. The stopper projection 22 projects downward with a substantially constant left-right width dimension in the left-right central portion of the inner shaft member 12. The protruding tip surface of the stopper projection 22 may be flat or the like, but in this embodiment, it has a curved shape that is convex downward when viewed in the axial direction. The stopper projection 22 in this embodiment is provided continuously over the entire axial length of the inner shaft member 12, but may have an axial length shorter than other portions of the inner shaft member 12, for example.

[0029] The outer tubular member 14 has a thin-walled, large-diameter, generally cylindrical shape, and is integrally formed at one axial end with a flange-like portion 24 that protrudes outward. Note that the flange-like portion 24 of the outer tubular member 14 can be omitted, for example, in cases where a stopper mechanism using a front cushion rubber 44 (described later) is not required.

[0030] The inner shaft member 12 is inserted into the inner circumference of the outer cylindrical member 14, and two rubber legs 16, 16 are provided between the inner shaft member 12 and the outer cylindrical member 14. The two rubber legs 16, 16 extend in a substantially vertical direction between the radially opposing surfaces of the inner shaft member 12 and the outer cylindrical member 14, with their upper end faces vulcanization bonded to the lower surfaces of the rubber fixing portions 20, 20 of the inner shaft member 12, and their lower end faces vulcanization bonded to the inner circumference surface of the outer cylindrical member 14. In this embodiment, the rubber legs 16 are vulcanization bonded not only to the lower surface of the rubber fixing portion 20, but also to the left and right side surfaces of the upper part of the stopper projection 22.

[0031] The two rubber legs 16, 16 are both disposed below the inner shaft member 12, and are compressed when the inner shaft member 12 is displaced downward relative to the outer cylindrical member 14 due to input of a main load when mounted on the vehicle, as described below. The two rubber legs 16, 16 are disposed apart from each other in the left-right direction, and extend in the up-down direction at positions apart from each other in the left-right direction. A stopper protrusion 22 of the inner shaft member 12 protrudes between the two rubber legs 16, 16. The upper ends of the two rubber legs 16, 16 are located above the vertical center of the outer cylindrical member 14, and the free length is made large.

[0032] The rubber legs 16 have an elastic main axis E in the vertical extension direction shown by a dashed line in Fig. 2 that is inclined downward and outward to the left and right, and the two rubber legs 16, 16 form a V-shape when viewed in the axial direction. In particular, in this embodiment, on both the left and right inner and left and right outer surfaces of each rubber leg 16, the end on the outer tubular member 14 side is located outward in the left and right direction with respect to the mount center line extending in the vertical direction than the end on the inner shaft member 12 side. As shown in Figs. 1 and 3, the rubber legs 16 have a smaller axial width dimension than the inner shaft member 12 and the outer tubular member 14, and are provided in the axial middle portion of the inner shaft member 12 and the outer tubular member 14.

[0033] Each rubber leg 16 has a connecting rubber part 26 that directly connects the opposing surfaces of the inner shaft member 12 and the outer cylindrical member 14. The connecting rubber part 26 is located between the opposing surfaces in the vertical direction of the rubber fixing part 20 of the inner shaft member 12 and the outer cylindrical member 14, and is continuous between the rubber fixing part 20 of the inner shaft member 12 and the outer cylindrical member 14 in the vertical direction.

[0034] The left-right width dimension w1 of the connecting rubber part 26 is preferably 20% or more, more preferably 40% or more, of the left-right width dimension W1 of the rubber leg 16. Furthermore, the left-right width dimension w1 of the connecting rubber part 26 is preferably 25% or more of the left-right width dimension W1' of the middle part of the rubber leg 16. Furthermore, the width dimension w2 of the connecting rubber part 26 in the direction perpendicular to the elastic main axis E of the rubber leg 16 is preferably 20% or more, more preferably 40% or more. In this way, the proportion of the connecting rubber part 26 in the rubber leg 16 is sufficiently large, so that the compression spring component of the rubber leg 16 is larger than the shear spring component when a downward main load is input so that the inner shaft member 12 is displaced downward relative to the outer cylindrical member 14. The connecting rubber part 26 is illustrated in FIG. 2 as surrounded by a two-dot chain line. The left-right width dimension W1 of the rubber leg 16 refers to the left-right width dimension of the portion of the rubber leg 16 outside the fillet surface (fillet radius) at the end portion of the inner shaft member 12 where the rubber leg 16 is fixed to the outer cylindrical member 14.

[0035] 1 to 3, a rubber protrusion 28 that protrudes in the axial direction is integrally formed with each rubber leg 16. The rubber protrusion 28 is substantially cylindrical in shape and protrudes from the center portion of the axial end face of the rubber leg 16. The rubber protrusion 28 is disposed on an elastic principal axis E that extends in the extension direction of the rubber leg 16.

[0036] The rubber projection 28 is disposed at a position that is located inside the left and right outer ends of the connecting rubber portion 26 of the rubber leg 16 in the left and right direction. In other words, the left and right outer ends of the rubber projection 28 are located at the same position in the left and right direction or inside the left and right outer ends of the connecting rubber portion 26 without protruding outward to the left and right. It is desirable that 60% or more of the projected area in the axial direction of the rubber projection 28 is located on the connecting rubber portion 26. More preferably, 90% or more of the projected area in the axial direction of the rubber projection 28 is located on the connecting rubber portion 26, and the rubber projection 28 is provided substantially only on the connecting rubber portion 26. In this embodiment, the rubber projection 28 is disposed between the left and right ends of the connecting rubber portion 26, and the entirety of the rubber projection 28 is located on the connecting rubber portion 26. In this embodiment, the left and right width dimension (diameter r) of the rubber projection 28 is approximately the same as or slightly smaller than the left and right width dimension w1 of the connecting rubber portion 26. As shown in FIG. 3, the rubber projection 28 is provided to protrude from both sides of the rubber leg 16 in the axial direction.

[0037] As shown in Figs. 1 to 3, the outer peripheral surface of the inner shaft member 12 is covered with an inner rubber layer 30 formed integrally with the rubber legs 16, 16. The inner rubber layer 30 has a substantially constant thickness covering the lower surface and both left and right side surfaces of the inner shaft member 12, and a thick inner cushioning rubber 32 covers the upper surface. However, the inner rubber layer 30 may have a substantially constant thickness overall, or may have different thicknesses at multiple locations. The inner rubber layer 30 has a shorter axial length than the inner shaft member 12, and both ends of the inner shaft member 12 protrude axially outward beyond the inner rubber layer 30 and are exposed to the outside.

[0038] The inner peripheral surface of the outer tubular member 14 is covered with an outer rubber layer 34 formed integrally with the rubber legs 16, 16. The outer rubber layer 34 is provided with an upper cushioning rubber 36 that protrudes toward the inner peripheral surface. The upper cushioning rubber 36 is provided above and on both the left and right sides of the inner shaft member 12, and is provided continuously in the circumferential direction over more than half the circumference of the upper part of the outer tubular member 14. The upper cushioning rubber 36 is spaced above and on both the left and right sides from the inner shaft member 12, and both circumferential ends of the upper cushioning rubber 36 are spaced circumferentially from the two rubber legs 16, 16. A first recess hole 38 that penetrates in the axial direction is formed between the upper cushioning rubber 36 and the inner shaft member 12 (inner rubber layer 30) and the two rubber legs 16, 16. Furthermore, when the inner shaft member 12 undergoes a large relative displacement upward or to the left or right relative to the outer tube member 14, the inner shaft member 12 and the outer tube member 14 abut against each other via the upper cushioning rubber 36, thereby forming a stopper mechanism that limits the amount of relative displacement of the inner shaft member 12 upward or to the left or right relative to the outer tube member 14.

[0039] The outer rubber layer 34 also includes a lower cushion rubber 40 as a stopper rubber. The lower cushion rubber 40 is provided below the stopper protrusion 22 of the inner shaft member 12, and protrudes upward from the outer cylindrical member 14 toward the inner shaft member 12. The lower cushion rubber 40 has a tapered shape that contracts in the front-rear and left-right directions toward the protruding tip. The lower cushion rubber 40 is located between the two rubber legs 16, 16 on the left and right, and is spaced downward from the stopper protrusion 22 of the inner shaft member 12 by a predetermined stopper clearance, and a second recessed hole 42 penetrating in the axial direction is formed between the lower cushion rubber 40 and the inner shaft member 12 (inner rubber layer 30) and the two rubber legs 16, 16. Furthermore, when the inner shaft member 12 undergoes a large relative downward displacement with respect to the outer tube member 14, the inner shaft member 12 and the outer tube member 14 abut against each other via the lower cushioning rubber 40, thereby forming a stopper mechanism that limits the amount of relative displacement of the inner shaft member 12 upward or to the left or right with respect to the outer tube member 14.

[0040] The stopper rubber may be formed integrally with the inner rubber layer 30 so as to protrude downward from the protruding tip surface of the stopper projection 22 of the inner shaft member 12, in which case it is disposed spaced apart above the inner circumferential surface of the outer tubular member 14 (outer rubber layer 34). In this case, the stopper rubber is preferably shaped to taper downward.

[0041] Further, the outer rubber layer 34 is provided with a front cushioning rubber 44 that is fixed to the flange-shaped portion 24. The front cushioning rubber 44 is formed continuously around the entire circumference, fixed to the front surface, which is the axial outer surface of the flange-shaped portion 24, and protrudes forward from the flange-shaped portion 24. The inner peripheral end of the front cushioning rubber 44 protrudes further inward than the outer tubular member 14, and is integrally continuous with the outer rubber layer 34 at the inner peripheral end. The outer peripheral end of the front cushioning rubber 44 is located inner than the outer peripheral end of the flange-shaped portion 24.

[0042] The motor mount 10 thus constructed connects an electric motor (not shown) to a vehicle body (not shown) in a vibration-proof manner. That is, the motor mount 10 is attached to the electric motor by using a bolt or the like inserted into the mounting hole 18 of the inner shaft member 12, and is attached to the vehicle body by, for example, press-fitting the outer tubular member 14 into a mounting hole (not shown) provided in the vehicle body. In this way, the motor mount 10 is mounted to the vehicle, and the electric motor is supported in a vibration-proof manner on the vehicle body via the motor mount 10. The inner shaft member 12 may be attached directly to the electric motor or indirectly via a bracket or the like. Similarly, the outer tubular member 14 may be attached directly to the vehicle body or indirectly via a bracket or the like. Alternatively, the inner shaft member 12 may be attached to the vehicle body side, and the outer tubular member 14 may be attached to the electric motor side.

[0043] When the motor mount 10 is mounted on the vehicle, vibrations are mainly input between the inner shaft member 12 and the outer tubular member 14 in the vertical direction. When the inner shaft member 12 is displaced downward relative to the outer tubular member 14 due to the input of such vibrations, the two rubber legs 16, 16 arranged on the lower side of the inner shaft member 12 are compressed in the vertical direction, and the compression spring component becomes dominant over the shear spring component. In particular, the connecting rubber part 26 provided continuously in the vertical direction between the opposing surfaces in the vertical direction of the inner shaft member 12 and the outer tubular member 14 has a smaller shear spring component in response to the input of a compressive load in the vertical direction, and is a region that is substantially purely compressed. When the inner shaft member 12 is displaced downward relative to the outer tubular member 14 due to such a main load input, the two rubber legs 16, 16 mainly function as compression springs, making it easier to realize higher dynamic spring characteristics and allowing a greater degree of freedom in adjusting the spring characteristics.

[0044] In the motor mount 10, the two rubber legs 16, 16 are provided only on the lower side of the inner shaft member 12, and not on the upper side of the inner shaft member 12. This allows the free length of the two rubber legs 16, 16 to be set with a large degree of freedom without increasing the diameter of the outer cylindrical member 14, and also makes it possible to ensure a large rubber volume, thereby realizing the degree of freedom in setting the spring characteristics of the rubber legs 16, 16 and ensuring durability, etc.

[0045] However, when a vibration load is input, if bending elastic deformation or the like occurs in the two rubber legs 16, 16 in a resonant state, the vibration-proof performance may deteriorate due to the high dynamic spring. In order to prevent such a deterioration in vibration-proof performance due to rubber surging, the motor mount 10 is provided with rubber protrusions 28, 28 protruding on both the front and rear sides of each rubber leg 16. That is, by providing each rubber leg 16 with the rubber protrusions 28, 28, the influence on the spring characteristics of the rubber legs 16, 16 is suppressed, and as shown in the graph of FIG. 4, the spring peak due to the resonance of the rubber legs 16, 16 is reduced by the mass damper action of the rubber protrusions 28, 28, etc., and the deterioration in vibration-proof performance due to the high dynamic spring can be suppressed. In particular, since the quietness of an electric motor is higher than that of an engine, and high-frequency vibrations are more likely to be a problem in the motor mount 10 than in an engine mount, by suppressing the deterioration in vibration-proof performance due to rubber surging of the rubber legs 16, 16 in the high-frequency range of about 1000 Hz, it is possible to provide better quietness and ride comfort. In the graph shown in Figure 4, the spring characteristics of the motor mount 10 of this embodiment, which is equipped with the rubber protrusions 28, are shown by a solid line, and the spring characteristics of a motor mount which does not have the rubber protrusions 28 are shown by a dashed line.

[0046] Here, the rubber protrusions 28 are arranged so as to fit inside the left and right outer ends of the connecting rubber parts 26 of the rubber feet 16. As a result, the rubber protrusions 28 are not provided in the shear deformation region outside the left and right of the connecting rubber parts 26 where shear deformation occurs when the main load is input, and are entirely located in the compression deformation region of the rubber feet 16. As a result, concentration of strain at the base ends of the rubber protrusions 28 due to large shear deformation of the rubber feet 16 is unlikely to occur, and deterioration in durability such as cracks occurring at the connection parts between the rubber protrusions 28 and the rubber feet 16 is prevented.

[0047] It is desirable that 60% or more of the rubber projection 28 is located on the connecting rubber part 26 in the axial projection. More preferably, 90% or more of the rubber projection 28 is located on the connecting rubber part 26 in the axial projection, and substantially the entirety is disposed on the connecting rubber part 26. In this way, by positioning almost the entirety of the rubber projection 28 on the connecting rubber part 26 where compressive deformation is more dominant, distortion at the base end of the rubber projection 28 is alleviated, and the durability of the rubber leg 16 and the rubber projection 28 is further improved. Particularly in this embodiment, the width dimension of the rubber projection 28 is equal to or less than the width dimension of the connecting rubber part 26, and the entirety of the rubber projection 28 is contained between the left and right ends of the connecting rubber part 26, so that distortion at the base end of the rubber projection 28 is more effectively reduced.

[0048] The left-right width dimension w1 of the connecting rubber part 26 is set to be 20% or more of the left-right width dimension W1 of the rubber foot 16, so that the proportion of the connecting rubber part 26, which is the compression region in the rubber foot 16, is set to be sufficiently large. This makes it easier to provide the rubber protrusions 28 in the region in the rubber foot 16 where the compression spring component is larger than the shear spring component. In particular, the large left-right width dimension w1 of the connecting rubber part 26 increases the degree of freedom in the arrangement of the rubber protrusions 28 located on the left and right inner sides of the left and right outer ends of the connecting rubber part 26, and also makes it easy to arrange substantially the entire rubber protrusions 28 on the connecting rubber part 26 while setting the size of the rubber protrusions 28 to be sufficiently large.

[0049] The motor mount 10 is provided with upper and lower cushioning rubbers 36, 40 in portions circumferentially offset from the two rubber legs 16, 16, and has top, bottom, left and right stopper mechanisms that limit the amount of relative displacement between the inner shaft member 12 and the outer cylindrical member 14. This makes it possible to prevent damage to the rubber legs 16 due to excessive relative displacement between the inner shaft member 12 and the outer cylindrical member 14, without restricting the degree of freedom in the shape and arrangement of the two rubber legs 16, 16.

[0050] Furthermore, a front cushion rubber 44 is provided on the flange-like portion 24 provided on the axial end portion of the outer cylindrical member 14, and a rear stopper mechanism is established that limits the amount of relative rearward displacement of the inner shaft member 12 with respect to the outer cylindrical member 14 by abutting the flange-like portion 24 and a member on the electric motor side via the front cushion rubber 44. This makes it possible to prevent damage to the rubber legs 16 due to excessive relative displacement in the axial direction between the inner shaft member 12 and the outer cylindrical member 14.

[0051] Although the embodiment of the present invention has been described above in detail, the present invention is not limited by the specific description. For example, at least one rubber protrusion 28 may be provided on each rubber leg 16. Specifically, for example, the rubber protrusion 28 may be provided to protrude only on one axial side of the rubber leg 16. In addition, the number and positions of the rubber protrusions 28 provided on the two rubber legs 16, 16 may be different from each other. However, considering the balance of the two rubber legs 16, 16 including the rubber protrusions 28, it is preferable that the same number of rubber protrusions 28 are provided on the two rubber legs 16, 16 at corresponding positions as shown in the above embodiment. It is also possible to provide three or more rubber protrusions 28 on the rubber leg 16, and in this case, two or more rubber protrusions 28 are provided to protrude on one axial surface of the rubber leg 16.

[0052] The shape of the rubber protrusions 28 is not limited to a cylindrical shape, and various shapes may be adopted, including, for example, a polygonal column shape, a tube shape, a plate shape, etc. Furthermore, the protruding height and the outer diameter of the rubber protrusions 28 are not particularly limited.

[0053] Furthermore, the rubber protrusions 28 are not limited to being formed from rubber alone, and can be a composite structure in which a mass member such as metal is provided on the rubber protrusions 28 and rubber feet 16 for the purpose of mass tuning, for example. When tuning the characteristics of the rubber protrusions 28, it is sufficient to achieve suppression of surging of the rubber feet 16, and it is also possible to take into account, for example, a dynamic damper effect in addition to or instead of a mass damper effect, or a tuning effect on the spring characteristics of the rubber feet 16.

[0054] In the above embodiment, the entire rubber protrusion 28 is located on the connecting rubber part 26, but the rubber protrusion 28 may include, for example, a part that protrudes laterally inward from the left and right inner ends of the connecting rubber part 26. The amount by which the rubber protrusion 28 protrudes laterally inward from the connecting rubber part 26 is not particularly limited, but it is desirable to set it as follows, for example, in consideration of preventing concentration of strain at the base end of the rubber protrusion 28. That is, since the two rubber legs 16, 16 are formed in a V-shape that slopes downward and outward from the left and right, when they are compressed vertically by the main load input and bulge in the left and right direction, the contact area between the lower end of the rubber leg 16 and the outer tubular member 14 expands laterally inward, and the inner end of the connecting rubber part 26 may move laterally inward. By arranging the rubber protrusions 28 so that the left and right inner ends of the rubber protrusions 28 are located on the left and right outer sides with respect to the left and right inner end positions of the connecting rubber parts 26 in such a compressed state of the rubber legs 16, it is possible to effectively prevent concentration of strain at the base end of the rubber protrusions 28 even if the rubber protrusions 28 are located on the left and right inner side of the connecting rubber parts 26 of the rubber legs 16 to which no load is input. In other words, in the pair of connecting rubber parts 26, 26, when the inner shaft member 12 moves downward relative to the outer tubular member 14 due to the input of a main load such as a static shared support load, the connecting rubber parts 26, 26 are elastically deformed so as to bulge in the left and right direction. Due to such elastic deformation, the left and right outer surfaces of each connecting rubber part 26 tend to move outward from the upper and lower opposing surfaces of the inner shaft member 12 and the outer tubular member 14 to increase the shear area, while the left and right inner surfaces of each connecting rubber part 26 tend to increase the compressed area that directly connects between the upper and lower opposing surfaces of the inner shaft member 12 and the outer tubular member 14. Therefore, even if the rubber projections 28 are positioned on the left and right inner side of the connecting rubber parts 26 of the rubber legs 16, this is unlikely to cause a major problem.

[0055] In the initial state where no load is applied to the rubber legs 16, the rubber protrusions 28 are preferably located laterally inward from the left and right outer ends of the connecting rubber parts 26, but may be located at least on the connecting rubber parts 26 of the rubber legs 16 in a compressed state. That is, when the motor mount 10 is mounted on a vehicle or the like, the rubber legs 16 are compressed by the input of a static shared support load (static main load) of a motor or the like. As a result, the rubber protrusions 28 are disposed in the compressed regions of the rubber legs 16 in the input state of the main load, so that concentration of strain around the rubber protrusions 28 is avoided, and durability is ensured. The left and right outer ends of the rubber protrusions 28 may be located laterally inward from the left and right outer ends of the inner shaft member 12, and may be located laterally outward from the left and right outer ends of the connecting rubber parts 26 of the rubber legs 16 in the initial state.

[0056] The inner shaft member may be configured, for example, by a cylindrical fixing tube portion fixed to the rubber legs 16, 16, and an inner bracket inserted into and fitted to the inner periphery of the fixing tube portion. The inner shaft member may have a cross-sectional shape that changes in the axial direction. The inner shaft member may not have the rubber fixing portions 20, 20 or the stopper projection 22.

[0057] The stopper mechanisms for the top and bottom, front and rear, and left and right directions are not essential, and only stopper mechanisms for one or two directions may be provided, or no stopper mechanism may be provided. [Explanation of symbols]

[0058] 10 Motor mount (Cylindrical vibration isolation device for motor mount, first embodiment) 12 Inner shaft member 14 Outer cylindrical member 16 Rubber feet 18 Mounting hole 20 Rubber fixing part 22 Stopper protrusion 24 Flange-shaped part 26 Connecting rubber part 28 Rubber protrusion 30 Inner rubber layer 32 Inner cushioning rubber 34 Outer rubber layer 36 Upper cushioning rubber 38 First Hole 40 Lower cushioning rubber (stopper rubber) 42 Second piercing hole 44 Front shock absorber rubber

Claims

1. A cylindrical vibration isolation device for a motor mount, in which an inner shaft member and an outer cylindrical member are connected by two rubber legs extending between opposing surfaces of the inner shaft member and the outer cylindrical member, The two rubber legs are both disposed below the inner shaft member which is compressed when a main load is input, and extend in the up-down direction at positions spaced apart from each other in the left-right direction, The two rubber legs are provided with connecting rubber parts that are continuous in the up-down direction and directly connect the opposing surfaces of the inner shaft member and the outer cylindrical member, The two rubber legs are each provided with a rubber protrusion that protrudes in the axial direction, The rubber protrusions are disposed so as to be located laterally inward relative to the left and right outer ends of the connecting rubber portions.

2. 2. The cylindrical vibration isolation device for a motor mount according to claim 1, wherein 90% or more of the rubber projections are disposed on the connecting rubber portion, so that the rubber projections are provided substantially only on the connecting rubber portion.

3. The inner shaft member has a pair of rubber fixing portions protruding on both the left and right sides, The two rubber legs are fixed to the pair of rubber fixing portions, 3. A cylindrical vibration isolating device for a motor mount according to claim 1, wherein a stopper projection is provided between the pair of rubber fixing portions of the inner shaft member, the stopper projection projecting downward between the two rubber legs.

4. 3. The cylindrical vibration isolation device for a motor mount according to claim 1, wherein a stopper rubber is provided between the two rubber legs, the stopper rubber protruding in the vertical direction between the inner shaft member and the outer cylindrical member.

5. 3. A cylindrical vibration-damping device for a motor mount as described in claim 1 or 2, wherein the width dimension of the connecting rubber portion is made 20% or more of the width dimension of the rubber foot, thereby making the compression spring component of the rubber foot against a downward input greater than the shear spring component.

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