pipe and shock absorber

Abstract

Shock absorber (1), which is to be installed between two parts that are movable relative to each other, the shock absorber (1) comprises: a cylinder (3) which encloses a working fluid; a piston (6) which is inserted into the cylinder (3); a piston rod (8) which is coupled to the piston (6) to extend outside the cylinder (3); an outer tube (2) which is arranged on an outer circumference of the cylinder (3); a separating tube (4) which is arranged to surround the outer circumference of the cylinder (3), the separating tube (4) having a cylindrical side wall which forms an annular passage which is in communication with an interior of the cylinder (3); a reservoir (5) which is formed outside the separating tube (4) between the cylinder (3) and the outer tube (2), the reservoir (5) enclosing the working fluid and a gas; and a damping force-generating mechanism (28) which is arranged outside the outer tube (2),wherein the separating tube (4) has a sealing ring groove (22) which is configured to extend in a circumferential direction of the separating tube (4) along an inner circumference of a side of an end section of the separating tube (4), and wherein the sealing ring groove (22) has a pair of side surfaces (72, 73) which are opposite each other beyond a sealing ring (23), wherein one side surface (72) of the pair of side surfaces (72, 73) is arranged at an opening end side of the separating tube (4), wherein the other side surface (73) of the pair of side surfaces (72, 73) is arranged at a side opposite the opening end side of the separating tube (4), wherein one side surface (72) has an angle of inclination (θ1) which is formed with respect to a plane perpendicular to an axis of the separating tube (4), wherein the angle of inclination (θ1) of one side surface (72) is greater than a Inclination angle (θ2) of the other side surface (73),wherein the inclination angle (θ1) of one side surface (72) is set between 8° and 30°, wherein one side surface (72) of the pair of side surfaces (72, 73) and an inner surface of the separating tube (4) are connected to each other at a connecting section having a radius of curvature of a rounded surface between 0.2 mm and 1.0 mm.

Description

TECHNICAL AREA

[0001] The present invention relates to a tube and a shock absorber. TECHNICAL BACKGROUND

[0002] A shock absorber installed in the chassis of a vehicle is known to have a separating tube arranged between a cylinder and an outer tube. In a shock absorber disclosed in patent literature 1, for example, a separating tube is attached to an outer circumference of a cylinder, and a space between the two radially shrunken end sections of the separating tube and the cylinder is sealed by sealing rings. Furthermore, sealing ring grooves (housings) are formed along an inner circumference of both end sections of the separating tube, each having a substantially rectangular cross-section and extending in a circumferential direction. The sealing ring grooves can be formed, for example, by a rolling process carried out on the separating tube, which has a cylindrical shape.

[0003] Furthermore, the roll forming process refers to a sequential rotary process performed by rotating and turning a roll forming die. This causes the material of the end section of the separating tube to flow plastically in both a circumferential and an axial direction. As a result, acute-angled, raised sections are formed along the circumferential direction at the corners of each sealing ring groove. These acute-angled, raised sections can be disregarded if the gap (distance) between the cylinder and the separating tube is essentially zero. However, a predetermined gap between the cylinder and the separating tube is ensured to accommodate assembly requirements.If the shock absorber is in a condition where the internal pressure on either the compression or decompression side repeatedly and violently varies, the sealing rings are repeatedly slightly forced out of and back into their grooves. In this configuration, the slightly forced sections of the sealing rings slide against the acute-angled, raised sections if no backup rings are used. As a result, the sealing rings can be damaged. LITERATURE LIST PATENT LITERATURE

[0004] [PTL 1] JP 2013-15163 A SUMMARY OF THE INVENTIONAL PROBLEM STATEMENT

[0005] The present invention was made in view of the circumstances described above and aims to improve the durability of sealing rings that are fitted into sealing ring grooves in a tube having sealing ring grooves formed by a sequential rotating process and in a shock absorber having the tube. SOLUTION TO THE PROBLEM

[0006] To achieve the above-described objective, according to one embodiment of the present invention, a tube is provided which has a sealing ring groove formed along an inner circumference on the side of an end section, wherein the sealing ring groove is formed in a substantially square shape in cross-section, such that it has a bottom surface and a pair of side surfaces opposite each other beyond the sealing ring, wherein at least one of the two side surfaces forms an angle of inclination of 5° or more with respect to a plane perpendicular to an axis of the tube.

[0007] To achieve the above-described objective, according to one embodiment of the present invention, a shock absorber is provided which is to be installed between two parts that are movable relative to each other, wherein the shock absorber comprises: a cylinder which encloses a working fluid; a piston which is inserted into the cylinder; a piston rod which is coupled to the piston in order to extend outside the cylinder; an outer tube which is arranged on an outer circumference of the cylinder; a separating tube which is provided such that it surrounds the outer circumference of the cylinder, wherein the separating tube has a cylindrical side wall which forms an annular passage which is in communication with the interior of the cylinder; a reservoir which is formed outside the separating tube between the cylinder and the outer tube, wherein the reservoir encloses a working fluid and a gas;and a damping force-generating mechanism arranged outside the outer tube, wherein the separating tube has a sealing ring groove configured to extend in a circumferential direction of the separating tube along an inner circumference of a side of an end section of the separating tube, and wherein an angle of inclination with respect to a plane perpendicular to an axis of the separating tube is formed by one of a pair of side faces of the sealing ring groove, which are opposite each other beyond the sealing ring, which is arranged at an opening end side of the separating tube, such that this angle is greater than the angle of inclination formed by the other of the pair of side faces, which is arranged at an opposite side of the opening end side of the separating tube. ADVANTAGEOUS EFFECTS

[0008] According to one embodiment of the present invention, the durability of the sealing rings, which are inserted in sealing ring grooves in the tube having sealing ring grooves formed by a sequential rotating process, and in a shock absorber that articulates the tube, can be improved. BRIEF DESCRIPTION OF THE FIGURES

[0009] Fig. Figure 1 is a sectional view along an axial plane of a damping force-adjustable hydraulic shock absorber.

[0010] Fig. Figure 2 is a sectional view taken along an axial plane of a separating tube, in particular a sectional view to show an end section of the separating tube.

[0011] Fig. Figure 3 is an enlarged view to show section A from Fig. 2.

[0012] Fig. Figure 4 is an explanatory view to illustrate a rolling press apparatus set up to perform a sequential rotary operation to form a sealing ring groove along an inner circumference of an end section of the separating tube, in particular a sectional view made along an axial plane of the separating tube.

[0013] Fig. Figure 5 is an explanatory view to illustrate a roll forming die used in the roll forming apparatus, in which an upper side, with respect to the central axis, is shown in a sectional view made along an axial plane.

[0014] Fig. Figure 6 is a view showing acute-angled, highlighted sections formed at the groove corners of a related sealing ring groove by the rolling process.

[0015] Fig. Figure 7 is an explanatory view to illustrate the effect of an embodiment of the present invention, in particular an illustration to show the relationship between an angle of inclination and a maximum tensile load applied to the O-ring.

[0016] Fig. Figure 8 is an explanatory view to illustrate the effect of the embodiment of the present invention, in particular an illustration to show the relationship between the inclination angle and a deformation component of the end section of an O-ring.

[0017] Fig. Figure 9 is an explanatory view to illustrate the effect of the embodiment of the present invention, in particular a view to illustrate deformation patterns of the end section of the O-ring at an associated angle of inclination and the distributions of the loads applied to the end section of the O-ring.

[0018] Fig. Figure 10 is an explanatory table to illustrate the effect of the embodiment of the present invention, in particular a table to illustrate the results of tests with variation of the inclination angle θ1 in the range of 2° to 10°, in order to confirm whether the acute-angled, highlighted sections at the groove corners of the sealing ring groove are formed during the sequential rotating process. DESCRIPTION OF THE EXECUTION FORMS

[0019] With reference to the accompanying drawings, an embodiment of the present invention is described. First, a damping-force-adjustable hydraulic shock absorber is described. 1 (hereinafter referred to as "shock absorber") 1 This embodiment is described in the phrase “”. Note that for the sake of clarity, the up and down directions are omitted. Fig. 1 as an up-and-down direction of the shock absorber 1 is defined. As in Fig. As shown in 1, the shock absorber 1 a double-tube structure, which includes an outer tube 2 and a cylinder 3 features, and a separating pipe 4 (Pipe) is provided such that an outer circumference of the cylinder 3 is surrounded. Furthermore, a reservoir, which is an annular space, is located on an outer section of the separating pipe. 4 between the outer pipe 2 and the cylinder 3 educated.

[0020] A piston 6 is in the cylinder 3 The piston is inserted in a sliding position. 6 is on one side of the piston rod 8 with a mother 7 fixed, and divides the interior of the cylinder 3 into a first chamber 3A and a second chamber 3B up. The piston rod 8 extends outside the cylinder 3 through a rod guide 9 and an oil seal 10, which are attached to the outer pipe 2 and an upper end section of the cylinder 3 are attached. The piston 6 shows oil passages 11 and 12 on, which are designed so that the first chamber 3A and the second chamber 3B are connected to each other. On a surface of the piston 6 on the side of the first chamber 3A is a check valve 13 arranged in such a way as to allow liquid oil to enter exclusively from the side of the second chamber 3B to the side of the first chamber 3A to flow through the oil passage. Furthermore, on a surface of the piston on the side of the second chamber. 3B a disc valve 14 arranged to open when pressure of liquid oil is applied to the side of the first chamber 3A a predetermined pressure is reached, thereby forcing the liquid oil onto the side of the first chamber 3Ato the side of the second chamber 3B to relieve the pressure through the passage of oil.

[0021] The shock absorber 1 a base valve 15 on, which is located at a lower end section of the cylinder 3 is arranged to form the second chamber 3B and the reservoir 5 to separate them. The base valve 15 shows oil passages 16 and 17 which are designed so that the second chamber 3B and the reservoir 5 are interconnected. Furthermore, the base valve 15 a check valve 18 on, which is designed to allow liquid oil to flow exclusively from the side of the reservoir. 5 to the side of the second chamber 3B through the oil passage 16 to flow. Furthermore, the base valve 15 a valve 19which is designed to open when pressure of liquid oil is applied to the side of the second chamber 3B a predetermined pressure is reached, thereby forcing the liquid oil onto the side of the second chamber. 3B to the side of the reservoir 5 through the oil passage 17 to relieve pressure. Note that the liquid oil is enclosed as a working fluid within the cylinder, and that the liquid oil and a gas are contained within the reservoir. 5 are included.

[0022] The separating pipe 4 features sealing ring grooves 22 and 22 (housing) which extends in a circumferential direction along an inner circumference 21 and 21 at both end sections 20 and 20 extend and the O-rings 23 and 23 (Sealing rings) allow into the sealing ring grooves 22 and 22 to be used. If these O-rings 23 and23 at both end sections 20 and 20 of the separating pipe 4 in close contact with the outer circumference of the cylinder 3 To be brought in, a ring-shaped oil passage will be created. 24 between the cylinder 3 and the separating pipe 4 formed. The ring-shaped oil passage 24 stands with the first chamber 3A through an oil passage 25 , which is located at an upper end section of the cylinder 5 is formed, in connection. Furthermore, a narrow radial opening is present. 26 at a lower end section of the separating pipe 4 Furthermore, a large radial opening is formed. 27 , which corresponds to the opening 26 is arranged through the outer tube 2 formed, and a damping force-generating mechanism 28 is at the opening 27 of the outer tube 2 appropriate.

[0023] The damping force-generating mechanism 28 features a cylindrical housing 29 up, which is connected to the opening 27 is adapted. A solenoid valve 31 is attached to the case 29 with a mother 32 fixed. The solenoid valve 31 It mainly features a main damping valve. 30 a pilot type (back-pressure type) and a pressure regulating valve designed to regulate the valve opening pressure of the main damping valve with a solenoid. The solenoid valve 31 is with the opening 26 connected, and generates a damping force by controlling the flow of liquid oil through the opening. 26 to the reservoir 5 .

[0024] The main damping valve 30 a disc valve 33 and a counter-pressure chamber 34 on the side of a rear surface of the disc valve 33 are formed. The plate valve33 It is deflected and opened to act as a main valve when there is pressure from the liquid oil on the side of the opening. 26 experiences, so that the liquid oil on the side of the opening 26 allowed to go to the side of the reservoir 5 to flow. The counterpressure chamber 34 applies internal pressure to the side of the back of the disc valve. 33 in a valve-closing direction of the poppet valve 33 Furthermore, there is an auxiliary passage. 36 with the opening 26 through a fixed aperture 35 connected. The auxiliary passage 36 stands through the passage 36A in conjunction with the counter-pressure chamber 34 .

[0025] Fig. Figure 2 is a sectional view taken along an axial plane of the separating tube. 4(the plane encloses a central axis C1) is made, in particular a section view to show an end section. 20 of the separating pipe 4 Note that one end section 20 and another end section 20 of the separating pipe 4 in Fig. They are vertically symmetrical to each other. Only one end section is described here. 20 of the separating pipe 4 , and the description of the other end section 20 is omitted. The one final section 20 and the other end section 20 of the separating pipe 4 The seals described in this embodiment are vertically symmetrical to each other, but replacement seals (backup seals) can only be placed in front of and behind the sealing ring groove on the other end section. 20be arranged. Furthermore, the sealing ring groove of the other end section may be formed in a shape that differs from that of the other end section. Note that each of the end sections 20 of the separating pipe 4 , that the sealing ring grooves 22 , which are formed by a rolling press process (sequential, rotary process), along the inner circumference 21 exhibits that they have been radially shrunk beforehand by a rolling process.

[0026] As in Fig. As shown in 3, the sealing ring groove is 22 formed into a shape that is essentially rectangular in cross-section, so that it forms a floor area 71 and a pair of side surfaces 72 and 73 , which are located beyond the O-ring 23 opposite (referring to Fig. 1), exhibits. Of the pair of side faces 72 and 73 is the side surface 72 , located on one side of an opening end20A of the final section 20 of the separating pipe 4 (left side in Fig. 2 and Fig. 3) is arranged towards the side of the opening end 20A open, and is at an angle of inclination θ1 with respect to a plane perpendicular to the axis of the separating tube 4 (a plane PL1, which encloses a straight line perpendicular to the central axis C1) is inclined. As described later, this inclination angle θ1 is set to 5° or more, in particular to 20° in this embodiment.

[0027] However, there is an (not shown) angle of inclination θ2 with respect to the plane PL1, perpendicular to the axis on the side surface. 73 , which are on an opposite side of the side surface 72 (right side in Fig. 2 and Fig. 3) is designed to be set to a range of 0° to 5° in accordance with the housing shape specified by JIS B 2401. In other words, the angle of inclination θ1 with respect to the plane PL1, perpendicular to the axis, is set on the side surface. 72 , located on the side of the opening end 20A is arranged, greater than the inclination angle θ2 (θ1 > θ2), which is perpendicular to the axis on the side surface with respect to the plane PL1 73 , which is located on the opposite side. In other words, the side surface 72 and the side surface 73 asymmetrical with respect to the plane PL1, perpendicular to the axis, and additionally the sealing ring groove 22 asymmetric with respect to the plane PL1, perpendicular to the axis.

[0028] Furthermore, there are groove corners, which are the connecting sections between the opening ends of the sealing ring groove. 22 and the inner circumference 21 are, at the sealing ring groove22 rounded. From the rounded section of the groove corner on the side of the side surface. 72 and the rounded section of the groove corner on the side of the side surface 73 the sealing ring groove 22 , is the rounded section of the groove corner on the side of the side surface 72 defined below as the groove corner rounding section R.

[0029] Note that the groove corner radius section R and the groove corner radius section are on the side of the face. 73 the sealing ring groove 22 the housing groove corner radius sections specified by JIS B 2401. Furthermore, the sealing ring groove has 22 It features a rounded housing groove base, specified by JIS B 2401. Furthermore, a gap (a clearance to ensure assembly performance), also specified by JIS B 2401, is located between the cylinder and the housing groove base. 2 (referring to Fig. 1) and each of the inner circumferences 20of the separating pipe 4 ensured.

[0030] Next, with reference to Fig. 4 the rolling press apparatus 41 described, which is set up to perform the rolling press process (sequential, rotary process) so that the sealing ring grooves 22 along the inner circumference 21 of the final section 20 of the separating pipe 4 be trained. Note that although both of the final sections 20 and 20 of the separating tube simultaneously by a pair of press rolling devices 41 Only one of the press rolling machines can be processed, corresponding to the one end section. 20 of the separating tube. Furthermore, for the sake of clarity in the description, the up-and-down direction and the right-and-left direction are not shown. Fig. 4 as an up-and-down direction and a right-and-left direction of the rolling press apparatus 41defined. Note that both of the end sections 20 and 20 of the separating pipe 4 not necessarily simultaneously by a pair of rolling presses 41 need to be processed, and both end sections can be processed alternately by using a single rolling press.

[0031] The rolling press apparatus 41 features a hollow shaft rolling press die 42 , which are on the side of the inner circumference 21 of the final section 20 of the separating pipe 4 is used, and an outer shape 43 on, which is located on an outer circumference of the end section 20 of the separating pipe 4 appropriate. As in Fig. As described in section 5, the rolling press form has 42 a ring-shaped, protruding section 44 on, which is designed in such a way that it extends in the circumferential direction along an outer circumference of the rolling press die 42extends. The protruding section 44 is at an intermediate position of the rolling press 42 arranged, in particular at an intermediate position in the direction of a central axis C2 of the press roll die 42 (right and left direction in Fig. 5) and is formed in a substantially rectangular shape in cross-section, which is made along an axial plane of the press die.

[0032] Furthermore, a side surface 75 of the prominent section 44 corresponding to a side surface 72 of the pair of side faces 72 and 73 the sealing ring groove, which is located on the side of an opening end 20A of the separating pipe 4 is arranged which the side surface 75 is, which is on one side, which is the side surface 72 forms, at an angle of inclination θ1 in relation to a plane, perpendicular to the axis of the rolling die 42(a plane PL2 enclosing a straight line perpendicular to the central axis C2) with an inclination to the side surface 76 is formed, which is arranged on the opposite side, so that it corresponds to the angle of inclination θ1 on the side surface 72 the sealing ring groove 22 corresponds to inclined. Note that the rolling press die 42 a flange section 45 exhibits a design that provides a distance to the side surface 75 of the prominent section 44 in the direction of the central axis C2 (left direction in Fig. 5) shows.

[0033] As in Fig. As shown in 4, the rolling press apparatus 41 a rotating drive mechanism 47 on, which is designed to drive the rolling press die and rotate it around a central axis C2 (referring to Fig. 5) rotates. The rotating drive mechanism 47features a mold support section 48 , which is designed to support the rolling press die, and a (not shown) servo motor that serves as a drive source. The die support section 48 has a basic section 50 , which is formed in an essentially square shape, a first wave section 51 , which has an outer circumference to which an inner circumference of the rolling press die is adapted, and a second shaft section 53 on, which has a regulatory part 52 is connected. An outer perimeter of the base section 50 of the mold support section 48 is through a pair of bearings 54 supported, arranged in such a way that they are spaced apart in the direction of the central axis (right-and-left direction in Fig. 4) exhibit, so that the mold support section 48It is rotatable around the central axis. Note that the pair of bearings 54 in a bearing housing 55 is housed, which has an essentially cylindrical shape, and a flanged section 55A of the bearing housing 55 at a section of the approach 56A a motor base 56 It is fixed with screws.

[0034] The mold support section 48 a borehole 57 on, which is located at a left end face of the base section 50 is open, so that the mold support section 48 with a (not shown) servomotor rotor shaft inserted into the bore, allowing power to be transmitted between them. Furthermore, on the mold support section 48 a flange section 58 at a right end section of the base section 50 trained so that the storage 54with the right side in contact with a left end face of the flange section 58 is held. Additionally, the flange section 45 the rolling press 42 in conjunction with the side of an inner circumference of a right end face of the flange section 58 This prevents a leftward movement of the rolling press die. 42 relative to the mold support section 48 regulated. Additionally, a clockwise movement of the rolling press die is permitted. 42 relative to the mold support section 48 through the regulatory part 52 , which is held in position against its right end surface, is regulated. This regulates the rolling press form. 42 in an axial line direction with respect to the outer shape 43 positioned.

[0035] Note that a left end section of the rolling press die 42 into a ring-shaped, recessed section 59, which is located in the right end face of the base section 50 is formed, is fitted. Furthermore, a remote end section of the first shaft section is in the mold support section. 48 in a bore 60 , which is formed in an end surface of the regulating part, fitted. As in Fig. The outer shape is shown in 4. 43 formed in a ring-shaped form, and the rolling press form 42 is inserted at the side of its inner circumference. Furthermore, the outer shape is attached to an outer shape support plate. 62 through a warehouse 61 stored. This results in the outer shape. 43 around a central axis of the outer shape 43 rotatable. Additionally, the outer shape features 43 a more in-depth section 63 on, which with the protruding section 44 the rolling press 42 agrees.

[0036] On a part on the inner side of the outer shape 43and on the right side in relation to the recessed section 63 is a relief section 65 trained, which is designed so that an intervention with the beveled section 64 of the separating pipe 4 This is avoided. Furthermore, a part on the inner side of the outer shape is... 43 on a left-hand side in relation to the recessed section 63 a section of the plant 66 formed, which has an inner diameter that is smaller than the inner diameter of an inner reference circumferential surface 43A the outer shape 43 The opening end 20A of the final section 20 The separating pipe is in an installation against a right end surface of the installation section. 66 This allows the material flow to be maintained during the rolling process in the separating tube. 4be regulated. Note that in a state immediately after completion of the rolling press process, a highlighted section 67 , which is at a terminal section 20 of the separating pipe 4 trained, in the advanced section 63 the outer shape 43 is fitted. Therefore, the separating pipe can 4 not from the outer shape 43 be solved.

[0037] For this reason, the outer shape 43 designed so that it can be divided into a total of four parts, in particular into two in one direction of the central axis (right and left direction in Fig. 4) and in two in a radial direction (top-and-bottom direction in Fig. 4), thus it is possible to use the separating pipe 4 to detach from the form. Note that the reference symbol 68 in Fig. 4 refers to a bearing clamp that is attached to the outer shape 43It is fixed with screws and is designed in such a way that it forms an outer ring of the bearing. 61 to the outer form support plate 62 fixed. Additionally, the reference symbol indicates 70 a base plate to which the outer form support plate 62 is attached by a pair of linear guides. (Effects and Effects)

[0038] If a sealing ring groove 22' a related separating pipe 4' , which is designed so that it is symmetrical with respect to a plane PL1, perpendicular to the axis, as shown in Fig. 6, is, in particular, a sealing ring groove 22' where the inclination angles of a side surface 72' and a side surface 73'with respect to the plane PL1, perpendicular to the axis, each in a range of 0° to 5° in accordance with the housing shapes specified by JIS B 2401, are set by using a rolling press apparatus described above. 41 being edited, acute-angled, highlighted sections 40 and 40 at both corners of the sealing ring groove 22' They will be trained. The reason for this is that the separating pipe 4' is held by the shape, and therefore the material flow of the separating tube. 4' during the sequential, rotating process. Note that in Fig. 6 the reference sign 42' a related rolling press mold, and the reference symbol 44' a protruding section of the rolling press 42' designated.

[0039] Therefore, the internal pressure of the first chamber varies. 3Aof the cylinder in connection with the displacement of the piston 6 in a shock absorber 1 in the state that is in Fig. 1 is shown, whereby the O-ring 23 is caused to repeatedly move slightly out of the sealing ring groove 22' to be pushed out and then pushed back in. In this configuration, the slightly pushed-out section of the O-ring slides out. 23 repeatedly against the acute-angled, highlighted sections 40 and 40 if no backup ring is used. Additionally, the formation of the acute-angled, highlighted sections is 40 and 40 more likely if the groove width of the sealing ring groove 22' gets smaller.

[0040] As a countermeasure, the sealing ring groove 22 of the separating pipe 4In this embodiment, it is designed such that it is asymmetrical with respect to the plane PL1, perpendicular to the axis. In particular, the pair of side surfaces 72 and 73 the sealing ring groove, as in Fig. 2 and Fig. Figure 3 shows the side surface located on the side of the opening end. 20A of the separating pipe 4 is arranged at an angle of inclination θ1 of 5° or more with respect to the plane PL1, perpendicular to the axis of the separating tube 4 , inclined. This means it is due to the material of the separating pipe. 4 to the protruding section 44 the press rolling die 42 This allows for smoother plastic flow during the sequential, rotating process. Thus, the formation of the acute-angled, highlighted section is facilitated. 40 (referring to Fig. 6) at least at the corner of the groove on the side of the side surface 72 from the side surface 72 and the side surface73 the sealing ring groove 22 suppressed.

[0041] Next, show Fig. 7 A figure for representing the results of experiments using a finite element method, in particular a relationship between the inclination angles θ1 of the side surface is shown. 72 the sealing ring groove 22 with respect to the plane PL1, perpendicular to the axis (hereinafter referred to as “inclination angle θ1”) and the maximum tensile load (MPa) applied to the O-ring 23 (Material: NBR-90) is applied, which is placed in the sealing ring groove in a state in which there is an internal pressure of the separating tube. 4 The value of 20 MPa is shown. Note that this is a test result of the maximum tensile load applied to the O-ring. 23 is applied, which is in a similar sealing ring groove 22' (referring to Fig. 6) is used, in a case where a replacement ring (backup ring) is used, is approximately 110 MPa, which is greater than the maximum tensile load that can be applied to an O-ring. 23 is applied, which is in a sealing ring groove 22 of the separating pipe 4 is used according to this embodiment. In other words, the durability of the O-ring is 23 lower than that of the O-ring 23 this embodiment. Furthermore, Fig. 8 Another figure to illustrate the relationship between the inclination angle θ1 and the deformation amount (mm) of an end section of the O-ring 23 .

[0042] With reference to Fig. Section 7 states that the maximum tensile load that can be applied to the O-ring 23 The applied area tends to be larger, while a groove corner rounding section R of the sealing ring groove 22The load is smaller when the inclination angle θ1 ranges from 0° to 20°. This is likely because, in a range where the inclination angle θ1 is 20° or less, while the groove corner radius section R becomes smaller, the load is concentrated more intensely on a portion (recessed section) of the O-ring. 23 , which is deformed in accordance with the groove corner rounding section R, is applied.

[0043] Referring to Fig. 7 it becomes clear that if the inclination angle θ1 is a certain angle or greater, the maximum tensile load that can be applied to the O-ring 23 When applied, it is less affected by the groove corner rounding section R and remains consistently low. Meanwhile, with reference to Fig. 8. It is clear that the deformation component is reduced once the inclination angle θ1 exceeds 30°, and that the deformation component increases as the inclination angle θ1 becomes even larger. As shown in particular by Fig. As becomes clear in section 9, these are the insertion edge positions of the O-ring. 23 , which lies in a gap between the cylinder 3 and the separating pipe 4 The results are essentially identical when the inclination angles θ1 are 10° and 30°. Meanwhile, the insertion edge position of the O-ring is 23 The O-ring's insertion edge is retracted when the inclination angle θ1 exceeds 40°, and when the inclination angle θ1 reaches 60°, the insertion edge position is retracted further. In other words, the deformation type begins to change when the inclination angle θ1 exceeds 30°. When the deformation type changes, the guide edge position for entering the gap between the cylinder is adjusted. 3 and the separating pipe 4withdrawn. As a result, unnecessary space is created, increasing the axial length and thus causing an overall increase in the size of the cylinder unit. In this way, increasing the inclination angle θ1 does not cause problems with the maximum tensile load. However, the change in the deformation mode causes an increase in the size of the cylinder unit, and therefore it is desirable for the maximum value of the inclination angle θ1 to be 30° or less.

[0044] Meanwhile, it is desirable that in the sealing ring groove 22 the groove corner, in particular the rounded section R of the connecting section between the opening end of the sealing ring groove and the inner circumference 21 , 0.2 mm or more and 1.0 mm or less. The reason for this is that, as shown by the results in Fig. As demonstrated in Figure 7, the maximum tensile load remains high until the inclination angle reaches 20° when the R is 0.05 mm. If the R is 0.05 mm or less, the degree of O-ring compression decreases. 23 between the cylinder 3 and the separating pipe 4 high, and therefore the O-ring is pushed into the narrow gap between the cylinder as it enters. 3 and the separating pipe 4 significantly affected. Furthermore, increasing the R-value does not change the maximum tensile load. However, the type of deformation does change. Therefore, for the reasons described above, it is desirable for the R-value to be 1.0 mm or less.

[0045] Furthermore, with reference to Fig. 7 and Fig. 8. It is clear that in the area where the angle of inclination θ1 is 50° or more, the maximum tensile load on the O-ring 23The applied force is essentially constant and therefore not affected by the groove corner radius section R when the groove corner radius section R ranges from 0.05 mm to 1.0 mm. Although the maximum tensile load acting on the O-ring 23 The effect can be reduced by setting a large tilt angle θ1, as well as with regard to Fig. As becomes clear in section 9, the groove width of the sealing ring groove increases, while the inclination angle θ1 is set larger. As a result, structural design problems arise, such as the need for the end section 20 of the separating pipe 4 to expand in the direction of the central axis. In this case, the volume of the separating tube cannot be adequately ensured. If, as a countermeasure, the axial lengths of the separating tube are increased, 4 and the cylinder 3 If the length is extended, a problem arises because the axial length of the entire shock absorber increases. 1The size is increased, resulting in a larger size. Additionally, the deformation of the end section of the O-ring increases. 23 , while the inclination angle θ1 increases. As a result, the deformation component of the O-ring increases. 23 enlarged, resulting in a deterioration of the O-ring's durability 23 is caused. In other words, the groove width of the sealing ring groove is affected. 22 enlarged, and the guide edge position for entering the gap between the cylinders 3 and the separating pipe 4 is retracted, creating an axial gap. Therefore, the separating tube 4 The cylinder lengthens in an axial direction as the tilt angle increases. As a result, the cylinder unit becomes larger. Therefore, it is desirable that the maximum value of the tilt angle θ1 be 30° or less so that the deformation characteristics do not change.

[0046] Next, the reason why the tilt angle θ1 is set to 5° or more is described in detail. Fig. Figure 10 shows test results of variations in the tilt angle in a range of 2° to 10° to confirm whether the acute-angled, highlighted section 40 at the corner of the sealing ring groove 22 during the sequential, rotating process. If the inclination angle θ1 is 3° or less, the acute-angled, highlighted section is formed. 40 trained, and therefore assigned the rating “X”. If the inclination angle θ1 is 4°, the acute-angled, highlighted section 40The raised section is barely formed, but a small, raised section can be found when scanning the corner of the groove, and therefore the rating "Δ" is assigned. If the inclination angle θ1 exceeds 5°, no raised section is found even when scanning the corner of the groove, and therefore the rating "O" is assigned. These test results demonstrate that by setting the inclination angle θ1 to 5° or higher, the formation of the acute-angled, raised section is reduced. 40 is suppressed. Furthermore, to ensure consistent product quality, a tolerance in the formation of the sealing ring groove is desirable. 22 The sequential, rotating process results in a deviation of ±2.5°. Therefore, it is more desirable for the inclination angle θ1 to be 8° or greater.

[0047] According to this embodiment, in the separating tube 4 (pipe) which has a sealing ring groove 22 , which run along the inner circumference 21 of the final section20 by a sequential rotating process with the rolling press apparatus 41 is designed, has, and in which the shock absorber 1 , which is a separating pipe 4 features the sealing ring groove 22 asymmetrical with respect to the plane PL1, perpendicular to the axis of the separating tube 4 , formed. The angle of inclination θ1, which is perpendicular to the plane PL1, perpendicular to the axis passing through the side surface. 72 of the pair of side surfaces 72 and 73 , which are located beyond the O-ring (sealing ring) in the sealing ring groove 22 opposite each other, is formed, which is located on the side of the opening end. 20A of the separating pipe 4 The angle is set to 8° or higher, in particular the tilt angle is set to 20°. This ensures that the acute-angled, highlighted section is not visible during the sequential, rotating process. 40 not at the corner of the sealing ring groove 22trained. As a result, a step of removing the acute-angled, highlighted section can be omitted, and the manufacturing steps can be streamlined, not only for the separating tube. 4 , but also for the shock absorber 1 can be achieved. Furthermore, the maximum tensile load that can be applied to the O-ring can be... 23 The applied force is reduced so that it is significantly smaller than the maximum tensile load in the case of using a backup ring. Therefore, the durability of the O-ring can be reduced. 23 The shock absorber can be set to have equivalent or improved durability compared to using a spare (backup) ring. As a result, the spare (backup) ring can be omitted, thus reducing the manufacturing costs. 1 significantly reduced. In addition, assembly performance is improved and productivity can be increased.

[0048] Note that although the O-ring is used as a sealing ring in the example described above in this embodiment, the invention is not limited thereto. The present invention is also applicable to sealing rings such as a square ring having a rectangular cross-section and a lip ring having a V-shape in cross-section. REFERENCE MARK LIST 1 Shock absorbers, 2 outer pipe, 3 Cylinder, 4 Separating pipe (tube), 5 Reservoir, 6 Pistons, 8 piston rod, 22 Sealing ring groove 28 damping force-generating mechanism

Claims

[1] Pipe having a sealing ring groove formed along an inner circumference on one side of an end section of the pipe, wherein the sealing ring groove is formed in an essentially square shape in cross-section, such that it has a bottom surface and a pair of side surfaces that are opposite each other beyond the sealing ring, wherein at least one of the pair of side faces forms an angle of inclination of 5° or more with respect to a plane perpendicular to an axis of the tube. [2] Pipe according to claim 1, wherein the angle of inclination is set to 8° or more. [3] Pipe according to claim 1, wherein the angle of inclination is set to 30° or less. [4] Pipe according to claim 2, wherein the angle of inclination is set to 30° or less. [5] Tube according to claim 1, wherein at least one of the pair of side surfaces and an inner surface of the tube are connected to each other at a connecting section having a rounded surface of 0.2 mm or larger. [6] Tube according to claim 2, wherein at least one of the pair of side surfaces and an inner surface of the tube are connected to each other at a connecting section having a rounded surface of 0.2 mm or larger. [7] Tube according to claim 3, wherein at least one of the pair of side surfaces and an inner surface of the tube are connected to each other at a connecting section having a rounded surface of 0.2 mm or larger. [8] Pipe according to claim 1, wherein the sealing ring groove is formed by a sequential, rotating process. [9] Pipe according to claim 2, wherein the sealing ring groove is formed by a sequential, rotating process. [10] Shock absorber to be installed between two parts that are movable relative to each other, the shock absorber having: a cylinder that encloses a working fluid; a piston that is inserted into the cylinder; a piston rod that is coupled to the piston to extend outside the cylinder; an outer tube that is arranged on an outer circumference of the cylinder; a separating tube designed to surround the outer circumference of the cylinder, wherein the separating tube has a cylindrical side wall forming an annular passage which is connected to an interior of the cylinder; a reservoir formed outside the separating tube between the cylinder and the outer tube, wherein the reservoir includes the working fluid and a gas; and a damping force-generating mechanism that is located outside the outer tube, wherein the separating tube has a sealing ring groove which is designed such that it extends in a circumferential direction of the separating tube along an inner circumference of a side of an end section of the separating tube, and wherein an angle of inclination with respect to a plane, perpendicular to an axis of the separating tube, is formed by one of a pair of side surfaces of the sealing ring groove, which are opposite each other beyond the sealing ring and which is arranged at an opening end side of the separating tube, such that this angle of inclination is greater than an angle of inclination formed by the other of the pair of side surfaces, which is arranged at an opposite side of the opening end side of the separating tube.