JP2004011702A - Hydraulic damper for vehicles - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably generate damping force at a pressure side depending on a compressed position in a simple structure in a hydraulic damper having an oil chamber in which a piston slides in an inner tube. <P>SOLUTION: The inner tube 12 comprises the circular oil chamber 17 between an outer tube 11 and the inner tube 12, a first oil hole 28 interlocking an oil chamber 21A at the piston rod side, and a second oil hole 29 interlocking the circular oil chamber 17 and oil chamber 21B at the piston side in the hydraulic damper 10 for vehicles. The second oil hole 29 is blocked against the oil chamber 21B at the piston side by the piston 26 in a compression stroke. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hydraulic shock absorber for a vehicle.
[0002]
[Prior art]
Actual registration 2529994 discloses an inverted front fork in which a damper including a damper cylinder and a piston rod is provided inside an outer tube and an inner tube. However, in this conventional technique, since a damper separate from the inner tube is provided inside the inner tube, a damper cylinder 47, a member for fixing the damper cylinder to the bottom of the inner tube, and the like are required, which increases costs. .
[0003]
In Japanese Utility Model Publication No. 5-11400, in order to reduce the number of parts, as a conventional technique without a damper cylinder, a bearing 8 through which a hollow piston rod 7 attached to the outer tube 2 is inserted is provided on the inner circumference of the upper end of the inner tube 3. A hydraulic oil chamber C, B filled with hydraulic oil is provided in an inner tube, and a piston 13 provided at the tip of a hollow piston rod slides directly in the hydraulic oil chambers C, B. are doing. This prior art is a simple inverted type in which an oil sump chamber A is provided above a bearing 8 for compensating for a volume when a piston rod enters the hydraulic oil chambers C and B or withdraws from the hydraulic oil chamber. It is a front fork.
[0004]
[Problems to be solved by the invention]
The front fork of Japanese Utility Model 5-11400 has a position-dependent mechanism including an adjustment valve element 51 and a port 22. The adjustment valve element 51 moves the hydraulic oil passage in the piston rod by an amount corresponding to the deflection of the detection spring 34 during compression. By closing, a compression-side damping force depending on the compression position is generated.
[0005]
However, the position-dependent mechanism of the Japanese Utility Model 5-11400 requires a regulating valve body 51 and a detection spring 34, and has a complicated structure and a high cost. Further, since the adjustment valve body 51 is sandwiched and supported between the detection spring and the suspension spring, the displacement of the adjustment valve body 51 is easily affected by the inertia force of the suspension spring and the adjustment valve body 51, and the adjustment valve body 51 is moved to the compression position. There is a possibility that the position-dependent damping force is not accurately obtained and a stable position-dependent damping force cannot be obtained.
[0006]
It is an object of the present invention to stably generate a compression-side damping force depending on a compression position by a simple structure in a hydraulic shock absorber having an oil chamber in which a piston slides in an inner tube.
[0007]
[Means for Solving the Problems]
According to the first aspect of the present invention, the inner tube is slidably inserted into the outer tube via upper and lower guide bushes, and is formed between the outer tube and the inner tube by the two guide bushes. And a partition member for slidably guiding a piston rod attached to the outer tube side is provided on the inner periphery of the inner tube, and oil is provided between the partition member and the inner periphery of the inner tube. An oil chamber in the inner tube is divided into a piston rod-side oil chamber that houses the piston rod and a piston-side oil chamber that does not house the piston rod by a piston provided at the tip of the piston rod. And a piston or piston rod provided with an oil passage communicating with the piston rod side oil chamber and the piston side oil chamber, and a pressure side damping force generating means. In the pressure buffer, a first oil hole that communicates the annular oil chamber and the piston rod-side oil chamber with the inner tube, and a second oil that communicates the annular oil chamber with the piston-side oil chamber. A hole is provided so that the second oil hole is blocked from the piston side oil chamber by the piston during a compression stroke.
[0008]
According to a second aspect of the present invention, in the first aspect of the present invention, an annular shape is provided between the piston and the piston rod, the diameter of the inner tube is reduced toward the bottom of the inner tube. A spring collar that forms a gap is provided, and a suspension spring is interposed between the spring collar and the inner tube.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
1 is a cross-sectional view showing the entire hydraulic shock absorber, FIG. 2 is a cross-sectional view showing an enlarged main part on the lower end side of FIG. 1, and FIG. 3 is a cross-sectional view showing an enlarged main part on the upper end side of FIG. 4 is a sectional view taken along line IV-IV of FIG. 3, FIG. 5 is an enlarged sectional view of a main part of FIG. 3, and FIG. 6 is a perspective view showing a check valve.
[0010]
The hydraulic shock absorber 10 is an inverted front fork in which the outer tube 11 is arranged on the vehicle body side and the inner tube 12 is arranged on the wheel side. As shown in FIGS. 1 to 3, the hydraulic shock absorber 10 is provided on the inner periphery of the lower end opening of the outer tube 11. The inner tube 12 is slidably inserted into the outer tube 11 via the fixed guide bush 11A and the guide bush 12A fixed to the outer periphery of the upper end opening of the inner tube 12. 11B is an oil seal, and 11C is a dust seal. A cap 13 is screwed to the upper end opening of the outer tube 11 in a liquid-tight manner, and vehicle body side mounting members 14A and 14B are provided on the outer periphery of the outer tube 11. A bottom bracket 15 is liquid-tightly inserted and screwed into the lower end opening of the inner tube 12 via an O-ring 12B, and the bottom bracket 15 is provided with a wheel-side mounting portion 16.
[0011]
The hydraulic shock absorber 10 defines an inner periphery of the outer tube 11, an outer periphery of the inner tube 12, and an annular oil chamber 17 defined by the two guide bushes 11A and 12A.
[0012]
The hydraulic shock absorber 10 is provided with a partition member 19 in a liquid-tight manner on the inner periphery of the upper end side of the inner tube 12 via an O-ring or the like, and partitions the oil chamber 21 below the rod guide portion 19A of the partition member 19, An oil reservoir 22 is defined at the upper part. The lower area of the oil reservoir 22 is an oil chamber 22A, and the upper area is an air chamber 22B.
[0013]
The hydraulic shock absorber 10 slidably inserts the piston rod 23 attached to the outer tube 11 into the rod guide 19 </ b> A of the partition member 19. Specifically, a spring load adjusting sleeve 24 is screwed into the center of the cap 13 in a liquid-tight manner, and a hollow piston rod 23 is screwed into the lower end of the sleeve 24 inserted into the oil reservoir 22, and locked. Fix with nut 25.
[0014]
The hydraulic shock absorber 10 fixes a piston 26 slidably in contact with the inner periphery of the inner tube 12 at the tip of a piston rod 23 inserted into the inner tube 12 from the rod guide portion 19A of the partition member 19, and The piston rod-side oil chamber 21A in which the rod 23 is accommodated and the piston-side oil chamber 21B in which the piston rod 23 is not accommodated are partitioned. The piston 26 is fixed by a nut 27.
[0015]
The hydraulic shock absorber 10 always communicates the annular oil chamber 17 with the piston rod side oil chamber 21 </ b> A via an oil hole 28 provided in the inner tube 12.
[0016]
The hydraulic shock absorber 10 abuts a spring collar 31 on a lower end surface of the piston 26 facing the piston side oil chamber 21B, and seats a spring seat 32 on a bottom portion of the inner tube 12 formed by the bottom bracket 15, so that the spring collar 31 will be described later. A suspension spring 33 is interposed between a spring seat 31C and a spring seat 32 provided at a step between the lowermost diameter-reducing portion 31B connected to the tapered portion 31A. The hydraulic shock absorber 10 vertically moves the piston rod 23 and the piston 26 by screwing the above-mentioned spring load adjusting sleeve 24, and adjusts the spring load of the suspension spring 33 by this vertical movement. The hydraulic shock absorber 10 absorbs the impact force received from the road surface when the vehicle travels by the expansion and contraction vibration of the suspension spring 33.
[0017]
The hydraulic shock absorber 10 includes a damping force generator 40 on the piston 26.
The damping force generator 40 includes a pressure-side flow path 41 and an extension-side flow path 42. The pressure side flow path 41 is opened and closed by a pressure side disk valve 41A backed up by a valve stopper 41B. The extension side flow path 42 is opened and closed by an extension side disk valve 42A that is backed up by a valve stopper 42B. The valve stopper 41B, the valve 41A, the piston 26, the valve 42A, and the valve stopper 42B constitute a valve assembly that is inserted into the piston rod 23, and include a stopper ring 41C fixed to the piston rod 23, and a piston rod 41C. The nut 23 is screwed into the nut 27 and fixed.
[0018]
The damping force generator 40 has an adjusting rod 43 screwed into the center of the spring load adjusting sleeve 24 in a liquid-tight manner, and a needle valve 44 fixed to the adjusting rod 43 is inserted into the hollow part of the piston rod 23. The degree of opening of the bypass passage 45 provided in is adjusted by the vertical movement of the needle valve 44. The bypass passage 45 bypasses the piston 26 and connects the piston rod side oil chamber 21A and the piston side oil chamber 21B.
[0019]
The damping force generator 40 generates a compression damping force in the compression stroke by a passage resistance of the bypass passage 45 whose opening degree is adjusted by the needle valve 44 in a low speed region, and a bending deformation of the compression disk valve 41A in a middle and high speed region. As a result, a compression damping force is generated. In the extension side stroke, the extension side damping force is generated by the passage resistance of the bypass passage 45 whose opening is adjusted by the needle valve 44 in the low speed range, and the extension side is caused by the bending deformation of the extension side disk valve 42A in the middle and high speed range. Generates side damping force. By the compression side damping force and the extension side damping force, the above-described expansion and contraction vibration of the suspension spring 33 is damped.
[0020]
In the hydraulic shock absorber 10, a stopper rubber 13A is fixed to the lower end surface of the cap 13 so that the upper end of the partition member 19 provided on the inner tube 12 abuts at the maximum compression stroke. Regulate.
[0021]
The hydraulic shock absorber 10 includes a spring seat 51 which is swaged and fixed to a lower end surface of the partition member 19 on the upper end side of the inner tube 12 facing the piston rod side oil chamber 21A, and a valve stopper 41B provided on the upper end surface side of the piston 26. And a rebound spring 52 is interposed therebetween. When the hydraulic shock absorber 10 is fully extended, the partition member 19 presses the rebound spring 52 with the valve stopper 41B, thereby regulating the maximum extension stroke.
[0022]
However, in the hydraulic shock absorber 10, as shown in FIG. 4, the sectional area S1 of the annular oil chamber 17 formed by the annular gap between the outer tube 11 and the inner tube 12 is changed to the sectional area of the piston rod 23 (to the outer diameter). (Surrounded area) S2 (S1> S2, but S1 ≧ S2 is also possible).
[0023]
As shown in FIG. 5, the rod guide portion 19A of the partition member 19 allows the oil flow from the oil reservoir 22 to the piston rod-side oil chamber 21A in the compression stroke, and the piston rod-side oil chamber in the extension stroke. A check valve 60 for preventing the flow of oil from 21A to the oil reservoir 22 is provided. A valve chamber 61 is provided on the inner periphery of the rod guide portion 19A of the partition member 19, and between the stepped portion 61A on the upper end side of the valve chamber 61 and the aforementioned spring seat 51 provided on the lower end side of the valve chamber 61. The check valve 60 is housed. As shown in FIG. 6, the check valve 60 is shorter than the gap between the step portion 61A and the spring seat 51, and has a lateral groove 62 formed on the lower end surface. The check valve 60 is slidably contacted with the inner periphery of a valve chamber 61 provided in the rod guide portion 19A of the partition wall member 19 so as to be vertically displaceable. A flow path that allows the flow of oil from the oil reservoir chamber 22 to the piston rod side oil chamber 21A between the outer circumference of the check valve 60 and the inner circumference of the valve chamber 61 provided in the rod guide portion 19A of the partition member 19. To form The check valve 60 includes a bush 70 that slidably supports the piston rod 23 and that is pressed into the inner periphery thereof. In the compression stroke, the check valve 60 moves along with the piston rod 23 entering the inner tube 12 and moves downward in FIG. 5 to abut the spring seat 51 and form a gap between the check valve 60 and the step 61A. The oil in the piston rod-side oil chamber 21A can be discharged from the lateral groove 62 to the oil reservoir 22 through the gap between the lateral groove 62 and the stepped portion 61A. In the extension side stroke, the check valve 60 moves along with the piston rod 23 retreating from the inner tube 12 and moves upward in FIG. 5, and abuts the step 61A to close the gap between the step 61A. This prevents the oil in the piston rod side oil chamber 21A from being discharged to the oil storage chamber 22 through the reverse path of the above-described compression side stroke.
[0024]
Further, since the rod guide portion 19A of the partition member 19 does not seal the oil seal around the piston rod 23, the bush 70 press-fitted into the inner periphery of the check valve 60 is formed around the piston rod 23. The gap (or the minute gap formed between the check valve 60 and the stepped portion 61A) forms a minute flow path (orifice) 71 (not shown) communicating the piston rod side oil chamber 21A and the oil reservoir 22. The minute flow passage 71 may be formed in the rod guide portion 19A of the partition member 19 to communicate the piston rod side oil chamber 21A and the oil reservoir chamber 22.
[0025]
However, the hydraulic shock absorber 10 has the following configuration in order to generate a compression-side damping force depending on the compression position.
[0026]
In the hydraulic shock absorber 10, the above-described oil hole 28 provided in the inner tube 12 so as to communicate the annular oil chamber 17 and the piston rod-side oil chamber 21A is a first oil hole, and the annular oil chamber 17 and the piston-side oil chamber are used. A second oil hole 29 communicating with the piston 21B is provided in the inner tube 12, and a piston ring 26A provided on the outer periphery of the piston 26 when compressing beyond a small stroke centered on the ride 1G (G is the acceleration of gravity). To block the second oil hole 29 from the piston-side oil chamber 21B (the second oil hole 29 may be blocked from the piston-side oil chamber 21B by a member attached to the piston 26 such as the spring collar 31). .
[0027]
Here, the spring collar 31 supported on the lower end surface of the piston 26 as described above has the second oil hole 29 provided before the piston 26 reaches the second oil hole 29 in the compression stroke. An annular gap is formed between the inner tube 12 and the inner circumference of the inner tube 12. The spring collar 31 has a tapered portion 31A on its outer periphery that reduces in diameter toward the bottom side of the inner tube 12 in a state where the outer diameter of the upper end that abuts on the piston 26 is equal to the outer diameter of the piston 26. As the compression stroke increases, the gap with the second oil hole 29 (the opening degree of the second oil hole 29) is gradually narrowed.
[0028]
The operation of the hydraulic shock absorber 10 is as follows.
(Pressure side stroke)
Hydraulic oil corresponding to the volume of the piston rod 23 that enters the inner tube 12 in the compression stroke is transferred from the oil chamber 21 </ b> A on the inner periphery of the inner tube 12 to the annular oil chamber 17 via the oil hole 28 of the inner tube 12. At this time, since the volume increase ΔS1 (replenishment amount) of the annular oil chamber 17 is larger than the volume increase ΔS2 of the piston rod 23, the shortage of (ΔS1−ΔS2) in the required oil supply amount to the annular oil chamber 17 is obtained. The oil is supplied from the oil reservoir 22 via the check valve 60.
[0029]
In the compression side stroke, as described above, the compression side damping force is generated by the passage resistance of the bypass passage 45 whose opening is adjusted by the needle valve 44 in the low speed range, and the compression side damping force is generated by the bending deformation of the compression side disc valve 41A in the middle and high speed range. Generates damping force.
[0030]
In the compression stroke, the compression damping force depends on the compression position as shown in (a) to (c) below.
[0031]
(A) In the small stroke range centering on the riding 1G position (FIG. 1), the piston 26 has the second oil hole 29 fully opened in the piston side oil chamber 21B, and the piston rod side oil chamber 21A and the piston side oil chamber 21B. The hydraulic oil flows from the piston-side oil chamber 21B to the piston-rod-side oil chamber 21A through the chamber 21B through a bypass oil passage formed by the annular oil chamber 17 together with the first oil hole 28 and the second oil hole 29. Is bypassed to the damping force generator 40, so that the compression side damping force is low.
[0032]
(B) As the compression stroke increases, the tapered portion 31A of the spring collar 31 gradually narrows the gap between the spring oil 31 and the second oil hole 29 and narrows the inlet opening of the bypass oil passage described in (a). The flow of hydraulic oil from the piston-side oil chamber 21B passing through the generator 40 to the piston-rod-side oil chamber 21A gradually increases, and the compression-side damping force gradually increases.
[0033]
(C) When the compression stroke is further increased beyond a small stroke range centered on the riding 1G position, the piston 26 blocks the second oil hole 29 from the piston side oil chamber 21B. The entire amount of hydraulic oil flowing from the piston side oil chamber 21B to the piston rod side oil chamber 21A passes through the damping force generator 40, and generates a high pressure side damping force.
[0034]
(Extension stroke)
Hydraulic oil corresponding to the retreat volume of the piston rod 23 retreating from the inner tube 12 in the extension side stroke is transferred from the annular oil chamber 17 to the oil chamber 21 </ b> A on the inner periphery of the inner tube 12 via the oil hole 29 of the inner tube 12. . At this time, since the volume decrease ΔS1 (discharge amount) of the annular oil chamber 17 is larger than the volume decrease ΔS2 of the piston rod 23, the excess amount of (ΔS1−ΔS2) in the oil discharge amount from the annular oil chamber 17 Is discharged to the oil reservoir 22 through the minute flow path 71.
[0035]
In the extension side stroke, as described above, the extension side damping force is generated by the passage resistance of the bypass passage 45 whose opening is adjusted by the needle valve 44 in the low speed range, and the bending of the extension side disc valve 42A in the middle and high speed range. Deformation generates an extension-side damping force. In addition, the extension-side damping force due to the passage resistance of the minute flow channel 71 is also generated.
[0036]
Also on this extension side stroke, on the most compression stroke side, the piston 26 blocks the second oil hole 29 from the piston side oil chamber 21B, and the extension side damping force by the damping force generator 40 is high. On the other hand, in a small stroke region centering on the riding 1G position, the piston 26 fully opens the second oil hole 29 to the piston side oil chamber 21B, and the extension side damping force is low. In the intermediate stroke region, the tapered portion 31A of the spring collar 31 gradually opens the gap with the second oil hole 29, and the extension-side damping force gradually decreases.
[0037]
The volume change due to the temperature change of the oil inside the inner tube 12 is discharged to the oil reservoir 22 through the minute flow path 71 or supplied from the oil reservoir 22 to compensate.
[0038]
Therefore, according to the present embodiment, the following operations are provided.
(Action corresponding to claim 1)
{Circle around (1)} In a small stroke region centered on the riding 1G position, the oil chambers 21A and 21B on both sides of the piston 26 communicate with each other through a bypass oil passage formed by the annular oil chamber 17, and the piston oil side 21B and the piston rod side. Since the flow of the hydraulic oil to the oil chamber 21A bypasses the damping force generator 40 provided on the piston 26, the generated pressure-side damping force is low, and a soft ride can be obtained. On the other hand, on the most compression side with a large stroke, the bypass oil passage is closed, and the flow of hydraulic oil from the piston side oil chamber 21B to the piston rod side oil chamber 21A passes through the damping force generator 40 provided on the piston 26. The compression-side damping force is increased, large input is buffered, and a feeling of swelling (prevention of bottoming out) can be obtained.
[0039]
{Circle around (2)} The annular oil chamber 17 formed between the outer tube 11 and the inner tube 12 is used to form a bypass oil passage connecting the oil chambers 21A and 21B on both sides of the piston 26, so that a special member is required. Instead, a position-dependent mechanism having a simple structure can be configured. Further, as compared with the case where the detection spring is used, the pressure-side damping force depending on the position can be generated stably and reliably.
[0040]
(Action corresponding to claim 2)
(3) Since the spring collar 31 supported on the side of the piston 26 is tapered, the gap formed between the spring collar 31 and the second oil hole 29 (second oil) increases as the compression stroke increases. The opening degree of the hole 29) is gradually narrowed, and as a result, the compression damping force is gradually increased. Thereby, it is possible to eliminate the uncomfortable feeling of the change in the damping force accompanying the switching of the opening and closing of the second oil hole 29, and to smoothly change the compression side damping force depending on the compression position.
[0041]
As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration of the present invention is not limited to the embodiments, and there may be a design change or the like without departing from the gist of the present invention. This is also included in the present invention. The hydraulic shock absorber to which the present invention is applied is characterized in that a change in hydraulic oil volume corresponding to an entry volume / exit volume of a piston rod entering / exiting the inner tube or a volume of hydraulic oil due to a temperature change in an oil chamber in the inner tube. The volume compensation chamber for compensating for the change is not limited to the one constituted by the annular oil chamber between the outer tube and the inner tube, but this volume compensation chamber is provided inside the inner tube or provided outside the inner tube. There may be.
[0042]
Further, the hydraulic shock absorber to which the present invention is applied may be an upright front fork in which the outer tube is arranged on the wheel side and the inner tube is arranged on the vehicle body side.
[0043]
【The invention's effect】
As described above, according to the present invention, in a hydraulic shock absorber provided with an oil chamber in which a piston slides in an inner tube, a compression-side damping force depending on a compression position can be stably generated with a simple structure. .
[Brief description of the drawings]
FIG. 1 is a sectional view showing the entire hydraulic shock absorber.
FIG. 2 is an enlarged sectional view showing a main part on a lower end side of FIG. 1;
FIG. 3 is an enlarged sectional view showing a main part on the upper end side of FIG. 1;
FIG. 4 is a sectional view taken along the line IV-IV in FIG. 3;
FIG. 5 is an enlarged sectional view of a main part of FIG. 3;
FIG. 6 is a perspective view showing a check valve.
[Explanation of symbols]
Reference Signs List 10 hydraulic shock absorber 11 outer tube 11A guide bush 12 inner tube 12A guide bush 17 annular oil chamber 19 partition member 21 oil chamber 21A piston rod side oil chamber 21B piston side oil chamber 23 piston rod 26 piston 28 first oil hole 29 2 oil hole 31 Spring collar 33 Suspension spring 40 Damping force generator (compression side damping force generating means)
41 Pressure side flow path (oil path)

Claims (2)

Insert the inner tube slidably into the outer tube via the upper and lower guide bushes,
An annular oil chamber defined by the two guide bushes is provided between the outer tube and the inner tube,
On the inner periphery of the inner tube, a partition member for slidably guiding the piston rod attached to the outer tube side is provided, and an oil chamber is defined between the partition member and the inner periphery of the inner tube,
With a piston provided at the tip of the piston rod, the oil chamber in the inner tube is partitioned into a piston rod-side oil chamber that houses the piston rod and a piston-side oil chamber that does not house the piston rod,
In a vehicle hydraulic shock absorber provided with an oil passage and a compression-side damping force generating unit that communicates the piston rod-side oil chamber and the piston-side oil chamber with the piston or the piston rod,
The inner tube is provided with a first oil hole communicating the annular oil chamber and the piston rod-side oil chamber, and a second oil hole communicating the annular oil chamber and the piston-side oil chamber. A hydraulic shock absorber for a vehicle, wherein the second oil hole is shut off from the piston side oil chamber by the piston during a stroke. A spring collar that is supported by the piston or the piston rod, reduces in diameter toward the bottom of the inner tube, and forms an annular gap with the second oil hole; The hydraulic shock absorber for a vehicle according to claim 1, wherein a suspension spring is interposed between the suspension and the tube.

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