JP2013200018A - Hydraulic shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive hydraulic shock absorber in which an inner tube directly slides with an inner diameter sliding surface of an outer tube, capable of simultaneously improving sliding performance between the outer tube and the inner tube and preventing wear thereof.SOLUTION: A hydraulic shock absorber 10 includes an inner tube 12 slidably inserted into an inner diameter sliding surface 11A of the outer tube 11. A number of depressions 100 are formed by dimpling in the circumferential direction and axial direction of the inner diameter sliding surface 11A of the outer tube 11 respectively.

Description

  The present invention relates to a hydraulic shock absorber suitable for use in a front fork of a motorcycle or a bicycle.

  As a front fork for a motorcycle, as described in Patent Document 1, there is one in which an inner tube is slidably inserted into an inner diameter sliding surface of an outer tube. In this front fork, in order to avoid the outer tube and the inner tube from colliding with each other due to the lateral force (load in the direction perpendicular to the center axis of the front fork) based on the resistance received from the road surface by the traveling wheel, A spiral oil groove is provided on the inner surface, and the inner tube is supported on the inner surface of the outer tube via an oil film.

  Also, in other conventional front forks, a guide bush is provided on the inner periphery of the outer tube opening that is always in sliding contact with the inner tube during the expansion / contraction stroke, or the outer tube opening serving as a fulcrum for bending due to the lateral force of the inner tube. The inner tube is slid smoothly on the guide bush.

53-160163

  A conventional front fork that is provided with a spiral oil groove on the inner surface of the outer tube or a guide bush at the opening of the outer tube is expensive.

  In addition, in the case where a spiral oil groove is provided on the inner surface of the outer tube, the oil pressure inside the outer tube and the inner tube does not directly act on the oil seal at the opening of the outer tube to cause oil leakage. An oil groove cannot be provided on the inner surface near the opening of the outer tube.

  As another prior art of the front fork, in the case where the inner tube slides directly on the inner diameter sliding surface of the outer tube, lubrication with so-called true contact, in which the metal and the metal contact each other without an oil film, is used. Dominant, high fiction and poor slidability. Abrasive wear due to true contact or wear powder occurs between the inner tube sliding surface of the outer tube and the inner tube, resulting in wear marks on the outer periphery of the inner tube or an oil seal lip at the opening of the outer tube. May cause oil leakage.

  SUMMARY OF THE INVENTION An object of the present invention is to simultaneously improve the slidability of the outer tube and the inner tube and suppress wear in an inexpensive hydraulic shock absorber in which the inner tube slides directly on the inner diameter sliding surface of the outer tube. .

  The invention according to claim 1 is a hydraulic shock absorber in which an inner tube is slidably inserted into an inner diameter sliding surface of an outer tube, and dimples are respectively provided in each of a circumferential direction and an axial direction of the inner tube sliding surface of the outer tube. A large number of depressions are formed by processing.

  According to a second aspect of the present invention, in the first aspect of the invention, the recess is formed in the inner diameter sliding surface of the outer tube in a length range of at least 10 mm in the axial direction from the opening end side. It is what I did.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the indentation exists even when viewed in the axial direction from any position in the circumferential direction of the inner diameter sliding surface of the outer tube. It is.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the recess has a long groove shape that crosses the axial direction of the outer tube.

  According to a fifth aspect of the present invention, in addition to the fourth aspect of the invention, the recess has a long groove shape with a length of 1 to 3 mm, a width of 0.1 to 0.3 mm, and a depth of 0.005 to 0.015 mm.

(Claim 1)
(a) A large number of dimples formed by dimple processing in each of the circumferential direction and the axial direction of the inner-diameter sliding surface of the outer tube become oil reservoirs to improve oil shortage. As a result, a fluid lubrication region by the lubricating oil is expanded between the inner diameter sliding surface of the outer tube and the inner tube, friction is reduced, and slidability is improved.

  Abrasion powder and contamination are not trapped inside these recesses and escaped, and the abrasive wear between the inner tube sliding surface of the outer tube and the inner tube is suppressed. As a result, there is no wear mark on the outer periphery of the inner tube, and the oil seal lip at the opening of the outer tube is not damaged, and oil leakage does not occur.

  Therefore, in an inexpensive hydraulic shock absorber in which the inner tube slides directly on the inner diameter sliding surface of the outer tube, it is possible to simultaneously improve the slidability of the outer tube and the inner tube and suppress wear.

(Claim 2)
(b) The recess is formed in the inner diameter sliding surface of the outer tube at least in a length range of 10 mm or more in the axial direction from the opening end side. During the expansion / contraction stroke of the inner tube, the inner tube sliding surface (which is at least 10 mm or more in the axial direction from the opening end side), which is the outer tube opening that is always in sliding contact, or the outer tube opening that serves as a fulcrum for bending due to the lateral force of the inner tube In the length range), the above-described action due to the indentation (a) is exerted, and the slidability of the outer tube and the inner tube can be improved and the wear can be reliably suppressed.

(Claim 3)
(c) The indentation exists when viewed in the axial direction from any position in the circumferential direction of the inner diameter sliding surface of the outer tube. It affects the entire inner sliding surface of the outer tube and the inner tube sliding range and acts due to the indentation described in (a) above, improving the slidability of the outer tube and the inner tube and suppressing wear. Realized reliably.

(Claim 4)
(d) The indentation has a long groove shape that crosses the axial direction of the outer tube. It is possible to increase the circumferential presence rate of each of the horizontally elongated indentations on the inner tube sliding surface of the outer tube, and to surely improve the slidability of the outer tube and the inner tube and suppress wear.

(Claim 5)
(e) The indentation has a long groove shape with a length of 1 to 3 mm, a width of 0.1 to 0.3 mm, and a depth of 0.005 to 0.015 mm. The indentation is significantly larger than the wear powder and contamination, and it does not catch the wear powder and contamination. There is no possibility that once worn abrasive powder or contamination escapes and abrasive wear occurs in the outer tube and the inner tube.

FIG. 1 is a half sectional view showing the entire hydraulic shock absorber. FIG. 2 is a side view showing the outer tube partially cut away. FIG. 3 is a schematic view showing a recess formed by dimple processing on the inner diameter sliding surface of the outer tube.

  As shown in FIG. 1, a front fork 10 of a motorcycle has a vehicle body side inner tube 12 slidably inserted into an inner diameter sliding surface 11A of a wheel side outer tube 11. A dust seal 13 and an oil seal 14 are provided at the opening end of the outer tube 11 where the inner tube 12 is inserted.

  A bolt 15A is inserted into the bottom of the outer tube 11, and the hollow rod 15 is erected by the bolt 15A. The upper end of the hollow rod 15 is enlarged in diameter to form a partition 16 that is in sliding contact with the inner periphery of the inner tube 12. In this embodiment, a check valve 17 made of a piston ring is provided in a ring groove provided on the outer periphery of the partition wall portion 16, and the check valve 17 is slidably contacted with the inner periphery of the inner tube 12.

  A suspension spring 19 is interposed between the upper end surface of the partition wall 16 of the hollow rod 15 and the spring seat 18 provided at the upper end of the inner tube 12. The spring sheet 18 is sealed to the inner diameter of the upper end of the inner tube 12 via an O-ring 18A and is held by a stopper ring 18B.

  The front fork 10 is provided with a piston valve 20 on the inner periphery of the inner end of the inner tube 12. The upper and lower oil chambers 21 and 22 where the piston valve 20 advances and retreats are defined on the outer periphery of the hollow rod 15. The oil reservoir chamber 23 is defined as an air chamber 24, and an oil hole 25 that communicates between the oil chambers 21, 22 and the oil reservoir chamber 23 is provided below the hollow rod 15. The oil reservoir chamber 23 extends to the inside of the inner tube 12, and the air chamber 24 is sealed with a spring seat 18 at the upper end portion of the inner tube 12. The oil holes 25 are formed at a plurality of positions in the axial direction and the circumferential direction of the hollow rod 15.

  On the inner periphery of the distal end portion of the inner tube 12, the valve housing 30 is caulked and fixed to the inner tube 12, and a piston valve 20 that can slide up and down with the hollow rod 15 inside the valve housing 30 is incorporated.

  The front fork 10 is provided with an oil hole (small hole) 26 communicating with the upper oil chamber 21 and the oil reservoir 23 in the hollow rod 15, and this oil hole (small hole) is used during the extension stroke to use the upper oil chamber 21. Based on the passage resistance of the oil flowing out from the oil reservoir chamber 23, the extension side damping force is generated.

  In the front fork 10, a rebound spring 27 at the maximum extension is provided between the valve housing 30 provided in the inner tube 12 and the partition wall 16 of the hollow rod 15.

  In the front fork 10, the impact received by the wheels is absorbed and buffered by the suspension spring 19 and the air spring of the air chamber 24, and the expansion and contraction vibration of the suspension spring 19 due to the absorption of the impact is absorbed by the oil chamber 21, Suppressed by the damping force generated at 22.

That is, the front fork 10 performs a damping action as follows.
(Compression process)
When the inner tube 12 enters the oil chambers 21 and 22 on the outer periphery of the hollow rod 15, the pressure in the lower oil chamber 22 below the piston valve 20 whose volume is reduced increases. The hydraulic oil in the lower oil chamber 22 below the piston valve 20 flows through the flow path formed by the piston valve 20 and flows into the upper oil chamber 21 to generate a compression-side damping force.

  Since the volume of the upper oil chamber 21 above the piston valve 20 is expanded and the pressure is reduced, the check valve 17 provided in the partition wall 16 of the hollow rod 15 is opened, and the oil above the partition wall 16 is opened. The hydraulic oil in the reservoir chamber 23 flows into the upper oil chamber 21 through the check valve 17.

  Further, hydraulic oil corresponding to the volume of entry into the oil chambers 21 and 22 of the inner tube 12 passes through the plurality of oil holes 25 formed in the lower part of the hollow rod 15 from the lower oil chamber 22, and the inside of the hollow rod 15. It flows to the peripheral oil reservoir 23. The compression side damping force is generated by the plurality of oil holes 25.

(Extension process)
When the inner tube 12 retreats from the oil chambers 21, 22 on the outer periphery of the hollow rod 15, the hydraulic oil in the upper oil chamber 21 above the piston valve 20 passes through the flow path formed by the piston valve 20, and the lower part of the piston valve 20 In addition to flowing into the lower oil chamber 22, the oil flows through an oil hole (small hole) 26 formed in the upper portion of the hollow rod 15, flows out into the oil reservoir chamber 23 on the inner periphery of the hollow rod 15, and increases the extension side damping force. Occur.

  Further, the hydraulic oil corresponding to the volume of the inner tube 12 withdrawing from the oil chambers 21 and 22 passes through the plurality of oil holes 25 formed in the lower part of the hollow rod 15 from the oil reservoir chamber 23, and the oil chambers 21 and 22. Flow into.

  However, the front fork 10 has the following configuration in order to simultaneously improve the slidability of the outer tube 11 and the inner tube 12 and suppress wear.

  That is, in the front fork 10, as shown in FIGS. 2 and 3, a large number of dimples 100 are formed by dimple processing discontinuously in the circumferential direction and the axial direction of the inner diameter sliding surface 11 </ b> A of the outer tube 11. Is formed.

  In the present invention, the recess 100 is formed in the inner diameter sliding surface 11A of the outer tube 11 in a length range R (FIGS. 2 and 3) of at least 10 mm in the axial direction from the opening end side. The length range R in which the indentation 100 is formed on the inner diameter sliding surface 11A of the outer tube 11 may extend from the opening end side of the outer tube 11 to the entire length of the inner diameter sliding surface 11A.

  Further, the indentation 100 exists when viewed in the axial direction (FIG. 3) from any position over the entire circumference in the circumferential direction of the inner diameter sliding surface 11 </ b> A of the outer tube 11.

  Further, the recess 100 has a long groove shape that crosses the axial direction of the outer tube 11. The indentation 100 has a long groove shape with a length L = 1 to 3 mm, a width W = 0.1 to 0.3 mm, and a depth D = 0.005 to 0.015 mm (FIG. 3).

According to the present embodiment, the following operational effects can be obtained.
(a) A large number of dimples 100 formed by dimple processing in each of the circumferential direction and the axial direction of the inner diameter sliding surface 11A of the outer tube 11 become oil sumps to improve oil shortage. As a result, the fluid lubrication region by the lubricating oil is expanded between the inner diameter sliding surface 11A of the outer tube 11 and the inner tube 12, friction is reduced, and slidability is improved.

  Abrasion powder and contamination are not trapped in the recesses 100 and escaped, and abrasive wear between the inner diameter sliding surface 11A of the outer tube 11 and the inner tube 12 is suppressed. As a result, no wear mark is generated on the outer periphery of the inner tube 12, and the oil seal lip at the opening of the outer tube 11 is not damaged and oil leakage does not occur.

  Therefore, in the inexpensive front fork 10 in which the inner tube 12 slides directly on the inner diameter sliding surface 11A of the outer tube 11, it is possible to simultaneously improve the slidability of the outer tube 11 and the inner tube 12 and suppress wear. it can.

  (b) The recess 100 is formed in the inner diameter sliding surface 11A of the outer tube 11 in a length range R of at least 10 mm in the axial direction from the opening end side. An inner diameter sliding surface 11A (in the axial direction from the opening end side) of the opening portion of the outer tube 11 that is always in sliding contact with the inner tube 12 during the expansion / contraction stroke, or the opening portion of the outer tube 11 that serves as a fulcrum for bending due to the lateral force of the inner tube 12 Thus, in the length range R) of at least 10 mm or more, the action due to the indentation 100 of (a) described above is exerted, and the slidability of the outer tube 11 and the inner tube 12 can be improved and the wear can be reliably suppressed.

  (c) The indentation 100 exists when viewed in the axial direction from any position in the circumferential direction of the inner diameter sliding surface 11A of the outer tube 11. It acts not only on the entire circumference of the sliding range of the inner diameter sliding surface 11A of the outer tube 11 and the inner tube 12 but also due to the depression 100 of the above (a), and the sliding property of the outer tube 11 and the inner tube 12 is improved. Improvement and suppression of wear can be realized reliably.

  (d) The indentation 100 has a long groove shape that crosses the axial direction of the outer tube 11. The circumferential presence rate of each of the horizontally elongated recesses 100 on the inner diameter sliding surface 11A of the outer tube 11 can be increased, and the improvement of the slidability of the outer tube 11 and the inner tube 12 and the suppression of wear can be reliably realized.

(e) The indentation 100 has a length L
It has a long groove shape of 1 to 3 mm, width W 0.1 to 0.3 mm, and depth D 0.005 to 0.015 mm. The indentation 100 is significantly larger than the wear powder and contamination, and captures the wear powder and contamination so as not to escape. There is no possibility that the wear powder and contamination once captured escape and abrasive wear occurs in the outer tube 11 and the inner tube 12.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention.

  The present invention relates to a hydraulic shock absorber in which an inner tube is slidably inserted into an inner diameter sliding surface of an outer tube, and a plurality of dimples are formed in each of the circumferential direction and the axial direction of the inner tube sliding surface of the outer tube. A depression is formed. As a result, in an inexpensive hydraulic shock absorber in which the inner tube slides directly on the inner diameter sliding surface of the outer tube, it is possible to simultaneously improve the slidability of the outer tube and the inner tube and suppress wear.

10 Front fork (hydraulic shock absorber)
11 Outer tube 11A Inner diameter sliding surface 12 Inner tube 100 Recess

Claims (5)

In the hydraulic shock absorber in which the inner tube is slidably inserted into the inner tube sliding surface of the outer tube,
A hydraulic shock absorber comprising a plurality of dimples formed in the circumferential direction and the axial direction of the inner diameter sliding surface of the outer tube.   2. The hydraulic shock absorber according to claim 1, wherein the recess is formed in a length range of at least 10 mm in an axial direction from an opening end side on an inner diameter sliding surface of the outer tube.   3. The hydraulic shock absorber according to claim 1, wherein the recess is present when viewed in the axial direction from any circumferential position of the inner diameter sliding surface of the outer tube.   The hydraulic shock absorber according to any one of claims 1 to 3, wherein the recess has a long groove shape that crosses the axial direction of the outer tube.   The hydraulic shock absorber according to claim 4, wherein the recess has a long groove shape with a length of 1 to 3 mm, a width of 0.1 to 0.3 mm, and a depth of 0.005 to 0.015 mm.

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