JP7438394B2 - buffer - Google Patents

Description

The present invention relates to a double-tube hydraulic shock absorber used in railway vehicles and the like.

Patent Document 1 discloses a double-tube shock absorber in which an orifice functioning as a damping force generating element and an air bleed element is formed by a notch provided in an annular plate interposed between a cylinder and a rod guide. ing.

Japanese Patent Application Publication No. 2012-233595

By the way, in the shock absorber disclosed in Patent Document 1 (hereinafter referred to as "conventional shock absorber"), a notch (orifice) with an extremely small flow path area (for example, "0.3 mm" in terms of hole diameter) is formed in the annular plate. need to be formed. For this reason, a thin plate (for example, plate thickness "0.3 mm") is used for the annular plate. In this case, if the tolerance of the thickness of the thin plate is not strictly controlled, the flow path area of the notch (orifice) will vary due to the influence of the tolerance of the thickness of the thin plate, which will lead to variations in air bleed performance between products. (damping force characteristics) may vary and reliability may decrease.

An object of the present invention is to provide a dual-tube hydraulic shock absorber with improved reliability.

A shock absorber according to an embodiment of the present invention includes a cylinder, a tube provided on the inner circumferential side of the cylinder and sealed with a working fluid, and a buffer provided between the cylinder and the tube to contain the working fluid and gas. a reservoir chamber in which a reservoir chamber is enclosed; a piston that is slidably provided within the tube and divides the tube into two chambers; one end is connected to the piston and the other end extends to the outside of the cylinder; a piston rod provided at the end of the tube to close off the cylinder and the tube, and a closing member provided between the closing member and the end of the tube and fitted into the closing member. an integral annular plate, a recess that communicates the tube with the reservoir chamber is formed on a surface of the annular plate facing the tube, and the closing member is arranged in a radial direction of the annular plate. It has a fitting part that comes into contact with the inner periphery or the radial outer periphery, and the height of the fitting part is shorter than the thickness of the annular plate.

According to one embodiment of the present invention, the reliability of a dual-tube hydraulic shock absorber can be improved.

FIG. 3 is a sectional view of the shock absorber of the first embodiment. FIG. 2 is a diagram showing an enlarged view of the main part in FIG. 1; It is a perspective view of the annular plate in the shock absorber of 1st Embodiment. FIG. 7 is an enlarged cross-sectional view showing the main parts of the shock absorber according to the second embodiment. 5 is a view taken along the line AA in FIG. 4. FIG. FIG. 7 is an enlarged cross-sectional view of main parts of a shock absorber according to a third embodiment. 7 is a view taken along the line BB in FIG. 6. FIG. FIG. 7 is an enlarged cross-sectional view showing main parts of a shock absorber according to a fourth embodiment. 9 is a view taken along the line CC in FIG. 8. FIG. FIG. 7 is an enlarged view showing main parts of a shock absorber according to a fifth embodiment. It is a perspective view of the annular plate in the shock absorber of 5th Embodiment. It is a perspective view of an annular plate for showing a modification of a recessed part. It is a perspective view of an annular plate for showing a modification of a recessed part. It is a perspective view of an annular plate for showing a modification of a recessed part. It is a perspective view of an annular plate for showing a modification of a recessed part.

(First Embodiment) A first embodiment of the present invention will be described with reference to the attached drawings.
Here, a horizontal double-tube hydraulic shock absorber 1 (hereinafter referred to as "shock absorber 1") will be described, which is disposed substantially horizontally as a left-right damper between the car body of a railway vehicle and a bogie. In addition, in the following description, for convenience, the up-down direction and the left-right direction in FIG. 1 are referred to as the up-down direction and the left-right direction, but this is not intended to limit the mounting direction (orientation) of the shock absorber 1.

As shown in FIG. 1, the shock absorber 1 includes a cylinder 2 and a tube 3 provided on the inner peripheral side of the cylinder 2. The left ends of the cylinder 2 and tube 3 are closed by a rod guide 41 (closing member). On the other hand, the right ends of the cylinder 2 and tube 3 are closed by an end plate 5. An annular reservoir 4 (reservoir chamber) is formed between the cylinder 2 and the tube 3. The end plate 5 is divided into an end plate 6 that closes the right end of the cylinder 2 and an end plate 7 that closes the right end of the tube 3. A bracket 8 connected to the body side of the railway vehicle is fixed to the end plate 6. The end plate 6 and the end plate 7 are integrated by fitting a shaft portion 9 formed at the right end of the end plate 7 into a recess 10 formed at the left end of the end plate 6.

A piston 12 is slidably fitted into the tube 3 . The piston 12 partitions the inside of the tube 3 into a first chamber 13 on the rod guide 41 side and a second chamber 14 on the end plate 5 side. The first chamber 13 and the second chamber 14 are filled with hydraulic fluid, and the reservoir 4 is filled with hydraulic fluid and air (gas). A right end (one end) of a piston rod 15 is connected to the piston 12 . The left end side (other end side) of the piston rod 15 is extended to the outside of the tube 3 through the first chamber 13 and the rod guide 41. A bracket 16 connected to the bogie side of the railway vehicle is fixed to the left end of the piston rod 15. A cylindrical cover 17 that covers the exposed portion of the piston rod 15 is attached to the bracket 16 .

The piston 12 has a valve that prevents the movement of hydraulic fluid from the second chamber 14 to the first chamber 13 during the retraction stroke of the piston rod 15, and opens when the hydraulic pressure in the second chamber 14 reaches a certain pressure. By doing so, a relief valve 18 is provided that releases the hydraulic pressure in the second chamber 14 to the first chamber 13. The piston 12 also has a mechanism that prevents the movement of hydraulic fluid from the first chamber 13 to the second chamber 14 during the extension stroke of the piston rod 15, so that when the hydraulic pressure in the first chamber 13 reaches a certain pressure, A relief valve 19 is provided that releases the hydraulic pressure in the first chamber 13 to the second chamber 14 when opened. On the other hand, the end plate 7 is provided with a relief valve 20 that opens when the hydraulic pressure in the second chamber 14 reaches a set pressure and releases the hydraulic pressure in the second chamber 14 to the reservoir 4 . Further, the end plate 7 is provided with a check valve 21 (check valve) that allows the hydraulic fluid to flow from the reservoir 4 to the second chamber 14 .

A cylindrical portion 22 whose left end is open is formed at the outer peripheral edge of the end plate 7 . The right end portion 23 of the tube 3 is fitted inside the cylindrical portion 22 . A seal ring 25 seals between the right end portion 23 of the tube 3 and the cylindrical portion 22 of the end plate 7. The tube 3 is positioned in the left-right direction (axial direction) by abutting the end surface 24 of the right end portion 23 against the bottom of the cylindrical portion 22 of the end plate 7 . On the other hand, the left end portion 26 of the tube 3 is fluid-tightly fitted into a concave tube fitting portion 43 provided on the right end surface 42 of the rod guide 41.

The outer circumferential surface 44 of the rod guide 41 is fitted into a rod guide fitting portion 37 formed on the inner circumferential surface 36 of the left end portion 35 of the cylinder 2 . A lock ring 29 is screwed into the opening of the left end 35 of the cylinder 2 . By tightening the lock ring 29, an axial force is applied to the tube 3 pressurized between the rod guide 41 and the end plate 7. An oil seal 31 that slides on the piston rod 15 is provided in the shaft hole 30 of the lock ring 29 . On the other hand, the shaft hole 47 of the rod guide 41 is provided with a seal ring 32 that comes into sliding contact with the piston rod 15 .

An annular groove 49 is formed near the bottom portion 48 of the tube fitting portion 43 of the rod guide 41 . In the first embodiment, the annular groove 49 has an endless circular shape extending in the circumferential direction of the tube fitting part 43. The tube fitting portion 43 may have an annular semicircular shape extending from the upper end to the lower end thereof.

As shown in FIG. 2, a small outer diameter portion 45 having a smaller diameter than the outer peripheral surface 44 is formed at the right end of the rod guide 41, in other words, at the outer periphery of the tube fitting portion 43. As a result, an annular gap 46 communicating with the reservoir 4 is formed between the small outer diameter portion 45 of the rod guide 41 and the inner circumferential surface 36 of the cylinder 2 . The annular gap 46 has a certain flow path area provided at the lower end (at the "6 o'clock" clock position) of the small outer diameter section 45 of the rod guide 41 when the shock absorber 1 is installed. The passage 50 communicates with the annular groove 49 formed in the tube fitting portion 43 of the rod guide 41 .

An annular plate 53 (see FIG. 3) is interposed between the bottom portion 48 of the tube fitting portion 43 of the rod guide 41 and the end surface 27 of the left end portion 26 of the tube 3. The annular plate 53 has a rectangular cross section taken along the axial plane of the shock absorber 1. A part of the outer circumferential surface 54 (see FIG. 3) of the annular plate 53 is located on the left side of the annular groove 49 in the tube fitting portion 43, in other words, the annular portion formed between the annular groove 49 and the bottom portion 48. It is fitted into the cylindrical surface of the plate fitting part 51 (fitting part) with a certain fitting tolerance. Note that the inner diameter of the annular plate 53 is smaller than the inner diameter of the left end portion 26 of the tube 3.

The height of the plate fitting part 51 of the rod guide 41, in other words, the distance in the left and right direction from the bottom part 48 of the tube fitting part 43 of the rod guide 41 to the annular groove 49 is determined by the thickness of the annular plate 53 (in the left and right direction). shorter than the length of That is, the right end of the outer peripheral surface 54 of the annular plate 53 faces the annular groove 49 of the rod guide 41. The left end surface 56 of the annular plate 53 is brought into contact with the bottom portion 48 of the tube fitting portion 43 of the rod guide 41 . On the other hand, the end surface 27 of the left end portion 26 of the tube 3 is brought into contact with the right end surface 57 of the annular plate 53 .

Referring to FIGS. 2 and 3, a recess 81 is formed in the right end surface 57 of the annular plate 53, which is the surface facing the tube 3. The recess 81 extends in the radial direction of the annular plate 53 from the outer peripheral surface 54 to the inner peripheral surface 55 (see FIG. 3). The recess 81 extends in the vertical direction from the upper end of the annular plate 53 (at the "12" clock position) when the shock absorber 1 is attached. The recess 81 is formed into a rectangular (channel-shaped) cross section by coining (press processing). The recess 81 allows the annular passage 52 defined by the annular groove 49 of the rod guide 41 to communicate with the first chamber 13 within the tube 3 . Note that the recess 81 can be processed by engraving, etching, etc. in addition to coining.

The shock absorber 1 includes an air bleed structure that discharges air accumulated in the first chamber 13 to the reservoir 4 . In the air vent structure configured in the shock absorber 1 of the first embodiment, air accumulated in the corners of the first chamber 13 is removed from the recess 81, the annular passage 52, the passage 50, and the annular gap during the extension stroke of the piston rod 15. 46 and is discharged to the reservoir 4. On the other hand, the recess 81 functions as an orifice that generates a damping force against the flow of the hydraulic fluid flowing from the first chamber 13 to the reservoir 4 via the recess 81, the annular passage 52, the passage 50, and the annular gap 46.

The operation of the first embodiment will be explained.
The piston rod 15 of the shock absorber 1 arranged laterally expands and contracts as the car body of the railway vehicle and the bogie move relative to each other in the horizontal direction. During the extension stroke of the piston rod 15, the hydraulic fluid in the first chamber 13 flows into the second chamber 14 through the relief valve 19 of the piston 12. In parallel with this, the hydraulic fluid in the first chamber 13 flows into the reservoir 4 through the recess 81 of the annular plate 53, the annular passage 52, the passage 50 of the rod guide 41, and the annular gap 46. At this time, the hydraulic fluid in the first chamber 13 flows through the relief valve 18 and the recess 81 (orifice), thereby generating damping force on the extension side.

In addition, during the extension stroke of the piston rod 15, the air accumulated in the corners of the first chamber 13 is contained in the hydraulic fluid as air bubbles (air-containing hydraulic fluid) and is transferred from the first chamber 13 to the annular plate 53. It is discharged into the reservoir 4 through the recess 81, the annular passage 52, the passage 50 of the rod guide 41, and the annular gap 46. Note that during the extension stroke of the piston rod 15, the hydraulic fluid corresponding to the volume of the piston rod 15 leaving the first chamber 13 is transferred from the reservoir 4 to the second chamber 14 by opening the check valve 21 of the end plate 7. be introduced.

On the other hand, during the retraction stroke of the piston rod 15, the hydraulic fluid in the second chamber 14 passes through the relief valve 18 of the piston 12 and flows into the first chamber 13. In parallel with this, the hydraulic fluid equivalent to the volume that the piston rod 15 has entered into the first chamber 13 is discharged from the second chamber 14 to the reservoir 4 via the relief valve 20 of the end plate 7. At this time, the hydraulic fluid in the second chamber 14 flows through the relief valve 18 and the relief valve 20, thereby generating a damping force on the contraction side.

Here, in conventional shock absorbers, it is necessary to form a notch (orifice) with an extremely small flow path area (for example, 0.3 mm in terms of hole diameter) in the annular plate. "0.3 mm") is used. However, if the tolerance of the thickness of the thin plate is not strictly controlled, the flow path area of the notch (orifice) will vary due to the influence of the tolerance of the thickness of the thin plate. Damping force characteristics) will vary, reducing the reliability of the shock absorber.
In addition, when a thin plate is used as the annular plate, it is not possible to secure a crushing allowance, so even if the end plate is slightly tilted due to welding accuracy etc., a gap will be created at the abutting part between the annular plate and the tube. There is a possibility that the working fluid (pressure) in the first chamber 13 leaks to the reservoir 4 side through the gap.
In addition, when a thin plate is used as the annular plate, it is not possible to secure a crushing margin, so the slight inclination of the end plate cannot be absorbed by the crushing margin, and the axial force acting on the tube is deflected, causing the lock to lock. The ring may become loose.
Further, in conventional shock absorbers, the thickness of the annular plate affects the flow path area of the orifice, so the damping force of the orifice characteristic varies depending on the tolerance of the plate thickness.
In addition, in conventional shock absorbers, notches are formed in a thin plate by pressing, so there is a risk that burrs generated in the notches may reduce the ability to drain contaminants.
Furthermore, in conventional shock absorbers, the end of the notch receives a jet of hydraulic fluid, so there is a risk of aeration and wear at the end of the notch.

In contrast, in the first embodiment, a recess 81 is formed in the right end surface 57 of the annular plate 53, which is the surface facing the tube 3, and the recess 81 allows the first chamber 13 in the tube 3 and the reservoir 4 to be connected to each other. (reservoir chamber), the cross-sectional area of the recess 81 and, by extension, the flow area of the passage defined by the recess 81 are not affected by the thickness of the annular plate 53. In addition, since the recess 81 is formed by coining (press processing), the recess 81 can be formed with extremely high precision.
Thereby, it is possible to suppress variations in air removal performance between products, and the reliability of the shock absorber 1 can be improved.
Furthermore, since the shape of the recess 81 and, by extension, the flow path area of the orifice formed by the recess 81 are not affected by the thickness of the annular plate 53, variations in damping force characteristics between products can be suppressed. This is possible, and the reliability of the buffer 1 can be improved.
Furthermore, since the thickness of the annular plate 53 and, in turn, the crushing margin of the annular plate 53 are ensured, leakage of the hydraulic fluid through the contact portion between the annular plate and the tube can be suppressed. Furthermore, since the inclination of the end plate 5 is absorbed by the crushing margin, it is possible to equalize the axial force acting on the tube 3 in the circumferential direction, and it is possible to prevent the lock ring 29 from loosening.
Furthermore, in the first embodiment, since the recess 81 is formed by coining (pressure processing), burrs do not form in the recess 81, and contaminants in the hydraulic fluid are removed from the first chamber 13 through the recess 81. It can be smoothly discharged to the reservoir 4. Furthermore, since the flow path area of the orifice can be set finely, it is possible to provide the shock absorber 1 with improved tunability of the damping force characteristics.
In the first embodiment, the recess 81 extends from the inner circumferential surface 55 (inner circumferential end surface) to the outer circumferential surface 54 (outer circumferential end surface) of the annular plate 53. There is no barrier that obstructs the radial direction), and wear of the annular plate 53 can be suppressed.

(Second Embodiment) Next, a second embodiment will be described with reference to FIGS. 4 and 5.
Note that for parts common to the first embodiment, the same names and numerals will be used, and overlapping explanations will be omitted. Here, differences from the first embodiment will be mainly explained.

In the first embodiment, the tube 3 is coupled to the rod guide 41 by fitting the left end 26 of the tube 3 into the concave tube fitting portion 43 provided on the right end surface 42 of the rod guide 41 .

On the other hand, in the second embodiment, the convex tube fitting portion 61 provided on the right end surface 42 of the rod guide 41 is fitted into the inside (inner peripheral surface) of the left end portion 26 of the tube. The tube 3 was connected to the rod guide 41. The tube fitting portion 61 has an outer circumferential surface 62 that is a cylindrical surface coaxial with the axis of the shock absorber 1 . An annular groove 49 is provided in the outer circumferential surface 62 . The annular groove 49 is formed near the right end surface 42 of the rod guide 41. The outer circumferential surface 62 is provided with a groove 63 that extends in the left-right direction (axial direction) from the upper end of the tube fitting portion 61 (at the "12 o'clock" clock position) when the shock absorber 1 is attached.

In the annular plate 53, the base of the tube fitting part 61 (the part on the left side of the annular groove 49) is fitted into a part of the inner peripheral surface 55 (see FIG. 5), and the left end surface 56 is on the right side of the rod guide 41. It abuts against the end face 42. The annular plate 53 has an outer diameter larger than the outer diameter of the tube 3. A recess 81 is formed in the right end surface 57 of the annular plate 53, which is the surface facing the tube 3. The recess 81 extends in the vertical direction at the lower end of the annular plate 53 (at the "6 o'clock" clock position) when the shock absorber 1 is attached. The recess 81 allows the annular passage 52 defined by the annular groove 49 of the rod guide 41 to communicate with the first chamber 13 within the tube 3 .

In the air venting structure of the shock absorber 1 of the second embodiment, during the extension stroke of the piston rod 15, the air accumulated in the corners of the first chamber 13 is removed from the groove 63 of the outer circumferential surface 62 of the tube fitting part 61, the annular passage 52, and is discharged into the reservoir 4 through the recess 81. On the other hand, the recess 81 functions as an orifice that generates a damping force against the flow of the hydraulic fluid flowing from the first chamber 13 through the groove 63, the annular passage 52, and the recess 81 to the reservoir 4.

According to the second embodiment, it is possible to obtain the same effects as those of the first embodiment described above.
In addition, in the second embodiment, when the guide length of the rod guide 41 is the same as in the first embodiment, the rod guide 41 It is possible to shorten the total length (axial length) of the shock absorber 1, and thus the total length of the shock absorber 1, and the shock absorber 1 can be made smaller.

(Third Embodiment) Next, a third embodiment will be described with reference to FIGS. 6 and 7.
Note that the same names and symbols are used for common parts with the first and second embodiments, and redundant explanation will be omitted. Here, differences from the second embodiment will be mainly explained.

In the second embodiment, it is necessary to assemble the annular plate 53 so that the recess 81 is located at the lower end (at the "6 o'clock" clock position) when the shock absorber 1 is installed. Therefore, in the third embodiment, a positioning mechanism 65 for positioning the annular plate 53 around the axis with respect to the rod guide 41 is provided.

When the shock absorber 1 is installed, the positioning mechanism 65 connects a groove 66 provided at the upper end of the tube fitting portion 61 of the rod guide 41 (at the "12 o'clock" clock position) and the inner part of the annular plate 53. It has a convex portion 67 that protrudes from the circumferential surface 55 in the radial direction and is fitted into the groove 66 . The groove 66 extends from the end surface 64 of the tube fitting part 61 to the right end surface 42 of the rod guide 41, and has a rectangular (channel-shaped) cross section taken along a plane perpendicular to the axis. On the other hand, the convex portion 67 has a rectangular cross section taken along a plane perpendicular to the axis, and is provided on the opposite side of the concave portion 81 (at the upper end when the shock absorber 1 is attached) through the center of the annular plate 53 . The positioning mechanism 65 is constructed by fitting a convex portion 67 of the annular plate 53 into a groove 66 with a certain gap in the vertical and horizontal directions in FIG. 7 .

In the third embodiment, the same effects as those of the first and second embodiments described above can be obtained.
Further, in the third embodiment, since the annular plate 53 is positioned around the axis with respect to the rod guide 41 by the positioning mechanism 65, the recess 81 is reliably positioned below the annular plate 53 when the shock absorber 1 is installed. It can be placed at the side edge. This prevents malfunctions due to poor assembly of the annular plate 53, and improves the reliability of the shock absorber 1.

(Fourth Embodiment) Next, a fourth embodiment will be described with reference to FIGS. 8 and 9.
Note that the same names and symbols are used for common parts with the first to third embodiments, and redundant explanation will be omitted. Here, differences from the first embodiment will be mainly explained.

In the first embodiment, it is necessary to assemble the annular plate 53 so that the recess 81 is located at the upper end (at the "12 o'clock" clock position) when the shock absorber 1 is installed. Therefore, in the fourth embodiment, a positioning mechanism 71 for positioning the annular plate 53 around the axis with respect to the rod guide 41 is provided.

An annular convex portion 72 having a constant height is provided on the inner peripheral edge of the bottom portion 48 of the tube fitting portion 43 of the rod guide 41. An annular plate 53 is provided on the outer periphery of the annular convex portion 72 . A certain gap is formed between the outer circumferential surface 73 of the annular convex portion 72 and the inner circumferential surface 55 of the annular plate 53. The height of the annular convex portion 72 (the amount of protrusion from the bottom portion 48) is set to, for example, the thickness of the annular plate 53.

When the shock absorber 1 is installed, the positioning mechanism 71 connects the groove 75 provided at the upper end of the annular convex portion 72 of the rod guide 41 (at the "12 o'clock" clock position) and the inner periphery of the annular plate 53. It has a convex portion 67 that protrudes radially from the surface 55 and is fitted into the groove 75. The groove 75 extends from the end surface 74 of the annular convex portion 72 to the bottom portion 48 of the tube fitting portion 43, and has a rectangular cross section taken on a plane perpendicular to the axis. On the other hand, the convex portion 67 has a rectangular cross section taken along a plane perpendicular to the axis, and is provided at the upper end when the shock absorber 1 is attached. The positioning mechanism 71 is constructed by fitting the convex portion 67 of the annular plate 53 into the groove 75 with certain gaps in the vertical and horizontal directions in FIG. Note that the recess 81 extends from the outer circumferential surface 54 of the annular plate 53 to the end surface 68 of the protrusion 67 .

In the fourth embodiment, the same effects as those of the first to third embodiments described above can be obtained.
In addition, in the fourth embodiment, since the annular plate 53 is positioned around the axis with respect to the rod guide 41 by the positioning mechanism 71, the upper end of the annular plate 53 can be reliably aligned with the recess 81 when the shock absorber 1 is attached. It can be placed in the section. This prevents malfunctions due to poor assembly of the annular plate 53, and improves the reliability of the shock absorber 1.

(Fifth Embodiment) Next, a fifth embodiment will be described with reference to FIGS. 10 and 11.
Note that the same names and numerals are used for common parts with the first to fourth embodiments, and overlapping explanations are omitted. Here, differences from the second embodiment will be mainly explained.

In the second embodiment, the target is a double-tube horizontal hydraulic shock absorber 1 in which the piston rod 15 expands and contracts in the horizontal direction. On the other hand, in the fifth embodiment, a dual-tube vertical hydraulic shock absorber 1A (hereinafter referred to as "shock absorber 1A") in which the piston rod 15 expands and contracts in the vertical direction is targeted.

Further, in the second embodiment, the number of recesses 81 formed in the lower end surface 57 of the annular plate 53, which is the surface facing the tube 3, is one. In contrast, in the fifth embodiment, a plurality of (six in the fifth embodiment) recesses 81 are formed in the lower end surface 57 of the annular plate 53. The plurality of recesses 81 are arranged at equal intervals in the circumferential direction of the annular plate 53 (in the fifth embodiment, "60 degrees around the axis").

Here, unlike the recesses 81 in the second embodiment, the plurality of recesses 81 in the fifth embodiment do not function as orifices. The flow path area of each of the plurality of recesses 81 in the fifth embodiment is smaller than the flow path area of the recess 81 in the second embodiment, which also functions as an orifice, and has no effect on damping force characteristics. It is set to almost nothing. As a result, in the fifth embodiment, as the piston rod 15 expands and contracts, the aerated hydraulic fluid containing air retained in the tube 3 is transferred to the groove 63, the annular passage 52, and The liquid is discharged into the reservoir 4 through a plurality of recesses 81 .

According to the fifth embodiment, the air accumulated in the tube 3 of the double-tube vertical hydraulic shock absorber 1A is transferred from the plurality of recesses 81 formed on the surface of the annular plate 53 facing the tube 3 to the reservoir. It can be discharged to 4.
Further, in the fifth embodiment, since the plurality of recesses 81 are formed (molded) by coining (press processing), it is possible to form a passage having an extremely small flow path area with high precision. This allows the aerated hydraulic fluid in the tube 3 to seep out to the reservoir 4 side through the passage with an extremely small flow path area defined by the recess 81, and the hydraulic fluid in the tube 3 flows through the recess. Since it is not discharged as a jet from 81, it is possible to suppress the occurrence of aeration.

The embodiment described above can be configured as follows.
In the first to fourth embodiments, the recess 81 had a constant cross-sectional shape from the outer peripheral surface 54 to the inner peripheral surface 55 of the annular plate 53.

On the other hand, the recessed part 81 shown in FIG. be done. The steady portion 82 extends in the radial direction from the inner circumferential surface 55 of the annular plate 53. On the other hand, the widened portion 83 is widened from the outer peripheral end of the steady portion 82 toward the outer peripheral surface 54 (end surface) of the annular plate 53.
In this case, the pressure (flow velocity) of the hydraulic fluid flowing through the steady section 82 is reduced (decelerated) at the widened section 83, so that the hydraulic fluid in the tube 3 is not discharged as a jet from the recessed section 81, resulting in aeration. can be prevented from occurring. Moreover, since the parts surrounding the recess 81 are not exposed to the jet flow from the recess 81, wear of the parts can be suppressed.

Further, the recessed portion 81 shown in FIG. 13 is formed on the inner peripheral side where the constant portion 82 of the recessed portion 81 shown in FIG. A widened portion 84 is provided. Note that the flow path area (orifice area) in the connecting portion 85 is set to be the same as the flow path area in the stationary portion 82 (see FIG. 12).
In this case, the opening width on the inner peripheral surface 54 side of the annular plate 53, that is, the opening width on the first chamber 13 side, in the recess 81 (inner peripheral widened part 84) is the opening width of the constant part 82 (see FIG. 12). Since it is larger than the width, it is possible to improve the ability to discharge air accumulated in the tube (3) and contaminants in the first chamber 13.

Further, in the recess 81 shown in FIG. 14, the bottom surface 86 of the widened portion 83 in the recess 81 shown in FIG. 12 is formed as a curved surface. The depth of the bottom surface 86 from the right end surface 57 of the annular plate 53, which is the surface facing the tube 3 (hereinafter referred to as the "depth of the bottom surface 86"), is such that the depth is such that the depth from the right end surface 57 of the annular plate 53, which is the surface facing the tube 3, is such that it is It gets deeper.
In this case, since the volume of the widened part 83 increases compared to the recessed part 81 shown in FIG. 12 where the depth of the bottom surface 86 is constant, it is possible to further reduce the pressure of the flowing hydraulic fluid, and the aeration The occurrence of can be more effectively suppressed.

On the other hand, the bottom surface 87 of the inner peripheral side widened portion 84 in the recessed portion 81 shown in FIG. 13 can be formed by a curved surface. The depth of the bottom surface 87 from the right end surface 57 of the annular plate 53, which is the surface facing the tube 3 (hereinafter referred to as "the depth of the bottom surface 87"), is such that it extends toward the inner circumferential surface 55 (end surface) of the annular plate 53. It gets deeper.
In this case, it is possible to further improve the ability to discharge air accumulated in the tube (3) and contaminants in the first chamber 13.

Further, as shown in FIG. 15, a first recess 81A is provided in the right end surface 57 of the annular plate 53, which is the surface facing the tube 3, and a second recess 81B is provided in the left end surface 56, which is the opposite surface. The shock absorber 1 can be configured by providing the following.
In this case, by setting the flow path area in the first recess 81A and the flow path area in the second recess 81B to different areas, one annular plate 53 has different characteristics depending on the direction in which the annular plate 53 is assembled (front and back). (air release performance, damping force characteristics) can be selected, and the tuning performance of the shock absorber 1 can be improved.
On the other hand, by setting the flow path area in the first recess 81A and the flow path area in the second recess 81B to be the same area, malfunctions caused by incorrect assembly direction (front and back) of the annular plate 53 are suppressed. Therefore, the reliability of the buffer 1 can be improved.

Note that the present invention is not limited to the embodiments described above, and includes various modifications. For example, the above-described embodiments have been described in detail to explain the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to having all the configurations described. Furthermore, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace some of the configurations of each embodiment with other configurations.

This application claims priority based on Japanese Patent Application No. 2020-185208 filed on November 5, 2020. The entire disclosure content of Japanese Patent Application No. 2020-185208 filed on November 5, 2020, including the specification, claims, drawings, and abstract, is incorporated into the present application by reference in its entirety.

1 Shock absorber, 2 Cylinder, 3 Tube, 4 Reservoir, 12 Piston, 13 First chamber, 14 Second chamber, 15 Piston rod, 41 Rod guide (closing member), 53 Annular plate, 57 Right end surface (opposite to tube) surface), 81 recess

Claims (8)

A buffer, the buffer comprising:
cylinder and
a tube provided on the inner peripheral side of the cylinder and sealed with a working fluid;
a reservoir chamber provided between the cylinder and the tube and filled with hydraulic fluid and gas;
a piston that is slidably provided within the tube and partitions the inside of the tube into two chambers;
a piston rod having one end connected to the piston and the other end extending outside the cylinder;
a closing member provided at an end of the tube and closing the cylinder and the tube;
an integral annular plate provided between the closure member and the end of the tube and fitted into the closure member;
A recessed portion communicating between the tube and the reservoir chamber is formed on a surface of the annular plate facing the tube,
The closing member has a fitting portion that comes into contact with the radially inner periphery or the radially outer periphery of the annular plate,
A shock absorber characterized in that the height of the fitting portion is shorter than the thickness of the annular plate. The buffer according to claim 1,
The shock absorber, wherein the recess extends from an inner end surface to an outer end surface of the annular plate. The buffer according to claim 1 or 2,
The buffer is characterized in that a plurality of the recesses are provided along the circumferential direction of the annular plate. A buffer, the buffer comprising:
cylinder and
a tube provided on the inner peripheral side of the cylinder and sealed with a working fluid;
a reservoir chamber provided between the cylinder and the tube and filled with hydraulic fluid and gas;
a piston that is slidably provided within the tube and partitions the inside of the tube into two chambers;
a piston rod having one end connected to the piston and the other end extending outside the cylinder;
a closing member provided at an end of the tube and closing the cylinder and the tube;
an annular plate provided between the closing member and the end of the tube and fitted into the closing member;
A recessed portion communicating between the tube and the reservoir chamber is formed on a surface of the annular plate facing the tube,
The buffer is characterized in that the concave portion is widened on the outer peripheral side of the annular plate toward the end surface. The buffer according to any one of claims 1 to 4,
The buffer is characterized in that the recess is formed so that the bottom becomes deeper toward the end surface on the outer peripheral side of the annular plate. The buffer according to any one of claims 1 to 5,
The buffer is characterized in that the recess is widened on the inner peripheral side of the annular plate toward the end surface. The buffer according to any one of claims 1 to 6,
The buffer is characterized in that the recess is formed such that the bottom becomes deeper toward the end surface on the inner peripheral side of the annular plate. The buffer according to any one of claims 4 to 7,
A shock absorber, wherein a second recess is formed in a surface of the annular plate facing the closing member.