axle spring

Abstract

Provided is a shaft spring capable of preventing cracking or peeling of the upper portion of the innermost elastic body and improving durability. The shaft spring includes a main shaft (2) arranged in the vertical direction; a conical outer cylinder (3) arranged concentrically with respect to the axis (P) of the main shaft (2) on the outer side of the main shaft (2) in the radial direction; and an elastic portion (4) sandwiched between the main shaft (2) and the outer cylinder (3), the elastic portion (4) having a laminated structure in which a conical elastic body (5-9) and an intermediate hard cylinder (11-14) arranged concentrically are alternately laminated in the radial direction, and a size relationship of W1 > W3 > W2 is satisfied between the thickness W1 of the upper portion of the innermost elastic body (5) fixed to the outer peripheral surface of the main shaft (2), the thickness W2 of the intermediate portion, and the thickness W3 of the lower portion.

Description

Technical Field

[0001] The present invention relates to an axle spring suitable for vehicles, particularly railway vehicles. Background Technology

[0002] For example, in railway vehicles, axle springs are sandwiched between the wheels running on the track and the bogies. These axle springs elastically suspend the bogies, thereby absorbing and mitigating the impacts they experience.

[0003] Regarding shaft springs, various practical solutions have been proposed to date (see, for example, patent documents 1 and 2). Here, Figure 9 An example of an existing shaft spring is shown.

[0004] Figure 9 This is a longitudinal sectional view showing an example of a conventional shaft spring. The illustrated shaft spring 101 includes a main shaft 102 arranged in the vertical direction, a conical cylindrical outer cylinder 103 arranged concentrically with respect to the axis P of the main shaft 102 on the radially outer side of the main shaft 102, and an elastic portion 104 sandwiched between the main shaft 102 and the outer cylinder 103. The elastic portion 104 is configured as a stacked structure consisting of multiple (five in the example) concentrically arranged conical cylindrical elastic bodies 105, 106, 107, 108, 109 and multiple (four in the example) conical cylindrical intermediate rigid cylinders 111, 112, 113, 114 alternately stacked radially.

[0005] In the shaft spring 101, the main shaft 102, outer cylinder 103, and intermediate rigid cylinders 111-114 are made of metal. Each elastic element 105-109 is made of rubber. The outer cylinder 103, each elastic element 105-109, and each intermediate rigid cylinder 111-114 are configured as a conical cylinder (frustum cone) inclined inward (radially inward) at a predetermined angle relative to the axis P of the main shaft 102, with the diameter decreasing upward. In this inclined (conical) shaft spring 101 with such an inclined outer cylinder 103, elastic elements 105-109, and intermediate rigid cylinders 111-114, the upper end of the outer cylinder 103 is mounted on the bogie side via a mounting plate (not shown), and the lower end of the main shaft 102 is mounted on an axle box (not shown). Furthermore, although not shown, the axle box rotatably supports the wheel and axle, and the shaft spring 101 is sandwiched between the axle box and the bogie. Existing technical documents Patent documents

[0006] Patent Document 1: Japanese Patent No. 6789094 Patent Document 2: Japanese Patent Application Publication No. 2020-063761 Summary of the Invention The problem that the invention aims to solve

[0007] exist Figure 9 In the existing shaft spring 101 shown, each elastic body 105 to 109 made of rubber is fixed between the main shaft 102 and the intermediate hard cylinder 111, between adjacent intermediate hard cylinders 111 and 112, 112 and 113 and 113 and 114, and between the outer cylinder 103 and the intermediate hard cylinder 114 by means of vulcanization bonding or other methods. However, this shaft spring 101 bears dynamic loads in the vertical, horizontal and forward and backward directions when it is under static load in the vertical direction. In this case, in the inclined shaft spring 101 with the elastic bodies 105-109 and the intermediate rigid cylinders 111-114 inclined, if a load is applied in the vertical direction, shear force and compressive force are applied to each elastic body 105-109. However, a large shear force is applied to each upper surface side of each elastic body 105-109. If each elastic body 105-109 is subjected to loads in the front-back and left-right directions in this state, tensile and compressive loads are applied to these elastic bodies 105-109.

[0008] As described above, if tensile and compressive loads are applied to each of the elastomers 105-109, then the upper part of these elastomers 105-109, especially the upper part of the innermost elastomer 105 ( Figure 9 The Y-section experiences large stress and deformation, resulting in cracking or peeling in this section, leading to a decrease in the durability of the shaft spring 101.

[0009] Therefore, the first objective of the present invention is to provide a shaft spring that can prevent cracking or peeling of the upper part of the innermost elastomer and can improve durability.

[0010] To solve the above problem, one could consider increasing the thickness of the innermost elastic body 105 to reduce the deformation rate (elastic body displacement / thickness). However, if the thickness of the elastic body 105 is increased, the spring constant of the elastic body 105 will decrease, and the required spring characteristics of the shaft spring 101 cannot be guaranteed.

[0011] In addition, although it is possible to adjust the spring constant of the shaft spring 101 by hardening the rubber elastomers 105 to 109, in this method, the spring constant of the innermost elastomer 105 is reduced, and the displacement caused by the load on the innermost elastomer 105 is increased. As a result, the deformation rate is equal or greater, which leads to a decrease in the durability of the shaft spring 101.

[0012] Therefore, a second object of the present invention is to provide a shaft spring that can maintain the required spring characteristics and achieve improved durability. Methods for solving problems

[0013] To achieve the above objectives, the shaft spring of the present invention includes: a main shaft disposed in a vertical direction; a conical outer cylinder disposed concentrically with respect to the axis of the main shaft on the radially outer side of the main shaft; and an elastic portion sandwiched between the main shaft and the outer cylinder. The elastic part has a stacked structure formed by alternating radial layers of concentrically arranged conical elastomers and intermediate rigid cylinders. The thickness W1 of the upper part of the innermost elastomer, which is fixed to the outer peripheral surface of the main shaft, is in the order of W1>W3>W2.

[0014] Furthermore, the shaft spring according to the present invention has the same spring characteristics as other shaft springs with the same vertical length and cross-sectional area of ​​the innermost elastic body and a fixed thickness of the innermost elastic body, and has higher durability than the aforementioned other shaft springs. Invention Effects

[0015] According to the present invention, since the thickness W1 of the upper part of the innermost elastic body fixed to the outer peripheral surface of the spindle is the thickest, the stress and deformation generated in this part can be suppressed to a smaller value. As a result, cracking or peeling can be prevented in the upper part of the innermost elastic body where the maximum stress and deformation occur, thereby improving the durability of the shaft spring.

[0016] Furthermore, by making the longitudinal cross-sectional area of ​​the innermost elastic element the same as that of the innermost elastic element of other shaft springs with a fixed thickness along the vertical direction, the required spring characteristics (spring constants in the vertical and horizontal directions, etc.) of the shaft spring can be satisfied. Therefore, the durability of the shaft spring can be improved while ensuring the required spring characteristics. Attached Figure Description

[0017] Figure 1 This is a side view of a main part of a railway vehicle showing an example of the use of a shaft spring according to Embodiment 1 of the present invention. Figure 2 This is a longitudinal sectional view of the shaft spring according to Embodiment 1 of the present invention. Figure 3 This is a top view of the shaft spring according to Embodiment 1 of the present invention. Figure 4 This is a comparison diagram showing the thickness variation of the innermost elastic body of the shaft spring according to Embodiment 1 of the present invention along the vertical direction with that of a comparative example. Figure 5 is a graph showing the stress analysis results of an elastic body based on the finite element method (FEM). Figure 5a This is a cross-sectional perspective view of the main elastic portion of the shaft spring according to Embodiment 1 of the present invention. Figure 5b This is a cross-sectional perspective view of the main elastic part of the shaft spring in the comparative example. Figure 6a This is a graph showing the relationship between the vertical displacement of the shaft spring and the load according to Embodiment 1 of the present invention. Figure 6b This is a graph showing the relationship between the horizontal displacement of the spring and the load. Figure 7 This is a longitudinal sectional view of the shaft spring according to Embodiment 2 of the present invention. Figure 8 This is a comparison diagram showing the change in the thickness of the innermost elastic element of the shaft spring according to Embodiment 2 of the present invention along the vertical direction with that of a comparative example. Figure 9 This is a longitudinal sectional view showing an example of an existing shaft spring. Detailed Implementation

[0018] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0019] <Implementation Method 1> Figure 1 This is a side view of a main part of a railway vehicle showing an example of the use of a shaft spring according to an embodiment of the present invention. Figure 1 As shown, the wheel 50 and axle 51 are rotatably supported by the axle box 60 via bearings 52. Furthermore, the axle 51 clamps the axle box 60 in such a way that it is positioned in front of and behind the axle 51. Figure 1 The axle springs 1 of this embodiment are respectively sandwiched between the left and right axle springs and the bogie frame 70A of the bogie 70. Therefore, a portion of the load on the bogie 70 is supported by the two axle springs 1, and it is suspended relative to the wheel 50 and axle 51 in the vertical, horizontal, and longitudinal directions. In addition, Figure 1 The text only indicates the width direction. Figure 1 The paper shows a single-sided support structure in the vertical direction, but in reality, the wheel 50, axle box 60, and a pair of front and rear axle springs 1 are respectively set on both sides in the width direction, and the bogie 70 is elastically supported by a total of 8 axle springs 1.

[0020] Below, refer to Figure 2 Figure 6 illustrates the shaft spring 1 of this embodiment. Since the structure of the front and rear pairs of shaft springs 1 is identical, only one shaft spring 1 will be described below.

[0021] like Figure 2 and Figure 3 As shown, the shaft spring 1 according to this embodiment is an inclined (conical) shaft spring, comprising a main shaft 2 arranged in the vertical direction, a conical cylindrical (conical) outer cylinder 3 arranged concentrically with respect to the axis P of the main shaft 2 on the radially outer side of the main shaft 2, and an elastic part 4 sandwiched between the main shaft 2 and the outer cylinder 3.

[0022] The spindle 2 is formed of metal in a generally cylindrical shape, with a hollow portion 2a and a threaded hole 2b formed at the upper and lower parts of its central portion, respectively. Additionally, a flange portion 2A is formed on the outer periphery of the lower end of the spindle 2. Furthermore, the lower end of the spindle 2 is mounted on a bolt (not shown). Figure 1 On the axle box 60 shown, bolts are screwed into threaded holes 2b.

[0023] The outer cylinder 3 is formed from the same metal as the main shaft 2 into a tapered cylindrical shape. Specifically, the outer cylinder 3 is formed into a tapered cylindrical shape that narrows upwards, and is inclined inwards (radially inwards) at a predetermined angle relative to the axis P of the main shaft 2. A fitting step portion 3a is formed on the inner circumference of the upper end of the outer cylinder 3, and a fitting step portion 3a is fitted on the fitting step portion 3a for mounting the outer cylinder 3 onto the bogie frame 70A (see reference). Figure 1 The circular mounting plate 71 on the plate.

[0024] The elastic part 4 is configured as a laminated structure (5-layer structure) consisting of multiple (five in the example) concentrically arranged conical cylindrical elastomers 5, 6, 7, 8, and 9, and multiple (four in the example) conical cylindrical intermediate rigid cylinders 11, 12, 13, and 14, which are alternately stacked radially. Each elastomer 5 to 9 is made of rubber. Each intermediate rigid cylinder 11 to 14 is made of the same metal as the main shaft 2 and the outer cylinder 3. The elastomers 5 to 9 and the intermediate rigid cylinders 11 to 14 are formed as conical cylinders with a tapered diameter that narrows upwards. Specifically, each elastomer 5 to 9 and the intermediate rigid cylinders 11 to 14 are inclined inwards (radially inwards) at a predetermined angle relative to the axis P of the main shaft 2 (the same angle as the inclination angle of the outer cylinder 3). Furthermore, natural rubber, neoprene rubber, nitrile rubber, butyl rubber, etc., are used as the rubber constituting each elastomer 5 to 9.

[0025] In the elastic part 4 constructed as described above, a plurality of rubber elastomers 5 to 9 are respectively vulcanized and bonded to the outer peripheral surface of the main shaft 2, the inner peripheral surface of the outer cylinder 3, or the inner and outer peripheral surfaces of adjacent intermediate rigid cylinders 11 to 14. Specifically, the inner peripheral surface of the innermost elastomer 5 is bonded to the outer peripheral surface of the main shaft 2, and its outer peripheral surface is bonded to the inner peripheral surface of the intermediate rigid cylinder 11. In addition, other elastomers 6 to 8 constituting the intermediate layer are respectively bonded to the inner and outer peripheral surfaces of two adjacent intermediate rigid cylinders 11 and 12, 12 and 13, and 13 and 14. The outermost elastomer 9 is bonded to the outer peripheral surface of the intermediate rigid cylinder 14 and the inner peripheral surface of the outer cylinder 3. Furthermore, in order to avoid stress concentration, the upper and lower end faces of each elastomer 5 to 9 are concave curved surfaces.

[0026] like Figure 1As shown, the shaft spring 1 configured as described above elastically supports the bogie 70 on the wheel 50 and axle 51. The load from the bogie 70 is input from the outer cylinder 3, and this load is borne by a plurality of elastic bodies 5 to 9 constituting the elastic part 4 of the laminated structure. In the shaft spring 1, since the outer cylinder 3, the plurality of elastic bodies 5 to 9 constituting the elastic part 4, and the intermediate rigid cylinders 11 to 14 are inclined at a predetermined angle relative to the axis P of the main shaft 2 as described above, each elastic body 5 to 9 bears dynamic loads in the vertical, horizontal, and front-back directions when subjected to static loads in the vertical direction. In this case, shear force and compressive force act on each elastic body 5 to 9, but the larger shear force acts on the upper surface side of each elastic body 5 to 9. When each elastic body 5 to 9 bears loads in the front-back and horizontal directions in this state, tensile and compressive loads are applied to these elastic bodies 5 to 9.

[0027] As described above, if tensile and compressive loads are applied to each of the elastomers 5-9, then in the upper part of each of the elastomers 5-9, especially in the upper part of the innermost elastomer 5 ( Figure 2 The Y-section will experience large stress and deformation, which will cause cracking or peeling in this section, resulting in a decrease in the durability of the shaft spring 1.

[0028] Therefore, in this embodiment, as Figure 2 As shown, a portion of the outer circumferential surface of the main shaft 2, to which the innermost elastic body 5 is fixed, is taken as part of the spherical surface 2c (in Figure 2 (represented as part of an arc in the longitudinal sectional view), the thickness W of the innermost elastic body 5 gradually decreases from the top to the middle (middle height position) and gradually increases from the middle to the bottom. Furthermore, when the thickness W of the elastic body 5 is set as W1 at the top, W2 at the middle, and W3 at the bottom, the size relationship shown in the following formula (1) holds. W1>W3>W2…(1) The thickness W of the elastomer 5 represents the thickness of the elastomer 5 in a direction perpendicular to the conical cylindrical surface of the intermediate rigid cylinder 11. The upper thickness W1 is the thickness of the part with the greatest thickness W in the upper part of the elastomer 5. The middle thickness W2 is the thickness of the part with the smallest thickness W in the middle part between the upper and lower parts of the elastomer 5. The lower thickness W3 is the thickness of the part with the greatest thickness W in the lower part of the elastomer 5.

[0029] The following describes the results of evaluating the characteristics of a shaft spring as an embodiment of shaft spring 1 according to this embodiment and a comparative example shaft spring. The comparative example shaft spring uses... Figure 9 The existing shaft spring 101 shown has the following characteristics. Figure 4 The thickness of the innermost elastomer is shown.

[0030] Figure 4 The thickness W of the innermost elastic body in the vertical direction of the shaft spring 1 of the embodiment and the shaft spring 101 of the comparative example is shown in comparison. The thickness W of the elastic body 5 of the shaft spring 1 of the embodiment shows a maximum value W1 at the top, gradually decreases from the top to the middle, and shows a minimum value W2 at the middle. Then, it gradually increases from the minimum value W2 at the middle to W3 at the bottom. W1, W2, and W3 satisfy the magnitude relationship of the above equation (1). The thickness W0 of the innermost elastic body 105 of the shaft spring 101 of the comparative example is as follows... Figure 4 The dashed line in the middle represents a constant value. The thickness W0 is set to be smaller than the thickness W1 at the upper end and the thickness W3 at the lower end of the innermost elastic body 5 of the shaft spring 1 in the embodiment, and larger than the thickness W2 in the middle part. Among these thicknesses W0, W1, W2, and W3, the following relationship (2) holds true. W1>W3>W0>W2…(2)

[0031] Furthermore, the area of ​​the elastic body 5 in the longitudinal sectional view of the shaft spring 1 of the embodiment and the area of ​​the elastic body 105 in the longitudinal sectional view of the shaft spring 101 of the comparative example are set to be equal values. Specifically, in Figure 4 In the middle, in the up and down direction ( Figure 4 The value ∑W, obtained by integrating the thickness W of the innermost elastic body 5 of the shaft spring 1 in the left-right direction, is 1 / 2 (=S / 2) of the longitudinal cross-sectional area S of the elastic body 5. Figure 4 The area is represented by the portion with solid shading. In the comparative example shaft spring 101, since the thickness W0 of the innermost elastic body 105 is constant, half (=S0 / 2) of the longitudinal cross-sectional area S0 of the elastic body 105 is... Figure 4 The area is represented by the portion with the dashed shading (rectangular portion). The longitudinal cross-sectional area S of elastomer 5 and the longitudinal cross-sectional area S0 of elastomer 105 are set to be equal (S=S0). The vertical lengths of the two elastomers 5 and 105 are equal. Furthermore, the two elastomers 5 and 105 are formed of the same rubber material.

[0032] For the shaft spring 1 of the embodiment and the shaft spring 101 of the comparative example, the deformation rates of the innermost elastic bodies 5 and 105 when a load of 2 mm is applied to produce the same displacement are calculated, and the results are shown in Table 1.

[0033] Table 1 As shown in Table 1, the thickness W0 of the innermost elastic body 105 of the comparative example shaft spring 101 is 17.9 mm in both the upper and middle portions. In contrast, the thicknesses W1 and W2 of the upper and middle portions of the innermost elastic body 5 of the embodiment shaft spring 1 are 24.2 mm and 13.6 mm, respectively. The deformation rates of the upper and middle portions of the innermost elastic bodies 105 of these two shaft springs 101 and 1 were calculated. As a result, the deformation rate of the upper and middle portions of the innermost elastic body 105 of the comparative example shaft spring 101 is 11%.

[0034] In contrast, the deformation rates of the upper and middle portions of the innermost elastic body 5 in the shaft spring 1 of the embodiment are 8% and 15%, respectively. This can suppress the deformation rate (tensile stress and deformation) of the upper portion of the elastic body 5, which is prone to cracking or peeling, to a low value, thus confirming that the durability of the shaft spring 1 can be improved.

[0035] In this embodiment, the ratio of the thickness W2 of the middle portion of the innermost elastic body 5 of the shaft spring 1 to the thickness W0 of the innermost elastic body 105 of the shaft spring 101 of the comparative example is W2 / W0 = 13.6 / 17.9 = 0.76. In the shaft spring 1 according to this embodiment, the ratio W2 of the middle portion of the innermost elastic body 5 to the thickness of the innermost elastic body of other shaft springs with the same vertical length and cross-sectional area and a fixed thickness of the innermost elastic body, i.e., the ratio W2 / W0, is preferably 70% or more, more preferably in the range of 70% to 80%.

[0036] then, Figure 5a , 5b The stress analysis results based on the finite element method (FEM) are shown when loads are applied simultaneously from both the vertical and horizontal directions to the shaft spring 1 of the embodiment and the shaft spring 101 of the comparative example.

[0037] In Figure 5, the darker the shaded line, the greater the stress. For example... Figure 5b As shown, in the comparative example shaft spring 101, the stress is most concentrated (shaded area) at the upper end near the region where the innermost elastic body 105 is fixed to the main shaft, resulting in a high stress of 1.27 MPa. In contrast, in Figure 5a In the shaft spring 1 of the illustrated embodiment, similar to the shaft spring 101 of the comparative example, a stress concentration area can be seen at the upper end near the region where the innermost elastic body 5 is fixed to the main shaft, but the maximum stress is suppressed to as low as 0.72 MPa. From this analysis, it can be seen that the shaft spring 1 according to this embodiment can suppress the stress and deformation at the upper part of the innermost elastic body 5, which is prone to cracking or peeling, and can improve durability.

[0038] Next, actual measurements were performed on the shaft spring 1 of the embodiment and the shaft spring 101 of the comparative example. Figure 6a The characteristics of the spring in the vertical direction are shown. Figure 6b The characteristics of the spring in the horizontal direction are shown.

[0039] Figure 6a , Figure 6b The horizontal axis represents displacement x, and the vertical axis represents load F. Figure 6a In the diagram, solid curves A and B represent the characteristics of the shaft spring 1 in the embodiment under load and unload, respectively, while dashed curves A' and B' represent the characteristics of the shaft spring 101 in the comparative example under load and unload, respectively. Figure 6a As shown, it can be seen that the relationship between the load F and the displacement x in the vertical direction of the shaft spring 1 in the embodiment and the shaft spring 101 in the comparative example is roughly overlapping, and the spring characteristics in the vertical direction are roughly the same.

[0040] exist Figure 6b In the diagram, solid curves C and D represent the characteristics of the shaft spring 1 in the embodiment under load and unload, respectively, while dashed curves C' and D' represent the characteristics of the shaft spring 101 in the comparative example under load and unload, respectively. Figure 6b As shown, the relationship between the horizontal load F and displacement x of the shaft spring 1 in the embodiment and the shaft spring 101 in the comparative example is approximately overlapping, and the spring characteristics in the horizontal direction are approximately the same.

[0041] The displacement of a shaft spring relative to a load, i.e., its spring characteristics, can be considered to be determined by the average thickness and length (height) of each layer of the elastic body in the vertical direction. Since the vertical lengths of the elastic bodies 5 and 105 are equal, and the longitudinal cross-sectional areas S of the elastic bodies 5 and 105 are equal, the shaft spring 1 of the embodiment and the shaft spring 101 of the comparative example can be considered to have the same spring characteristics.

[0042] Therefore, the shaft spring 1 of this embodiment, which satisfies the relationship between the thickness W of the innermost elastic body 5 in the upper part W1, the thickness W2 of the middle part and the thickness W3 of the lower part as shown in Equation (1), has the same spring characteristics as other shaft springs with the same vertical length and cross-sectional area of ​​the innermost elastic body and a fixed thickness of the innermost elastic body. Moreover, compared with other shaft springs with the same vertical length and cross-sectional area of ​​the innermost elastic body and a fixed thickness of the innermost elastic body, the stress and deformation generated in the upper part of the innermost elastic body 5 can be suppressed to a lower value.

[0043] As shown above, the shaft spring 1 according to this embodiment has the same spring characteristics as other shaft springs with the same vertical length and cross-sectional area of ​​the innermost elastic body and a fixed thickness of the innermost elastic body, and has higher durability than the other shaft springs.

[0044] In other words, by setting the longitudinal cross-sectional area S of the innermost elastic body 5 to be the same as the longitudinal cross-sectional area S0 of the innermost elastic body 105 of the existing shaft spring 101, which has a fixed thickness in the vertical direction (S = S0), the required spring characteristics (spring constants in the vertical and horizontal directions, etc.) of the shaft spring 1 can be satisfied. Therefore, the effect of ensuring the required spring characteristics of the shaft spring 1 while improving its durability can be obtained.

[0045] Furthermore, the fact that the longitudinal cross-sectional area S of the innermost elastic body 5 of the shaft spring 1 according to this embodiment is the same as the longitudinal cross-sectional area S0 of the innermost elastic body 105 of the shaft spring 101 in the comparative example (S=S0) does not mean that they are completely identical. It also includes cases where there is some error (around ±5%) between the two longitudinal cross-sectional areas S and S0.

[0046] Furthermore, in the shaft spring 1 according to this embodiment, the center of the sphere constituting a part of the spherical surface 2c formed on the outer peripheral surface of the main shaft 2 does not need to be located on the axis P of the main shaft 2. In addition, the portion of the outer peripheral surface of the main shaft 2 to which at least the innermost elastic body 5 is fixed can be a convex curved surface, for example, it can also be an elliptical curved surface.

[0047] Furthermore, the shaft spring 1 according to this embodiment has an elastic part 4 with a 5-layer structure formed by alternatingly stacking five elastic bodies 5 to 9 and four intermediate rigid cylinders 11 to 14 in the radial direction. However, the layer structure of the elastic part 4 is arbitrary and can be configured as a layer structure with fewer than 5 layers or more than 6 layers.

[0048] <Implementation Method 2> Below, based on Figure 7 and Figure 8 Embodiment 2 of the present invention will be described.

[0049] Figure 7 This is a longitudinal sectional view of the shaft spring according to Embodiment 2 of the present invention. Additionally, in Figure 7 In the middle, to and Figure 2 The same elements shown are given the same symbols, and further explanation of them will be omitted below.

[0050] In the shaft spring 1A according to this embodiment, such as Figure 7As shown, a portion of the outer circumferential surface of the main shaft 2 to which the innermost elastic body 5 is fixed is made into multiple (three in the example) conical surfaces 2d, 2e, and 2f with different inclination angles. The thickness W of the innermost elastic body 5 gradually decreases from the top to the middle and gradually increases from the middle to the bottom. The thickness W of the elastic body 5 shows a maximum value W1 at the top, gradually decreases from the top to the middle, and shows a minimum value W2 at the middle. Furthermore, the thickness W of the elastic body 5 gradually increases from the minimum value W2 at the middle to W3 at the bottom. The thickness W1 at the top and the thickness W3 at the bottom are greater than the thickness W2 at the middle, and the thickness W1 at the top is greater than the thickness W3 at the bottom. The same magnitude relationship of equation (1) is satisfied as with the shaft spring 1 according to embodiment 1.

[0051] Of the three conical surfaces 2d, 2e, and 2f, the upper conical surface 2d and the lower conical surface 2f have opposite inclination angles. Conical surface 2d is inclined inwards with its diameter decreasing upwards, while conical surface 2f is inclined outwards with its diameter increasing upwards. For example, the inclination angle α of the upper conical surface 2d relative to the axis P of the main shaft 2 is set to be greater than the inclination angle β (α>β) of the lower conical surface 2f relative to the axis P of the main shaft 2. In addition, the middle conical surface 2e is inclined inwards (radially inwards) at the same angle as the middle rigid cylinder 11 with its diameter decreasing upwards, and the gap between this conical surface 2e and the middle rigid cylinder 11 (the thickness W2 of the middle part of the elastomer 5) remains constant.

[0052] Here, in Figure 8 In the example, the variation of the thickness W of the innermost elastic body 5 along the vertical direction is shown in comparison with the comparative example. According to the embodiment, the thickness W of the elastic body 5 of the shaft spring 1A exhibits a maximum value W1 at the upper part, gradually decreases from the upper part towards the middle part, shows a minimum value W2 at the middle part, and gradually increases from the minimum value W2 at the middle part towards the lower part to W3. In this case, the thickness W1 at the upper part and the thickness W3 at the lower part are greater than the thickness W2 at the middle part, and the thickness W1 at the upper part is greater than the thickness W3 at the lower part.

[0053] In addition, such as Figure 8 As shown by the dashed line, the thickness W0 of the innermost elastic body 105 of the comparative example shaft spring 101 is fixed. This thickness W0 is set to be smaller than the upper thickness W1 and the lower thickness W3 of the innermost elastic body 5 of the shaft spring 1A of this embodiment, and larger than the middle thickness W2.

[0054] In this embodiment, the longitudinal cross-sectional area of ​​the innermost elastic body 5 may also be set to be equal to the longitudinal cross-sectional area of ​​the innermost elastic body 105 of the shaft spring 101 in the comparative example.

[0055] exist Figure 8 In the middle, along the vertical direction ( Figure 8The value ∑W, obtained by integrating over the thickness W of the innermost elastic body 5 in the left-right direction, is 1 / 2 (=S / 2) of the longitudinal cross-sectional area S of the elastic body 5. Figure 8 The area is represented by the portion with solid shading. In contrast, in the comparative example's shaft spring 101, since the thickness W0 of the innermost elastic body 105 is constant, half (=S0 / 2) of the longitudinal cross-sectional area S0 of the elastic body 105 is determined by… Figure 8 The area of ​​the rectangular portion (with the dashed shading line) is represented.

[0056] In this embodiment, similarly to Embodiment 1, the longitudinal cross-sectional area S of the innermost elastic body 5 of the shaft spring 1 is set to be equal to the longitudinal cross-sectional area S0 of the innermost elastic body 105 of the shaft spring 101 in the comparative example (S=S0). At this time, the vertical lengths of the two elastic bodies 5 and 105 are equal. In addition, the two elastic bodies 5 and 105 are formed of the same rubber material.

[0057] Therefore, even if the thickness W of the innermost elastic body 5 is such as in the shaft spring 1A of this embodiment, Figure 8 When the height varies as shown, by setting the longitudinal cross-sectional area S of the elastic body 5 to be the same as the longitudinal cross-sectional area S0 of the innermost elastic body 105 of the existing shaft spring 101 with a thickness of a certain value in the vertical direction (S=S0), the spring characteristics (spring constants in the vertical and horizontal directions, etc.) required for the shaft spring 1A according to this embodiment can be met, and the stress and deformation generated in the upper part of the innermost elastic body 5 of the shaft spring 1A can be suppressed to a lower value, and the durability of the shaft spring 1A can be improved.

[0058] Furthermore, in the shaft spring 1A of this embodiment, although three conical surfaces 2d, 2e, and 2f with different inclination angles are formed on the outer peripheral surface of the main shaft 2, to which at least the innermost elastic body 5 is fixed, the number of conical surfaces is arbitrary.

[0059] Furthermore, the present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the technical concept set forth in the claims, specification and drawings. Explanation of reference numerals in the attached figures

[0060] 1. 1A: Shaft spring; 2: Spindle; 2c: Spherical surface (convex surface); 2d~2f: Conical surface; 3: Outer cylinder; 4: Elastic part; 5-9: Elastomers; 11-14: Intermediate hard cylinder; W0: The thickness of the middle part of the innermost elastic element of the shaft spring in the comparative example; W1: The thickness of the upper part of the innermost elastomer; W2: The thickness of the middle part of the innermost elastomer; W3: The thickness of the lower part of the innermost elastomer; S: The longitudinal cross-sectional area of ​​the innermost elastic body; S0: The longitudinal cross-sectional area of ​​the elastic body of the shaft spring in the comparative example; α, β: Inclination angles of the cone surface.

Claims

1. A shaft spring, comprising: The spindle is configured along the vertical direction; A conical outer cylinder is arranged concentrically with respect to the axis of the main shaft on the radially outer side of the main shaft; as well as The elastic part is sandwiched between the main shaft and the outer cylinder. The elastic part has a laminated structure formed by alternating radial layers of concentrically arranged conical cylindrical elastomers and intermediate rigid cylinders, wherein the elastomers and the intermediate rigid cylinders are formed into a conical cylinder that narrows upwards and is open at the top and bottom ends. Among the innermost layer of the conical cylindrical elastic body, which is fixed to the outer circumferential surface of the main shaft and has open upper and lower ends, the relationship W1>W3>W2 holds true. The portion of the outer circumferential surface of the main shaft to which at least the innermost layer of the elastic body is fixed is part of a sphere.

2. A shaft spring, comprising: The spindle is configured along the vertical direction; A conical outer cylinder is arranged concentrically with respect to the axis of the main shaft on the radially outer side of the main shaft; as well as The elastic part is sandwiched between the main shaft and the outer cylinder. The elastic part has a laminated structure formed by alternating radial layers of concentrically arranged conical cylindrical elastomers and intermediate rigid cylinders, wherein the elastomers and the intermediate rigid cylinders are formed into a conical cylinder that narrows upwards and is open at the top and bottom ends. Among the innermost layer of the conical cylindrical elastic body, which is fixed to the outer circumferential surface of the main shaft and has open upper and lower ends, the relationship W1>W3>W2 holds true. The portion of the outer circumferential surface of the main shaft to which at least the innermost elastic body is fixed consists of multiple conical surfaces with different inclination angles. The inclination angles of the upper and lower conical surfaces are in opposite directions. The upper conical surface is inclined inward with a diameter reduction towards the top, while the lower conical surface is inclined outward with a diameter expansion towards the top.

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