Vibration isolation device

Abstract

To provide a vibration isolation device that can increase the spring constant in the first direction while suppressing fluctuations in the spring constants in the second direction and the axial direction. [Solution] Since the minimum gap in the left-right direction (first direction) between the opposing inner stopper 20 and outer stopper 30 is 0 to 0.3 mm, when the inner member 11 and the outer member 12 move relative to each other in the left-right direction, the inner stopper 20 and the outer stopper 30 come into contact from the beginning or initial stage. Further relative movement compresses the inner stopper 20 and the outer stopper 30, thereby increasing the left-right spring constant of the vibration damping device 10. On the other hand, in the vertical direction (second direction) and the direction of axis C, relative movement between the inner member 11 and the outer member 12 causes the opposing inner stopper 20 and outer stopper 30 to shift, thereby suppressing fluctuations in the vertical direction and the direction of axis C of the vibration damping device 10 caused by their presence.

Description

Technical Field

[0001] The present invention relates to a vibration isolator, and more particularly to a vibration isolator that can increase the spring constant in a predetermined direction while suppressing fluctuations in the spring constant in a direction perpendicular thereto.

Background Art

[0002] Conventionally, a vibration isolator is known in which an outer peripheral surface of a shaft-shaped inner member and an inner peripheral surface of a cylindrical outer member are connected at two locations in the circumferential direction by two elastic legs made of an elastic body. In Patent Document 1, the two elastic legs extend from the outer peripheral surface of the inner member to both sides in a first direction perpendicular to the axis of the inner member and to one side in a second direction perpendicular to the axis and the first direction, and are arranged in a V shape.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a vibration isolator in which the elastic legs are arranged in a V shape as in the above prior art, in order to increase the spring constant in the first direction, it is conceivable to bring the elastic legs closer to parallel to the first direction. However, in this case, there is a risk that the spring constant in the axial direction of the vibration isolator increases and the spring constant in the second direction decreases.

[0005] The present invention has been made to solve the above-described problems, and an object thereof is to provide a vibration isolator that can increase the spring constant in the first direction while suppressing fluctuations in the spring constants in the second direction and the axial direction.

Means for Solving the Problems

[0006] To achieve this objective, the vibration isolation device of the present invention comprises: an axial inner member extending along an axis; a cylindrical outer member surrounding the outer circumference of the inner member; two elastic legs made of elastic material extending from the outer surface of the inner member on both sides in a first direction perpendicular to the axis and on one side in a second direction perpendicular to the axis and the first direction, respectively, and connecting the outer surface of the inner member and the inner surface of the outer member at two points in the circumferential direction; a pair of elastic inner stoppers provided on the inner member on both sides in the first direction relative to the axis; and a pair of elastic outer stoppers provided on the outer member on both sides in the first direction relative to the axis, respectively, and facing the pair of inner stoppers in the first direction, wherein, in an unloaded state and viewed in the axial direction, the minimum gap in the first direction between the opposing inner stoppers and outer stoppers is 0 to 0.3 mm. [Effects of the Invention]

[0007] According to the vibration isolation device described in claim 1, the minimum gap in the first direction between the opposing inner stopper and outer stopper is 0 to 0.3 mm, so when the inner member and outer member move relative to each other in the first direction, the inner stopper and outer stopper come into contact from the beginning or initial stage. Further relative movement compresses the inner and outer stoppers, increasing the spring constant of the vibration isolation device in the first direction. On the other hand, with relative movement between the inner member and outer member in the second direction or axial direction, the opposing inner and outer stoppers shift, which suppresses fluctuations in the spring constant of the vibration isolation device in the second direction or axial direction caused by their presence.

[0008] The vibration isolation device described in claim 2 provides the following effects in addition to the effects of the vibration isolation device described in claim 1. In an unloaded state, the opposing inner stopper and outer stopper are in contact with each other. Therefore, when the inner member and outer member move relative to each other in the first direction, it is possible to suppress the rapid increase in the spring constant of the vibration isolation device in the first direction due to the inner stopper and outer stopper coming into contact midway. Furthermore, in an unloaded state, the dimensions of the contacting inner stopper and outer stopper in the first direction are 95 to 100% of the free length of the inner stopper and outer stopper in the first direction. That is, the amount of compression of the inner stopper and outer stopper due to contact can be reduced to zero or small. This makes it easier for the opposing inner stopper and outer stopper to shift in the second direction and axial direction, and further suppresses fluctuations in the spring constant of the vibration isolation device in the second direction and axial direction.

[0009] The vibration isolation device described in claim 3 provides the following effects in addition to the effects of the vibration isolation device described in claim 1 or 2. The minimum gap is formed by a first surface portion of the inner stopper that forms the outer shape on the side facing the outer stopper, and a second surface portion of the outer stopper that forms the outer shape on the side facing the inner stopper. In the cross section perpendicular to the axis that includes the minimum gap, the first surface portion and the second surface portion are each formed parallel to the second direction. As a result, when the first surface portion and the second surface portion shift in the second direction, they are less likely to be compressed in the second direction. Consequently, fluctuations in the spring constant of the vibration isolation device in the second direction caused by the provision of the inner stopper and the outer stopper can be further suppressed.

[0010] The vibration isolation device described in claim 4 provides the following effects in addition to the effects of the vibration isolation device described in claim 1 or 2: In an axial view, the area between the inner member and the outer member, or the area inside the outer member, of the region obtained by projecting the portion where the minimum gap is formed to both sides in the first direction, is filled with an elastic material except for the minimum gap. As a result, when the inner member and the outer member move relative to each other in the first direction, the inner stopper and the outer stopper are more easily compressed in the first direction, making it easier to increase the spring constant of the vibration isolation device in the first direction.

[0011] The vibration isolation device described in claim 5 provides the following effects in addition to the effects of the vibration isolation device described in claim 1 or 2. The minimum gap is formed by a first surface portion that forms the outer shape of the inner stopper on the side facing the outer stopper, and a second surface portion that forms the outer shape of the outer stopper on the side facing the inner stopper. In an unloaded state, the first surface portion and the second surface portion are in contact at the center in the axial direction, while separating from each other at both ends in the axial direction. This reduces the contact area between the first surface portion and the second surface portion, thereby reducing the sliding resistance when they slide in the second direction or axial direction. As a result, the opposing inner stopper and outer stopper can be made to shift more easily in the second direction or axial direction, further suppressing fluctuations in the spring constant of the vibration isolation device in the second direction or axial direction.

[0012] The vibration isolation device according to claim 6 provides the following effects in addition to the effects of the vibration isolation device according to claim 1 or 2. In an axial view, at least one of the inner stopper and the outer stopper in the region obtained by projecting the portion where the minimum gap is formed to both sides in the first direction has a recess formed in the axial direction from the end face in the axial direction. As a result, when the inner member and the outer member move relative to each other in the first direction, the inner stopper and the outer stopper are less likely to be compressed in the first direction until both wall surfaces of the recess in the first direction come into contact with each other. As a result, it is possible to suppress a sharp increase in the spring constant of the vibration isolation device in the first direction. [Brief explanation of the drawing]

[0013] [Figure 1] This is a front view of the vibration isolation device in the first embodiment. [Figure 2] (a) is a cross-sectional view of the vibration isolation device along the line IIa-IIa in Figure 1, and (b) is a cross-sectional view of the vibration isolation device along the line IIb-IIb in Figure 2(a). [Figure 3] (a) is a front view of the vibration isolation device before the drawing process, and (b) is a cross-sectional view of the vibration isolation device along the line IIIb-IIIb in Figure 3(a). [Figure 4] (a) is a front view of the vibration isolation device in the second embodiment, and (b) is a cross-sectional view of the vibration isolation device along the line IVb-IVb in Figure 4(a). [Figure 5] This is a front view of the vibration isolation device in the third embodiment. [Figure 6] (a) is a cross-sectional view of the vibration isolation device along the line VIa-VIa in Figure 5, and (b) is a cross-sectional view of the vibration isolation device in the fourth embodiment. [Modes for carrying out the invention]

[0014] Preferred embodiments will be described below with reference to the attached drawings. Figure 1 is a front view of the vibration isolation device 10 in the first embodiment. Figure 2(a) is a cross-sectional view of the vibration isolation device 10 along the line IIa-IIa in Figure 1. Figure 2(b) is a cross-sectional view of the vibration isolation device 10 along the line IIb-IIb in Figure 2(a).

[0015] The arrows U, D, L, R, F, and B in each drawing indicate the upward, downward, leftward, rightward, forward, and backward directions of the vibration isolation device 10, respectively. The upward / downward, leftward / rightward, and forward / backward directions are perpendicular to each other. Note that these directions are set for the sake of explanation and may or may not coincide with the actual upward / downward direction, etc. Also, the vibration isolation device 10 in Figures 1, 2(a), and 2(b) all show the device in an unloaded state where no vibration is applied. Unless otherwise specified, the explanation using these figures will describe the vibration isolation device 10 in an unloaded state.

[0016] The vibration isolation device 10 is a vibration isolation bush for elastically connecting a vibration source side, such as an engine, motor, or suspension mechanism arm of an automobile, with a vibration receiving side, such as the vehicle body. The vibration isolation device 10 mainly comprises an axial inner member 11 extending along axis C, a cylindrical outer member 12 surrounding the outer circumference of the inner member 11, and two elastic legs 13 connecting them at two points in the circumferential direction.

[0017] The vibration isolation device 10 is installed on the vehicle with the axis C direction as the longitudinal direction. Furthermore, each part of the vibration isolation device 10 is formed symmetrically in the left-right direction (first direction) with respect to the axis C. An inner member 11 is fixed to one of the vibration source side and vibration receiving side, and an outer member 12 is fixed to the other of the vibration source side and vibration receiving side.

[0018] The inner member 11 is a cylindrical member surrounding the axis C and is composed of a rigid material such as a steel material or an aluminum alloy. The inner peripheral surface of the inner member 11 is formed by a cylindrical surface centered on the axis C.

[0019] The outer peripheral surface of the inner member 11 is formed such that a cross-section perpendicular to the axis C is substantially trapezoidal. The outer peripheral surface of the inner member 11 includes an upper surface portion 11a forming the upper side of the substantially trapezoidal shape, a lower surface portion 11b forming the lower side and being substantially parallel to the upper surface portion 11a, and a pair of side surface portions 11c connecting the upper surface portion 11a and the lower surface portion 11b.

[0020] The upper surface portion 11a and the lower surface portion 11b are formed in a planar shape substantially perpendicular to the vertical direction (second direction). A pair of protrusions 11d protrude upward from both ends of the upper surface portion 11a in the left-right direction. An upper inner stopper 14 made of an elastic body such as rubber or a thermoplastic elastomer protrudes upward from the upper surface portion 11a between the pair of protrusions 11d.

[0021] When the inner member 11 relatively moves upward with respect to the outer member 12 due to the application of vibration to the vibration isolation device 10, the upper inner stopper 14 contacts the outer member 12 side and is compressed, thereby gradually restricting the relative movement. Therefore, the spring constant of the vibration isolation device 10 during the relative movement can be set to be kept low until the upper inner stopper 14 contacts the outer member 12 side and then rapidly increase after the contact.

[0022] The lower surface portion 11b is shorter in the left-right direction than the upper surface portion 11a. A lower inner stopper 15 made of an elastic body protrudes downward (one side of the second direction) from the lower surface portion 11b. The pair of side surface portions 11c approach each other as they extend from the upper surface portion 11a toward the lower surface portion 11b. Each of the side surface portions 11c is formed such that a cross-section perpendicular to the axis C is an arcuate shape convex toward the outer side in the radial direction.

[0023] The outer member 12 is a cylindrical member centered on axis C and is made of a rigid material such as steel or aluminum alloy. The lower outer stopper 16 protrudes toward the lower inner stopper 15 from the portion of the inner circumferential surface of the outer member 12 that is radially opposite to the lower surface portion 11b.

[0024] When the inner member 11 moves downward relative to the outer member 12, the lower inner stopper 15 and the lower outer stopper 16 come into contact with each other and are compressed, gradually restricting the relative movement. This allows the spring constant of the vibration isolation device 10 during the relative movement to be kept low until the lower inner stopper 15 and the lower outer stopper 16 come into contact, and then increased sharply after they come into contact.

[0025] Each of the two elastic legs 13 is made of an elastic material. The two elastic legs 13 are vulcanized and bonded to a pair of side surfaces 11c of the inner member 11 and the inner circumferential surface of the outer member, respectively, connecting them. One of the two elastic legs 13 extends diagonally to the left and downward from the left side surface 11c, and the other extends diagonally to the right and downward from the right side surface 11c. That is, the two elastic legs 13 are arranged in a V-shape, narrowing from each other as they move upward.

[0026] Between the inner member 11 and the outer member 12, grooves 19a and 19b are formed, partitioned in the circumferential direction by two elastic legs 13. Both grooves 19a and 19b are through holes opening on both sides in the direction of the axis C of the vibration isolation device 10. Groove 19a is provided on the upper side of the inner member 11, and groove 19b is provided on the lower side. Groove 19a has a larger circumferential dimension than groove 19b.

[0027] An elastic membrane 17 made of an elastic material is provided on the outer circumferential surface of the inner member 11 so as to connect a pair of elastic legs 13, an upper inner stopper 14, and a lower inner stopper 15, respectively. Similarly, an elastic membrane 18 made of an elastic material is provided on the inner circumferential surface of the outer member 12 so as to connect a pair of elastic legs 13 and a lower outer stopper 16, respectively. Therefore, the elastic legs 13, upper inner stopper 14, lower inner stopper 15, lower outer stopper 16, and elastic membranes 17 and 18 are integrally molded from an elastic material.

[0028] The vibration isolation device 10 further includes an inner stopper 20 and an outer stopper 30 for increasing the spring constant in the left-right direction. The inner stopper 20 is a pair of elastic members provided on the inner member 11 on both sides in the left-right direction with respect to the axis C. The inner stopper 20 is formed so that a portion of the elastic leg portion 13 on the inner member 11 side and the upper side bulges outward in the left-right direction.

[0029] The outer stoppers 30 are a pair of elastic members provided on the outer member 12 on both sides in the left-right direction with respect to the axis C. The pair of outer stoppers 30 are provided in positions opposite to the pair of inner stoppers 20 in the left-right direction, and are formed to cause the elastic membrane 18 near the elastic leg portion 13 to bulge inward in the left-right direction.

[0030] In an unloaded state and viewed along axis C, it is preferable that the minimum gap G in the left-right direction between the inner stopper 20 and the outer stopper 30 is set to 0 mm. More specifically, it is preferable that the inner stopper 20 and the outer stopper 30 are in contact with each other in an unloaded state. In this case, when the inner member 11 and the outer member 12 move relative to each other in the left-right direction, the inner stopper 20 and the outer stopper 30 are in contact from the beginning, and therefore undergo compressive deformation. Thus, the left-right spring constant of the vibration isolation device 10 can be increased compared to the case without the inner stopper 20 and the outer stopper 30.

[0031] On the other hand, during relative movement between the inner member 11 and the outer member 12 in the vertical direction and along the axis C, the opposing inner stopper 20 and outer stopper 30 shift relative to each other. Therefore, the presence of the inner stopper 20 and outer stopper 30 suppresses fluctuations in the spring constant of the vibration isolation device 10 in the vertical direction and along the axis C. As a result, compared to a vibration isolation device 10 without the inner stopper 20 and outer stopper 30, the presence of these stoppers increases the spring constant in the left-right direction while suppressing fluctuations in the spring constant in the vertical direction and along the axis C.

[0032] In Figure 1, viewed in the direction of axis C, region A is shown projected to both sides in the left-right direction by the inside of two parallel dashed lines, where the minimum gap G is formed. In the direction of axis C, the space between the inner member 11 and the outer member 12 in region A is filled with an elastic material, except for the minimum gap G. That is, no gaps are formed in region A other than the minimum gap G. As a result, when the inner member 11 and the outer member 12 move relative to each other in the left-right direction, the inner stopper 20 and the outer stopper 30 can be compressed more easily in the left-right direction compared to when such gaps are formed. Consequently, the spring constant of the vibration isolation device 10 in the left-right direction can be more easily increased by the inner stopper 20 and the outer stopper 30.

[0033] In region A, the portion of the inner stopper 20 that forms the outer shape (surface portion) on the side facing the outer stopper 30 is defined as the first surface portion 21. Similarly, in region A, the portion of the outer stopper 30 that forms the outer shape (surface portion) on the side facing the inner stopper 20 is defined as the second surface portion 31. In other words, the first surface portion 21 and the second surface portion 31 form the minimum gap G.

[0034] As shown in Figure 2(a), the first table portion 21 has a vertex 22 at its center in the direction of axis C (front-to-back direction), and slopes away from the second table portion 31 in the left-to-right direction as it moves from the vertex 22 toward each end in the direction of axis C. Similarly, the second table portion 31 has a vertex 32 at its center in the direction of axis C, and slopes away from the first table portion 21 in the left-to-right direction as it moves from the vertex 32 toward each end in the direction of axis C. The vertices 22 and 32 are at the same position in the direction of axis C.

[0035] The minimum gap G is between these vertices 22 and 32. Therefore, the inner stopper 20 and the outer stopper 30 do not overlap when viewed in the direction of axis C. As a result, when the first surface portion 21 and the second surface portion 31 shift in the direction of axis C, the inner stopper 20 and the outer stopper 30 are less likely to be compressed in the direction of axis C. Thus, the presence of the inner stopper 20 and the outer stopper 30 further suppresses fluctuations in the spring constant in the direction of axis C of the vibration isolation device 10 compared to a device without them.

[0036] Furthermore, in an unloaded state, the first surface portion 21 and the second surface portion 31 are in contact at the center side in the direction of axis C (near the vertices 22 and 32), while separating from each other at both ends in the direction of axis C. This reduces the contact area between the first surface portion 21 and the second surface portion 31, thereby reducing the sliding resistance when they slide in the vertical direction and in the direction of axis C. As a result, the opposing inner stopper 20 and outer stopper 30 can be made to shift more easily in the vertical direction and in the direction of axis C. Therefore, the presence of the inner stopper 20 and outer stopper 30 can further suppress fluctuations in the spring constants of the vibration isolation device 10 in the vertical direction and in the direction of axis C compared to a device without them.

[0037] As shown in Figure 2(b), in the cross section perpendicular to axis C that includes the minimum gap G (vertices 22, 32), the first surface portion 21 (vertex 22) and the second surface portion 31 (vertex 32) are formed parallel to the vertical direction. This "parallelism" does not necessarily mean perfect parallelism; it is sufficient if they are approximately parallel, taking into account manufacturing tolerances, etc. For example, a parallelism of 0.3 mm or less between the two surfaces may be considered "parallel," or a parallelism of 0.1 mm or less between the two surfaces may be considered "parallel."

[0038] In this parallel state, when the first surface portion 21 and the second surface portion 31 shift vertically, they become less susceptible to vertical compression. Therefore, the presence of the inner stopper 20 and the outer stopper 30 further suppresses fluctuations in the vertical spring constant of the vibration isolation device 10 compared to a device without them.

[0039] Furthermore, the first surface portion 21 and the second surface portion 31 are not limited to the parallel state described above, but may also be formed in a curved shape when viewed in the direction of axis C. In this case, it is preferable to form a minimum gap G between the peak of the curved first surface portion 21 and the peak of the curved second surface portion 31.

[0040] Here, when the vibration isolation device 10 supports one side, the vibration source side, and the vibration receiving side, the inner member 11 and the outer member 12 move relative to each other in the vertical direction relative to their position before support, in accordance with the support load. That is, both the inner stopper 20 on the inner member 11 side and the outer stopper 30 on the outer member 12 side move relative to each other in the vertical direction. The amount of this relative movement varies according to the variation in weight on the other side, the vibration source side and the vibration receiving side.

[0041] If the relative displacement varies, the peaks of the curved first surface section 21 and the second surface section 31 will shift vertically, and the minimum gap G will also fluctuate. This may cause variations in the timing at which the lateral spring constant of the vibration isolation device 10 increases due to contact between the inner stopper 20 and the outer stopper 30.

[0042] In contrast, if the first surface portion 21 and the second surface portion 31 are facing each other with a predetermined width in a parallel state as described above, even if the relative vertical movement of the inner member 11 and the outer member 12 varies, fluctuations in the minimum gap G can be suppressed. Therefore, it is possible to make it less likely for variations to occur in the timing at which the spring constant increases.

[0043] Next, the manufacturing method of the vibration isolation device 10 will be described with reference to Figures 3(a) and 3(b). Figure 3(a) is a front view of the vibration isolation device 10 before drawing. Figure 3(b) is a cross-sectional view of the vibration isolation device 10 along the line IIIb-IIIb in Figure 3(a).

[0044] To manufacture the vibration isolation device 10, first, the inner member 11 and the outer member 12 are set in the lower mold 41 of a mold that opens in the direction of axis C. This outer member 12 has a larger outer diameter than the outer member 12 shown in Figure 1, etc. After setting the inner member 11, etc., the mating surfaces 43 of the lower mold 41 and the upper mold 42 are aligned and the mold is clamped, and then the elastic material is injected into the cavity 44 between the lower mold 41 and the upper mold 42.

[0045] Next, the raw material is vulcanized to vulcanize and mold the elastic leg portion 13, upper inner stopper 14, lower inner stopper 15, lower outer stopper 16, elastic membranes 17, 18, inner stopper 20, and outer stopper 30, and also to form the trim pieces 19a and 19b. By opening the lower mold 41 and the upper mold 42, an intermediate vibration damping device 10 is obtained. In this intermediate, each part of the elastic body of the vibration damping device 10 is in an uncompressed state, and each part of the elastic body is formed at its free length.

[0046] The gaps 19a and 19b, including the space between the inner stopper 20 and the outer stopper 30 (minimum gap G), are formed by the lower protrusion 45 and the upper protrusion 46. The lower protrusion 45 is a portion that protrudes from the lower mold 41 in the direction of axis C within the cavity 44. The upper protrusion 46 is a portion that protrudes from the upper mold 42 in the direction of axis C within the cavity 44. During mold clamping, the tip of the lower protrusion 45 and the tip of the upper protrusion 46 come into contact with each other at the mating surface 43.

[0047] These lower protrusions 45 and upper protrusions 46 need to be formed relatively thick so that they can withstand the pressure during injection of the elastic material and during vulcanization molding. Therefore, in the vibration isolation device 10 of the intermediate body, the minimum gap G formed by the lower protrusions 45 and upper protrusions 46 is relatively large.

[0048] Finally, the outer member 12 of the intermediate body is reduced in diameter by drawing so that the minimum gap G becomes 0 mm, thereby completing the manufacturing of the vibration isolation device 10 shown in Figures 1 and 2. However, the minimum gap G may not be 0 mm due to manufacturing errors, etc. The minimum gap G in the unloaded state should be at least 0.3 mm or less, preferably 0.1 mm or less, and more preferably 0 mm.

[0049] If the minimum gap G in the unloaded state is greater than 0 mm and less than or equal to 0.3 mm, the inner stopper 20 and the outer stopper 30 will come into contact from the initial stage when the inner member 11 and the outer member 12 move relative to each other in the left-right direction. This allows the spring constant in the left-right direction of the vibration isolation device 10, which has the inner stopper 20 and the outer stopper 30, to be increased from the initial stage compared to the case where the inner stopper 20 and the outer stopper 30 are not present. Furthermore, if the minimum gap G is less than or equal to 0.1 mm, this spring constant can be increased from an even earlier stage.

[0050] Furthermore, when the minimum gap G is greater than 0 mm, relative movement between the inner member 11 and the outer member 12 in the vertical direction and along the axis C makes it difficult for the opposing inner stopper 20 and outer stopper 30 to slide against each other, and they are prone to shifting. Therefore, the fluctuation of the spring constant of the vibration damping device 10 in the vertical direction and along the axis C direction can be further suppressed by providing the inner stopper 20 and outer stopper 30 to increase the spring constant in the left-right direction.

[0051] On the other hand, if the minimum gap G in the unloaded state is 0 mm, then the inner member 11 and the outer member 12 are in contact in the unloaded state. Therefore, when the inner member 11 and the outer member 12 move relative to each other in the left-right direction, it is possible to suppress the sudden increase in the left-right spring constant of the vibration isolation device 10 due to the inner stopper 20 and the outer stopper 30 coming into contact along the way.

[0052] However, when the minimum gap G is 0 mm, it is preferable to bring the compression amount of the inner stopper 20 and the outer stopper 30 as close to zero as possible in the unloaded state. Specifically, in the unloaded state, the total left-right dimension L1 (see Figure 1) of the inner stopper 20 and the outer stopper 30 in contact with each other is preferably 95 to 100% (compression ratio of 0 to 5%) of the sum of the left-right free length L2 (see Figure 3(a)) of the inner stopper 20 and the left-right free length L3 (see Figure 3(a)) of the outer stopper 30. That is, it is preferable that 95% ≤ L1 / (L2 + L3) ≤ 100%.

[0053] In this way, by reducing the amount of compression of the inner stopper 20 and the outer stopper 30 due to contact to zero or small, their sliding resistance can be reduced. As a result, the inner stopper 20 and the outer stopper 30 that are in contact can be made to slide more easily in the vertical direction and along the axis C. Therefore, the fluctuation of the spring constant of the vibration isolation device 10 in the vertical direction and along the axis C can be suppressed more effectively compared to the case where the inner stopper 20 and the outer stopper 30 are absent.

[0054] Furthermore, it is more preferable that L1 / (L2+L3) ≥ 97%, and even more preferable that L1 / (L2+L3) ≥ 99%. The closer the compression amount is to zero, the more effectively fluctuations in the spring constants of the vibration damping device 10 in the vertical direction and along the axis C direction can be suppressed compared to the case where the inner stopper 20 and outer stopper 30 are absent.

[0055] In the uncompressed state, the first surface portion 21 and the second surface portion 31 each tilt away from each other in the left-right direction as they move from the center (vertices 22, 32) in the axial direction C toward each end, similar to the unloaded state after drawing shown in Figure 2(b). By positioning the vertices 22, 32 on the mating surface 43 and using this tilt as a draft angle, the inner stopper 20 and the outer stopper 30 can be easily formed by the lower die 41 and upper die 42 which open in the axial direction C.

[0056] Furthermore, since the first surface portion 21 and the second surface portion 31 are inclined to have vertices 22 and 32 in the uncompressed state, only the vertices 22 and 32 make contact when the compression amount is zero. By reducing the contact area in this way, the inner stopper 20 and the outer stopper 30 can be easily shifted in the vertical direction and along the axis C. Moreover, even if the compression amount is slightly greater than zero, the contact area between the first surface portion 21 and the second surface portion 31 only increases slightly near the vertices 22 and 32, so the inner stopper 20 and the outer stopper 30 can maintain a state where they can easily shift in the vertical direction and along the axis C. Therefore, the presence of the inner stopper 20 and the outer stopper 30 can further suppress fluctuations in the vertical direction and along the axis C of the vibration isolation device 10 compared to a device without them.

[0057] Next, a second embodiment will be described with reference to Figures 4(a) and 4(b). In the first embodiment, a case was described in which inner stoppers 20 are provided on both the left and right sides of the inner member 11. In contrast, in the second embodiment, a case will be described in which an inner stopper 52 is provided on the upper side of the inner member 51. Note that parts identical to those in the first embodiment are denoted by the same reference numerals and their descriptions will be omitted below.

[0058] Figure 4(a) is a front view of the vibration isolation device 50 in the second embodiment. Figure 4(b) is a cross-sectional view of the vibration isolation device 50 along the line IVb-IVb in Figure 4(a). The vibration isolation device 50 is a vibration isolation bush similar to the vibration isolation device 10 in the first embodiment. The vibration isolation device 50 is installed on the vehicle with the axis C direction as the front-rear direction. Furthermore, each part of the vibration isolation device 50 is formed symmetrically in the left-right direction with respect to the axis C.

[0059] The vibration isolation device 50 comprises an axial inner member 51 extending along the axis C, a cylindrical outer member 12 surrounding the outer circumference of the inner member 51, two elastic legs 13 connecting them at two points in the circumferential direction, and an inner stopper 52 and an outer stopper 53 for increasing the spring constant in the left-right direction. The inner member 51 is the same as the inner member 11 of the first embodiment, with the projection 11d omitted, and is otherwise identical in configuration to the inner member 11.

[0060] The inner stoppers 52 are a pair of elastic members provided on the upper side of the inner member 51 on both sides in the left-right direction with respect to the axis C. Each inner stopper 52 is formed to bulge upward from the upper surfaces 11a on both the left and right sides of the upper inner stopper 14. The pair of inner stoppers 52 are connected to the upper inner stopper 14 in the left-right direction.

[0061] The outer stoppers 53 are a pair of elastic members provided on the outer member 12 on both sides in the left-right direction with respect to the axis C. The pair of outer stoppers 53 are positioned opposite the pair of inner stoppers 52 in the left-right direction and are formed to cause the elastic membrane 18 near the elastic leg portion 13 to bulge inward in the left-right direction.

[0062] In an unloaded state and viewed in the direction of axis C, the minimum lateral gap G between the opposing inner stopper 52 and outer stopper 53 is set to 0 mm. Figure 4(a) in the direction of axis C shows the region A projected onto both sides in the lateral direction by the inside of two parallel dashed lines, where the minimum gap G is formed.

[0063] Region A is located above the inner member 51. In a view along axis C, the inside of the outer member 12 within region A is filled with an elastic material except for the minimum gap G. That is, no recesses are formed in region A except for the minimum gap G. This makes it easier to increase the spring constant of the vibration isolation device 50 in the left-right direction using the inner stopper 52 and the outer stopper 53, similar to the first embodiment.

[0064] In region A, the portion of the inner stopper 52 that forms the outer shape on the side of the outer stopper 53 is defined as the first surface portion 54. Similarly, in region A, the portion of the outer stopper 53 that forms the outer shape on the side of the inner stopper 52 is defined as the second surface portion 55. In other words, the first surface portion 54 and the second surface portion 55 form the minimum gap G.

[0065] As shown in Figure 4(b), the first table portion 54 has a vertex 56 approximately in the center in the direction of axis C (front-to-back direction), and as it moves from vertex 56 toward each end in the direction of axis C, it tilts away from the second table portion 55 in the left-to-right direction. Similarly, the second table portion 55 has a vertex 57 approximately in the center in the direction of axis C, and as it moves from vertex 57 toward each end in the direction of axis C, it tilts away from the first table portion 54 in the left-to-right direction. Vertices 56 and 57 are offset in the direction of axis C.

[0066] Therefore, in an unloaded state, if the vertex 57 is located further inward in the left-right direction than the vertex 56, the minimum gap G becomes 0 mm even if the first surface portion 54 and the second surface portion 55 are not in contact with each other. Thus, if the minimum gap G in an unloaded state is 0 to 0.3 mm or less, the inner stopper 52 and the outer stopper 53 will come into contact from the beginning or initial stage when the inner member 51 and the outer member 12 move relative to each other in the left-right direction. This makes it possible to increase the left-right spring constant of the vibration isolation device 50.

[0067] On the other hand, with respect to the vertical movement and axial C direction of the inner member 51 and the outer member 12, the opposing inner stopper 52 and outer stopper 53 shift, thereby suppressing fluctuations in the spring constant of the vibration isolation device 50 in the vertical direction and axial C direction caused by their presence. As a result, the vibration isolation device 50 can increase the spring constant in the left-right direction while suppressing fluctuations in the spring constant in the vertical direction and axial C direction, compared to the case without the inner stopper 52 and outer stopper 53.

[0068] Since vertices 56 and 57 are offset in the direction of axis C, when the first surface portion 54 and the second surface portion 55 come into contact, surface contact occurs between vertex 56 and vertex 57, ensuring a sufficient contact area. This allows for a larger area of ​​compression of the inner stopper 52 and the outer stopper 53 when the inner member 51 and the outer member 12 move relative to each other in the left-right direction. As a result, it becomes easier to increase the left-right spring constant of the vibration isolation device 50.

[0069] Since vertex 57 is located behind vertex 56, when the minimum gap G in the unloaded state is 0 mm, the inner stopper 52 and the outer stopper 53 move apart from each other when the outer member 12 moves backward relative to the inner member 51. On the other hand, when the minimum gap G in the unloaded state is 0 mm and the outer member 12 moves forward relative to the inner member 51, the inner stopper 52 and the outer stopper 53 are pressed against each other. Therefore, in the vibration isolation device 50, the spring constant on the front side of the axis C can be made larger than the spring constant on the rear side of the axis C.

[0070] This is also true when vertex 57 is positioned forward of vertex 56, and the minimum gap G in the unloaded state is set to 0 mm. In this case, the vibration isolation device 50 can make the spring constant on the rear side of the axis C larger than the spring constant on the front side of the axis C.

[0071] In the second embodiment, as in the first embodiment, in the cross section perpendicular to the axis C that includes the minimum gap G, the first surface portion 54 and the second surface portion 55 are each formed parallel to the vertical direction. This further suppresses the fluctuation of the vertical spring constant of the vibration isolation device 50 compared to one without the inner stopper 52 and outer stopper 53, due to the presence of these stoppers.

[0072] Next, a third embodiment will be described with reference to Figures 5 and 6(a). In the first embodiment, the space between the inner member 11 and the outer member 12 in region A is filled with an elastic material except for the minimum gap G (no recesses other than the minimum gap G are formed in region A). In contrast, the third embodiment will describe a case in which recesses 61 and 62, which are recesses other than the minimum gap G, are formed in region A. Note that parts identical to those in the first embodiment are denoted by the same reference numerals and their descriptions are omitted below.

[0073] Figure 5 is a front view of the vibration isolation device 60 in the third embodiment. Figure 6(a) is a cross-sectional view of the vibration isolation device 60 along the line VIa-VIa in Figure 5. The vibration isolation device 60 is configured identically to the vibration isolation device 10 of the first embodiment, except that recesses 61 and 62 are provided in region A.

[0074] The recesses 61 are formed so as to be recessed in the direction of axis C from both end faces of the inner stopper 20 in the direction of axis C in region A. In this embodiment, the recesses 61 are holes with bottoms. The recesses 62 are formed so as to be recessed in the direction of axis C from both end faces of the outer stopper 30 in the direction of axis C in region A. In this embodiment, the recesses 62 are holes with bottoms.

[0075] Thus, recesses 61 and 62 are formed in region A of the vibration isolation device 60, acting as gaps other than the minimum gap G. As a result, when the inner member 11 and the outer member 12 move relative to each other in the left-right direction, the inner stopper 20 and the outer stopper 30 are less likely to be compressed in the left-right direction until the left-right walls of the recesses 61 and 62 come into contact with each other. Consequently, a sharp increase in the left-right spring constant of the vibration isolation device 60 can be suppressed.

[0076] Next, a fourth embodiment will be described with reference to Figure 6(b). In the third embodiment, the case in which the recesses 61 and 62 are holes with bottoms was described. In contrast, in the fourth embodiment, the case in which the recesses 71 and 72 are through holes without bottoms will be described. Note that parts identical to those in the first embodiment are denoted by the same reference numerals and their descriptions are omitted below.

[0077] The front view of the vibration isolation device 70 in the fourth embodiment is substantially the same as the front view of the vibration isolation device 60 in the third embodiment shown in Figure 5. Figure 6(b) is a cross-sectional view of the vibration isolation device 70 in the fourth embodiment, and is a cross-sectional view of the same location as in Figure 6(a). The vibration isolation device 70 is configured identically to the vibration isolation device 10 in the first embodiment, except that recesses 71 and 72 are provided in region A.

[0078] The recesses 71 are formed so as to be recessed in the direction of axis C from both end faces of the inner stopper 20 in the direction of axis C in region A. The recesses 71 on both sides in the direction of axis C communicate with each other and form a bottomless through hole. The recesses 72 are formed so as to be recessed in the direction of axis C from both end faces of the outer stopper 30 in the direction of axis C in region A. The recesses 72 on both sides in the direction of axis C communicate with each other and form a bottomless through hole.

[0079] Thus, recesses 71 and 72 are formed in region A of the vibration isolation device 70, acting as gaps other than the minimum gap G. As a result, when the inner member 11 and the outer member 12 move relative to each other in the left-right direction, the inner stopper 20 and the outer stopper 30 are less likely to be compressed in the left-right direction until the left-right walls of the recesses 71 and 72 come into contact with each other. Consequently, a sharp increase in the left-right spring constant of the vibration isolation device 70 can be suppressed.

[0080] In particular, compared to the third embodiment where the recesses 61 and 62 are holes with bottoms, in the fourth embodiment the recesses 71 and 72 are through holes, so the inner stopper 20 and the outer stopper 30 are less likely to be compressed in the left-right direction by the recesses 71 and 72. Furthermore, when the inner member 11 and the outer member 12 move relative to each other in the left-right direction, the vicinity of the vertices 22 and 32 of the inner stopper 20 and the outer stopper 30 are compressed first. The recesses 71 and 72 are provided at positions that overlap with the vertices 22 and 32 when viewed from the left-right direction. Therefore, from the initial stage when the inner stopper 20 and the outer stopper 30 are compressed in the left-right direction, the compression can be suppressed by the recesses 71 and 72, and the rapid increase in the left-right spring constant of the vibration isolation device 70 can be further suppressed.

[0081] Although the present invention has been described above based on embodiments, it is easy to infer that the present invention is not limited in any way to the above embodiments, and that various improvements and modifications are possible without departing from the spirit of the present invention. For example, the shapes, materials, and numerical values ​​given in each of the above embodiments are just examples, and it is of course possible to adopt other shapes, materials, and numerical values. The vibration isolation devices 10 and 50 may also be asymmetrical in the left-right direction.

[0082] The inner members 11 and 51 are not limited to a cylindrical shape; they may also be rod-shaped with the inner circumference hole omitted. The outer surface of the inner members 11 and 51 is not limited to a roughly trapezoidal cross-section perpendicular to axis C; it may be circular, elliptical, or a polygonal shape other than a trapezoid, and a part of it in the direction of axis C may bulge or be recessed. The outer member 12 is not limited to a cylindrical shape; it may also be elliptical or polygonal, and a part of it in the direction of axis C may bulge or be recessed. Furthermore, the upper inner stopper 14, lower inner stopper 15, and lower outer stopper 16 may be omitted.

[0083] In the above embodiment, the case in which the vibration damping devices 10 and 50 are mounted on a vehicle with the axis C direction as the front-rear direction was described, but this is not necessarily the only case. The vibration damping devices 10 and 50 may be mounted on something other than a vehicle. Also, the vibration damping devices 10 and 50 may be arranged so that the axis C direction is the vertical or horizontal direction of the vehicle or other object.

[0084] In the above embodiment, the case was described in which the first surface portion 21, 54 and the second surface portion 31, 55 are formed parallel to the vertical direction (straight line) in a cross section containing the minimum gap G among the cross sections perpendicular to the axis C, but the embodiment is not necessarily limited to this. For example, in the above cross section, at least one of the first surface portion 21, 54 and the second surface portion 31, 55 may be formed in a straight line that is not parallel to the vertical direction, or it may be formed in a curved or undulating shape.

[0085] In the above embodiment, the case was described in which the first table portions 21, 54 and the second table portions 31, 55 are inclined to move away from each other as they move from approximately the center in the direction of axis C toward each end, but the embodiment is not necessarily limited to this. At least one of the first table portions 21, 54 and the second table portions 31, 55 may be inclined to move away from the opposing one as they move from one end toward the other in the direction of axis C. Also, at least one of the first table portions 21, 54 and the second table portions 31, 55 may be formed substantially parallel to the direction of axis C (with almost no inclination with respect to the direction of axis C).

[0086] In the third and fourth embodiments described above, the case in which recesses 61 and 71 are provided in the inner stopper 20 and recesses 62 and 72 are provided in the outer stopper 30 was explained, but the invention is not limited to this. Either one of the recesses 61 and 71 or the recesses 62 and 72 may be omitted. Alternatively, the inner stopper 20 may have a recess 71 while the outer stopper 30 has a recess 62. Alternatively, the inner stopper 20 may have a recess 61 while the outer stopper 30 has a recess 72. Furthermore, the recesses 61 and 62, which are holes with bottoms, may be provided only on one end face in the direction of axis C. The recesses 61, 62, 71, and 72 may also be applied to the vibration isolation device 50 of the second embodiment. [Explanation of symbols]

[0087] 10, 50, 60, 70 Vibration Isolator 11,51 Inner member 12 Outer member 13 Elastic Legs 20.52 Inner stopper 21,54 Table 1 30,53 Outer stopper 31, 55 Table 2 61, 62, 71, 72 recess G Minimum gap

Claims

1. An axial inner member extending along the axis, A cylindrical outer member surrounding the outer circumference of the inner member, Two elastic legs made of elastic material extend from the outer circumferential surface of the inner member to both sides in a first direction perpendicular to the axis, and to one side in a second direction perpendicular to the axis and the first direction, respectively, connecting the outer circumferential surface of the inner member and the inner circumferential surface of the outer member at two points in the circumferential direction, A pair of elastic inner stoppers are provided on the inner member on both sides in the first direction with respect to the axis, The outer member is provided on both sides in the first direction with respect to the axis, and comprises a pair of inner stoppers and a pair of elastic outer stoppers facing each other in the first direction, A vibration isolation device characterized in that, in an unloaded state and viewed in the axial direction, the minimum gap in the first direction between the opposing inner stopper and the outer stopper is 0 to 0.3 mm.

2. Under no-load conditions, The inner stopper and the outer stopper, which are facing each other, come into contact. The vibration isolation device according to claim 1, characterized in that the dimensions of the inner stopper and the outer stopper in the first direction that are in contact with each other are 95 to 100% of the free length of the inner stopper and the outer stopper in the first direction.

3. The minimum gap is formed by a first surface portion of the inner stopper that forms the outer shape on the side facing the outer stopper, and a second surface portion of the outer stopper that forms the outer shape on the side facing the inner stopper. The vibration isolation device according to claim 1 or 2, characterized in that, in a cross section perpendicular to the axis and including the minimum gap, the first surface portion and the second surface portion are each formed parallel to the second direction.

4. The vibration isolation device according to claim 1 or 2, characterized in that, in an axial view, the area between the inner member and the outer member, or the area inside the outer member, of the region obtained by projecting the portion where the minimum gap is formed toward both sides in the first direction, is filled with an elastic material except for the minimum gap.

5. The minimum gap is formed by a first surface portion of the inner stopper that forms the outer shape on the side facing the outer stopper, and a second surface portion of the outer stopper that forms the outer shape on the side facing the inner stopper. The vibration isolation device according to claim 1 or 2, characterized in that, in an unloaded state, the first surface portion and the second surface portion are in contact with each other at the central side in the axial direction, while being separated from each other at both ends in the axial direction.

6. The vibration isolation device according to claim 1 or 2, characterized in that, in an axial view, at least one of the inner stopper and the outer stopper has a recess formed in the axial direction from the end face in the axial direction in the region obtained by projecting the portion in which the minimum gap is formed to both sides in the first direction.

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