Shock absorber cover and shock absorber

Abstract

The buffer cover is used in a buffer. The shock absorber is provided with: a cylinder; the piston is arranged in the cylinder body; the first end of the piston rod is connected to the piston, and the second end of the piston rod extends out of the cylinder body. The shock absorber cover is provided at an end of the cylinder on the side from which the piston rod extends, is molded by die casting or injection molding, and has: a cover part which is in contact with an axial end surface of the cylinder and has a through hole through which the piston rod is inserted; a cylindrical tube part that is provided further to the outside in the radial direction than the through hole and that covers at least a part of the outer peripheral surface of the cylinder; and a communication hole which is provided in the cylinder part and which communicates between the inner peripheral surface and the outer peripheral surface of the cylinder part. The first end portion of the edge of the communication hole, which is located on the downstream side into which the material flows during molding, is thinner than the second end portion located on the upstream side.

Description

Technical Field

[0001] The invention relates to a buffer cover and a buffer.

[0002] This application claims priority based on Japanese application No. 2022-110369, filed on July 8, 2022, the contents of which are incorporated herein by reference. Background Art

[0003] Some shock absorbers have a shock absorber cover that covers a side of a cylinder from which a rod protrudes (see, for example, Patent Document 1).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2016-061425 Summary of the invention

[0007] Technical problem to be solved by the invention

[0008] In a shock absorber, it is desired to improve the durability of the shock absorber cover.

[0009] Therefore, an object of the present invention is to provide a bumper cover and a bumper capable of improving durability.

[0010] Technical solutions for solving technical problems

[0011] In order to achieve the above-mentioned purpose, one scheme of the present invention adopts the following structure: a buffer cover is used in a buffer, and the buffer comprises: a cylinder body; a piston, which is arranged in the cylinder body; a piston rod, a first end of which is connected to the piston and a second end of which extends from the cylinder body; the buffer cover is arranged at the end of the cylinder body on the side where the piston rod extends, and is formed by die casting or injection molding, and the buffer cover has: a cover part, which abuts against the axial end surface of the cylinder body and has a through hole for the piston rod to be inserted; a cylindrical barrel part, which is arranged radially outward of the through hole and covers at least a part of the outer peripheral surface of the cylinder body; a connecting hole, which is arranged in the barrel part and connects the inner peripheral surface and the outer peripheral surface of the barrel part; the first end of the edge of the connecting hole, which is located on the downstream side where the material flows in during molding, is thinner than the second end located on the upstream side.

[0012] Another embodiment of the present invention adopts the following structure: a buffer cover, which is a buffer cover of a buffer, the buffer comprising: a cylinder; a piston, which is arranged in the cylinder; a piston rod, one end of which is connected to the piston and the other end of which extends from the cylinder; the buffer is arranged at the end of the cylinder on the side where the piston rod extends, and the buffer cover comprises: a cover portion, which abuts against the axial end surface of the cylinder and has a through hole for the piston rod to be inserted; a cylindrical barrel portion, which is arranged radially outward of the through hole and covers at least a part of the outer circumferential surface of the cylinder; a connecting hole, which is arranged in the barrel portion and connects the inner circumferential surface and the outer circumferential surface of the barrel portion; the edge of the connecting hole comprises: a circumferential edge portion, which extends in the circumferential direction of the barrel portion; an axial edge portion, which extends in the axial direction of the barrel portion; at least a part of the circumferential edge portion comprises an inclined portion, which is formed to be inclined with respect to the axial direction of the barrel portion and is an end side of the axial direction of the barrel portion that serves as the edge of the connecting hole.

[0013] Another embodiment of the present invention adopts a buffer, which has the following structure: the buffer comprises: a cylinder body; a piston, which is arranged in the cylinder body; a piston rod, one end of which is connected to the piston and the other end extends from the cylinder body; a buffer cover; the buffer cover has: a cover portion, which abuts against the axial end surface of the cylinder body and has a through hole for the piston rod to be inserted; a cylindrical barrel portion, which is arranged at the radially outer end of the cover portion and covers at least a portion of the outer circumferential surface of the cylinder body; a connecting hole, which is arranged in the barrel portion and connects the inner circumferential surface and the outer circumferential surface of the barrel portion; the first end of the connecting hole located on the downstream side where the material flows in during forming is thinner than the second end located on the upstream side.

[0014] Effects of the Invention

[0015] According to the above aspects of the present invention, the durability of the bumper cover can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a partially cross-sectional front view showing a shock absorber including a shock absorber cover according to the first embodiment of the present invention.

[0017] Figure 2 It is an enlarged perspective view showing the main part of the shock absorber including the shock absorber cover according to the first embodiment.

[0018] Figure 3 It is a development view showing the communication hole of the shock absorber cover of the shock absorber according to the first embodiment.

[0019] Figure 4 It is a developed cross-sectional view showing a mold portion forming a communication hole of a mold for forming the bump stopper cover of the bump stopper according to the first embodiment.

[0020] Figure 5 It is a development view showing a communication hole of a shock absorber cover of a shock absorber according to a second embodiment of the present invention.

[0021] Figure 6 It is a development view showing a communication hole of a shock absorber cover of a shock absorber according to a third embodiment of the present invention.

[0022] Figure 7 It is a development view showing a communication hole of a shock absorber cover of a shock absorber according to a fourth embodiment of the present invention.

[0023] Figure 8 It is a development view showing a communication hole of a shock absorber cover of a shock absorber according to a fifth embodiment of the present invention.

[0024] Fig. 9 It is a development view showing a communication hole of a shock absorber cover of a shock absorber according to a sixth embodiment of the present invention.

[0025] Fig.10 It is a development view showing a communication hole of a shock absorber cover of a shock absorber according to a seventh embodiment of the present invention.

[0026] Fig.11 It is a development view showing a communication hole of a shock absorber cover of a shock absorber according to an eighth embodiment of the present invention.

[0027] Fig.12 It is a development view showing a communication hole of a shock absorber cover of a shock absorber according to a ninth embodiment of the present invention. DETAILED DESCRIPTION

[0028] [First embodiment]

[0029] Below, refer to Figure 1 to Figure 4 A first embodiment of the present invention will be described.

[0030] Figure 1 The shock absorber of the first embodiment is shown. The shock absorber 11 of the first embodiment is a multi-tube hydraulic shock absorber. The shock absorber 11 is used in a strut type suspension device of a vehicle (specifically, an automobile). The shock absorber 11 includes a shock absorber body 12 and a shock absorber cover 13.

[0031] The shock absorber body 12 includes a cylinder 21 , a main bracket 22 , a spring seat 23 , and a sub-bracket 24 .

[0032] The cylinder body 21 includes an inner cylinder 31 and an outer cylinder 32, both of which are made of metal. The inner cylinder 31 is cylindrical. The outer cylinder 32 is cylindrical with a bottom. The inner cylinder 31 is arranged radially inward of the outer cylinder 32. A storage chamber 33 is provided between the inner cylinder 31 and the outer cylinder 32. In the cylinder body 21, oil L as a working fluid is sealed in the inner cylinder 31, and oil L and gas G as a working fluid are sealed in the storage chamber 33.

[0033] The outer tube 32 has a cylindrical body 36 and a bottom 37 closing one axial end of the body 36. The end of the body 36 of the outer tube 32 on the opposite side of the bottom 37 in the axial direction is an opening.

[0034] The main bracket 22 is made of metal and is fitted and fixed by welding to a portion of the trunk 36 closer to the bottom 37 than the axial center of the outer tube 32. The main bracket 22 is connected to the wheel (not shown) of the vehicle by fasteners (not shown) inserted into a plurality of mounting holes 39.

[0035] The spring seat 23 is made of metal and is fitted and fixed by welding to a portion of the trunk 36 on the side opposite to the bottom 37 from the axial center of the outer tube 32. The spring seat 23 supports the lower end of a coil spring (not shown) that supports the vehicle body (not shown).

[0036] The sub-bracket 24 is made of metal and is fixed to the outer peripheral side of the main bracket 22 by welding. The sub-bracket 24 supports a wire harness, a hose, and the like disposed around the shock absorber 11.

[0037] The damper body 12 has a piston 40 disposed in the cylinder 21. The piston 40 is slidably fitted in the inner tube 31 of the cylinder 21. The piston 40 divides a first chamber 41 and a second chamber 42 in the inner tube 31. The first chamber 41 is disposed on the side of the inner tube 31 opposite to the bottom 37 of the piston 40 in the axial direction. The second chamber 42 is disposed on the side of the bottom 37 of the inner tube 31 in the axial direction of the piston 40.

[0038] The shock absorber body 12 includes a piston rod 50. A first end portion of the piston rod 50 at one axial end is disposed in the inner tube 31 of the cylinder 21. The first end portion of the piston rod 50 is connected to the piston 40. A second end portion of the piston rod 50 at the other axial end opposite to the first end portion extends from the cylinder 21 to the outside of the cylinder 21.

[0039] The piston rod 50 has a main shaft portion 51 and a mounting shaft portion 52. Both the main shaft portion 51 and the mounting shaft portion 52 are rod-shaped. The outer diameter of the mounting shaft portion 52 is smaller than the outer diameter of the main shaft portion 51. The mounting shaft portion 52 is arranged in the inner tube 31. The piston rod 50 has a piston 40 mounted on the mounting shaft portion 52. The piston 40 moves integrally with the piston rod 50.

[0040] The piston 40 is formed with a passage 54 and a passage 55 penetrating in the axial direction. The passage 54 and the passage 55 can both connect the first chamber 41 and the second chamber 42.

[0041] The shock absorber body 12 includes a disk valve 56 and a disk valve 57 .

[0042] The disk valve 56 is provided on the side of the piston 40 opposite to the bottom portion 37 in the axial direction. The disk valve 56 can close the passage 54 by abutting against the piston 40.

[0043] The disk valve 57 is provided on the bottom 37 side of the piston 40 in the axial direction. The disk valve 57 can close the passage 55 by abutting against the piston 40. The disk valve 56 and the disk valve 57 are attached to the mounting shaft portion 52 of the piston rod 50 together with the piston 40 by means of a nut 59.

[0044] If the piston rod 50 moves toward the contraction side to increase the amount of entry into the cylinder 21 and the piston 40 moves in the direction of shrinking the second chamber 42, and the pressure of the second chamber 42 becomes higher than the pressure of the first chamber 41 by a predetermined value or more, the disk valve 56 opens the passage 54 to allow the oil L to flow. At this time, the disk valve 56 generates a damping force. A fixed orifice (not shown) is provided on at least one of the piston 40 and the disk valve 56 to communicate the first chamber 41 with the second chamber 42 via the passage 54 even when the disk valve 56 closes the passage 54 to the maximum extent.

[0045] If the piston rod 50 moves to the extension side that increases the amount of protrusion from the cylinder 21 and the piston 40 moves in the direction of shrinking the first chamber 41, and the pressure of the first chamber 41 is higher than the pressure of the second chamber 42 by a predetermined value or more, the disk valve 57 opens the passage 55 to allow the oil L to flow. At this time, the disk valve 57 generates a damping force. A fixed orifice (not shown) that allows the first chamber 41 and the second chamber 42 to communicate through the passage 55 even when the disk valve 57 closes the passage 55 to the maximum extent is provided on at least one of the piston 40 and the disk valve 57.

[0046] The buffer cover 13 is provided at the end portion of the cylinder 21 so as to cover the end portion on the side where the piston rod 50 extends. Here, the buffer body 12 has a sealing member (not shown) at the outer end portion on the side where the piston rod 50 of the cylinder 21 protrudes, which seals the gap between the cylinder 21 and the piston rod 50. The buffer cover 13 covers and protects the sealing member.

[0047] Here, when the buffer 11 is mounted on the vehicle, a buffer rubber (not shown) is provided on the piston rod 50 at a portion thereof protruding outward from the sealing member in the axial direction. The buffer rubber is made of a cylindrical elastic material, and the piston rod 50 is inserted into the inner side thereof. When the cylinder 21 of the buffer body 12 is reduced in distance from the vehicle body (not shown), the buffer rubber abuts against the vehicle body and the buffer cover 13, and elastically deforms to absorb the impact. The buffer cover 13 suppresses the collision between the buffer rubber and the sealing member (not shown) at this time. In addition, the buffer cover 13 suppresses the adhesion of dust and the like from the outside to the sealing member (not shown).

[0048] The buffer cover 13 used in the buffer 11 is a covered cylindrical shape. Figure 2 As shown, the shock absorber cover 13 includes a cover portion 70 , an axially protruding portion 71 , a cylindrical portion 72 , a flange portion 73 , and a radially protruding portion 74 .

[0049] The cover 70 is in the shape of a perforated disk, and has a through hole 81 penetrating in the axial direction at the center in the radial direction. The through hole 81 is a circular hole. In other words, the inner peripheral edge 82 of the through hole 81 of the cover 70 is circular.

[0050] The axial protrusion 71 protrudes from the cover 70 toward one side in the axial direction of the cover 70. The axial protrusion 71 is provided partially in the circumferential direction of the cover 70. The axial protrusion 71 extends linearly outward from the inner peripheral edge 82 of the cover 70 along the radial direction of the cover 70. In the shock absorber cover 13, a plurality of (specifically, three) axial protrusions 71 of the same shape are provided at equal intervals in the circumferential direction of the cover 70 on the same side in the axial direction of the cover 70.

[0051] The barrel 72 is cylindrical and extends from the entire circumference of the outer peripheral edge of the cover 70 coaxially with the cover 70 to the side of the cover 70 opposite to the axial protrusion 71 in the axial direction. In other words, the barrel 72 is provided at the radially outer end of the cover 70. The barrel 72 is provided radially outward of the through hole 81 provided in the radial center of the cover 70. In the barrel 72, a concave portion 83 is formed at the end on the side opposite to the cover 70 in the axial direction, which is axially recessed from the end surface on the side opposite to the cover 70 in the axial direction. The concave portion 83 penetrates the barrel 72 in the radial direction of the barrel 72. In the barrel 72, a plurality of (specifically, three) concave portions 83 of the same shape are provided at predetermined equal intervals in the circumferential direction of the barrel 72. These concave portions 83 align the phase of the barrel 72 in the circumferential direction with one of the axial protrusions 71. The cylinder 72 has an opening 85 on the axially opposite side to the cover 70. The opening 85 includes a plurality of recessed portions 83. The buffer cover 13 has the opening 85 at one axial end and the axially protruding portion 71, the cover 70, and a through hole 81 penetrating the cover 70 at the other axial end.

[0052] Here, the central axis of the coaxially arranged through hole 81, cover 70, and cylinder 72 is set as the central axis of the buffer cover 13. Thus, the through hole 81, cover 70, cylinder 72, and buffer cover 13 are aligned in the axial direction, circumferential direction, and radial direction.

[0053] The flange portion 73 protrudes from the end edge portion of the cylinder portion 72 on the side opposite to the cover portion 70 in the axial direction to the outside of the cylinder portion 72 in the radial direction. The flange portion 73 is provided locally in the circumferential direction of the cylinder portion 72. The flange portion 73 is formed between adjacent concave portions 83 and concave portions 83 in the end edge portion of the cylinder portion 72 on the side opposite to the cover portion 70 in the axial direction. In the buffer cover 13, a plurality of (specifically, three) flange portions 73 of the same shape are provided at equal intervals in the circumferential direction of the cylinder portion 72. These flange portions 73 align the position of the cylinder portion 72 in the axial direction.

[0054] The radial protrusion 74 protrudes from between the cover 70 and the flange 73 in the axial direction of the cylinder 72 to the radial outer side of the cylinder 72. The radial protrusion 74 is provided locally in the circumferential direction of the cylinder 72. The radial protrusion 74 is provided at the position of the concave portion 83 in the end edge portion of the cylinder 72 on the opposite side of the cover 70 in the axial direction. In the buffer cover 13, a plurality of (specifically, three) radial protrusions 74 of the same shape are provided at equal intervals in the circumferential direction of the cylinder 72. These radial protrusions 74 align the axial position of the cylinder 72. These radial protrusions 74 align the phase of the cover 70 in the circumferential direction with one of the axial protrusions 71. The radial protrusion 74 is different in position from the flange 73 in the circumferential direction of the cylinder 72. The radial protrusions 74 and the flange 73 are alternately arranged at equal intervals in the circumferential direction of the cylinder 72.

[0055] The cylinder 72 has a communication hole 91 formed between the radial protrusion 74 and the cover 70 in the axial direction of the cylinder 72. In other words, the communication hole 91 is provided in the cylinder 72 to connect the cylinder 72 to the cover 70. Figure 1 The inner circumferential surface 72a and the outer circumferential surface 72b shown are connected. The communication hole 91 is a horizontal hole that penetrates the cylinder 72 in the radial direction of the buffer cover 13. In the buffer cover 13, a plurality of (specifically, three) communication holes 91 of the same shape are provided at equal intervals in the circumferential direction of the cylinder 72. These communication holes 91 align the position of the cylinder 72 in the axial direction. These communication holes 91 align the phase of the cylinder 72 in the circumferential direction with one of the radial protrusions 74.

[0056] The edge 101 of the communication hole 91 is in a closed ring shape.

[0057] like Figure 2As shown, the edge 101 has a first axial edge 102 and a second axial edge 103 as axial edges extending in the axial direction of the cylinder 72. The first axial edge 102 and the second axial edge 103 align the axial position of the cylinder 72, and are separated in the circumferential direction of the cylinder 72 to be mirror-symmetrical. Here, in the buffer cover 13, the side of the cylinder 72 opposite to the cover 70 in the axial direction is set as the first end side, and the cover 70 side of the cylinder 72 in the axial direction is set as the second end side. In addition, in the communicating hole 91, the end of the cylinder 72 opposite to the cover 70 in the axial direction is set as the first end, and the end of the cylinder 72 on the cover 70 side in the axial direction is set as the second end.

[0058] like Figure 3 As shown, the first axial edge portion 102 has a first straight portion 111 , a first chamfered portion 112 and a second chamfered portion 113 .

[0059] The first linear portion 111 includes an inner surface 111a facing the space in the communication hole 91 and extends linearly in the axial direction of the inner cylinder 72. The inner surface 111a of the first linear portion 111 is also flat along the radial direction of the cylinder 72.

[0060] The first chamfered portion 112 extends from the end of the first straight portion 111 on the first end side of the cylinder 72 in the axial direction to the first end. The inner surface 112a of the first chamfered portion 112 facing the space in the communicating hole 91 extends from the end of the inner surface 111a of the first straight portion 111 on the first end side of the cylinder 72 in the axial direction to the first end. The first chamfered portion 112 includes an inner surface 112a, and is in an arc shape having a center on the second axial edge 103 side of the cylinder 72 in the circumferential direction of the cylinder 72 relative to the inner surface 112a. The first chamfered portion 112 is round chamfered. The first chamfered portion 112 includes an inner surface 112a, and the closer it is to the first end side in the axial direction of the cylinder 72, the closer it is to the second axial edge 103 in the circumferential direction of the cylinder 72. The inner surface 112a of the first chamfered portion 112 is also in a cylindrical surface shape along the radial direction of the cylinder 72.

[0061] The second chamfered portion 113 extends from the end of the first straight portion 111 on the second end side of the cylinder 72 in the axial direction to the second end. The inner surface 113a of the second chamfered portion 113 facing the space in the communicating hole 91 extends from the end of the inner surface 111a of the first straight portion 111 on the second end side of the cylinder 72 in the axial direction to the second end. The second chamfered portion 113 includes an inner surface 113a, and is in an arc shape having a center on the second axial edge 103 side of the cylinder 72 in the circumferential direction of the cylinder 72 relative to the inner surface 113a. The second chamfered portion 113 is an R chamfer. The second chamfered portion 113 includes an inner surface 113a, and the closer it is to the second axial edge 103 in the circumferential direction of the cylinder 72 in the axial direction of the cylinder 72, the closer it is to the second end side. The inner surface 113a of the second chamfered portion 113 is also in a cylindrical surface shape along the radial direction of the cylinder 72.

[0062] The second axial edge portion 103 has a second straight portion 121 , a third chamfered portion 122 , and a fourth chamfered portion 123 .

[0063] The second straight portion 121 includes an inner surface 121a facing the space in the communicating hole 91 and extends linearly in the axial direction of the inner cylinder 72. The inner surface 121a of the second straight portion 121 is also flat along the radial direction of the cylinder 72. The second straight portion 121 is aligned with the first straight portion 111 in the axial direction of the cylinder 72, and is separated in the circumferential direction of the cylinder 72 to be mirror-symmetrical.

[0064] The third chamfered portion 122 extends from the end of the second straight portion 121 on the first end side of the cylinder 72 in the axial direction to the direction of the first end. The inner surface 122a of the third chamfered portion 122 facing the space in the communicating hole 91 extends from the end of the inner surface 121a of the second straight portion 121 on the first end side of the cylinder 72 in the axial direction to the direction of the first end. The third chamfered portion 122 includes an inner surface 122a, and is in an arc shape having a center on the first axial edge 102 side of the cylinder 72 in the circumferential direction of the inner surface 122a. The third chamfered portion 122 is an R chamfer. The third chamfered portion 122 includes an inner surface 122a, and the closer it is to the first axial edge 102 in the circumferential direction of the cylinder 72 in the axial direction of the cylinder 72, the closer it is to the first end side in the axial direction of the cylinder 72. The inner surface 122a of the third chamfered portion 122 is also in a cylindrical surface shape along the radial direction of the cylinder 72. The third chamfered portion 122 is aligned with the first chamfered portion 112 in the axial direction of the cylindrical portion 72 , and is separated in the circumferential direction of the cylindrical portion 72 to be mirror-symmetrical.

[0065] The fourth chamfered portion 123 extends from the end of the second straight portion 121 on the second end side of the cylinder 72 in the axial direction to the second end. The inner surface 123a of the fourth chamfered portion 123 facing the space in the communicating hole 91 extends from the end of the inner surface 121a of the second straight portion 121 on the second end side of the cylinder 72 in the axial direction to the second end. The fourth chamfered portion 123 includes an inner surface 123a and is in an arc shape having a center on the first axial edge 102 side of the cylinder 72 in the circumferential direction of the cylinder 72 relative to the inner surface 123a. The fourth chamfered portion 123 is an R chamfer. The fourth chamfered portion 123 includes an inner surface 123a and is closer to the first axial edge 102 in the circumferential direction of the cylinder 72 as it is located on the second end side in the axial direction of the cylinder 72. The inner surface 123a of the fourth chamfered portion 123 is also in a cylindrical surface shape along the radial direction of the cylinder 72. The fourth chamfered portion 123 is aligned with the second chamfered portion 113 in the axial direction of the cylindrical portion 72 , and is separated in the circumferential direction of the cylindrical portion 72 to be mirror-symmetrical.

[0066] The edge 101 has a first circumferential edge portion 131 and a second circumferential edge portion 132 as circumferential edge portions extending in the circumferential direction of the cylinder portion 72. The edge 101 has the first circumferential edge portion 131 at an end portion on the first end side in the axial direction of the cylinder portion 72. The edge 101 has the second circumferential edge portion 132 at an end portion on the second end side in the axial direction of the cylinder portion 72.

[0067] The first circumferential edge portion 131 is mirror-symmetrical and has a first inclined portion 141 , a second inclined portion 142 , and a fifth chamfered portion 143 .

[0068] The first inclined portion 141 is formed to extend obliquely from one end of the first axial edge portion 102 on the first end side of the cylindrical portion 72 in the axial direction relative to the first straight portion 111 of the first axial edge portion 102. The first inclined portion 141 is linear inside, including an inner surface 141a facing the space in the communicating hole 91. The inner surface 141a of the first inclined portion 141 is also flat along the radial direction of the cylindrical portion 72.

[0069] The first inclined portion 141 extends from one end of the first chamfered portion 112 on the first end side of the barrel 72 in the axial direction toward the first end side of the barrel 72 in the axial direction. Furthermore, the closer the first inclined portion 141 is to the first end side in the axial direction of the barrel 72, the closer it is to the second straight portion 121 in the circumferential direction of the barrel 72. The inner surface 141a of the first inclined portion 141 extends from one end of the inner surface 112a of the first chamfered portion 112 on the first end side of the barrel 72 in the axial direction toward the first end side of the barrel 72 in the axial direction. Furthermore, the closer the inner surface 141a of the first inclined portion 141 is to the first end side in the axial direction of the barrel 72, the closer it is to the second straight portion 121 in the circumferential direction of the barrel 72.

[0070] The second inclined portion 142 is formed to extend obliquely from one end of the second axial edge portion 103 on the first end side of the cylinder portion 72 in the axial direction relative to the second straight line portion 121 of the second axial edge portion 103. The second inclined portion 142 is linear inside, including an inner surface 142a facing the space in the communicating hole 91. The inner surface 142a of the second inclined portion 142 is also flat along the radial direction of the cylinder portion 72.

[0071] The second inclined portion 142 extends from one end of the third chamfered portion 122 on the first end side of the barrel 72 in the axial direction toward the first end side of the barrel 72 in the axial direction. Moreover, the closer the second inclined portion 142 is to the first end side in the axial direction of the barrel 72, the closer it is to the first straight portion 111 in the circumferential direction of the barrel 72. The inner surface 142a of the second inclined portion 142 extends from one end of the inner surface 122a of the third chamfered portion 122 on the first end side of the barrel 72 in the axial direction toward the first end side of the barrel 72 in the axial direction. Moreover, the closer the inner surface 142a of the second inclined portion 142 is to the first end side in the axial direction of the barrel 72, the closer it is to the first straight portion 111 in the circumferential direction of the barrel 72. The second inclined portion 142 is aligned with the first inclined portion 141 in the axial direction of the barrel 72, and is separated in the circumferential direction of the barrel 72 to be mirror-symmetrical. The angle formed by the inner surface 142 a of the second inclined portion 142 and the inner surface 141 a of the first inclined portion 141 is an acute angle.

[0072] The fifth chamfered portion 143 connects one end of the first inclined portion 141 on the first end side in the axial direction of the barrel portion 72 and one end of the second inclined portion 142 on the first end side in the axial direction of the barrel portion 72. The inner surface 143a of the fifth chamfered portion 143 facing the space in the communicating hole 91 connects one end of the inner surface 141a of the first inclined portion 141 on the first end side in the axial direction of the barrel portion 72 and one end of the inner surface 142a of the second inclined portion 142 on the first end side in the axial direction of the barrel portion 72.

[0073] The fifth chamfered portion 143 includes an inner surface 143a which is in an arc shape having a center at the second end side in the axial direction of the cylinder 72 relative to the inner surface 143a. The fifth chamfered portion 143 is an R chamfer. The closer the fifth chamfered portion 143 is from the central position to the first inclined portion 141 in the circumferential direction of the cylinder 72, the more the inner surface 143a is located in the axial direction of the second end of the inner cylinder 72. The closer the fifth chamfered portion 143 is from the central position to the second inclined portion 142 in the circumferential direction of the cylinder 72, the more the inner surface 143a is located in the axial direction of the second end of the inner cylinder 72.

[0074] The second circumferential edge 132 includes an inner surface 132a extending in the circumferential direction of the inner cylinder 72 toward the space in the communicating hole 91. The inner surface 132a of the second circumferential edge 132 is also planar along the radial direction of the cylinder 72. The inner surface 132a is planar extending perpendicularly to the central axis of the cylinder 72. The second circumferential edge 132 connects the end of the second chamfered portion 113 on the opposite side to the first straight portion 111 and the end of the fourth chamfered portion 123 on the opposite side to the second straight portion 121. The inner surface 132a of the second circumferential edge 132 connects the end of the inner surface 113a of the second chamfered portion 113 on the opposite side to the inner surface 111a of the first straight portion 111 and the end of the inner surface 123a of the fourth chamfered portion 123 on the opposite side to the inner surface 121a of the second straight portion 121.

[0075] As can be seen from the above, the first circumferential edge 131 includes the first inclined portion 141 and the second inclined portion 142 as inclined portions that are formed to be inclined relative to the axial direction of the cylinder 72 and form a part of the first end side of the cylinder 72 in the axial direction of the edge 101. It should be noted that the first circumferential edge 131 only needs to include an inclined portion that is formed to be inclined relative to the axial direction of the cylinder 72 and forms at least a part of the first end side of the cylinder 72 in the axial direction of the edge 101. The first inclined portion 141 and the second inclined portion 142 are provided on the first end side of the cylinder 72 in the axial direction of the edge 101. The fifth chamfered portion 143 is provided at the first end of the cylinder 72 in the axial direction of the edge 101.

[0076] The edge 101 of the communication hole 91 is formed so that a first end portion in the axial direction of the cylindrical portion 72 is thinner than a second end portion in the axial direction of the cylindrical portion 72 .

[0077] Each corner of the communication hole 91 is rounded to form a first chamfered portion 112 , a second chamfered portion 113 , a third chamfered portion 122 , a fourth chamfered portion 123 , and a fifth chamfered portion 143 .

[0078] The bumper cover 13 of the above shape is made of synthetic resin or metal. When the bumper cover 13 is made of synthetic resin material, it is formed by injection molding. When the bumper cover 13 is made of metal material, for example, when the bumper cover 13 is made of aluminum alloy material, it is formed by die casting.

[0079] In either the case of injection molding or die casting, the molten material is pressurized and caused to flow into a mold cavity having a cavity in the shape of the bumper cover 13 to form the bumper cover 13. In either the case of injection molding or die casting, the bumper cover 13 is formed in the cavity. Figure 2 The portion of the through hole 81 of the cover portion 70 shown in the figure becomes the inlet of the material. For example, when the buffer cover 13 is injection molded, a plurality of (for example, 6) inlets are provided at equal intervals in the circumferential direction at the portion of the inner peripheral edge portion 82 of the through hole 81 forming the cover portion 70. And, if the material is caused to flow into the cavity from these inlets, the material flows in a manner that expands outward in the radial direction of the cover portion 70 in the space portion forming the cover portion 70 of the cavity, and then flows in a direction away from the space portion forming the cover portion 70 in the axial direction of the cylinder portion 72 in the space portion forming the cylinder portion 72 of the cavity.

[0080] Here, in order to form the communicating hole 91, a Figure 4 The mold section 200 shown. The mold section 200 is Figure 3 The space in the connecting hole 91 shown in FIG. Figure 4 As shown, the mold part 200 has a Figure 3 The edge portion forming surface 201 of the edge 101 of the communication hole 91 shown in the figure. The edge portion forming surface 201 has a first straight portion forming surface 211, a first chamfered portion forming surface 212, a second chamfered portion forming surface 213, a second straight portion forming surface 221, a third chamfered portion forming surface 222, and a fourth chamfered portion forming surface 223. In addition, the edge portion forming surface 201 has a second circumferential direction edge forming surface 232, a first inclined portion forming surface 241, a second inclined portion forming surface 242, and a fifth chamfered portion forming surface 243.

[0081] The first straight line portion forming surface portion 211 is formed Figure 3 The first chamfered portion 212 is formed by forming an inner surface 111a of the first straight portion 111. Figure 3 The inner surface 112a of the first chamfered portion 112 is shown. The second chamfered portion forming the surface portion 213 is formed Figure 3 The second straight line portion forming surface 221 forms the inner surface 113a of the second chamfered portion 113. Figure 3The inner surface 121a of the second straight line portion 121 is shown. The third chamfered portion forming surface portion 222 is formed Figure 3 The inner surface 122a of the third chamfered portion 122 is shown. The fourth chamfered portion forming surface 223 is formed Figure 3 The inner surface 123a of the fourth chamfered portion 123 is shown. The second circumferential edge forming surface portion 232 is formed Figure 3 The first inclined portion forming surface 241 forms the inner surface 132a of the second circumferential edge portion 132. Figure 3 The inner surface 141a of the first inclined portion 141 is shown. The second inclined portion forming surface 242 forms Figure 3 The inner surface 142a of the second inclined portion 142 is shown. The fifth chamfered portion forming surface portion 243 is formed Figure 3 The inner surface 143a of the fifth chamfered portion 143 is shown. The angle formed by the first inclined portion forming surface portion 241 and the second inclined portion forming surface portion 242 is an acute angle.

[0082] In either the case of injection molding or die casting, as described above, the material is moved away from the space portion of the cavity forming the cylindrical portion 72 in the axial direction of the cylindrical portion 72 to form the cover portion 70 (see Figure 2 That is, the material flows from the second end side to the first end side in the axial direction of the cylinder 72 in the space portion forming the cylinder 72 of the cavity. Figure 4 As shown by the arrow of the double-dashed line, the material flows from the side of the second circumferential edge forming surface 232 opposite to the fifth chamfer forming surface 243 toward the side of the fifth chamfer forming surface 243 opposite to the second circumferential edge forming surface 232. In addition, a part of the material is guided in sequence by a part of the second chamfer forming surface 213, the first straight line forming surface 211, the first chamfer forming surface 212, the first inclined portion forming surface 241, and the first inclined portion forming surface 241 side of the fifth chamfer forming surface 243, and flows along them. In addition, a part of the material is guided in sequence by a part of the fourth chamfer forming surface 223, the second straight line forming surface 221, the third chamfer forming surface 222, the second inclined portion forming surface 242, and the second inclined portion forming surface 242 side of the fifth chamfer forming surface 243, and flows along them.

[0083] At this time, the first inclined portion forming surface 241 and the second inclined portion forming surface 242 are arranged along the direction of material flow so that the interval between them is narrower on the downstream side than on the upstream side. As a result, the confluence angle of the material flowing along the first inclined portion forming surface 241 and the material flowing along the second inclined portion forming surface 242 becomes larger, and these materials merge smoothly.

[0084] Figure 3The edge 101 of the communication hole 91 shown is formed so that the portion on the side of the fifth chamfer 143 of the first circumferential edge 131 constituting the first end portion located on the downstream side where the material flows in during molding is thinner than the portion on the side of the second circumferential edge 132 constituting the second end portion located on the upstream side. In other words, the communication hole 91 of the buffer cover 13 is formed so that the first end portion located on the downstream side where the material flows in during molding is thinner than the second end portion located on the upstream side. In addition, the edge 101 of the communication hole 91 of the buffer cover 13 is formed so that the second circumferential edge 132, which is the end portion on the upstream side of the material flowing in during molding, is substantially perpendicular to the flow of the material. The first end portion of the communication hole 91 of the buffer cover 13 located on the downstream side in the flow direction of the material during molding is a tapered shape that becomes thinner toward the downstream side.

[0085] like Figure 2 As shown, the damper cover 13 is attached to the cylinder 21 by covering the end of the main body 36 of the outer tube 32 of the cylinder 21, where the piston rod 50 extends in the axial direction of the main body 36. At this time, the piston rod 50 is inserted into the through hole 81 of the cover 70.

[0086] When installed in the cylinder body 21, Figure 1 As shown, the cylindrical portion 72 of the buffer cover 13 covers the outer peripheral surface of the cylinder body 21, that is, a part of the outer peripheral surface 32a of the outer cylinder 32, on the radially outer side. In this state, the cover portion 70 of the buffer cover 13 abuts against the axial end surface of the cylinder body 21 on the opposite side to the bottom 37 in the axial direction, that is, the axial end surface 32b of the outer cylinder 32. In this state, the cylindrical portion 72 abuts against and fits with the outer peripheral surface 32a of the outer cylinder 32 at the inner peripheral surface 72a and is fixed to the outer cylinder 32. The outer peripheral surface 32a of the outer cylinder 32 is the outer peripheral surface of the trunk portion 36.

[0087] It should be noted that the cylindrical portion 72 of the buffer cover 13 may also cover the entire outer peripheral surface of the cylinder 21, that is, the outer peripheral surface 32a of the outer cylinder 32, in the radial direction. That is, the cylindrical portion 72 of the buffer cover 13 only needs to cover at least a portion of the outer peripheral surface of the cylinder 21, that is, the outer peripheral surface 32a of the outer cylinder 32, in the radial direction.

[0088] Here, when the shock absorber 11 is assembled to the vehicle, one end of a dust cover (not shown) covering the portion of the piston rod 50 extending from the cylinder 21 is engaged with the flange portion 73 of the shock absorber cover 13. The communication hole 91 of the shock absorber cover 13 forms a flow path for air to flow from the gap between the outer tube 32 of the cylinder 21 and the shock absorber cover 13 to the outside of the shock absorber cover 13. Figure 2The dust that enters the gap between the outer tube 32 and the buffer cover 13 through the through hole 81 is discharged to the outside of the buffer cover 13 by the flow of air that flows from the through hole 81 through the gap between the outer tube 32 and the buffer cover 13 and flows to the outside through the communication hole 91 .

[0089] Patent Document 1 discloses a buffer in which a side of a rod protruding from a cylinder body is covered with a buffer cover. In the buffer, the buffer cover has a cylindrical portion formed in a cylindrical shape and a top plate portion formed to block one end of the cylindrical portion, and an opening is formed in the cylindrical portion. In the buffer, it is desired to improve the durability of the buffer cover. For example, in a case where the above-mentioned opening is formed during mold-based molding of the buffer cover, if there is turbulence in the flow of material flowing around the mold portion for forming the opening, surface defects are likely to occur on the surface around the opening. If such surface defects exist, there is a possibility that the strength of the buffer cover is reduced and the durability is reduced.

[0090] In the shock absorber 11 of the first embodiment, the shock absorber cover 13 provided at the end of the cylinder 21 on the side where the piston rod 50 extends is formed by die casting or injection molding. The edge 101 of the communication hole 91 provided in the cylinder 72 of the shock absorber cover 13 and connecting the inner peripheral surface 72a and the outer peripheral surface 72b of the cylinder 72 is formed so that the first end located on the downstream side where the material flows in during molding is thinner than the second end located on the upstream side. Therefore, the shock absorber cover 13 can increase the confluence angle when the materials flowing on both sides of the mold part 200 forming the communication hole 91 merge on the downstream side, and can make the materials merge smoothly. As a result, the shock absorber cover 13 can suppress the strength reduction caused by the surface defect, that is, the weld line, which appears on the surface as a groove or pattern at the part where the materials merge. Therefore, the durability of the shock absorber cover 13 and the shock absorber 11 including the shock absorber cover 13 can be improved.

[0091] In addition, the buffer 11 is formed such that the second circumferential edge 132 of the edge 101 of the communicating hole 91 of the buffer cover 13, which is the end portion on the upstream side of the material flowing in during molding, is substantially perpendicular to the flow of the material. Thus, the buffer cover 13 can suppress the reduction in strength caused by the shape of the second circumferential edge 132. Thus, the durability of the buffer cover 13 and the buffer 11 including the buffer cover 13 can be further improved.

[0092] In the bumper 11, the corners of the edge 101 of the communication hole 91 of the bumper cover 13 are chamfered to form the first chamfer 112, the second chamfer 113, the third chamfer 122, the fourth chamfer 123, and the fifth chamfer 143. Therefore, the material can flow smoothly around the mold portion 200 forming the communication hole 91 of the bumper cover 13. Thus, the durability of the bumper cover 13 and the bumper 11 including the bumper cover 13 can be further improved.

[0093] Furthermore, in the shock absorber 11 , since the shock absorber cover 13 is formed of metal or resin, the shock absorber cover 13 can be easily formed.

[0094] In the buffer 11, at least a portion of the first circumferential edge 131 of the edge 101 of the communicating hole 91 of the buffer cover 13 extending in the circumferential direction of the cylinder 72 includes the first inclined portion 141 and the second inclined portion 142 which are formed to be inclined with respect to the axial direction of the cylinder 72 and are the end side of the edge 101 in the axial direction of the cylinder 72. Therefore, the buffer cover 13 can increase the merging angle when the materials flowing on both sides of the circumferential direction of the cylinder 72 of the die 200 forming the communicating hole 91 by flowing the materials in the axial direction of the cylinder 72 merge on the first circumferential edge 131 side, and can merge the materials smoothly. As a result, the buffer cover 13 can suppress the strength reduction caused by the generation of surface defects, i.e., weld lines, which appear as grooves or patterns on the surface at the portion where the materials merge. Therefore, the durability of the buffer cover 13 and the buffer 11 including the buffer cover 13 can be improved.

[0095] In addition, the buffer cover 13 of the buffer 11 has a first axial edge portion 102 and a second axial edge portion 103 as axial edge portions extending in the axial direction of the cylinder portion 72. In addition, the buffer cover 13 has a first inclined portion 141 formed to extend obliquely from one axial end of the first axial edge portion 102 and a second inclined portion 142 formed to extend obliquely from one axial end of the second axial edge portion 103 as inclined portions formed to be inclined with respect to the axial direction of the cylinder portion 72. Therefore, the buffer cover 13 can reduce the angle difference between the angle formed by the first axial edge portion 102 and the first inclined portion 141 and the angle formed by the second axial edge portion 103 and the second inclined portion 142. Thus, the buffer cover 13 can reduce the speed difference of the flow speed of the material flowing on both sides in the circumferential direction of the cylinder portion 72 of the die portion 200 in which the communicating hole 91 is formed by flowing the material in the axial direction of the cylinder portion 72, and can make the materials merge more smoothly. Therefore, the durability of the bumper cover 13 and the bumper 11 including the bumper cover 13 can be further improved.

[0096] In addition, in the buffer cover 13 of the buffer 11, the first inclined portion 141 and the second inclined portion 142 are provided on the first end side in the axial direction of the cylinder 72. Therefore, the buffer cover 13 can increase the merging angle when the materials flowing toward the first end side on both sides in the circumferential direction of the cylinder 72 of the mold 200 forming the communicating hole 91 by flowing the materials in the axial direction of the cylinder 72 merge, and can make the materials merge smoothly. Therefore, the durability of the buffer cover 13 and the buffer 11 including the buffer cover 13 can be improved.

[0097] In addition, in the shock absorber cover 13 of the shock absorber 11, the first circumferential edge 131 of the first end portion in the axial direction of the cylinder portion 72 is formed at an acute angle compared with the second circumferential edge 132 of the second end portion in the axial direction of the cylinder portion 72. Thus, the shock absorber cover 13 can suppress the occurrence of weld lines on the first end side while suppressing a decrease in strength due to the shape of the second end side.

[0098] It should be noted that, in the edge 101 of the communicating hole 91 of the shock absorber cover 13 , the portion on the second end side including the second circumferential edge 132 can also be mirror-symmetrical with respect to the portion on the first end side including the first circumferential edge 131 .

[0099] [Second embodiment]

[0100] Mainly based on Figure 5 The second embodiment of the present invention will be described with the focus on the parts that are different from the first embodiment. It should be noted that the parts common to the first embodiment are denoted by the same names and the same reference numerals.

[0101] In a second embodiment, if Figure 5 As shown, a partially different buffer cover 13A is used instead of the buffer cover 13 of the first embodiment. The buffer cover 13A has a cylinder portion 72A that is partially different from the cylinder portion 72 instead of the cylinder portion 72. The cylinder portion 72A has a communicating hole 91A that is partially different from the communicating hole 91 instead of the communicating hole 91. The communicating hole 91A connects the outer peripheral surface 72Ab of the cylinder portion 72A with the inner peripheral surface (not shown).

[0102] The edge 101A of the communicating hole 91A has a first axial edge 102A that is partially different from the first axial edge 102 instead of the first axial edge 102. The edge 101A has a second axial edge 103A that is partially different from the second axial edge 103 instead of the second axial edge 103. Here, in the damper cover 13A, the axial direction of the cylinder 72A is also aligned with the cover 70 (see Figure 2) is set as the first end side, and the cover 70 side of the cylinder 72A in the axial direction is set as the second end side. In addition, in the communicating hole 91A, the end of the cylinder 72A on the opposite side of the cover 70 in the axial direction is set as the first end, and the end of the cylinder 72A on the cover 70 side in the axial direction is set as the second end.

[0103] The first axial edge portion 102A has a first chamfered portion 112A instead of the first chamfered portion 112 , and has a second chamfered portion 113A instead of the second chamfered portion 113 .

[0104] The first chamfered portion 112A extends from the end of the first end side of the cylinder 72A in the axial direction of the first straight portion 111 in the direction of the first end. The inner surface 112Aa of the first chamfered portion 112A facing the space in the connecting hole 91A extends from the end of the inner surface 111a of the first straight portion 111 on the first end side of the cylinder 72A in the axial direction in the direction of the first end. The first chamfered portion 112A is a plane chamfering (Chamfering) in which the inner surface 112Aa becomes a plane. The first chamfered portion 112A includes an inner surface 112Aa, and the closer it is to the second axial edge 103A in the circumferential direction of the cylinder 72A in the axial direction of the cylinder 72A. The inner surface 112Aa of the first chamfered portion 112A is also along the radial direction of the cylinder 72A. The angle formed by the inner surface 112Aa and the inner surface 111a is an obtuse angle.

[0105] The second chamfered portion 113A extends from the end of the first straight portion 111 on the second end side of the cylinder 72A in the axial direction toward the second end. The inner surface 113Aa of the second chamfered portion 113A facing the space in the communicating hole 91A extends from the end of the inner surface 111a of the first straight portion 111 on the second end side of the cylinder 72A in the axial direction toward the second end. The second chamfered portion 113A is a planar chamfer in which the inner surface 113Aa becomes planar. The second chamfered portion 113A includes an inner surface 113Aa, and the closer it is to the second axial edge 103A in the circumferential direction of the cylinder 72A in the axial direction of the cylinder 72A. The inner surface 113Aa of the second chamfered portion 113A is also along the radial direction of the cylinder 72A. The angle formed by the inner surface 113Aa and the inner surface 111a is an obtuse angle and is smaller than the angle formed by the inner surface 112Aa and the inner surface 111a. The angle formed by the inner surface 113Aa and the inner surface 111a is equal to the angle formed by the inner surface 113Aa and the inner surface 132a of the second circumferential edge 132.

[0106] The second axial edge portion 103A has a third chamfered portion 122A instead of the third chamfered portion 122 , and has a fourth chamfered portion 123 instead of the fourth chamfered portion 123A.

[0107] The third chamfered portion 122A extends from the end of the first end side of the cylinder 72A in the axial direction of the second straight portion 121 in the direction of the first end. The inner surface 122Aa of the third chamfered portion 122A facing the space in the connecting hole 91A extends from the end of the inner surface 121a of the second straight portion 121 on the first end side of the cylinder 72A in the axial direction in the direction of the first end. The third chamfered portion 122A is a planar chamfer in which the inner surface 122Aa becomes planar. The third chamfered portion 122A includes an inner surface 122Aa, and the closer it is to the first axial edge 102A in the circumferential direction of the cylinder 72A in the axial direction of the cylinder 72A. The inner surface 122Aa of the third chamfered portion 122A is also along the radial direction of the cylinder 72A. The third chamfered portion 122A is aligned with the first chamfered portion 112A in the axial direction of the cylindrical portion 72A, and is separated in the circumferential direction of the cylindrical portion 72A to be mirror-symmetrical.

[0108] The fourth chamfered portion 123A extends from the end of the second end side of the cylinder 72A in the axial direction of the second straight portion 121 in the direction of the second end. The inner surface 123Aa of the fourth chamfered portion 123A facing the space in the connecting hole 91A extends from the end of the inner surface 121a of the second straight portion 121 on the second end side of the cylinder 72A in the axial direction in the direction of the second end. The fourth chamfered portion 123A is a planar chamfer in which the inner surface 123Aa becomes planar. The fourth chamfered portion 123A includes an inner surface 123Aa, and the closer it is to the first axial edge 102A in the circumferential direction of the cylinder 72A, the closer it is to the second end side in the axial direction of the cylinder 72A. The inner surface 123Aa of the fourth chamfered portion 123A is also along the radial direction of the cylinder 72A. The angle formed by the inner surface 123Aa and the inner surface 121a is an obtuse angle and is smaller than the angle formed by the inner surface 122Aa and the inner surface 121a. The angle formed by the inner surface 123Aa and the inner surface 121a is equal to the angle formed by the inner surface 123Aa and the inner surface 132a of the second circumferential edge 132. The fourth chamfered portion 123A aligns the axial position of the cylinder 72A with respect to the second chamfered portion 113A, and is separated in the circumferential direction of the cylinder 72A to be mirror-symmetrical.

[0109] The edge 101A has a first circumferential edge portion 131A instead of the first circumferential edge portion 131. The first circumferential edge portion 131A is mirror-symmetrical and has a fifth chamfered portion 143A instead of the fifth chamfered portion 143.

[0110] The fifth chamfered portion 143A connects one end of the first inclined portion 141 on the axial first end side of the cylinder portion 72A to one end of the second inclined portion 142 on the axial first end side of the cylinder portion 72A. An inner surface 143Aa of the fifth chamfered portion 143A facing the space in the communicating hole 91A connects one end of the inner surface 141a of the first inclined portion 141 on the axial first end side of the cylinder portion 72A to one end of the inner surface 142a of the second inclined portion 142 on the axial first end side of the cylinder portion 72A.

[0111] The fifth chamfered portion 143A is a plane chamfer whose inner surface 143Aa is planar. The angle formed by the inner surface 143Aa of the fifth chamfered portion 143A and the inner surface 141a of the first inclined portion 141 is equal to the angle formed by the inner surface 143Aa of the fifth chamfered portion 143A and the inner surface 142a of the second inclined portion 142. The angle formed by the inner surface 112Aa and the inner surface 141a is equal to the angle formed by the inner surface 112Aa and the inner surface 111a. The angle formed by the inner surface 122Aa and the inner surface 142a is equal to the angle formed by the inner surface 122Aa and the inner surface 121a.

[0112] As can be seen from the above, the first circumferential edge 131A includes the first inclined portion 141 and the second inclined portion 142 as inclined portions formed to be inclined relative to the axial direction of the tube 72A and forming a part of the first end side of the tube 72A in the axial direction of the edge 101A. The fifth chamfered portion 143A is provided at the first end of the tube 72A in the axial direction of the edge 101A.

[0113] The edge 101A of the communication hole 91A is formed so that a first end portion in the axial direction of the cylindrical portion 72A is thinner than a second end portion in the axial direction of the cylindrical portion 72A.

[0114] Each corner of the communication hole 91A is chamfered by a plane to form a first chamfered portion 112A, a second chamfered portion 113A, a third chamfered portion 122A, a fourth chamfered portion 123A, and a fifth chamfered portion 143A.

[0115] The bumper cover 13A having the shape described above is formed by injection molding of a synthetic resin material or die casting of an aluminum alloy material, similarly to the bumper cover 13. In either the case of injection molding or die casting, similarly to the bumper cover 13, the cavity is formed so that the cover portion 70 (see Figure 2 ) through hole 81 (refer to Figure 2) portion becomes the inlet of the material. And, if the material is caused to flow into the cavity from the inlet, the material flows in a manner that expands outward in the radial direction of the cover portion 70 in the space portion forming the cover portion 70 of the cavity, and then flows in a direction away from the space portion forming the cover portion 70 in the axial direction of the cylinder portion 72A in the space portion forming the cylinder portion 72A of the cavity. That is, the material flows in the space portion forming the cylinder portion 72A of the cavity from the second end side to the first end side in the axial direction of the cylinder portion 72A.

[0116] The edge 101A of the communicating hole 91A is formed so that the portion on the fifth chamfered portion 143A side of the first circumferential edge 131A constituting the first end portion located on the downstream side where the material flows in during molding is thinner than the portion on the second circumferential edge 132 side constituting the second end portion located on the upstream side. In other words, the communicating hole 91A of the buffer cover 13A is formed so that the first end portion located on the downstream side where the material flows in during molding is thinner than the second end portion located on the upstream side. In addition, the edge 101A of the communicating hole 91A of the buffer cover 13A is formed so that the second circumferential edge 132, which is the end portion on the upstream side where the material flows in during molding, is substantially perpendicular to the flow of the material. The first end portion of the communicating hole 91A of the buffer cover 13A located on the downstream side in the flow direction of the material during molding is a tapered shape that becomes thinner toward the downstream side.

[0117] The edge 101A of the communication hole 91A provided in the cylinder 72A of the buffer cover 13A of the second embodiment is formed so that the first end portion located on the downstream side where the material flows in during molding is thinner than the second end portion located on the upstream side. Therefore, the buffer cover 13A can increase the merging angle when the materials flowing on both sides of the mold portion forming the communication hole 91A merge on the downstream side, and can make the materials merge smoothly. As a result, the buffer cover 13A can suppress the strength reduction caused by the surface defects, i.e., weld lines, which appear as grooves or patterns on the surface at the part where the materials merge. Therefore, the durability of the buffer cover 13A can be improved.

[0118] In addition, the corners of the edge 101A of the communication hole 91A of the buffer cover 13A are chamfered to form a first chamfered portion 112A, a second chamfered portion 113A, a third chamfered portion 122A, a fourth chamfered portion 123A, and a fifth chamfered portion 143A. Therefore, the material can flow smoothly around the mold portion forming the communication hole 91A of the buffer cover 13A. As a result, the durability of the buffer cover 13A can be further improved.

[0119] Note that, in the edge 101A of the communicating hole 91A of the shock absorber cover 13A, the portion on the second end side including the second circumferential edge 132 can also be mirror-symmetrical with respect to the portion on the first end side including the first circumferential edge 131A.

[0120] [Third Embodiment]

[0121] Mainly based on Figure 6 The third embodiment of the present invention will be described with the focus on the parts that are different from the first embodiment. It should be noted that the parts that are common to the first embodiment are denoted by the same names and the same reference numerals.

[0122] In a third embodiment, if Figure 6 As shown, a partially different buffer cover 13B is used instead of the buffer cover 13 of the first embodiment. The buffer cover 13B has a cylinder portion 72B that is partially different from the cylinder portion 72 instead of the cylinder portion 72. The cylinder portion 72B has a communicating hole 91B that is partially different from the communicating hole 91 instead of the communicating hole 91. The communicating hole 91B connects the outer peripheral surface 72Bb of the cylinder portion 72B with the inner peripheral surface (not shown).

[0123] The edge 101B of the communication hole 91B has a first axial edge 102B that is partially different from the first axial edge 102 instead of the first axial edge 102. The edge 101B has a second axial edge 103B that is partially different from the second axial edge 103 instead of the second axial edge 103. Here, in the damper cover 13B, the axial direction of the cylinder 72B is also aligned with the cover 70 (see Figure 2 ) is set as the first end side, and the cover 70 side of the cylinder 72B in the axial direction is set as the second end side. In addition, in the communicating hole 91B, the end of the cylinder 72B on the opposite side of the cover 70 in the axial direction is set as the first end, and the end of the cylinder 72B on the cover 70 side in the axial direction is set as the second end.

[0124] The first axial edge portion 102B does not have the first chamfered portion 112 and the second chamfered portion 113. The first axial edge portion 102B is a shape obtained by extending the first straight portion 111 in the axial direction of the cylinder portion 72B as it is without the first chamfered portion 112 and the second chamfered portion 113. The inner surface 102Ba of the first axial edge portion 102B is a shape obtained by extending the inner surface 111a of the first straight portion 111 in the axial direction of the cylinder portion 72B as it is.

[0125] The second axial edge portion 103B does not have the third chamfered portion 122 and the fourth chamfered portion 123. The second axial edge portion 103B is a shape obtained by extending the second straight line portion 121 in the axial direction of the cylinder portion 72B as it is without the third chamfered portion 122 and the fourth chamfered portion 123. The inner surface 103Ba of the second axial edge portion 103B is a shape obtained by extending the inner surface 121a of the second straight line portion 121 in the axial direction of the cylinder portion 72B as it is.

[0126] The edge 101B has a first circumferential edge portion 131B instead of the first circumferential edge portion 131. The first circumferential edge portion 131B has a first inclined portion 141B instead of the first inclined portion 141, and has a second inclined portion 142B instead of the second inclined portion 142. The first circumferential edge portion 131B does not have the fifth chamfered portion 143.

[0127] The first inclined portion 141B is a shape obtained by extending the first inclined portion 141 as it is in the axial direction and circumferential direction of the cylinder portion 72B by the amount obtained by adding the amount of not providing the fifth chamfered portion 143 and the amount of not providing the first chamfered portion 112 in the first axial edge portion 102B. The inner surface 141Ba of the first inclined portion 141B is a shape obtained by extending the inner surface 141a of the first inclined portion 141 as it is in the axial direction and circumferential direction of the cylinder portion 72B.

[0128] The second inclined portion 142B is a shape obtained by extending the second inclined portion 142 as is in the axial and circumferential directions of the barrel 72B by the amount obtained by adding the amount of not providing the fifth chamfered portion 143 and the amount of not providing the third chamfered portion 122 at the second axial edge 103B. The inner surface 142Ba of the second inclined portion 142B is a shape obtained by extending the inner surface 142a of the second inclined portion 142 as is in the axial and circumferential directions of the barrel 72B. The end of the first end side of the first inclined portion 141B in the axial direction of the barrel 72B is connected to the end of the first end side of the second inclined portion 142B in the axial direction of the barrel 72B. The end of the first end side of the inner surface 141Ba in the axial direction of the barrel 72B is connected to the end of the first end side of the inner surface 142Ba in the axial direction of the barrel 72B.

[0129] The edge 101B has a second circumferential edge portion 132B instead of the second circumferential edge portion 132. The second circumferential edge portion 132B is a shape obtained by extending the second circumferential edge portion 132 in the circumferential direction of the cylinder 72B as it is by adding the amount of the second chamfered portion 113 not being provided in the first axial edge portion 102B and the amount of the fourth chamfered portion 123 not being provided in the second axial edge portion 103B. The inner surface 132Ba of the second circumferential edge portion 132B is a shape obtained by extending the inner surface 132a of the second circumferential edge portion 132 in the circumferential direction of the cylinder 72B as it is.

[0130] As can be seen from the above, the first circumferential edge portion 131B includes the first inclined portion 141B and the second inclined portion 142B as inclined portions which are formed to be inclined with respect to the axial direction of the tube portion 72B and serve as the first end portion of the tube portion 72B in the axial direction to form the edge 101B.

[0131] The edge 101B of the communication hole 91B is formed such that a first end portion in the axial direction of the cylindrical portion 72B is thinner than a second end portion in the axial direction of the cylindrical portion 72B.

[0132] The bumper cover 13B having the shape described above is formed by injection molding of a synthetic resin material or die casting of an aluminum alloy material, similarly to the bumper cover 13. In either the case of injection molding or die casting, similarly to the bumper cover 13, the cavity is formed so that the cover portion 70 (see Figure 2 ) through hole 81 ( Figure 2 ) portion becomes the entrance of the material. And, if the material is caused to flow into the cavity from the entrance, the material flows in a manner that expands outward in the radial direction of the cover portion 70 in the space portion of the cavity that forms the cover portion 70, and then flows in a direction away from the space portion that forms the cover portion 70 in the axial direction of the cylinder portion 72B in the space portion of the cavity that forms the cylinder portion 72B. That is, the material flows from the second end side to the first end side in the axial direction of the cylinder portion 72B in the space portion of the cavity that forms the cylinder portion 72B.

[0133] The edge 101B of the communicating hole 91B is formed so that the portion on the first circumferential edge 131B side constituting the first end portion located on the downstream side where the material flows in during molding is thinner than the portion on the second circumferential edge 132B side constituting the second end portion located on the upstream side. In other words, the communicating hole 91B of the buffer cover 13B is formed so that the first end portion located on the downstream side where the material flows in during molding is thinner than the second end portion located on the upstream side. In addition, the edge 101B of the communicating hole 91B of the buffer cover 13B is formed so that the second circumferential edge 132B, which is the end portion on the upstream side of the material flowing in during molding, is substantially perpendicular to the flow of the material. The first end portion of the communicating hole 91B of the buffer cover 13B located on the downstream side in the flow direction of the material during molding is a tapered shape that becomes thinner toward the downstream side.

[0134] The edge 101B of the communication hole 91B provided in the barrel 72B of the buffer cover 13B of the third embodiment is formed such that the first end portion located on the downstream side where the material flows in during molding is thinner than the second end portion located on the upstream side. Therefore, the buffer cover 13B can increase the confluence angle when the materials flowing on both sides of the mold portion forming the communication hole 91B merge on the downstream side, and can make the materials merge smoothly. As a result, the buffer cover 13B can suppress the strength reduction caused by the surface defects, i.e., weld lines, which appear as grooves or patterns on the surface at the part where the materials merge. Therefore, the durability of the buffer cover 13B can be improved.

[0135] Note that, in the edge 101B of the communicating hole 91B of the shock absorber cover 13B, the portion on the second end side including the second circumferential edge 132B can be mirror-symmetrical with respect to the portion on the first end side including the first circumferential edge 131B.

[0136] [Fourth Embodiment]

[0137] Mainly based on Figure 7 The fourth embodiment of the present invention will be described with the focus on the parts that are different from the third embodiment. It should be noted that the parts common to the third embodiment are denoted by the same names and the same reference numerals.

[0138] In a fourth embodiment, if Figure 7 As shown, the buffer cover 13B of the third embodiment is replaced with a buffer cover 13C that is partially different from the buffer cover 13B. The buffer cover 13C has a barrel portion 72C that is partially different from the barrel portion 72B as the barrel portion 72B. The barrel portion 72C has a connecting hole 91C that is partially different from the connecting hole 91B as the connecting hole 91B. The connecting hole 91C connects the outer peripheral surface 72Cb of the barrel portion 72C and the inner peripheral surface (not shown) of the barrel portion 72C. Here, in the buffer cover 13C, the axial direction of the barrel portion 72C and the cover portion 70 (see Figure 2 ) is set as the first end side, and the cover 70 side of the cylinder 72C in the axial direction is set as the second end side. In addition, in the communicating hole 91C, the end of the cylinder 72C on the opposite side of the cover 70 in the axial direction is set as the first end, and the end of the cylinder 72C on the cover 70 side in the axial direction is set as the second end.

[0139] The edge 101C of the communication hole 91C has a first circumferential edge portion 131C instead of the first circumferential edge portion 131B. The first circumferential edge portion 131C has a first inclined portion 141C instead of the first inclined portion 141B, and has a second inclined portion 142C instead of the second inclined portion 142B.

[0140] The first inclined portion 141C is formed to extend obliquely relative to the first axial edge portion 102B from one end of the first axial edge portion 102B on the axial first end side of the barrel portion 72C. The first inclined portion 141C includes an inner surface 141Ca facing the space in the communicating hole 91C, which is arc-shaped inside. The first inclined portion 141C includes an inner surface 141Ca, which is arc-shaped inside and has a center at the second end side of the barrel portion 72C in the axial direction relative to the inner surface 141Ca. The inner surface 141Ca of the first inclined portion 141C is also cylindrical along the radial direction of the barrel portion 72C.

[0141] The first inclined portion 141C extends from one end of the first axial edge portion 102B on the first end side of the barrel portion 72C in the axial direction toward the first end side of the barrel portion 72C in the axial direction. Moreover, the closer the first inclined portion 141C is to the first end side in the axial direction of the barrel portion 72C, the closer it is to the second axial edge portion 103B in the circumferential direction of the barrel portion 72C. The inner surface 141Ca of the first inclined portion 141C extends from one end of the inner surface 102Ba of the first axial edge portion 102B on the first end side of the barrel portion 72C in the axial direction toward the first end side of the barrel portion 72C in the axial direction. Moreover, the closer the inner surface 141Ca of the first inclined portion 141C is to the first end side in the axial direction of the barrel portion 72C, the closer it is to the second axial edge portion 103B in the circumferential direction of the barrel portion 72C.

[0142] The second inclined portion 142C is formed to extend obliquely relative to the second axial edge portion 103B from one end of the first end side of the barrel portion 72C in the axial direction of the second axial edge portion 103B. The second inclined portion 142C includes an inner surface 142Ca facing the space in the communicating hole 91C, which is arc-shaped inside. The second inclined portion 142C includes an inner surface 142Ca, which is arc-shaped inside and has a center at the second end side of the barrel portion 72C in the axial direction than the inner surface 142Ca. The inner surface 142Ca of the second inclined portion 142C is also cylindrical along the radial direction of the barrel portion 72C.

[0143] The second inclined portion 142C extends from one end of the second axial edge 103B on the first end side of the barrel 72C in the axial direction toward the first end side of the barrel 72C in the axial direction. Moreover, the closer the second inclined portion 142C is to the first end side in the axial direction of the barrel 72C, the closer it is to the first axial edge 102B in the circumferential direction of the barrel 72C. The inner surface 142Ca of the second inclined portion 142C extends from one end of the inner surface 103Ba of the second axial edge 103B on the first end side of the barrel 72C in the axial direction toward the first end side of the barrel 72C in the axial direction. Moreover, the closer the inner surface 142Ca of the second inclined portion 142C is to the first axial edge 102B in the circumferential direction of the barrel 72C, the closer it is to the first axial edge 102B in the circumferential direction of the barrel 72C. The second inclined portion 142C is aligned with the first inclined portion 141C in the axial direction of the barrel 72C, and is mirror-symmetrical. The inner surface 141Ca of the first inclined portion 141C and the inner surface 142Ca of the second inclined portion 142C are continuous and have the same cylindrical surface shape.

[0144] As can be seen from the above, the first circumferential edge portion 131C includes the first inclined portion 141C and the second inclined portion 142C as inclined portions which are formed to be inclined with respect to the axial direction of the tube portion 72C and serve as the first end portion of the tube portion 72C in the axial direction to form the edge 101C.

[0145] The edge 101C of the communication hole 91C is formed such that a first end portion of the cylindrical portion 72C in the axial direction is thinner than a second end portion of the cylindrical portion 72C in the axial direction.

[0146] The bumper cover 13C having the above-described shape is formed by injection molding of a synthetic resin material or die casting of an aluminum alloy material, similarly to the bumper cover 13. In either the case of injection molding or die casting, the bumper cover 13C is formed by making the cavity of the cover portion 70 (see Figure 2 ) through hole 81 (refer to Figure 2 ) portion becomes the entrance of the material. And, if the material is caused to flow into the cavity from the entrance, the material flows in a manner that expands radially outward in the space portion forming the cover portion 70 of the cavity, and then flows in a direction away from the space portion forming the cover portion 70 in the axial direction of the cylinder portion 72C in the space portion forming the cylinder portion 72C of the cavity. That is, the material flows in the space portion forming the cylinder portion 72C of the cavity from the second end side to the first end side in the axial direction of the cylinder portion 72C.

[0147] The edge 101C of the communicating hole 91C is formed so that the first circumferential edge 131C constituting the first end portion located on the downstream side where the material flows in during molding is thinner than the second circumferential edge 132B side constituting the second end portion located on the upstream side. In other words, the communicating hole 91C of the buffer cover 13C is formed so that the first end portion located on the downstream side where the material flows in during molding is thinner than the second end portion located on the upstream side. In addition, the edge 101C of the communicating hole 91C of the buffer cover 13C is formed so that the second circumferential edge 132B, which is the end portion on the upstream side of the material flowing in during molding, is substantially perpendicular to the flow of the material. The first end portion of the communicating hole 91C of the buffer cover 13C located on the downstream side in the flow direction of the material during molding is a tapered shape that becomes thinner toward the downstream side.

[0148] The edge 101C of the communication hole 91C provided in the cylinder 72C of the buffer cover 13C of the fourth embodiment is formed such that the first end portion located on the downstream side where the material flows in during molding is thinner than the second end portion located on the upstream side. Therefore, the buffer cover 13C can increase the confluence angle when the materials flowing on both sides of the mold portion forming the communication hole 91C merge on the downstream side, and can make the materials merge smoothly. As a result, the buffer cover 13C can suppress the strength reduction caused by the surface defects, i.e., weld lines, which appear as grooves or patterns on the surface at the part where the materials merge. Therefore, the durability of the buffer cover 13C can be improved.

[0149] Note that, in the edge 101C of the communicating hole 91C of the shock absorber cover 13C, the portion on the second end side including the second circumferential edge 132B can be mirror-symmetrical with respect to the portion on the first end side including the first circumferential edge 131C.

[0150] [Fifth Embodiment]

[0151] Mainly based on Figure 8 The fifth embodiment of the present invention will be described with the focus on the differences from the first embodiment. It should be noted that the same parts as those in the first embodiment are denoted by the same names and reference numerals.

[0152] In a fifth embodiment, if Figure 8 As shown in FIG. 1 , a buffer cover 13D that is partially different from the buffer cover 13 of the first embodiment is used instead of the buffer cover 13. The buffer cover 13D includes a cylinder portion 72D that is partially different from the cylinder portion 72, instead of the cylinder portion 72. The cylinder portion 72D includes a connecting hole 91D that is partially different from the connecting hole 91, instead of the connecting hole 91. The connecting hole 91D connects the outer peripheral surface 72Db of the cylinder portion 72D with the inner peripheral surface (not shown). Here, in the buffer cover 13D, the axial direction of the cylinder portion 72D is also connected to the cover portion 70 (see FIG. 1 ). Figure 2 ) is set as the first end side, and the cover 70 side of the cylinder 72D in the axial direction is set as the second end side. In addition, in the communicating hole 91D, the end of the cylinder 72D on the opposite side of the cover 70 in the axial direction is set as the first end, and the end of the cylinder 72D on the cover 70 side in the axial direction is set as the second end.

[0153] The edge 101D of the communication hole 91D is in the shape of a closed ring.

[0154] The edge 101D has a first axial edge 102D and a second axial edge 103D as axial edges extending in the axial direction of the cylinder 72D. The first axial edge 102D and the second axial edge 103D align the axial position of the cylinder 72D and are separated in the circumferential direction of the cylinder 72D to be mirror-symmetrical.

[0155] The first axial edge 102D includes an inner surface 102Da facing the space in the communicating hole 91D and extending in the axial direction of the cylinder 72D. The first axial edge 102D includes an inner surface 102Da and is curved in a shape having a center with a radius of curvature on the second axial edge 103D side in the circumferential direction of the cylinder 72D. The inner surface 102Da of the first axial edge 102D is also curved along the radial direction of the cylinder 72D.

[0156] The second axial edge 103D includes an inner surface 103Da facing the space in the connecting hole 91D and extending in the axial direction of the cylinder 72D. The second axial edge 103D includes an inner surface 103Da that is curved in a center having a radius of curvature on the first axial edge 102D side in the circumferential direction of the cylinder 72D. The inner surface 103Da of the second axial edge 103D is also curved along the radial direction of the cylinder 72D. The second axial edge 103D is aligned with the first axial edge 102D in the axial direction of the cylinder 72D, and is separated in the circumferential direction of the cylinder 72D to be mirror-symmetrical.

[0157] The edge 101D has a first circumferential edge 131D and a second circumferential edge 132D as circumferential edges extending in the circumferential direction of the cylinder 72D. The edge 101D has the first circumferential edge 131D at an end portion on the first end side in the axial direction of the cylinder 72D. The edge 101D has the second circumferential edge 132D at an end portion on the second end side in the axial direction of the cylinder 72D. The first circumferential edge 131D and the second circumferential edge 132D are mirror-symmetrical.

[0158] The first circumferential edge portion 131D is mirror-symmetrical and has a first inclined portion 141D and a second inclined portion 142D.

[0159] The first inclined portion 141D is formed to extend obliquely from one end of the first axial edge portion 102D on the first end side of the cylinder portion 72D in the axial direction relative to the first axial edge portion 102D of the first axial edge portion 102D. The first inclined portion 141D includes an inner surface 141Da facing the space in the communicating hole 91D, and is curved with a center having a radius of curvature on the second axial edge portion 103D side in the circumferential direction of the cylinder portion 72D. The inner surface 141Da of the first inclined portion 141D is also curved along the radial direction of the cylinder portion 72D.

[0160] The first inclined portion 141D extends from one end of the first axial edge portion 102D on the first end side of the barrel portion 72D in the axial direction toward the first end side of the barrel portion 72D in the axial direction. Moreover, the closer the first inclined portion 141D is to the first end side in the axial direction of the barrel portion 72D, the closer it is to the second axial edge portion 103D in the circumferential direction of the barrel portion 72D. The inner surface 141Da of the first inclined portion 141D extends from one end of the inner surface 102Da of the first axial edge portion 102D on the first end side of the barrel portion 72D in the axial direction toward the first end side of the barrel portion 72D in the axial direction. Moreover, the closer the inner surface 141Da of the first inclined portion 141D is to the first end side in the axial direction of the barrel portion 72D, the closer it is to the second axial edge portion 103D in the circumferential direction of the barrel portion 72D.

[0161] The second inclined portion 142D is formed to extend obliquely from one end of the second axial edge portion 103D on the first end side of the cylinder portion 72D in the axial direction relative to the second axial edge portion 103D of the second axial edge portion 103D. The second inclined portion 142D includes an inner surface 142Da facing the space in the communicating hole 91D, and is curved with a center having a radius of curvature on the first axial edge portion 102D side in the circumferential direction of the cylinder portion 72D. The inner surface 142Da of the second inclined portion 142D is also curved along the radial direction of the cylinder portion 72D.

[0162] The second inclined portion 142D extends from one end of the second axial edge portion 103D on the first end side of the cylinder 72D in the axial direction toward the first end side of the cylinder 72D in the axial direction. Moreover, the closer the second inclined portion 142D is to the first end side in the axial direction of the cylinder 72D, the closer it is to the first axial edge portion 102D in the circumferential direction of the cylinder 72D. The inner surface 142Da of the second inclined portion 142D extends from one end of the inner surface 103Da of the second axial edge portion 103D on the first end side of the cylinder 72D in the axial direction toward the first end side of the cylinder 72D in the axial direction. Moreover, the closer the inner surface 142Da of the second inclined portion 142D is to the first axial edge portion 102D in the circumferential direction of the cylinder 72D, the closer it is to the first axial edge portion 102D in the circumferential direction of the cylinder 72D. The second inclined portion 142D is aligned with the first inclined portion 141D in the axial direction of the cylinder 72D, and is mirror-symmetrical.

[0163] The second circumferential edge portion 132D is mirror-symmetrical and has a third inclined portion 151D and a fourth inclined portion 152D.

[0164] The third inclined portion 151D is formed to extend obliquely relative to the first axial edge portion 102D from one end of the first axial edge portion 102D on the second end side of the cylinder portion 72D in the axial direction. The third inclined portion 151D includes an inner surface 151Da facing the space in the communicating hole 91D, and is curved with a center having a radius of curvature on the second axial edge portion 103D side in the circumferential direction of the cylinder portion 72D. The inner surface 151Da of the third inclined portion 151D is also curved along the radial direction of the cylinder portion 72D.

[0165] The third inclined portion 151D extends from one end of the first axial edge portion 102D on the second end side of the cylinder 72D in the axial direction toward the second end side of the cylinder 72D in the axial direction. Moreover, the closer the third inclined portion 151D is to the second end side in the axial direction of the cylinder 72D, the closer it is to the second axial edge portion 103D in the circumferential direction of the cylinder 72D. The inner surface 151Da of the third inclined portion 151D extends from one end of the inner surface 102Da of the first axial edge portion 102D on the second end side of the cylinder 72D in the axial direction toward the second end side of the cylinder 72D in the axial direction. Moreover, the closer the inner surface 151Da of the third inclined portion 151D is to the second axial edge portion 103D in the circumferential direction of the cylinder 72D, the closer it is to the second axial edge portion 103D in the circumferential direction of the cylinder 72D.

[0166] The fourth inclined portion 152D is formed to extend obliquely relative to the second axial edge portion 103D from one end of the second axial edge portion 103D on the second end side of the cylinder portion 72D in the axial direction. The fourth inclined portion 152D includes an inner surface 152Da facing the space in the communicating hole 91D, and is curved with a center having a radius of curvature on the first axial edge portion 102D side in the circumferential direction of the cylinder portion 72D. The inner surface 152Da of the fourth inclined portion 152D is also curved along the radial direction of the cylinder portion 72D.

[0167] The fourth inclined portion 152D extends from one end of the second axial edge portion 103D on the second end side of the cylinder 72D in the axial direction to the direction of the second end side of the cylinder 72D in the axial direction. Moreover, the closer the fourth inclined portion 152D is to the second end side in the axial direction of the cylinder 72D, the closer it is to the first axial edge portion 102D in the circumferential direction of the cylinder 72D. The inner surface 152Da of the fourth inclined portion 152D extends from one end of the inner surface 103Da of the second axial edge portion 103D on the second end side of the cylinder 72D in the axial direction to the second end side of the cylinder 72D in the axial direction. Moreover, the closer the inner surface 152Da of the fourth inclined portion 152D is to the first axial edge portion 102D in the circumferential direction of the cylinder 72D, the closer it is to the second end side in the axial direction of the cylinder 72D. The fourth inclined portion 152D is aligned with the third inclined portion 151D in the axial direction of the cylinder 72D, and is mirror-symmetrical.

[0168] The first axial edge 102D, the second axial edge 103D, the first inclined portion 141D, the second inclined portion 142D, the third inclined portion 151D, and the fourth inclined portion 152D are continuous and identical elliptical shapes. The inner surface 102Da, the inner surface 103Da, the inner surface 141Da, the inner surface 142Da, the inner surface 151Da, and the inner surface 152Da are continuous and identical elliptical shapes.

[0169] As can be seen from the above, the first circumferential edge 131D includes the first inclined portion 141D and the second inclined portion 142D as inclined portions that are formed to be inclined relative to the axial direction of the cylinder 72D and form the first end portion of the cylinder 72D in the axial direction of the edge 101D. The second circumferential edge 132D includes the third inclined portion 151D and the fourth inclined portion 152D as inclined portions that are formed to be inclined relative to the axial direction of the cylinder 72D and form the second end portion of the cylinder 72D in the axial direction of the edge 101D.

[0170] The bumper cover 13D having the above-mentioned shape is formed by injection molding of synthetic resin material or die casting of aluminum alloy material, similarly to the bumper cover 13. In either case of injection molding or die casting, the bumper cover 13D is formed by making the cavity of the cover portion 70 (see Figure 2 ) through hole 81 (refer to Figure 2 ) portion becomes the inlet of the material. And, if the material is caused to flow into the cavity from the inlet, the material flows in a manner that expands outward in the radial direction of the cover portion 70 in the space portion forming the cover portion 70 of the cavity, and then flows in a direction away from the space portion forming the cover portion 70 in the axial direction of the cylinder portion 72D in the space portion forming the cylinder portion 72D of the cavity. That is, the material flows in the space portion forming the cylinder portion 72D of the cavity from the second end side to the first end side in the axial direction of the cylinder portion 72D.

[0171] In the buffer cover 13D of the fifth embodiment, the first circumferential edge 131D of the edge 101D of the communicating hole 91D extending in the circumferential direction of the cylinder 72D includes a first inclined portion 141D and a second inclined portion 142D which are formed to be inclined with respect to the axial direction of the cylinder 72D and serve as the axial end of the cylinder 72D of the edge 101D. Therefore, the buffer cover 13D can increase the merging angle when the materials flowing on both sides in the circumferential direction of the cylinder 72D of the die forming the communicating hole 91D merge on the first circumferential edge 131D side by causing the materials to flow in the axial direction of the cylinder 72D, and can make the materials merge smoothly. As a result, the buffer cover 13D can suppress the strength reduction caused by the generation of surface defects, i.e., weld lines, which appear as grooves or patterns on the surface at the portion where the materials merge. Therefore, the durability of the buffer cover 13D can be improved.

[0172] In addition, the buffer cover 13D includes a first axial edge 102D and a second axial edge 103D as axial edges extending in the axial direction of the cylinder 72D. In addition, the buffer cover 13D includes a first inclined portion 141D formed to extend obliquely from one axial end of the first axial edge 102D and a second inclined portion 142D formed to extend obliquely from one axial end of the second axial edge 103D as inclined portions formed to be inclined relative to the axial direction of the cylinder 72D. Therefore, the buffer cover 13D can reduce the angle difference between the angle formed by the first axial edge 102D and the first inclined portion 141D and the angle formed by the second axial edge 103D and the second inclined portion 142D. Thus, the buffer cover 13D can reduce the speed difference of the flow speed of the material flowing on both sides of the cylinder 72D in the circumferential direction of the mold portion forming the communicating hole 91D by allowing the material to flow in the axial direction of the cylinder 72D, and can make the materials merge more smoothly. Therefore, the durability of the bumper cover 13D can be further improved.

[0173] In addition, in the buffer cover 13D, the first inclined portion 141D and the second inclined portion 142D are provided at the first end portion in the axial direction of the cylinder portion 72D. Therefore, the buffer cover 13D can increase the merging angle when the materials flowing toward the first end portion side on both sides in the circumferential direction of the cylinder portion 72D of the mold portion forming the communicating hole 91D merge by allowing the materials to flow in the axial direction of the cylinder portion 72D, and can make the materials merge smoothly. Therefore, the durability of the buffer cover 13D can be improved.

[0174] In addition, in the buffer cover 13D, the first inclined portion 141D and the second inclined portion 142D are provided on the first end side of the cylindrical portion 72D in the axial direction, and the third inclined portion 151D and the fourth inclined portion 152D are provided on the second end side of the cylindrical portion 72D in the axial direction. Moreover, in the buffer cover 13D, the first inclined portion 141D and the second inclined portion 142D and the third inclined portion 151D and the fourth inclined portion 152D are formed symmetrically. Therefore, the buffer cover 13D can make the material flow smoothly around the mold portion forming the communication hole 91D. Therefore, the durability of the buffer cover 13D can be improved.

[0175] [Sixth Embodiment]

[0176] Mainly based on Fig. 9 The sixth embodiment of the present invention will be described with the focus on the parts that are different from the third embodiment. It should be noted that the parts common to the third embodiment are denoted by the same names and the same reference numerals.

[0177] In the sixth embodiment, if Fig. 9As shown, the buffer cover 13B of the third embodiment is replaced with a buffer cover 13E that is partially different from the buffer cover 13B. The buffer cover 13E has a barrel portion 72E that is partially different from the barrel portion 72B instead of the barrel portion 72B. The barrel portion 72E has a connecting hole 91E that is partially different from the connecting hole 91B instead of the connecting hole 91B. The connecting hole 91E connects the outer peripheral surface 72Eb of the barrel portion 72E with the inner peripheral surface (not shown). Here, in the buffer cover 13E, the axial direction of the barrel portion 72E is also connected to the cover portion 70 (see Figure 2 ) is set as the first end side, and the cover 70 side of the cylinder 72E in the axial direction is set as the second end side. In addition, in the communicating hole 91E, the end of the cylinder 72E on the opposite side of the cover 70 in the axial direction is set as the first end, and the end of the cylinder 72E on the cover 70 side in the axial direction is set as the second end.

[0178] The edge 101E of the communicating hole 91E has a first axial edge 102E that is partially different from the first axial edge 102B. The first axial edge 102E is different from the first axial edge 102B in that the length of the cylinder 72E in the axial direction is longer than the first axial edge 102B. The inner surface 102Ea of the first axial edge 102E facing the space in the communicating hole 91E is also different in that the length of the cylinder 72E in the axial direction is longer than the inner surface 102Ba of the first axial edge 102B.

[0179] The edge 101E of the connecting hole 91E has a first circumferential edge 131E (inclined portion) instead of the first circumferential edge 131B. The first circumferential edge 131E is formed to extend obliquely from one end of the second axial edge 103B on the first end side of the cylinder 72E in the axial direction toward the second axial edge 103B. The end of the first circumferential edge 131E on the opposite side of the second axial edge 103B is connected to one end of the first axial edge 102E on the first end side of the cylinder 72E in the axial direction. The first circumferential edge 131E includes an inner surface 131Ea facing the space in the connecting hole 91E and is linear inside. The inner surface 131Ea is also planar along the radial direction of the cylinder 72E.

[0180] The first circumferential edge 131E extends from one end of the second axial edge 103B on the first end side of the barrel 72E in the axial direction toward the first end side of the barrel 72E in the axial direction. Moreover, the closer the first circumferential edge 131E is located to the first end side in the axial direction of the barrel 72E, the closer it is to the first axial edge 102E in the circumferential direction of the barrel 72E. The inner surface 131Ea of the first circumferential edge 131E extends from one end of the inner surface 103Ba of the second axial edge 103B on the first end side of the barrel 72E in the axial direction toward the first end side of the barrel 72E in the axial direction. Moreover, the closer the inner surface 131Ea of the first circumferential edge 131E is located to the first end side in the axial direction of the barrel 72E, the closer it is to the first axial edge 102E in the circumferential direction of the barrel 72E and the inner surface 102Ea is connected to the inner surface 102Ea.

[0181] As can be seen from the above, the first circumferential edge portion 131E is an inclined portion formed to be inclined with respect to the axial direction of the tube portion 72E and is located on the first end side of the tube portion 72E in the axial direction and serves as the edge 101E.

[0182] The edge 101E of the communication hole 91E is formed such that a first end portion of the cylindrical portion 72E in the axial direction is thinner than a second end portion of the cylindrical portion 72E in the axial direction.

[0183] The bumper cover 13E having the shape described above is formed by injection molding of a synthetic resin material or die casting of an aluminum alloy material, similarly to the bumper cover 13. In either the case of injection molding or die casting, similarly to the bumper cover 13, the cavity is formed so that the cover portion 70 (see Figure 2 ) through hole 81 (refer to Figure 2 ) portion becomes the entrance of the material. And, if the material is caused to flow into the cavity from the entrance, the material flows in a manner that expands outward in the radial direction of the cover portion 70 in the space portion forming the cover portion 70 of the cavity, and then flows in a direction away from the space portion forming the cover portion 70 in the axial direction of the cylinder portion 72E in the space portion forming the cylinder portion 72E of the cavity. That is, the material flows from the second end side to the first end side in the axial direction of the cylinder portion 72E in the space portion forming the cylinder portion 72E of the cavity.

[0184] The edge 101E of the communicating hole 91E is formed so that the portion on the first circumferential edge 131E side constituting the first end portion located on the downstream side where the material flows in during molding is thinner than the portion on the second circumferential edge 132B side constituting the second end portion located on the upstream side. In other words, the communicating hole 91E of the buffer cover 13E is formed so that the first end portion located on the downstream side where the material flows in during molding is thinner than the second end portion located on the upstream side. In addition, the edge 101E of the communicating hole 91E of the buffer cover 13E is formed so that the second circumferential edge 132B, which is the end portion on the upstream side of the material flowing in during molding, is substantially perpendicular to the flow of the material. The first end portion of the communicating hole 91E of the buffer cover 13E located on the downstream side in the flow direction of the material during molding is a tapered shape that becomes thinner toward the downstream side.

[0185] The edge 101E of the communication hole 91E provided in the cylinder 72E of the buffer cover 13E of the sixth embodiment is formed such that the first end portion located on the downstream side where the material flows in during molding is thinner than the second end portion located on the upstream side. Therefore, the buffer cover 13E can increase the merging angle when the materials flowing on both sides of the mold portion forming the communication hole 91E merge on the downstream side, and can make the materials merge smoothly. As a result, the buffer cover 13E can suppress the strength reduction caused by the surface defects, that is, weld lines, which appear on the surface as grooves or patterns at the part where the materials merge. Therefore, the durability of the buffer cover 13E can be improved.

[0186] It should be noted that, in the edge 101E of the communicating hole 91E of the buffer cover 13E, the portion on the second end side including the second circumferential edge 132B can also be mirror-symmetrical or point-symmetrical with respect to the portion on the first end side including the first circumferential edge 131E.

[0187] [Seventh Embodiment]

[0188] Mainly based on Fig.10 The seventh embodiment of the present invention will be described with the focus on the parts that are different from the sixth embodiment. It should be noted that the parts common to the sixth embodiment are denoted by the same names and the same reference numerals.

[0189] In the seventh embodiment, if Fig.10 As shown, the buffer cover 13E of the sixth embodiment is replaced with a buffer cover 13F that is partially different from the buffer cover 13E. The buffer cover 13F has a cylinder 72F that is partially different from the cylinder 72E instead of the cylinder 72E. The cylinder 72F has a connecting hole 91F that is partially different from the connecting hole 91E instead of the connecting hole 91E. The connecting hole 91F connects the outer peripheral surface 72Fb of the cylinder 72F and the inner peripheral surface (not shown) of the cylinder 72F. Here, in the buffer cover 13F, the axial direction of the cylinder 72F is also connected to the cover 70 (see Figure 2) is set as the first end side, and the cover 70 side of the cylinder 72F in the axial direction is set as the second end side. In addition, in the communicating hole 91F, the end of the cylinder 72F on the opposite side of the cover 70 in the axial direction is set as the first end, and the end of the cylinder 72F on the cover 70 side in the axial direction is set as the second end.

[0190] The edge 101F of the connecting hole 91F has a first circumferential edge 131F (inclined portion) instead of the first circumferential edge 131E. The first circumferential edge 131F is formed to extend obliquely relative to the second axial edge 103B from one end on the axial first end side of the cylinder 72E of the second axial edge 103B. The end of the first circumferential edge 131F on the opposite side of the second axial edge 103B is connected to one end on the axial first end side of the cylinder 72F of the first axial edge 102E. The first circumferential edge 131F includes an inner surface 131Fa facing the space in the connecting hole 91F and is arc-shaped inside. The inner surface 131Fa is also cylindrical along the radial direction of the cylinder 72F.

[0191] The first circumferential edge 131F extends from one end of the second axial edge 103B on the first end side of the cylinder 72F in the axial direction toward the first end side of the cylinder 72F in the axial direction. Moreover, the closer the first circumferential edge 131F is located to the first end side in the axial direction of the cylinder 72F, the closer it is to the first axial edge 102E in the circumferential direction of the cylinder 72F. The inner surface 131Fa of the first circumferential edge 131F extends from one end of the inner surface 103Ba of the second axial edge 103B on the first end side of the cylinder 72F in the axial direction toward the first end side of the cylinder 72F in the axial direction. Moreover, the closer the inner surface 131Fa of the first circumferential edge 131F is located to the first end side in the circumferential direction of the cylinder 72F, the closer it is to the first axial edge 102E in the circumferential direction of the cylinder 72F and the inner surface 102Ea is connected.

[0192] As can be seen from the above, the first circumferential edge portion 131F is an inclined portion formed to be inclined with respect to the axial direction of the tube portion 72F and located on the first end side of the tube portion 72F in the axial direction, which serves as the edge 101F.

[0193] The edge 101F of the communication hole 91F is formed such that a first end portion of the cylindrical portion 72F in the axial direction is thinner than a second end portion of the cylindrical portion 72F in the axial direction.

[0194] The bumper cover 13F having the shape described above is formed by injection molding of a synthetic resin material or die casting of an aluminum alloy material, similarly to the bumper cover 13. In either the case of injection molding or die casting, similarly to the bumper cover 13, the cavity is formed so that the cover portion 70 of the bumper cover 13F (see Figure 2) through hole 81 (refer to Figure 2 ) portion becomes the entrance of the material. And, if the material is made to flow into the cavity from the entrance, the material flows in the space portion forming the cover portion 70 of the cavity in a manner that expands radially outward of the cover portion 70, and then flows in the space portion forming the cylinder portion 72E of the cavity in a direction away from the space portion forming the cover portion 70 in the axial direction of the cylinder portion 72F. That is, the material flows in the space portion forming the cylinder portion 72F of the cavity from the second end side to the first end side in the axial direction of the cylinder portion 72F.

[0195] The edge 101F of the communicating hole 91F is formed so that the portion on the first circumferential edge 131F side constituting the first end portion located on the downstream side where the material flows in during molding is thinner than the portion on the second circumferential edge 132B side constituting the second end portion located on the upstream side. In other words, the communicating hole 91F of the buffer cover 13F is formed so that the first end portion located on the downstream side where the material flows in during molding is thinner than the second end portion located on the upstream side. In addition, the edge 101F of the communicating hole 91F of the buffer cover 13F is formed so that the second circumferential edge 132B, which is the end portion on the upstream side of the material flowing in during molding, is substantially perpendicular to the flow of the material. The first end portion of the communicating hole 91F of the buffer cover 13F located on the downstream side in the flow direction of the material during molding is a tapered shape that becomes thinner toward the downstream side.

[0196] The edge 101F of the communication hole 91F provided in the cylinder 72F of the buffer cover 13F of the seventh embodiment is formed such that the first end portion located on the downstream side where the material flows in during molding is thinner than the second end portion located on the upstream side. Therefore, the buffer cover 13F can increase the merging angle when the materials flowing on both sides of the mold portion forming the communication hole 91F merge on the downstream side, and can make the materials merge smoothly. As a result, the buffer cover 13F can suppress the strength reduction caused by the surface defects, that is, weld lines, which appear as grooves or patterns on the surface at the part where the materials merge. Therefore, the durability of the buffer cover 13F can be improved.

[0197] It should be noted that, in the edge 101F of the communicating hole 91F of the buffer cover 13F, the second end portion including the second circumferential edge 132B can also be mirror-symmetrical or point-symmetrical with respect to the first end portion including the first circumferential edge 131F.

[0198] [Eighth Embodiment]

[0199] Mainly based on Fig.11 The eighth embodiment of the present invention will be described with the focus on the parts that are different from the first embodiment. It should be noted that the parts that are common to the first embodiment are denoted by the same names and the same reference numerals.

[0200] In an eighth embodiment, if Fig.11 As shown, a partially different buffer cover 13G is used instead of the buffer cover 13 of the first embodiment. The buffer cover 13G has a cylindrical portion 72G that is partially different from the cylindrical portion 72 instead of the cylindrical portion 72. The cylindrical portion 72G has a communicating hole 91G that is partially different from the communicating hole 91 instead of the communicating hole 91. The communicating hole 91G connects the outer peripheral surface 72Gb of the cylindrical portion 72G and the inner peripheral surface (not shown).

[0201] The edge 101G of the communication hole 91G has a first axial edge 102G that is partially different from the first axial edge 102 instead of the first axial edge 102. The edge 101G has a second axial edge 103G that is partially different from the second axial edge 103 instead of the second axial edge 103. Here, in the shock absorber cover 13G, the axial direction of the cylinder 72G is also aligned with the cover 70 (see Figure 2 ) is set as the first end side, and the cover 70 side of the cylinder 72G in the axial direction is set as the second end side. In addition, in the communicating hole 91G, the end of the cylinder 72G on the opposite side of the cover 70 in the axial direction is set as the first end, and the end of the cylinder 72G on the cover 70 side in the axial direction is set as the second end.

[0202] The first axial edge portion 102G does not have the first chamfered portion 112 . The second axial edge portion 103G does not have the third chamfered portion 122 .

[0203] The edge 101B has a first circumferential edge portion 131G instead of the first circumferential edge portion 131. The first circumferential edge portion 131G has a first inclined portion 141G instead of the first inclined portion 141, and has a second inclined portion 142G instead of the second inclined portion 142. The first circumferential edge portion 131G does not have the fifth chamfered portion 143.

[0204] The first inclined portion 141G is formed to extend obliquely from one end of the first axial edge portion 102G on the first end side of the barrel portion 72G in the axial direction relative to the first straight portion 111 of the first axial edge portion 102G. The first inclined portion 141G includes an inner surface 141Ga facing the space in the connecting hole 91G, which is in the shape of an arc inside. The first inclined portion 141G includes an inner surface 141Ga, which is in the shape of an arc inside and has a center at the second end side of the barrel portion 72G in the axial direction relative to the inner surface 141Ga. The inner surface 141Ga of the first inclined portion 141G is also in the shape of a cylindrical surface along the radial direction of the barrel portion 72G.

[0205] The first inclined portion 141G extends from one end of the first axial edge portion 102G on the first end side of the barrel portion 72G in the axial direction toward the first end side of the barrel portion 72G in the axial direction. Moreover, the closer the first inclined portion 141G is to the first end side in the axial direction of the barrel portion 72G, the closer it is to the second axial edge portion 103G in the circumferential direction of the barrel portion 72G. The inner surface 141Ga of the first inclined portion 141G extends from one end of the inner surface 111a of the first straight portion 111 on the first end side of the barrel portion 72G in the axial direction toward the first end side of the barrel portion 72G in the axial direction. Moreover, the closer the inner surface 141Ga of the first inclined portion 141G is to the first end side in the axial direction of the barrel portion 72G, the closer it is to the second axial edge portion 103G in the circumferential direction of the barrel portion 72G.

[0206] The second inclined portion 142G is formed to extend obliquely from one end of the second axial edge portion 103G on the first end side of the barrel portion 72G in the axial direction relative to the second straight line portion 121 of the second axial edge portion 103G. The second inclined portion 142G includes an inner surface 142Ga facing the space in the connecting hole 91G, which is in an arc shape inside. The second inclined portion 142G includes an inner surface 142Ga, which is in an arc shape having a center at the second end side of the barrel portion 72G in the axial direction relative to the inner surface 142Ga. The inner surface 142Ga of the second inclined portion 142G is also in a cylindrical surface shape along the radial direction of the barrel portion 72G.

[0207] The second inclined portion 142G extends from one end of the second axial edge portion 103G on the first end side of the barrel 72G in the axial direction toward the first end side of the barrel 72G in the axial direction. Moreover, the closer the second inclined portion 142G is to the first end side in the axial direction of the barrel 72G, the closer it is to the first axial edge portion 102G in the circumferential direction of the barrel 72G. The inner surface 142Ga of the second inclined portion 142G extends from one end of the inner surface 121a of the second straight line portion 121 of the second axial edge portion 103G on the first end side of the barrel 72G in the axial direction toward the first end side of the barrel 72G in the axial direction. Moreover, the closer the inner surface 142Ga of the second inclined portion 142G is to the first axial edge portion 102G in the circumferential direction of the barrel 72G, the closer it is to the first axial edge portion 102G in the circumferential direction of the barrel 72G. The second inclined portion 142G is aligned with the first inclined portion 141G in the axial direction of the barrel 72G, and is mirror-symmetrical. The inner surface 141Ga of the first inclined portion 141G and the inner surface 142Ga of the second inclined portion 142G are continuous and identical cylindrical surfaces.

[0208] As can be seen from the above, the first circumferential edge portion 131G includes the first inclined portion 141G and the second inclined portion 142G as inclined portions which are formed to be inclined with respect to the axial direction of the tube portion 72G and serve as the first end portion of the tube portion 72G in the axial direction to form the edge 101G.

[0209] The edge 101G of the communication hole 91G is formed such that a first end portion of the cylindrical portion 72G in the axial direction is thinner than a second end portion of the cylindrical portion 72G in the axial direction.

[0210] The bumper cover 13G having the shape described above is formed by injection molding of a synthetic resin material or die casting of an aluminum alloy material, similarly to the bumper cover 13. In either the case of injection molding or die casting, similarly to the bumper cover 13, the cavity is formed so that the cover portion 70 (see Figure 2 ) through hole 81 (refer to Figure 2 ) portion becomes the entrance of the material. And, if the material is caused to flow into the cavity from the entrance, the material flows in a manner that expands radially outward in the space portion forming the cover portion 70 of the cavity, and then flows in a direction away from the space portion forming the cover portion 70 in the axial direction of the cylinder portion 72G in the space portion forming the cylinder portion 72G of the cavity. That is, the material flows in the space portion forming the cylinder portion 72G of the cavity from the second end side toward the first end side in the axial direction of the cylinder portion 72G.

[0211] The edge 101G of the communicating hole 91G is formed such that the first circumferential edge 131G constituting the first end portion located on the downstream side where the material flows in during molding is thinner than the second circumferential edge 132G side constituting the second end portion located on the upstream side. In other words, the communicating hole 91G of the buffer cover 13G is formed such that the first end portion located on the downstream side where the material flows in during molding is thinner than the second end portion located on the upstream side. In addition, the edge 101G of the communicating hole 91G of the buffer cover 13G is formed such that the second circumferential edge 132G serving as the end portion on the upstream side of the material flowing in during molding is substantially perpendicular to the flow of the material. The first end portion of the communicating hole 91G of the buffer cover 13G located on the downstream side in the flow direction of the material during molding is a tapered shape that becomes thinner toward the downstream side.

[0212] The edge 101G of the communication hole 91G provided in the cylinder 72G of the buffer cover 13G of the eighth embodiment is formed such that the first end portion located on the downstream side where the material flows in during molding is thinner than the second end portion located on the upstream side. Therefore, the buffer cover 13G can increase the merging angle when the materials flowing on both sides of the mold portion forming the communication hole 91G merge on the downstream side, and can make the materials merge smoothly. As a result, the buffer cover 13G can suppress the strength reduction caused by the surface defects, that is, weld lines, which appear on the surface as grooves or patterns at the part where the materials merge. Therefore, the durability of the buffer cover 13G can be improved.

[0213] Note that, in the edge 101G of the communicating hole 91G of the shock absorber cover 13G, the portion on the second end side including the second circumferential edge 132 can be mirror-symmetrical with respect to the portion on the first end side including the first circumferential edge 131G.

[0214] [Ninth Embodiment]

[0215] Mainly based on Fig.12 The ninth embodiment of the present invention will be described with the focus on the parts that are different from the third embodiment. It should be noted that the parts common to the third embodiment are denoted by the same names and the same reference numerals.

[0216] In the ninth embodiment, if Fig.12 As shown, the buffer cover 13B of the third embodiment is replaced with a buffer cover 13H that is partially different from the buffer cover 13B. The buffer cover 13H has a cylinder 72H that is partially different from the cylinder 72B instead of the cylinder 72B. The cylinder 72H has a connecting hole 91H that is partially different from the connecting hole 91B instead of the connecting hole 91B. The connecting hole 91H connects the outer peripheral surface 72Hb of the cylinder 72H with the inner peripheral surface (not shown). Here, in the buffer cover 13H, the axial direction of the cylinder 72H is also connected to the cover 70 (see Figure 2 ) is set as the first end side, and the cover 70 side of the cylinder 72H in the axial direction is set as the second end side. In addition, in the communicating hole 91H, the end of the cylinder 72H on the opposite side of the cover 70 in the axial direction is set as the first end, and the end of the cylinder 72H on the cover 70 side in the axial direction is set as the second end.

[0217] The first axial edge 102B and the second axial edge 103B are not provided on the edge 101H of the communicating hole 91H. The edge 101H has a first circumferential edge 131H instead of the first circumferential edge 131B. The first circumferential edge 131H has a first inclined portion 141H instead of the first inclined portion 141B, and has a second inclined portion 142H instead of the second inclined portion 142B.

[0218] The first inclined portion 141H extends from one end of the second circumferential edge 132B in the circumferential direction of the cylinder 72H. The first inclined portion 141H includes an inner surface 141Ha facing the space in the connecting hole 91H and is linear. The inner surface 141Ha of the first inclined portion 141H is also flat along the radial direction of the cylinder 72H.

[0219] The first inclined portion 141H extends from one end of the barrel 72H in the circumferential direction of the second circumferential edge 132B toward the direction of the first end in the axial direction of the barrel 72H. Moreover, the closer the first inclined portion 141H is located to the first end in the axial direction of the barrel 72H, the closer it is to the other end of the barrel 72H in the circumferential direction of the barrel 72H of the second circumferential edge 132B in the circumferential direction of the barrel 72H. The inner surface 141Ha of the first inclined portion 141H extends from one end of the barrel 72H in the circumferential direction of the inner surface 132Ba of the second circumferential edge 132B toward the first end in the axial direction of the barrel 72H. Moreover, the closer the inner surface 141Ha of the first inclined portion 141H is located to the first end in the axial direction of the barrel 72H, the closer it is to the other end of the barrel 72H in the circumferential direction of the inner surface 132Ba in the circumferential direction of the barrel 72H.

[0220] The second inclined portion 142H extends from the other end of the second circumferential edge 132B in the circumferential direction of the cylinder 72H. The second inclined portion 142H includes an inner surface 142Ha facing the space in the connecting hole 91H and is linear. The inner surface 142Ha of the second inclined portion 142H is also flat along the radial direction of the cylinder 72H.

[0221] The second inclined portion 142H extends from the other end of the barrel 72H in the circumferential direction of the second circumferential edge 132B toward the direction of the first end of the barrel 72H in the axial direction. Moreover, the closer the second inclined portion 142H is to the first end in the axial direction of the barrel 72H, the closer it is to one end of the barrel 72H in the circumferential direction of the barrel 72H of the second circumferential edge 132B in the circumferential direction of the barrel 72H. The inner surface 142Ha of the second inclined portion 142H extends from the other end of the barrel 72H in the circumferential direction of the inner surface 132Ba of the second circumferential edge 132B toward the first end in the axial direction of the barrel 72H. Moreover, the closer the inner surface 142Ha of the second inclined portion 142H is to the first end in the axial direction of the barrel 72H, the closer it is to one end of the barrel 72H in the circumferential direction of the inner surface 132Ba in the circumferential direction of the barrel 72H, and is connected to the inner surface 141Ha of the first inclined portion 141H. The second inclined portion 142H is aligned with the first inclined portion 141H in the axial direction of the cylinder 72H and is mirror-symmetrical. The angle formed by the inner surface 141Ha of the first inclined portion 141H and the inner surface 142Ha of the second inclined portion 142H is an acute angle.

[0222] As can be seen from the above, the first circumferential edge portion 131H includes the first inclined portion 141H and the second inclined portion 142H as inclined portions which are formed to be inclined with respect to the axial direction of the tube portion 72H and extend over the entire circumferential edge 101H in the axial direction of the tube portion 72H.

[0223] The edge 101H of the communication hole 91H is formed such that a first end portion in the axial direction of the cylindrical portion 72H is thinner than a second end portion in the axial direction of the cylindrical portion 72H.

[0224] The bumper cover 13H of the above shape is formed by injection molding of synthetic resin material or die casting of aluminum alloy material, similarly to the bumper cover 13. In either case of injection molding or die casting, the bumper cover 13H is formed by forming the cover portion 70 (see Figure 2 ) through hole 81 (refer to Figure 2 ) portion becomes the entrance of the material. And, if the material is made to flow into the cavity from the entrance, the material flows in the space portion forming the cover portion 70 of the cavity in a manner that expands outward in the radial direction of the cover portion 70, and then flows in the space portion forming the cylinder portion 72H of the cavity in a direction away from the space portion forming the cover portion 70 in the axial direction of the cylinder portion 72H. That is, the material flows in the space portion forming the cylinder portion 72H of the cavity from the second end side to the first end side in the axial direction of the cylinder portion 72H.

[0225] The edge 101H of the connecting hole 91H is formed so that the first circumferential edge 131H constituting the first end portion located on the downstream side where the material flows in during molding is thinner than the second circumferential edge 132H side constituting the second end portion located on the upstream side. In other words, the connecting hole 91H of the buffer cover 13H is formed so that the first end portion located on the downstream side where the material flows in during molding is thinner than the second end portion located on the upstream side. In addition, the edge 101H of the connecting hole 91H of the buffer cover 13H is formed so that the second circumferential edge 132B, which is the end portion on the upstream side of the material flowing in during molding, is substantially perpendicular to the flow of the material. The connecting hole 91H of the buffer cover 13H has a tapered shape that becomes thinner as it is located on the downstream side in the flow direction of the material during molding.

[0226] The edge 101H of the communication hole 91H provided in the cylinder 72H of the buffer cover 13H of the ninth embodiment is formed such that the first end portion located on the downstream side where the material flows in during molding is thinner than the second end portion located on the upstream side. Therefore, the buffer cover 13H can increase the confluence angle when the materials flowing on both sides of the mold portion forming the communication hole 91H merge on the downstream side, and can make the materials merge smoothly. As a result, the buffer cover 13H can suppress the strength reduction caused by the surface defects, i.e., weld lines, which appear on the surface as grooves or patterns at the part where the materials merge. Therefore, the durability of the buffer cover 13H can be improved.

[0227] It should be noted that, in the edge 101H of the communication hole 91H of the shock absorber cover 13H, the second circumferential edge portion 132B can also be made mirror-symmetrical with respect to the first circumferential edge portion 131H.

[0228] Industrial Applicability

[0229] According to the above aspects of the present invention, a bumper cover and a bumper capable of improving durability can be provided, thereby having high industrial applicability.

[0230] Description of Reference Numerals

[0231] 11…buffer, 13, 13A to 13H…buffer cover, 21…cylinder body, 32b…axial end surface, 40…piston, 50…piston rod, 70…cover portion, 72, 72A to 72E…cylinder portion, 72a…inner peripheral surface, 72b, 72Ab to 72Hb…outer peripheral surface, 81…through hole, 91, 91A to 91H…communication hole, 101, 101A to 101H…edge, 102, 102A, 102B, 102D, 102E… The first axial edge, 103, 103A, 103B, 103D...the second axial edge, 112, 112A...the first chamfered portion, 113, 113A...the second chamfered portion, 122, 122A...the third chamfered portion, 123, 123A...the fourth chamfered portion, 131, 131A~131H...the first circumferential edge, 141, 141D...the first inclined portion, 142, 142D...the second inclined portion, 143, 143A...the fifth chamfered portion.

Claims

1. A buffer cover used in a buffer, the buffer comprising: a cylinder; a piston disposed in the cylinder; a piston rod, a first end of which is connected to the piston and a second end of which extends from the cylinder; The buffer cover is disposed at the end of the cylinder body on the side from which the piston rod extends, and is formed by die casting or injection molding. The buffer cover has: a cover portion abutting against an axial end surface of the cylinder body and having a through hole for the piston rod to pass through; a cylindrical barrel portion, which is arranged radially outward of the through hole and covers at least a portion of the outer peripheral surface of the cylinder body; A communication hole, which is provided in the cylinder and connects the inner circumference and the outer circumference of the cylinder; The first end portion of the edge of the communicating hole located on the downstream side where the material flows in during molding is thinner than the second end portion located on the upstream side.

2. The buffer cover according to claim 1, The edge of the communicating hole is formed so that the end portion on the upstream side of the material flowing in during molding is substantially perpendicular to the flow of the material.

3. The buffer cover according to claim 1 or 2, Corners of the communication hole are chamfered.

4. The buffer cover according to claim 1 or 2, The bumper cover is formed of metal or resin.

5. A buffer cover, which is a buffer cover of a buffer, the buffer comprising: a cylinder; a piston, which is arranged in the cylinder; a piston rod, one end of which is connected to the piston and the other end of which extends from the cylinder; the buffer is arranged at the end of the cylinder on the side where the piston rod extends, The buffer cover has: a cover portion abutting against an axial end surface of the cylinder body and having a through hole for the piston rod to pass through; a cylindrical barrel portion, which is arranged radially outward of the through hole and covers at least a portion of the outer peripheral surface of the cylinder body; A communication hole, which is provided in the cylinder and connects the inner circumference and the outer circumference of the cylinder; The edge of the communicating hole has: A circumferential edge portion extending in the circumferential direction of the cylinder portion; an axial edge portion extending in the axial direction of the barrel portion; At least a portion of the circumferential edge portion includes an inclined portion which is formed to be inclined with respect to the axial direction of the cylindrical portion and is located on an end side of the cylindrical portion in the axial direction which serves as an edge of the communicating hole.

6. The buffer cover according to claim 5, The axial edge portion has a first axial edge portion and a second axial edge portion, The inclined portion includes a first inclined portion formed to extend obliquely from one axial end of the first axial edge portion and a second inclined portion formed to extend obliquely from one axial end of the second axial edge portion.

7. The buffer cover according to claim 6, The inclined portion is provided on the first end side in the axial direction of the cylindrical portion.

8. The buffer cover according to claim 7, The inclined portions are provided on a first end portion side of the cylindrical portion in the axial direction and on a second end portion side of the cylindrical portion in the axial direction, and are formed symmetrically with each other.

9. The buffer cover according to claim 5, A first end portion of the circumferential edge portion in the axial direction of the cylindrical portion is formed at an acute angle compared to a second end portion of the cylindrical portion in the axial direction.

10. The bumper cover according to any one of claims 5 to 9, The bumper cover is formed of metal or resin.

11. A buffer, comprising: a cylinder; a piston disposed in the cylinder; a piston rod, one end of which is connected to the piston and the other end of which extends from the cylinder; and a buffer cover; The buffer cover has: a cover portion abutting against an axial end surface of the cylinder body and having a through hole for the piston rod to pass through; a cylindrical barrel portion, which is provided at a radially outer end portion of the cover portion and covers at least a portion of an outer peripheral surface of the cylinder body; A communication hole, which is provided in the cylinder and connects the inner circumference and the outer circumference of the cylinder; The communicating hole has a first end portion located on the downstream side into which the material flows during molding, which is thinner than a second end portion located on the upstream side.

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