Cylinder device

Abstract

Cylinder device (1), comprising: comprising a cylinder (2) having an opening (2A1) at one end thereof and comprising a hydraulic fluid enclosed therein; a rod (7) extending from at least one end of the cylinder (2); a ring-shaped element (9) that is arranged at one end of the cylinder (2); an annular oil sealing element (10) which is arranged in a position that is closer to one end of the cylinder (2) than the annular element (9) and points towards it, and a notched section (2C) formed at one end of the cylinder (2) to secure the oil sealing element (10) between the notched section (2C) and the annular element (9) in an axial direction of the cylinder (2); wherein the oil sealing element (10) comprises a metal ring (11) and a sealing element (13) that surrounds the metal ring (11); wherein the metal ring (11) has a plurality of radially extending ribs (12) which are provided by local deformation of the metal ring (11), wherein the ribs (12) are formed to extend from a position where the oil sealing element (10) is secured in the axial direction by the notched section (2C) closer to an inner diameter side (11E) than a distal end (2C1) of the notched section (2C), wherein the notched section (2C) comprises locally notched sections (2C) formed by locally notching the cylinder (2) at a plurality of circumferentially spaced positions, wherein the notched sections (2C) each have a circumferential length dimension, wherein a length dimension between a pair of adjacent ribs (12) is narrower than the circumferential length dimension of each of the notched sections (2C).

Description

TECHNICAL AREA

[0001] The present invention relates to a cylinder device that is arranged in a vehicle, for example in a four-wheeled vehicle, and is used in a suitable manner to dampen vibrations of the vehicle. STATE OF THE ART

[0002] Vehicles, such as automobiles, are equipped with a cylinder device acting as a shock absorber between the vehicle body and a wheel to reduce vibrations generated during driving. The cylinder device has an outer tube and an inner tube, and a rod, connected to a piston in the inner tube, extends from an open end of the outer tube. The inner tube has a rod guide provided at one open end, and the open end of the outer tube is provided with an oil seal element that seals between the outer tube and the rod. The oil seal element consists of a metal ring and a lip seal provided at least on the inner circumferential side of the metal ring (see, for example, JP H4-105 648 Y2).

[0003] Further cylinder devices are described in DE 10 2011 079 953 A1, JP 2009- 222 128 A DE 60 2005 003 637 T2, US 2 249 141 A, JP H11- 218 178 A and EP 2 647 890 A2. PRESENTATION OF THE INVENTIONAL PROBLEM

[0004] Furthermore, when the oil seal element is installed in the outer tube, it is pressed into the tube, and during this process, the opening (distal) end of the outer tube is notched. However, during the notching process, the oil seal element is subjected to significant axial stress along the outer tube, which can cause elastic deformation of the metal ring of the oil seal element. Studies have been conducted to increase the deformation resistance (mechanical strength) of the metal ring, and a conventional approach to this problem is to increase the thickness of the metal ring or to stack multiple metal rings. However, this approach leads to an increase in the weight of the oil seal element, which in turn adversely increases the weight of the cylinder assembly.

[0005] The following invention is made in consideration of the problems of known techniques described above, and it is an object of the present invention to provide a cylinder device designed to achieve, in a compatible manner, an increase in mechanical strength and a reduction in the weight of a metal ring of an oil sealing ring. SOLUTION TO THE PROBLEM

[0006] To solve the problems described above, the present device provides a cylinder assembly comprising a cylinder open at one end and containing a hydraulic fluid, a rod extending from at least one end of the cylinder, an annular element provided at one end of the cylinder, an annular oil sealing element located closer to the one end of the cylinder than the annular element, and a notched (or corrugated) section provided at one end of the cylinder to seal the oil sealing element between itself and the annular element. The oil sealing element comprises a metal ring and a sealing element. The metal ring has a plurality of radially extending ribs formed by locally deforming the metal ring. ADVANTAGES OF THE INVENTION

[0007] According to the present invention, it is possible to achieve a compatible increase in mechanical strength and a weight reduction of the metal ring of the oil sealing element. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a vertical sectional view of a hydraulic shock absorber according to a first embodiment of the present invention. Fig. Figure 2 is a partially enlarged vertical sectional view of a section (II) of the hydraulic shock absorber in Fig. 1. Fig. Figure 3 is a sectional view of the hydraulic shock absorber made of Fig. 1, when viewed from the direction of arrow III-III. Fig. Figure 4 is a perspective view showing a metal ring of an oil sealing element as a single element. Fig. Figure 5 is a vertical sectional view of a hydraulic shock absorber according to a second embodiment of the present invention, taken from a position similar to that shown in Figure 5. Fig. 2 considered. Fig. Figure 6 is a vertical sectional view of a hydraulic shock absorber according to a third embodiment of the present invention, taken from a position similar to that shown in Figure 6. Fig. 2 considered Fig. 7 is a perspective view of a metal ring according to a first modification of the present invention, taken from a position similar to that of Fig. 4 considered. Fig. Figure 8 is a perspective view of a metal ring according to a second modification of the present invention, taken from a position similar to that shown in Figure 8. Fig. 4 considered. Fig. Figure 9 is a cross-sectional view of the metal ring made of Fig. 8, when viewed from the direction of arrow IX-IX. DESCRIPTION OF THE EXECUTION FORMS

[0008] A cylinder device according to embodiments of the present invention is described in detail below with reference to the accompanying drawings.

[0009] First, show Fig. 1, Fig. 2, Fig. 3 to Fig. 4 a first embodiment of the present invention. One in Fig. The cylinder device shown in Figure 1 is a hydraulic shock absorber, a typical example of a cylinder device. The hydraulic shock absorber 1 is formed by having an outer tube 2, an inner tube 4, a piston 6, a piston rod 7, a rod guide 9, an oil sealing element 10, etc. The outer tube 2 and the inner tube 4 form a cylinder. It should be noted that in the following explanation, the term "an end face" refers to the upper end face (top face in Figure 1). Fig. 1) of the hydraulic shock absorber 1 and the term “the other end” refers to the lower end (bottom side in Fig. 1) of the hydraulic shock absorber 1.

[0010] The outer tube 2, being a cylinder, forms an outer shell of the hydraulic shock absorber 1. The outer tube 2 has an opening 2A1 at one end 2A (upper end) and the other end 2B (lower end) is closed, sealed by a lower cap 3. The outer tube 2 contains hydraulic fluid. This hydraulic fluid is not limited to hydraulic oil; it can also be water mixed with an additive, for example.

[0011] As in Fig. 2 and Fig. As shown in Figure 3, the outer tube 2 has notched sections 2C provided at one end 2A by bending the distal end of the outer tube 2 radially inward. The notched sections 2C are provided, for example, at a plurality (e.g., 4) of circumferentially spaced positions. That is, the notched sections 2C are locally notched sections provided by locally notching the outer tube at a plurality of positions spaced circumferentially. The notched sections 2C secure the oil sealing element 10 described below between itself and the rod guide 9 described below.

[0012] In this case, each notched section 2C is arranged on ribs 12 formed on a metal ring 11 of the oil sealing element 10 described above. That is, as in Fig. As shown in Figure 3, each notched section 2C has a circumferential length dimension L that is larger than a length dimension M between a pair of adjacent ribs 12. Consequently, each notched section 2C is designed to extend over two adjacent ribs 12. The ribs 12 extend closer to the inner diameter face 11E of the metal ring 11 than the distal ends 2C1 of the notched sections 2C. Consequently, an axial force applied to the notched sections 2C can be distributed evenly across the ribs 12, thereby securing the oil sealing element 10.

[0013] The inner tube 4 is designed as a cylinder within the outer tube 2 in a coaxial relationship to the latter. The inner tube 4 has the rod guide 9 described below, which is arranged at its upper end. The lower end of the inner tube 4 is connected to the lower cap 3 via a bottom valve 5 (described later).

[0014] An annular reservoir chamber A is formed between the outer tube 2 and the inner tube 4. Reservoir chamber A contains a gas, along with the hydraulic oil described above. The gas can be air at atmospheric pressure or a compressed gas, such as nitrogen. The gas in reservoir chamber A is compressed when the piston rod 7 described below contracts (compression stroke) to compensate for a change in volume in the cylinder due to the piston rod 7's entry into it.

[0015] The bottom valve 5 is provided between the lower cap 3 and the inner tube 4, which is located at the lower end of the inner tube 4. The bottom valve 5 essentially comprises a stepped, disc-shaped valve body 5A, which is arranged and fixed between the lower end of the inner tube 4 and the upper surface of the lower cap 3 and has annular valve seats formed on its front and rear faces, respectively; oil passages 5B and 5C formed in the valve body 5A; a check valve 5D formed on the top of the valve body 5A; and a disc valve 5E provided on the bottom of the valve body 5A.

[0016] The bottom valve 5 operates as follows. When the piston rod 7 extends together with the piston 6 (described below), the disc valve 5E closes and the check valve 5D opens, allowing the hydraulic oil in reservoir chamber A to flow into the oil chamber B on the underside (described later) through oil line 5B. Conversely, when the piston rod 7 retracts, the check valve 5D closes and the disc valve 5E opens, allowing the hydraulic oil in the oil chamber on the underside to flow into reservoir chamber 5A. At this point, the disc valve 5E imparts flow resistance to the hydraulic oil flowing through oil line 5C to generate a damping force.

[0017] The piston 6 is slidably arranged within the inner tube 4. The piston 6 divides the interior of the inner tube 4 into two chambers: an oil chamber B at the bottom and an oil chamber C on the rod side. Furthermore, the piston 6 is provided with oil lines 6A and 6B, which enable communication between the oil chamber B at the bottom and the oil chamber C on the rod side.

[0018] Furthermore, a compression-side disc valve 6C is arranged on the upper end surface of the piston 6. The compression-side disc valve 6C imparts resistance to the hydraulic oil flowing through the oil line 6A to generate a predetermined damping force when the piston 6 is moved downwards in response to the retraction of the piston rod 7. On the other side of the lower end surface of the piston 6, an extension-side disc valve 6D is arranged, which imparts resistance to the hydraulic oil flowing through the oil line 6B to generate a predetermined damping force when the piston 6 is moved upwards in response to the extension of the piston rod 7.

[0019] The piston rod 7, being a single rod, is connected to the piston 6 at its upper end. That is, the lower end of the piston rod 7 is inserted into the inner tube 4 and secured at the central position of the piston 6 with a nut 8, etc. On the other hand, the upper end of the piston rod 7 extends and retracts from the outer and inner tubes 2 and 4 via the rod guide 9, etc. Furthermore, the outer circumferential surface 7A of the piston rod 7 is in airtight and fluid-tight sliding contact with a sealing element 13 of the oil sealing element 10 described below.

[0020] The rod guide 9, an annular element, is formed in a stepped, circular cylindrical shape and is located at the upper end of the outer tube 2 and also on the inner tube 4, thereby securing it. Consequently, the rod guide 9 positions an upper end section of the inner tube 4 in a coaxial relationship to the outer tube 2 and guides the piston rod 7 slidably in the axial direction along its inner circumferential side. Furthermore, the rod guide 9 forms a support structure that supports the oil sealing element 10 (described below) and the notched sections 2C of the outer tube 2 from the inside (bottom side) when the oil sealing element 10 (secured by notching) is pressed against the notched sections 2C of the outer tube 2 from the outside (top side).

[0021] The rod guide 9 is formed in a predetermined shape from, for example, a metal material, a rigid resin material, or the like. That is, the rod guide 9 is a stepped circular cylinder consisting of a large-diameter section 9A, located at the top and on the inner circumferential side of the outer tube 2, and a small-diameter section 9B, located below the large-diameter section 9A and on the inner circumferential side of the inner tube 4. The small-diameter section 9B has a guide section 9C provided on its inner circumferential side. The guide section 9C guides the piston rod in a slidable manner in the axial direction.The guide section 9C is designed as a bearing made from a metallic cylinder with an inner circumferential surface coated, for example, with a resin containing fluorine (tetrafluoroethylene).

[0022] The upper surface of the large-diameter section 9A, which faces the oil sealing element 10 described below in the axial (vertical) direction, forms an annular, substantially flat upper region 9D. The large-diameter section 9A has an annular, crown-shaped projection 9E formed on the outer circumferential side of the upper region 9D and further comprises a plurality of connecting lines 9F (only one connecting line is shown in the figures) formed at the position of the annular projection 9E. The connecting lines 9F extend axially through the large-diameter section 9A.

[0023] An oil retention chamber D is formed between the rod guide 9 and the oil sealing element 10. The oil retention chamber D is a space that temporarily stores hydraulic oil or gas that flows out of the rod-side oil chamber C through a small gap between the piston rod 7 and the rod guide 9. Hydraulic oil flowing out into the oil retention chamber D can be returned to the reservoir chamber A via the connecting lines 9F in the rod guide 9.

[0024] The following is an explanation of the oil sealing element 10 according to this embodiment.

[0025] The oil sealing element 10 is positioned closer to one end 2A (upper end) of the outer tube 2 than the rod guide 9 is to one end 2A of the outer tube 2. The oil sealing element 10 is annular in shape and is designed to prevent hydraulic oil from flowing out of the cylinder containing the sealing element 13 (described later), which is in sliding contact with the outer circumferential surface 7A of the piston rod 7. Furthermore, the oil sealing element seals between itself and the piston rod 7, preventing dust, rainwater, etc., from entering the cylinder. The oil sealing element 10 is integrally formed with the metal ring 11 and the sealing element 13.

[0026] The metal ring 11 is embedded to be surrounded by the forming material of the sealing element 13 described below, for example by a molding process using a mold or the like to form a core metal of the oil sealing element 10. That is, the metal ring 13 is coated on the outside with the resin that forms the sealing element 13. As in Fig. As shown in Figure 4, the metal ring has a through-hole 11C extending through a central section of it from an upper surface 11A, as a flat section, to a lower surface 11B. The through-hole 11C has the piston rod 7, which is movably inserted through it in the vertical direction, with the sealing element 13 positioned between them. Furthermore, the metal ring 11 has a plurality (for example, 8) of circumferentially spaced ribs 12 formed on it such that the ribs 12 extend upwards from the upper surface 11A and extend radially.

[0027] The ribs 12 are formed by locally deforming the metal ring 11, for example by pressing a stainless steel plate or the like. The ribs 12 are formed in a mountain-like shape from the following sections: a plurality of rising sections 12A, which are located on the upper surface 11A over its entire circumference substantially perpendicular to the upper surface 11A; connecting sections 12B, which connect the distal ends (upper ends) 12A1 of a pair of adjacent rising sections 12; etc.

[0028] As in Fig. 3 and Fig. As shown in Figure 4, each pair of adjacent rising sections 12A extends to gradually approach each other, starting from the outer diameter side 11D and moving towards the inner diameter side 11E of the metal ring 11. Each pair of adjacent rising sections 12A is connected (joined) by a connecting section 12C on the inner diameter side 11E of the metal ring 11. That is, each pair of adjacent rising sections 12A and the associated connecting section 12C are essentially formed in a V- or U-shape in plan view (when viewed from the upper surface side 11A). Consequently, each pair of adjacent rising sections 12A extends from the outer diameter side 11D to the inner diameter side 11E of the metal ring 11 and is connected to each other by a connecting section 12C before reaching the through-hole 11C.Accordingly, the circumferential edge of the through hole 11C in the metal ring 11, that is, the inner diameter side 11E of the metal ring 11, forms a circumferentially ring-shaped, flat surface.

[0029] Each connecting section 12B is arranged at the distal ends 12A1 of the associated rising sections 12A and forms a substantially triangular or trapezoidal flat surface in plan view. Accordingly, the ribs 12 are inclined from the outer diameter side 11D towards the inner diameter side 11E of the metal ring 11 and extend radially at a position one level higher than the upper surface 11A of the metal ring 11. Consequently, the metal ring can be improved with respect to its yield strength with respect to an axial force applied to it.

[0030] As in Fig. As shown in Figure 3, the ribs 12 are designed to extend closer to the inner diameter side 11E of the metal ring 11 than the distal ends 2C1 of the notched sections 2C. Additionally, the length dimension M between each pair of adjacent ribs 12 is set shorter than the circumferential length dimension L of each notched section 2C. Preferably, the length dimension between the connecting sections 12B of each pair of adjacent ribs 12 is set shorter than the circumferential length dimension L of the notched section 2C. With this structure, the notched sections 2C can be arranged on the ribs 12. As a result, an axial force applied to the notched sections 2C can be transmitted evenly to the ribs 12, and the oil sealing element 10 can be securely fastened.

[0031] Additionally, the rising sections 12A are formed by bending them at nearly right angles (perpendicular) to the upper surface 11A, as far as possible. In this case, the angle of the rising sections 12A to the upper surface 11A is preferably in the range of not less than 60° to not more than 90°, preferably from not less than 80° to not more than 90°. With this structure, an axial force acting on the connecting sections 12B of the ribs 12 can be effectively transferred to the upper surface 11A via the rising sections 12, and it is therefore possible to increase the mechanical strength of the metal ring 11.

[0032] The sealing element 13 is designed to cover the metal ring 11. The sealing element 13 is formed in a stepped, cylindrical shape from a synthetic resin material (elastic material), for example, nitrile rubber or the like. The sealing element 13 slidably contacts the outer circumferential side of the piston rod 7 to seal between the metal ring 11 and the piston rod 7. As shown in Fig. As shown in Figure 2, the sealing element 13 has an upper lip section 13A, which is provided on its inner diameter side at an upper position extending axially outwards from the metal ring 11. The sealing element 13 further has two vertically spaced lower lip sections 13B and 13C, which are provided on its inner diameter side at a lower position extending axially inwards from the metal ring 11.

[0033] Furthermore, the sealing element 13 has an upper, annular plate section 13D and a lower, annular plate section 13E, which is formed integrally with it, such that the upper and lower annular plate sections 13D and 13E face each other. The upper, annular plate section 13D extends from the proximal end of the upper lip section 13A towards the outer diameter side along the upper surface 11A of the metal ring 11. The lower plate section 13E extends from the common proximal end of the lower lip sections 13B and 13C towards the outer diameter side along the lower surface 11B of the metal ring 11. A mounting groove 13F is provided between the annular plate sections 13D and 13E. The metal ring 11 is fastened in the mounting groove 13F by a process such as welding, bonding, or the like.Here, the lower, annular plate section 13E of the sealing element 13 extends to the outer diameter side 11D of the metal ring 11 and has a check valve element 13G, which is integrally formed with it at a centrally located position in the radial direction of the lower, annular plate section 13E. Furthermore, the lower, annular plate section 13E has a sealing ring 13H, which is integrally formed with its outermost diameter section.

[0034] The check valve element 13G is arranged between the oil retention chamber D and the reservoir chamber A, and its distal end engages the upper section 9D of the rod guide 9. The check valve element 13G allows the hydraulic oil in the oil retention chamber D to flow into the reservoir chamber A through the connecting lines 9F in the rod guide 9, but prevents flow in the opposite direction. That is, the check valve element 13G prevents the gas and hydraulic oil in the reservoir chamber 13 from flowing towards the oil retention chamber D. Additionally, the sealing ring 13H prevents the gas and hydraulic oil in the reservoir chamber 8 from leaking outwards between the outer tube 2 and the metal ring 11.

[0035] The sealing element 13 has the upper lip section 13A, which is brought into sliding contact with the outer circumferential side of the piston rod 10 by an annular retaining spring 14A, and further has the lip sections 13B, which are brought into sliding contact with the outer circumferential side of the piston rod 7 by a retaining spring 14B, thereby creating a fluid-tight seal between the sealing element 13 and the piston rod 7.

[0036] The following is an explanation of an example of a process for securing the oil sealing element 10 to the upper end of the outer tube 2 of the hydraulic shock absorber 1 according to this embodiment comprising the structure described above.

[0037] First, the piston rod 7 is inserted through the guide section 9C of the rod guide 9, and during this process, the large-diameter section 9A is press-fitted into the outer tube 2, and the small-diameter section 9B is press-fitted into the inner tube 4. Subsequently, the piston rod 7 is inserted through the sealing element 13 in such a state that the upper lip section 13A and the lower lip sections 13B and 13C of the sealing element 13 of the oil seal 10 are in contact with the outer circumferential surface 7A of the piston rod 7.

[0038] Next, the lower, annular plate section 13E of the sealing element 13 is brought into contact (positioned) with the annular projection 9E of the rod guide 9. In this case, the distal end of the check valve element 13G rests against the upper region 9D of the rod guide 9 in an influencing manner. Consequently, the oil retention chamber D is formed between the rod guide 9 and the oil sealing element 10.

[0039] Next, the distal end (notched sections 2C) of the outer tube 2 is bent radially inwards, while the oil sealing element 10 is pressed (compressed) from above with a pressing tool (not shown) to leave a residual axial force in the outer and inner tubes 2 and 4. Consequently, the oil sealing element 10 is secured in a notched manner by the notched sections 2C between it and the rod guide 9.

[0040] Furthermore, the known technique has the problem that if a large pressing force is applied to the oil seal element, the metal ring of the oil seal element can be elastically deformed, making it impossible to reliably seal the upper end of the hydraulic shock absorber. Under these circumstances, it is conceivable to increase the mechanical strength of the metal ring by increasing its thickness or by stacking multiple metal rings. However, this approach leads to an increase in the weight of the oil seal ring, which in turn results in an undesirable increase in the weight of the hydraulic shock absorber.

[0041] In light of the above, in this embodiment the metal ring 11 of the oil sealing element 10 is formed with a plurality of radially extending ribs 12. Specifically, the metal ring 11 has a plurality (for example, 8) of circumferentially spaced radial ribs 12, which are formed such that the ribs 12 project upwards from the upper surface 11A and extend radially. Furthermore, the ribs are formed to extend closer to the inner diameter side 11E of the metal ring 11 than the distal ends 2C1 of the notched sections 2C. With this structure, a compressive force applied to the oil sealing element 10 acts on the connecting sections 12B of the ribs 12 via the annular plate section 13D of the sealing element 13.Accordingly, even if the pressing force applied to the oil sealing element 10 is large, elastic deformation (bending) of the metal ring 11 can be suppressed by the ribs 12.

[0042] Additionally, as in Fig. As shown in Figure 3, the length dimension M between each pair of adjacent ribs 12 is set shorter than the circumferential length dimension L of each notched section 2C. With this structure, the notched sections 2C can be positioned on the ribs 12. As a result, an axial force applied to the notched sections 2C can be distributed evenly across the ribs 12, and the oil sealing element 10 can be securely fastened.

[0043] Additionally, the rising sections 12A of the ribs 12 are formed by bending them at nearly right angles (perpendicular) to the upper surface 12A, as far as possible. With this structure, the axial force acting on the connecting sections 12B of the ribs 12 can be effectively transferred to the upper surface 11A of the metal ring 11 via the rising sections 12A, thus increasing the mechanical strength of the metal ring 11.

[0044] Consequently, according to this embodiment, the metal ring 11, which forms the oil sealing element 10 of the hydraulic shock absorber 1, has a plurality of radially extending ribs 12, which are provided by locally deforming the metal ring 11. Therefore, it is possible to achieve a compatible increase in the mechanical strength and a reduction in the weight of the metal ring 11, and consequently, it is possible to reduce the weight of the hydraulic shock absorber 1.

[0045] Next, show Fig. 5. A second embodiment of the present invention. The feature of the second embodiment is that the metal ring 11 is provided with an annular plate 22 for reinforcement. It should be noted that in the second embodiment, the same forming elements as those of the aforementioned first embodiment are designated with the same reference numerals as those used in the first embodiment, and a description thereof is omitted.

[0046] An oil sealing element 21 is arranged closer to one end 2A of the outer tube 2 than the rod guide 9 is located near that end 2A of the outer tube 2. The oil sealing element 21 is formed integrally from the metal ring 11, an annular plate 22, and a sealing element 23. The annular plate 22, as a first annular plate, is positioned closer to the notched sections 2C than the metal ring 11. The annular plate 22 is a plate material used for reinforcement, which suppresses the deformation of the metal ring 11 caused by an axial force acting upon it. The annular plate 22 is formed, for example, from an annular metal plate and has an upper surface 22A and a lower surface 22B, which are uniformly flat surfaces.Furthermore, the annular plate 22 has a through-hole 22C extending from the upper surface 22A to the lower surface 22B in a coaxial relationship with the through-hole 11C in the metal ring 11. The piston rod 7 is inserted into the through-hole 22C, allowing it to move vertically with the sealing element 23 positioned between them. It should be noted that the bore diameter of the through-hole 22C can be the same as or different from that of the through-hole 11C in the metal ring 11.

[0047] Furthermore, the annular plate 22, together with the metal ring 11, is formed in a mounting groove 22F of the sealing element 23 and, in this state, is bonded to the lower surface 22B, which rests against the connecting sections 12B of the ribs 12 formed on the metal ring 11. It should be noted that the area between the lower surface 22B and the annular plate 22 and the upper surface 11A of the metal ring 11 is filled with the sealing element 23 described below. That is, the oil sealing element 21 comprises the metal ring 11 and the annular plate 22, which is formed integrally with the sealing element 23. Accordingly, the metal ring 11 and the annular plate 22 are coated externally with the resin-containing sealing element 23 in the state in which they are arranged one above the other.

[0048] The sealing element 23 is designed to cover the metal ring 11 and the annular plate 22. The sealing element 23 is formed using a synthetic resin material, essentially in the same way as the sealing element 13 in the first embodiment described above. The sealing element 23 comprises an upper lip section 23A, lower lip sections 23B and 23C, an upper annular plate section 23D, a lower annular plate section 23E, a mounting groove 23F, a check valve element 23G, a sealing ring 23H, etc.

[0049] According to the second embodiment, which is structured as described above, the mechanical strength can be further increased by the two elements, for example, the metal ring 11 and the annular plate 22. In this case, the metal ring 11 is provided with ribs 12. Therefore, the thickness of the annular plate 22 can be reduced compared to a structure where, for example, an annular reinforcing plate is arranged over a metal ring without ribs. Consequently, it is possible to achieve a combined increase in mechanical strength and a reduction in weight, and thus it is possible to reduce the weight of the hydraulic shock absorber 1.

[0050] Next, show Fig. 6 a third embodiment of the present invention. The feature of the third embodiment relates in that the metal ring 11 is provided with a first annular plate 32 and a second annular plate 33 for reinforcement. It should be noted that in the third embodiment the same forming elements as those of the aforementioned first embodiment are designated with the same reference numerals as those used in the first embodiment, and a description thereof is omitted.

[0051] An oil sealing element 31 is arranged closer to one end 2A of the outer tube 2 than the rod guide 9 is located near one end 2A of the outer tube 2. The oil sealing element 31 is formed in one piece from the metal ring 11, a first annular plate 32, a second annular plate 33, and a sealing element 34.

[0052] The first annular plate 32 is positioned closer to the notched sections 2C than the metal ring 11. The first annular plate 32 has a similar structure to the annular plate 22 described above and comprises an upper surface 32A, a lower surface 32B, and a through-hole 32C. The through-hole 32C has a piston rod 7 inserted into it, which is movable in the vertical direction with the sealing element 34 positioned between it and the piston rod. The first annular plate 32 rests against the connecting sections 12B of the ribs 12 formed on the metal ring 11. It should be noted that the area between the lower surface 32B of the first annular plate 32 and the upper surface 11A of the metal ring 11 is filled with the sealing element 34 described below.

[0053] The second annular plate 33 is positioned closer to the rod guide 9 than the metal ring 11. The second annular plate has a similar structure to that of the first annular plate 32 and comprises an upper surface 33A, a lower surface 33B, and a through-hole 33C. The through-hole 33C accommodates the piston rod 7, which is movably inserted through it in the vertical direction, with the sealing element 34 positioned between them.

[0054] It should be noted that the plate density of the second annular plate 33 may be the same as or different from that of the first annular plate 32. The bore diameter of the through-hole 33C may be the same as or different from that of the through-hole 11C in the metal ring 11 or that of the through-hole 32C in the first annular plate 32. The second annular plate 33 rests against the lower surface 11B of the metal ring 11 at its upper surface 33A. It should be noted that the area between the upper surface 33A of the second annular plate 33 and the ribs 12 is filled with the sealing element 34 described below.

[0055] The metal ring 11 and the first and second annular plates 32 and 33 are arranged in a mounting groove 34F of the sealing element 34 and bonded in this state. That is, the oil sealing element 31 comprises the metal ring 11 and the first and second annular plates 32 and 33, which are integrally formed with the sealing element 34. Accordingly, the metal ring 11 and the first and second annular plates 32 and 33 are coated externally with resin in the sealing element 34 in the state in which they are arranged one above the other.

[0056] According to the third embodiment, which is constructed as described above, the mechanical strength can be further increased by the three elements: the metal ring 11, the first annular plate 32, and the second annular plate 33. In this case, the metal ring 11 is provided with ribs 12. Therefore, the thickness of the first annular plate 32 and the second annular plate 33 can be reduced compared to a structure where, for example, the first and second annular plates are stacked on top of each other on a metal ring without ribs for reinforcement. Consequently, it is possible to achieve a combined increase in mechanical strength and a reduction in weight, thus reducing the weight of the hydraulic shock absorber 1.

[0057] It should be noted that in the aforementioned first embodiment, the present invention was described with reference to an example of a case in which each pair of adjacent rising sections 12A of the ribs 12 formed on the metal ring 11 is connected to one another via a connecting section 12C on the inner diameter side 11E of the metal ring 11. However, the present invention is not limited thereto. For example, as in the first modification, the Fig. As shown in Figure 7, a metal ring 41 is provided with alternating raised and recessed features in the circumferential direction. That is, ribs 32 formed on the metal ring 41 can each be provided with rising sections 42A extending from the outer diameter side 41A to the through-hole 41B of the metal ring 41, and connecting sections 42B connecting the distal ends 42A1 of the rising sections 42A. This is applied similarly in the second and third embodiments.

[0058] Furthermore, as with a second modification, the following can be added: Fig. 8 and Fig.As shown in Figure 9, ribs 52, formed, for example, on a metal ring 51, are connected to each other circumferentially on the outer diameter side 51A of the metal ring 51 to provide a notched, abutting section 52A. That is, a notched abutting section 52, intended to abut the notched sections 2C, can be formed on the outer diameter side 51A of the metal ring 51, which is connected by the ribs 52. Consequently, an axial force applied to the notched sections 2C can be absorbed over a wide area by the notched, abutting section 52A and the connected sections 52B. Therefore, the oil sealing element can be secured more stably. This is applied similarly in the second and third embodiments and the first modification.

[0059] Furthermore, with reference to the aforementioned first embodiment, the present invention was explained by way of an example of a case in which the notched sections 2C are locally notched sections provided at four positions spaced apart from one another in the circumferential direction of the outer tube 2. However, the present invention is not limited thereto. For example, the notched sections may be provided at two or three positions, or at five or more positions. Alternatively, the entire circumference of the outer tube 2 may be notched to provide a circumferentially notched section. This applies similarly to the second and third embodiments.

[0060] Furthermore, in the aforementioned first embodiment, the invention was described with reference to an example of a case in which the metal ring 11 is provided with eight circumferentially spaced ribs 12. However, the present invention is not limited thereto. For example, the metal ring can be provided with 3 to 7 ribs or 9 or more ribs. This applies similarly to the second and third embodiments and the first and second modifications.

[0061] Furthermore, in the aforementioned first embodiment, the invention was described with respect to an example case in which the notched section 2C is provided to extend between a pair of adjacent ribs 12. However, the present invention is not limited thereto. For example, each notched section may be provided on one rib or may be provided to extend over three or more ribs. This applies similarly to the second and third embodiments and the first and second modifications.

[0062] Furthermore, in the aforementioned first embodiment, the present invention was explained with reference to an example of the hydraulic shock absorber 1, in which the piston rod 7 extends from one end 2A of the outer tube 2 and in which the other end 2B of the outer tube 2 is closed with the lower cap 3. However, the present invention is not limited thereto. For example, the present invention is also applicable to a two-rod hydraulic shock absorber in which a piston rod extends from opposite ends of the outer tube, i.e., one end and the other end thereof, and in which the oil sealing element 21 is provided at each of the two ends of the outer tube. This applies similarly to the second and third embodiments and the first and third modifications.

[0063] Furthermore, in the aforementioned first embodiment, the present invention was described with reference to an example of a case in which the oil sealing element 21, comprising the metal ring 14, is provided in the hydraulic shock absorber 1 with two tubes, the inner and outer tubes 2 and 4 forming a cylinder. However, the present invention is not limited thereto. For example, the oil sealing element 21, comprising the metal ring 14, can be applied to a hydraulic shock absorber with one tube. This applies similarly to the second and third embodiments and the first and second modifications.

[0064] Furthermore, in the aforementioned third embodiment, the present invention was described with reference to an example of a case in which the first annular plate 32 is provided on the upper side of the metal ring 11 and the second annular plate 33 is provided on the lower side of the metal ring 11. However, the present invention is not limited thereto. For example, the structure can be such that the first annular plate 32 is not provided and the second annular plate 33 is provided only on the lower side of the metal ring 11.

[0065] Furthermore, in the aforementioned embodiments, the present invention was described with reference to an example of the hydraulic shock absorber 1, which is attached to a wheel of a four-wheeled automobile. However, the present invention is not limited thereto. For example, the present invention can also be applied to a hydraulic shock absorber used in a two-wheeled vehicle. It is also possible to apply the present invention to hydraulic shock absorbers used in addition to vehicles, in various machines, architectural structures, etc., and also to a cylinder device that is driven on demand to supply and discharge pressurized oil.

[0066] The following is a description of inventions encompassed in the aforementioned embodiments. According to the present invention, the ribs are designed to extend closer to the inner diameter face than the distal ends of the notched sections. Consequently, the axial force applied to the oil sealing element can be absorbed by the ribs. Accordingly, deformation of the metal ring can be suppressed, even if a pressing force applied to the oil sealing element is large. In addition, since the notched sections can be provided over a wide area above the ribs, an axial force applied to the notched sections can be transmitted to the ribs.

[0067] Additionally, the oil sealing element comprises the metal ring and a first annular plate, positioned closer to the notched sections than the metal ring, and / or a second annular plate, positioned closer to the annular element than the metal ring. The metal ring and either the first annular plate or the second annular plate are integrally formed with the sealing element. This structure suppresses deformation of the metal ring.

[0068] The notched sections are locally notched sections provided by locally notching the outer tube at a multitude of circumferentially spaced positions. Each notched section has a circumferential length dimension. The length dimension between a pair of adjacent ribs is narrower than the circumferential length dimension of each of the notched sections. This structure allows each notched section to extend across a pair of adjacent ribs. Furthermore, an axial force applied to the notched sections can be distributed evenly across the ribs, and the oil seal element can be securely held in place.

[0069] The ribs are formed in a mountain-like shape, originating from a multitude of rising sections that project onto a flat section of the metal ring around its entire circumference, essentially perpendicular to the flat section, and connecting sections that link the distal ends of each pair of adjacent rising sections. This structure allows an axial force acting on the connecting sections of the ribs to be effectively transferred to the upper surface of the metal ring via the rising sections, thus increasing the mechanical strength of the metal ring.

[0070] Additionally, a notched, abutting section, designed to align with the notched sections, can be formed on the outer diameter side of the metal ring connected to the ribs. This structure allows an axial force applied to the notched sections to be absorbed by the notched, abutting section and the connected sections over a wide area. Therefore, the oil sealing element can be secured even more reliably.

[0071] Although only some exemplary embodiments of this invention have been described above, the person skilled in the art can readily see that various modifications or improvements can be made to these exemplary embodiments without substantially departing from the new teaching and advantages of this invention. Accordingly, it is intended that all such modifications be included in the scope of protection of this invention. The aforementioned embodiments can be combined in any way desired.

[0072] The present application claims priority from Japanese patent application no. 2014-262421, filed on December 25, 2014. The entire disclosure of Japanese patent application no. 2014-262421, filed on December 25, 2014, including the description, claims, drawings, and abstract, is hereby incorporated by reference in its entirety. REFERENCE MARK LIST 1 Hydraulic shock absorber (cylinder assembly) 2 outer pipe (cylinder) 2A an end 2A1 Opening 2B the other end 2C notched section 2C1 distal end 4 inner tube (cylinder) 7 Piston rod 9 Rod guide (ring-shaped element) 10, 21, 31 Oil sealing element 11, 41, 51 metal ring 11A upper surface (flat section) 12th, 42nd, 52nd rib 12A, 42A Ascending section 12A1, 42A1 Distal end 12B, 42B, 52B connection section 13, 23, 34 Sealing element 22 ring-shaped plate (first ring-shaped plate) 32 first ring-shaped plate 33 second ring-shaped plate

Claims

Cylinder device (1) comprising: a cylinder (2) having an opening (2A1) at one end thereof and comprising a hydraulic fluid enclosed therein; a rod (7) extending from at least one end of the cylinder (2); an annular element (9) arranged at one end of the cylinder (2); an annular oil sealing element (10) arranged in a position closer to and pointing towards one end of the cylinder (2) than the annular element (9); and a notched section (2C) formed at one end of the cylinder (2) to secure the oil sealing element (10) between the notched section (2C) and the annular element (9) in an axial direction of the cylinder (2); wherein the oil sealing element (10) comprises a metal ring (11) and a sealing element (13) surrounding the metal ring (11);wherein the metal ring (11) has a plurality of radially extending ribs (12) provided by local deformation of the metal ring (11), wherein the ribs (12) are formed to extend from a position where the oil sealing element (10) is secured in the axial direction by the notched section (2C) closer to an inner diameter side (11E) than a distal end (2C1) of the notched section (2C), wherein the notched section (2C) comprises locally notched sections (2C) formed by locally notching the cylinder (2) at a plurality of circumferentially spaced positions, wherein the notched sections (2C) each have a circumferential length dimension, wherein a length dimension between a pair of adjacent ribs (12) is narrower than the circumferential length dimension of each of the notched sections (2C) .; Cylinder device (1) according to claim 1, wherein the oil sealing element (10) comprises the metal ring (11) and a first annular plate (32) which is arranged closer to the notched section (2C) than the metal ring (11), and / or a second annular plate (33) which is arranged closer to the annular element (9) than the metal ring (11), wherein the metal ring (11) and the first annular plate (32) and / or the second annular plate (33) are formed integrally with the sealing element (13). Cylinder device (1) according to claim 1 or 2, wherein the ribs (12) are formed in a mountain shape from a plurality of rising sections (12A) which are highlighted on a flat section of the metal ring (11) over its entire circumference in order to be substantially perpendicular to the flat section, and connecting sections (12B) which each connect distal ends (2C1) of a pair of adjacent rising sections (12A). Cylinder device (1) according to claim 1, 2 or 3, further comprising: a notched, abutting section (52A) which abuts the notched section (2C), wherein the notched, abutting section (52A) is formed on an outer diameter side of the metal ring (11) and is connected to the ribs (12).

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