JP2020159466A - Shock absorber - Google Patents

Abstract

To provide a shock absorber which can suppress the lowering of productivity.SOLUTION: A shock absorber has: a passage 185 from which a working fluid flows to a chamber at a downstream side from a chamber at an upstream side in a cylinder 2 by the movement of a piston 18; first attenuation force generation mechanisms 41, 42 arranged in the passage 185, valve-closed in a region in which a piston speed is low, and valve-opened in a region in which the piston speed is higher than the low speed; and a second attenuation force generation mechanism 182 arranged in the passage 185, and valve-opened from the region in which the piston speed is low. The second attenuation force generation mechanism 182 has a disc valve 102 which is cantilevered by support members 100, 105 and 106, and elastically deformed by a pressure difference between the two chambers. A free end of the disc valve 102 opposes a piston rod 21.SELECTED DRAWING: Figure 2

Description

The present invention relates to a shock absorber.

Some shock absorbers have two valves that open in the same stroke (see, for example, Patent Document 1).

Special Fairness No. 2-4-1666

It is required to suppress the decrease in productivity in the shock absorber.

Therefore, an object of the present invention is to provide a shock absorber capable of suppressing a decrease in productivity.

In order to achieve the above object, the present invention has a passage through which the working fluid flows from the chamber on the upstream side to the chamber on the downstream side in the cylinder due to the movement of the piston, and a region provided in the passage where the piston speed is low. The first damping force generating mechanism that closes the valve and opens the valve in the speed region where the piston speed is higher than the low speed, and the second damping force generating mechanism that is provided in the passage and opens the valve from the region where the piston speed is low. The second damping force generating mechanism has a disc valve that is cantilevered by a support member and elastically deforms due to a differential pressure between the two chambers, and the free end of the disc valve is attached to the piston rod. The configuration was such that they face each other.

According to the present invention, it is possible to suppress a decrease in productivity.

It is sectional drawing which shows the shock absorber of 1st Embodiment which concerns on this invention. It is a partial cross-sectional view which shows the main part of the shock absorber of 1st Embodiment which concerns on this invention. It is a partial cross-sectional view which shows the periphery of the disk valve of the shock absorber of 1st Embodiment which concerns on this invention. It is a partial cross-sectional view which shows the main part of the shock absorber of the 2nd Embodiment which concerns on this invention.

[First Embodiment]
The first embodiment according to the present invention will be described with reference to FIGS. 1 to 3. In the following, for convenience of explanation, the upper side in the drawing will be referred to as “upper” and the lower side in the drawing will be referred to as “lower”.

As shown in FIG. 1, the shock absorber 1 of the first embodiment is a so-called double-cylinder type hydraulic shock absorber, and includes a cylinder 2 in which an oil solution (not shown) as a working fluid is sealed. The cylinder 2 has a cylindrical inner cylinder 3 and a bottomed cylindrical outer cylinder 4 having a diameter larger than that of the inner cylinder 3 and concentrically provided so as to cover the inner cylinder 3. A reservoir chamber 6 is formed between the cylinder 3 and the outer cylinder 4.

The outer cylinder 4 is composed of a cylindrical body member 11 and a bottom member 12 that is fitted to the lower side of the body member 11 and fixed by welding to close the lower part of the body member 11. A mounting eye 13 is fixed to the bottom member 12 by welding at an outer position opposite to the body member 11.

The shock absorber 1 includes a piston 18 slidably provided inside the inner cylinder 3 of the cylinder 2. The piston 18 defines two chambers in the inner cylinder 3, an upper chamber 19 which is an inner chamber of one cylinder and a lower chamber 20 which is an inner chamber of the other cylinder. In other words, the piston 18 is slidably provided in the cylinder 2 and divides the inside of the cylinder 2 into an upper chamber 19 on one side and a lower chamber 20 on the other side. An oil solution as a working fluid is sealed in the upper chamber 19 and the lower chamber 20 in the inner cylinder 3, and an oil liquid and a gas as a working fluid are contained in the reservoir chamber 6 between the inner cylinder 3 and the outer cylinder 4. And are enclosed.

The shock absorber 1 includes a piston rod 21 whose one end side portion in the axial direction is arranged inside the inner cylinder 3 of the cylinder 2 and is connected and fixed to the piston 18 and the other end side portion extends to the outside of the cylinder 2. ing. The piston rod 21 penetrates the upper chamber 19 and does not penetrate the lower chamber 20. Therefore, the upper chamber 19 is a rod side chamber through which the piston rod 21 penetrates, and the lower chamber 20 is a bottom side chamber on the bottom side of the cylinder 2.

The piston 18 and the piston rod 21 move integrally. In the extension stroke of the shock absorber 1 in which the piston rod 21 increases the amount of protrusion from the cylinder 2, the piston 18 moves toward the upper chamber 19, and the piston rod 21 reduces the amount of protrusion from the cylinder 2. In the contraction stroke, the piston 18 moves toward the lower chamber 20 side.

A rod guide 22 is fitted to the upper end opening side of the inner cylinder 3 and the outer cylinder 4, and a seal member 23 is fitted to the outer cylinder 4 on the upper side which is the outer side of the cylinder 2 with respect to the rod guide 22. ing. The rod guide 22 and the seal member 23 both have an annular shape, and the piston rod 21 is slidably inserted inside each of the rod guide 22 and the seal member 23 from the inside to the outside of the cylinder 2. It has been postponed.

The rod guide 22 supports the piston rod 21 so as to be movable in the axial direction while restricting its radial movement, and guides the movement of the piston rod 21. The seal member 23 is in close contact with the outer cylinder 4 at its outer peripheral portion, and is in sliding contact with the outer peripheral portion of the piston rod 21 moving in the axial direction at its inner peripheral portion. As a result, the seal member 23 prevents the oil liquid in the inner cylinder 3 and the high-pressure gas and the oil liquid in the reservoir chamber 6 in the outer cylinder 4 from leaking to the outside.

The outer peripheral portion of the rod guide 22 has a stepped shape in which the upper portion has a larger diameter than the lower portion, and the rod guide 22 fits into the inner peripheral portion of the upper end of the inner cylinder 3 at the lower portion of the small diameter and is outer at the upper portion of the large diameter. It fits into the inner peripheral portion of the upper part of the cylinder 4. A base valve 25 that defines the lower chamber 20 and the reservoir chamber 6 is installed on the bottom member 12 of the outer cylinder 4, and the inner peripheral portion of the lower end of the inner cylinder 3 is fitted to the base valve 25. ing. The upper end portion of the outer cylinder 4 is crimped inward in the radial direction to form a locking portion 26, and the locking portion 26 and the rod guide 22 sandwich the seal member 23.

The piston rod 21 has a spindle portion 27, a mounting shaft portion 28 having a diameter smaller than that of the spindle portion 27, and a screw shaft portion 31 on the side opposite to the spindle portion 27 of the mounting shaft portion 28. In the piston rod 21, the spindle portion 27 is slidably fitted to the rod guide 22 and the seal member 23, and the mounting shaft portion 28 and the screw shaft portion 31 are arranged in the cylinder 2 and connected to the piston 18 and the like. There is. The end portion of the main shaft portion 27 on the mounting shaft portion 28 side is a shaft step portion 29 extending in the direction orthogonal to the axis. A passage notch 30 extending in the axial direction is formed at an intermediate position in the axial direction on the outer peripheral portion of the mounting shaft portion 28. The passage cutout portion 30 is formed by, for example, notching the outer peripheral portion of the mounting shaft portion 28 in a plane on a plane parallel to the central axis of the mounting shaft portion 28. The passage cutout portion 30 can be formed in a so-called two-sided width shape formed by cutting out two positions of the mounting shaft portion 28 that differ by 180 degrees in the circumferential direction in parallel in a plane. The portion of the mounting shaft portion 28 other than the passage notch portion 30 has a cylindrical surface. The screw shaft portion 31 is provided at the tip position inside the cylinder 2 on the piston rod 21, and a male screw 32 is formed on the outer peripheral portion.

In the shock absorber 1, for example, the protruding portion of the piston rod 21 from the cylinder 2 is arranged at the upper part and supported by the vehicle body, and the mounting eye 13 on the cylinder 2 side is arranged at the lower part and connected to the wheel side. On the contrary, the cylinder 2 side may be supported by the vehicle body and the piston rod 21 may be connected to the wheel side.

As shown in FIG. 2, the piston 18 is a composite of a metal piston body 35 connected to the piston rod 21 and an annular shape that is integrally mounted on the outer peripheral surface of the piston body 35 and slides in the inner cylinder 3. It is composed of a sliding member 36 made of resin.

The piston body 35 can communicate with a plurality of passage holes 37 capable of communicating the upper chamber 19 and the lower chamber 20 (only one place is shown in FIG. 2 due to the cross section), and the upper chamber 19 and the lower chamber 20 can communicate with each other. There are a plurality of passage holes 39 (only one is shown in FIG. 2 because of the cross section). The piston body 35 is a sintered product.

The plurality of passage holes 37 are formed at equal pitches with one passage hole 39 sandwiched between them in the circumferential direction of the piston body 35, and form half of the passage holes 37 and 39. The plurality of passage holes 37 have a crank shape having two bending points, and one side in the axial direction of the piston 18 (upper side in FIG. 2) is outside in the radial direction of the piston 18, and the other side in the axial direction of the piston 18 (upper side in FIG. 2). The lower side of FIG. 2) opens inward in the radial direction of the piston 18 rather than one side. The piston body 35 is formed with an annular groove 55 on the lower chamber 20 side in the axial direction to communicate a plurality of passage holes 37.

On the lower chamber 20 side of the annular groove 55, a first damping force generating mechanism 41 for opening and closing the passages in the annular groove 55 and the plurality of passage holes 37 to generate a damping force is provided. By arranging the first damping force generating mechanism 41 on the lower chamber 20 side, the passages in the plurality of passage holes 37 and the annular groove 55 move to the upper chamber 19 side of the piston 18, that is, upstream in the extension stroke. It is a passage on the extension side where the oil liquid flows out from the upper chamber 19 on the side to the lower chamber 20 on the downstream side. The first damping force generating mechanism 41 provided for the passages in the plurality of passage holes 37 and the annular groove 55 is from the passages in the plurality of passage holes 37 on the extension side and the passages in the annular groove 55 to the lower chamber 20. It is a damping force generation mechanism on the extension side that suppresses the flow of oil and liquid and generates damping force.

The passage holes 39, which form the other half of the passage holes 37 and 39, are formed at equal pitches with one passage hole 37 sandwiched between them in the circumferential direction of the piston body 35. The plurality of passage holes 39 have a crank shape having two bending points, and the other side in the axial direction of the piston 18 (lower side in FIG. 2) is outward in the radial direction of the piston 18 and one side in the axial direction of the piston 18. (Upper side of FIG. 2) opens inward in the radial direction of the piston 18 with respect to the other side. The piston body 35 is formed with an annular groove 56 for communicating a plurality of passage holes 39 on the upper chamber 19 side in the axial direction.

On the upper chamber 19 side of the annular groove 56, a first damping force generating mechanism 42 for opening and closing the passages in the plurality of passage holes 39 and the annular groove 56 to generate a damping force is provided. By arranging the first damping force generating mechanism 42 on the upper chamber 19 side, the passages in the plurality of passage holes 39 and the annular groove 56 move to the lower chamber 20 side of the piston 18, that is, upstream in the contraction stroke. It is a contraction-side passage through which oil liquid flows from the lower chamber 20 on the side to the upper chamber 19 on the downstream side. The first damping force generating mechanism 42 provided for the passages in the plurality of passage holes 39 and the annular groove 56 is from the passages in the plurality of passage holes 39 on the contraction side and the passages in the annular groove 56 to the upper chamber 19. It is a damping force generation mechanism on the contraction side that suppresses the flow of oil and liquid and generates damping force.

The piston body 35 has a substantially disk shape, and an insertion hole 44 into which the mounting shaft portion 28 of the piston rod 21 is inserted is formed in the center in the radial direction so as to penetrate in the axial direction. The insertion hole 44 has a small-diameter hole portion 45 on one side in the axial direction for fitting the mounting shaft portion 28 of the piston rod 21, and a large-diameter hole portion 46 on the other side in the axial direction having a larger diameter than the small-diameter hole portion 45. It has a stepped shape.

At the end of the piston body 35 on the lower chamber 20 side in the axial direction, an annular inner seat portion 47 is formed inside the piston body 35 in the radial direction from the opening on the lower chamber 20 side of the annular groove 55. There is. Further, at the end of the piston body 35 on the lower chamber 20 side in the axial direction, a first damping force generating mechanism 41 is provided outside the opening on the lower chamber 20 side of the annular groove 55 in the radial direction of the piston body 35. An annular valve seat portion 48 forming a part thereof is formed.

At the end of the piston body 35 on the upper chamber 19 side in the axial direction, an annular inner seat portion 49 is formed inside the piston body 35 in the radial direction from the opening on the upper chamber 19 side of the annular groove 56. .. Further, at the end of the piston body 35 on the upper chamber 19 side in the axial direction, a first damping force generating mechanism 42 is provided outside the opening of the annular groove 56 on the upper chamber 19 side in the radial direction of the piston body 35. An annular valve seat portion 50 forming a part thereof is formed.

The insertion hole 44 of the piston body 35 is provided with a large-diameter hole portion 46 on the inner seat portion 47 side in the axial direction with respect to the small-diameter hole portion 45. The passage in the large-diameter hole portion 46 of the piston body 35 is always communicated with the passage in the passage notch 30 of the piston rod 21 by superimposing the position in the axial direction.

In the piston body 35, the outer side in the radial direction of the valve seat portion 48 has a stepped shape having a lower axial height than the valve seat portion 48, and the lower chamber of the passage hole 39 on the contraction side is formed in this stepped portion. An opening on the 20 side is arranged. Similarly, in the piston body 35, the radial outer side of the valve seat portion 50 has a stepped shape having a lower axial height than the valve seat portion 50, and the extension side passage is formed in this stepped portion. An opening on the upper chamber 19 side of the hole 37 is arranged.

The first damping force generating mechanism 42 on the contraction side includes the valve seat portion 50 of the piston 18, and sequentially from the piston 18 side in the axial direction, one disc 62 and a plurality of discs having the same inner diameter and the same outer diameter (s). Specifically, it has four disks 63 and a plurality of disks (specifically two) having the same inner diameter and the same outer diameter. On the side of the disk 64 opposite to the disk 63, one disk 65, one disk 66, and one annular member 67 are provided in this order from the disk 64 side. The annular member 67 is in contact with the shaft step portion 29 of the piston rod 21. The discs 62 to 66 and the annular member 67 are all made of metal, and each has a perforated circular flat plate having a constant thickness and a constant radial width in which the mounting shaft portion 28 of the piston rod 21 can be fitted. ..

The disc 62 has an outer diameter larger than the outer diameter of the inner seat portion 49 of the piston 18 and a smaller diameter than the inner diameter of the valve seat portion 50, and is in constant contact with the inner seat portion 49. The plurality of discs 63 have an outer diameter substantially equal to the outer diameter of the valve seat portion 50 of the piston 18, and can be seated on the valve seat portion 50.

The plurality of discs 64 have an outer diameter smaller than the outer diameter of the disc 63. The disc 65 has an outer diameter smaller than the outer diameter of the disc 64 and a smaller diameter than the outer diameter of the inner seat portion 49 of the piston 18. The disk 66 has an outer diameter larger than the outer diameter of the disk 64 and a smaller diameter than the outer diameter of the disk 63. The annular member 67 has an outer diameter smaller than the outer diameter of the disc 66 and a larger diameter than the outer diameter of the shaft step portion 29 of the piston rod 21. The annular member 67 is thicker and more rigid than the discs 62 to 66.

A plurality of discs 63 and a plurality of discs 64 made of a thin metal plate form a contraction-side main valve 71 that is flexible and can be taken off and seated on the valve seat portion 50. By separating the main valve 71 from the valve seat portion 50, the passages in the annular groove 56 and the plurality of passage holes 39 are communicated with the upper chamber 19, and the flow of oil and liquid between the main valve 71 and the valve seat portion 50. To generate damping force. The annular member 67, together with the disc 66, regulates the deformation of the main valve 71 in the opening direction beyond the specified value.

The passage between the main valve 71 and the valve seat portion 50 that appears at the time of valve opening and the passage in the annular groove 56 and in the plurality of passage holes 39 move into the cylinder 2 due to the movement of the piston 18 toward the lower chamber 20 side. The first passage portion 72 on the contraction side through which the oil liquid flows out from the lower chamber 20 on the upstream side to the upper chamber 19 on the downstream side is formed. Therefore, the first passage portion 72 is formed in the piston 18.

The contraction-side first damping force generating mechanism 42 that generates a damping force includes a main valve 71 and a valve seat portion 50, and is therefore provided in the first passage portion 72. The first passage portion 72 is provided in the piston 18 including the valve seat portion 50, and the oil liquid passes through when the piston rod 21 and the piston 18 move to the contraction side.

Here, in the first damping force generating mechanism 42 on the contraction side, the valve seat portion 50 and the main valve 71 in contact with the valve seat portion 50 are in contact with the upper chamber 19 and the lower chamber 20 even if they are in contact with each other. No fixed orifice is formed to communicate with each other. That is, the first damping force generating mechanism 42 on the contraction side does not communicate the upper chamber 19 and the lower chamber 20 if the valve seat portion 50 and the main valve 71 are in contact with each other over the entire circumference. In other words, the first passage portion 72 is not formed with a fixed orifice that constantly communicates the upper chamber 19 and the lower chamber 20, and is not a passage that constantly communicates the upper chamber 19 and the lower chamber 20.

The first damping force generating mechanism 41 on the extension side includes the valve seat portion 48 of the piston 18, and one disc 82 and a plurality of discs having the same inner diameter and the same outer diameter (in order from the piston 18 side in the axial direction). Specifically, it has five discs 83. A single disk 84 is provided on the opposite side of the disk 83 from the disk 82. The discs 82 to 84 are made of metal, and all have a perforated circular flat plate shape having a constant thickness to which the mounting shaft portion 28 of the piston rod 21 can be fitted inside. The discs 83 and 84 have a constant radial width.

The disc 82 has an outer diameter larger than the outer diameter of the inner seat portion 47 of the piston 18 and a smaller diameter than the inner diameter of the valve seat portion 48, and is in constant contact with the inner seat portion 47. As shown in FIG. 3, the disk 82 is formed with a notch portion 88 from an intermediate position outside the inner sheet portion 47 in the radial direction to an inner peripheral edge portion. The notch 88 constantly communicates the passage in the annular groove 55 and the plurality of passage holes 37 with the passage in the large diameter hole 46 of the piston 18 and the passage in the passage notch 30 of the piston rod 21. The notch 88 is formed during press forming of the disc 82.

As shown in FIG. 2, the plurality of discs 83 have an outer diameter substantially equal to the outer diameter of the valve seat portion 48 of the piston 18, and can be seated on the valve seat portion 48. The disc 84 has an outer diameter smaller than the outer diameter of the disc 83 and smaller than the outer diameter of the inner seat portion 47 of the piston 18.

A plurality of discs 83 made of a thin metal plate constitute a main valve 91 on the extension side that is flexible and can be taken off and seated on the valve seat portion 48. By separating the main valve 91 from the valve seat portion 48, the passages in the annular groove 55 and the plurality of passage holes 37 are communicated with the lower chamber 20, and the flow of oil and liquid between the main valve 91 and the valve seat portion 48. To generate damping force.

The passage between the main valve 91 and the valve seat portion 48 that appears at the time of valve opening and the passage in the annular groove 55 and in the plurality of passage holes 37 move into the cylinder 2 due to the movement of the piston 18 toward the upper chamber 19 side. The first passage portion 92 on the extension side through which the oil liquid flows out from the upper chamber 19 on the upstream side to the lower chamber 20 on the downstream side is formed. Therefore, the first passage portion 92 is formed in the piston 18.

The extension-side first damping force generating mechanism 41 that generates a damping force includes a main valve 91 and a valve seat portion 48, and is therefore provided in the first passage portion 92. The first passage portion 92 is provided in the piston 18 including the valve seat portion 48, and the oil liquid passes through when the piston rod 21 and the piston 18 move to the extension side.

The first damping force generating mechanism 41 on the extension side communicates the upper chamber 19 and the lower chamber 20 with both the valve seat portion 48 and the main valve 91 in contact with the valve seat portion 48 even when they are in contact with each other. No fixed orifice is formed. That is, the first damping force generating mechanism 41 on the extension side does not communicate the upper chamber 19 and the lower chamber 20 if the valve seat portion 48 and the main valve 91 are in contact with each other over the entire circumference. In other words, the first passage portion 92 is not formed with a fixed orifice that constantly communicates the upper chamber 19 and the lower chamber 20, and is not a passage that constantly communicates the upper chamber 19 and the lower chamber 20.

On the side of the extension side of the main valve 91 opposite to the piston 18, in order from the main valve 91 side, the above-mentioned one disk 84, one first case member 100 (support member), and one disk 101 , One disc valve 102, one disc 103, one disc 104, one disc 105 (support member), and one second case member 106 (support member) are pistons. The mounting shaft portion 28 of the rod 21 is provided so as to be fitted inside each of them.

A screw shaft portion 31 is formed on the piston rod 21 at a portion of the mounting shaft portion 28 opposite to the main shaft portion 27 and projecting from the second case member 106 to the side opposite to the piston 18. A nut 108 is screwed into the male screw 32 of the screw shaft portion 31. The nut 108 is in contact with the second case member 106. The screw shaft portion 31 has a male screw 32 which is a complete screw portion to be screwed into the nut 108, and an incomplete screw portion 109 at the end on the mounting shaft portion 28 side. 2 Case member 106 covers.

The first case member 100, the discs 101, 103 to 105, the disc valve 102, and the second case member 106 are all made of metal. The discs 101, 103 to 105 and the disc valve 102 have a perforated circular flat plate shape having a constant thickness and a constant radial width in which the mounting shaft portion 28 of the piston rod 21 can be fitted. The first case member 100 and the second case member 106 have an annular shape in which the mounting shaft portion 28 of the piston rod 21 can be fitted.

The first case member 100 is a bottomed tubular integrally molded product, and is a cylindrical cylinder that projects from the perforated disk-shaped bottom 111 and the outer peripheral edge of the bottom 111 to one side in the axial direction of the bottom 111. It has an annular protruding portion 113 that protrudes from the inner peripheral edge portion of the bottom portion 111 and the tubular portion 112 on the opposite side in the axial direction. The tubular portion 112 has a cylindrical shape centered on the central axis of the bottom portion 111, and the annular protrusion 113 has an annular shape centered on the central axis of the bottom portion 111.

The first case member 100 is arranged so that the annular protrusion 113 is located closer to the piston 18 than the bottom 111, and is fitted to the mounting shaft 28 at the inner peripheral portion of the bottom 111 to form the annular protrusion 113. It is in contact with the disk 84 on the tip surface.

The bottom portion 111 has a flat outer bottom portion 115 extending in the axially orthogonal direction of the first case member 100 in order from the outer side in the radial direction on the tubular portion 112 side in the axial direction, and the tubular portion 112 in the axial direction toward the inner side in the radial direction. It has a tapered intermediate bottom 116 that is inclined apart, and a flat inner bottom 117 that extends in the direction orthogonal to the axis of the first case member 100. The thickness of the bottom portion 111 becomes thinner toward the inner side in the radial direction.

The tubular portion 112 has a continuous cylindrical shape over the entire circumference, and the inner peripheral surface is a straight cylindrical surface having a constant inner diameter. The outer peripheral surface of the tubular portion 112 constitutes the same cylindrical surface as the outer peripheral surface of the bottom portion 111.

The first case member 100 has an insertion hole 125 in the center of the radial direction through which the bottom portion 111 and the annular protrusion 113 are axially penetrated and the mounting shaft portion 28 and the screw shaft portion 31 of the piston rod 21 are inserted. It is formed.

The discs 101, 103 to 105 and the disc valve 102 all have an outer diameter that can be fitted to the inner peripheral surface of the tubular portion 112 of the first case member 100 on the outer peripheral surface. The inner peripheral surface of the tubular portion 112 is coaxial with the insertion hole 125. Further, the discs 101, 103 to 105 and the disc valve 102 all have an inner diameter through which the mounting shaft portion 28 of the piston rod 21 can be inserted.

The inner diameter of the disk 101 is smaller than the inner diameter of the outer bottom portion 115. The inner diameter of the disc valve 102 is smaller than the inner diameter of the disc 101. The inner diameter of the disc 103 is smaller than the inner diameter of the disc 101 and larger than the inner diameter of the disc valve 102. The inner diameter of the disk 104 is larger than the inner diameter of the disk 101. The inner diameter of the disc 105 is larger than the inner diameter of the disc 104 and is equivalent to the inner diameter of the outer bottom portion 115.

The second case member 106 is an integrally molded product having a perforated disk shape, and has a perforated disk-shaped base portion 131 and a passage forming portion 132 protruding axially from the inner peripheral edge portion of the base portion 131. Have. A passage groove 134 recessed inward in the radial direction is formed in the base portion 131 so as to penetrate in the axial direction on the outer peripheral portion. A plurality of passage grooves 134 are formed in the base portion 131 at intervals in the circumferential direction of the base portion 131. The base portion 131 is a plane in which the end surface on the passage forming portion 132 side extends in the direction orthogonal to the axis.

The passage forming portion 132 has a neck portion 135 protruding axially from the inner peripheral edge portion of the base portion 131 and an outer diameter larger than that of the neck portion 135, and protrudes from the neck portion 135 to the opposite side of the base portion 131 in the axial direction. It has a head 136.

As shown in FIG. 3, the neck portion 135 has a cylindrical shape centered on the central axis of the base portion 131, and the outer peripheral surface 141 thereof is a cylindrical surface having a constant diameter.

The head 136 has a cylindrical shape centered on the central axis of the base 131, and its outer peripheral surface 142 is on the intermediate cylindrical surface 143 having a constant diameter and the neck 135 side of the intermediate cylindrical surface 143, and is closer to the neck 135 side. It has a neck tapered surface 144 having a small diameter and a top tapered surface 145 on the side opposite to the neck 135 of the intermediate cylindrical surface 143 and having a smaller diameter as the distance from the neck 135 increases. The neck tapered surface 144 and the top tapered surface 145 are inclined at the same angle with respect to the intermediate cylindrical surface 143. The outer diameter of the intermediate cylindrical surface 143 is a predetermined amount smaller than the inner diameter of the disc valve 102.

The second case member 106 has an insertion hole 151 in the center of the radial direction thereof, through which the base portion 131 and the passage forming portion 132 are axially penetrated and through which the mounting shaft portion 28 and the screw shaft portion 31 of the piston rod 21 are inserted. It is formed. The outer diameter surface of the base 131, the outer peripheral surface 141 of the neck 135, and the outer peripheral surface 142 of the head 136 are coaxial with the insertion hole 151.

The second case member 106 is arranged so that the passage forming portion 132 is located closer to the piston 18 than the base portion 131, fits into the mounting shaft portion 28 at the insertion hole 151, and is the first on the outer peripheral portion of the base portion 131. It is fitted to the tubular portion 112 of the case member 100. The disc 101, the disc valve 102, and the discs 103 to 105 are sandwiched between the outer bottom portion 115 of the bottom portion 111 of the first case member 100 and the base portion 131 of the second case member 106. At this time, the outer peripheral side of the disc valve 102 is clamped axially by the outer bottom portion 115 of the first case member 100 and the disc 105 together with the outer peripheral side of the discs 101, 103, 104. The inner peripheral surface 155 formed of the cylindrical surface of the disc valve 102 is vertically opposed to the intermediate cylindrical surface 143 of the head 136 of the passage forming portion 132 of the second case member 10 by overlapping the positions in the axial direction.

The first case member 100, the second case member 106, and the disc 105 are integrally connected to the piston rod 21, and the outer peripheral side of the disc valve 102 is cantilevered and supported via the discs 101, 103, 104. The inner peripheral end of the disc valve 102 is a free end. In addition to the disc valve 102, the discs 101, 103, and 104 also have free ends on the inner peripheral side and are elastically deformable. The disc valve 102 and the discs 101, 103, 104 are connected so that the outer peripheral side is integrally moved to the piston rod 21, and the inner peripheral side constitutes a sub-valve 161 that can be elastically deformed. The disc valve 102 has a perforated disk-shaped inner peripheral portion that is a free end and faces the piston rod 21 via a passage forming portion 132.

The first case member 100 and the second case member 106 sandwich the disc 101, the disc valve 102, and the discs 103, 104, 105, and form a passage between the inner bottom portion 117 of the first case member 100 and the second case member 106. The portions 132 are separated from each other in the axial direction and face each other, and the passage cutout portion 30 of the piston rod 21 is opened between them.

The second case member 106 covers the incompletely threaded portion 109 of the piston rod 21. An incomplete threaded portion 109 is arranged within the axial range of the base portion 131 of the second case member 106, and mounting shaft portions 28 and male threads 32 on both sides in the axial direction are also arranged.

The first case member 100 and the second case member 106 form a case inner chamber 165 inside them. The sub valve 161 including the disc valve 102 is provided in the case inner chamber 165. In the second case member 106, a predetermined range on the side opposite to the axial passage forming portion 132 of the base portion 131 covers the incompletely threaded portion 109 of the piston rod 21, and this range is the washer portion 166. .. Further, in the second case member 106, the passage forming portion 132 and the predetermined range of the base portion 131 on the passage forming portion 132 side in the axial direction form the case portion 167 forming the case inner chamber 165. In other words, the second case member 106 is integrally molded including a case portion 167 forming the case inner chamber 165 and a washer portion 166 covering the incompletely threaded portion 109 of the piston rod 21.

An incomplete threaded portion 109 is arranged within the axial range of the washer portion 166, and mounting shaft portions 28 and male threads 32 on both sides in the axial direction are also arranged. The washer portion 166 of the second case member 106 is fitted to the mounting shaft portion 28 and is positioned in the radial direction. By covering the incompletely threaded portion 109 with the washer portion 166, the nut 108 can be properly screwed by completely overlapping the male screw 32, which is a completely threaded portion, with the axial position. The washer portion 166 also serves to stabilize and balance the fastening axial force of the nut 108.

Since the passage notch 30 of the piston rod 21 is opened between the inner bottom portion 117 of the first case member 100 and the passage forming portion 132 of the second case member 106, the inner bottom portion 117 and the passage forming portion 132 are formed. The case inner chamber 165 including the space is always connected to the passage in the passage notch 30 of the piston rod 21. Therefore, the case inner chamber 165 has a passage in the passage cutout 30 of the piston rod 21, a passage in the large-diameter hole 46 of the piston 18, a passage in the cutout 88 of the disc 82, and an annular groove of the piston 18. It always communicates with the upper chamber 19 shown in FIG. 2 through the passages in the 55 and the plurality of passage holes 37. Further, the case inner chamber 165 is always communicated with the lower chamber 20 via the passage in the passage groove 134 of the second case member 106.

The case inner chamber 165 is divided into an upper chamber communication chamber 171 on the upper chamber 19 side and a lower chamber communication chamber 172 on the lower chamber 20 side by a sub valve 161 including a disc valve 102, and these upper chamber communication chambers 171. The lower chamber communication chamber 172 is constantly communicated with the lower chamber communication chamber 172 via a variable passage 173 between the disc valve 102 and the passage forming portion 132. Along with the disks 101, 103, 104, the disk valve 102 cantilevered and supported by the first case member 100, the disk 105, and the second case member 106 has a differential pressure between the upper chamber communication chamber 171 and the lower chamber communication chamber 172, that is, It is elastically deformed by the differential pressure between the upper chamber 19 and the lower chamber 20.

As shown in FIG. 3, the variable passage 173 has a minimum flow path cross section when the disc valve 102 is not elastically deformed and the intermediate cylindrical surface 143 of the head 136 and the axial position are overlapped with each other. The flow path cross section increases as the valve 102 elastically deforms and moves away from the head 136.

The passage in the passage groove 134 of the second case member 106, the lower chamber communication chamber 172, the variable passage 173 between the sub valve 161 and the passage forming portion 132, the upper chamber communication chamber 171 and the passage notch of the piston rod 21. The passage in 30, the passage in the large-diameter hole 46 of the piston 18, the passage in the notch 88 of the disk 82, and the passage in the annular groove 55 of the piston 18 and in the plurality of passage holes 37 are pistons. The second passage portion 181 through which the oil liquid flows out from the lower chamber 20 on the upstream side in the cylinder 2 to the upper chamber 19 shown in FIG. 2 on the downstream side is configured by moving the 18 to the lower chamber 20 side.

As the second passage portion 181 moves to the upper chamber 19 side of the piston 18, the oil liquid flows out from the upper chamber 19 on the upstream side in the cylinder 2 to the lower chamber 20 on the downstream side. Therefore, the second passage portion 181 moves to the lower chamber 20 side of the piston 18, that is, the contraction side passage through which the oil liquid flows from the lower chamber 20 on the upstream side to the upper chamber 19 on the downstream side in the contraction stroke. At the same time, the piston 18 moves to the upper chamber 19 side, that is, the passage on the extension side where the oil liquid flows out from the upper chamber 19 on the upstream side to the lower chamber 20 on the downstream side in the extension stroke.

The second passage portion 181 and the first passage portions 72, 92 provided on the piston 18 are downstream from one of the upper chamber 19 and the lower chamber 20 in the cylinder 2 due to the movement of the piston 18. It constitutes a passage 185 through which the working fluid flows out to the other side. The passage 185 is capable of communicating the upper chamber 19 and the lower chamber 20 by traversing the piston 18 in the axial direction.

The second passage portion 181 includes a passage in the passage cutout portion 30 formed by cutting out the piston rod 21, in other words, a part thereof is formed by cutting out the piston rod 21. In addition to forming the piston rod 21 by cutting out, one end is opened between the inner bottom portion 117 of the first case member 100 and the passage forming portion 132 of the second case member 106, and the large diameter hole portion 46 of the piston 18 is formed. A passage may be formed by penetrating the inside of the piston rod 21 in a hole shape so that the other end opens in the inner passage.

The sub-valve 161 and the passage forming portion 132 of the second case member 106 are the second passage portion 181 in which the oil liquid flows in both expansion and contraction strokes in the passage 185 composed of the first passage portions 72 and 92 and the second passage portion 181. The second passage portion 181 is opened and closed, and a second damping force generation mechanism 182 is configured in both expansion and contraction strokes in which the flow of oil and liquid in the second passage portion 181 is suppressed to generate a damping force. ing.

In the second passage portion 181 the passage in the notch 88 of the disk 82 shown in FIG. 3 becomes the narrowest in the fixed passage cross section and is narrowed more than the front and rear, and the second passage portion It becomes the orifice 175 in 181. The orifice 175 is arranged on the downstream side of the sub valve 161 of the oil liquid flow when the oil liquid flows in the second passage portion 181 in the contraction stroke, and when the oil liquid flows in the second passage portion 181 in the extension stroke. It is arranged on the upstream side of the sub valve 161 of the flow of oil and liquid. In other words, as shown in FIG. 2, the orifice 175 is arranged on the upper chamber 19 side of the sub valve 161 in the second passage portion 181.

The second passage portion 181 capable of communicating the upper chamber 19 and the lower chamber 20 is parallel to the first passage portion 72, which is a passage on the contraction side capable of communicating the upper chamber 19 and the lower chamber 20, and is the first. The passage portion 72 is provided with the first damping force generating mechanism 42, and the second passage portion 181 is provided with the second damping force generating mechanism 182. Therefore, the first damping force generating mechanism 42 and the second damping force generating mechanism 182 are arranged in parallel.

The second passage portion 181 capable of communicating the upper chamber 19 and the lower chamber 20 is a plurality of passages on the extension side that can communicate the upper chamber 19 and the lower chamber 20 on the first passage portion 92 and the upper chamber 19 side. Except for the passages in the passage hole 37 and the annular groove 55, they are parallel to each other. In the parallel portion, the first damping force generating mechanism 41 is generated in the first passage portion 92 and the second damping force is generated in the second passage portion 181. Each mechanism 182 is provided. Therefore, the first damping force generation mechanism 41 and the second damping force generation mechanism 182 are arranged in parallel.

As shown in FIG. 1, the base valve 25 described above is provided between the bottom member 12 of the outer cylinder 4 and the inner cylinder 3. The base valve 25 includes a base valve member 191 that separates the lower chamber 20 and the reservoir chamber 6, a disk 192 provided on the lower side of the base valve member 191, that is, on the reservoir chamber 6 side, and an upper side, that is, a lower side of the base valve member 191. It has a disc 193 provided on the chamber 20 side, and a mounting pin 194 for mounting the disc 192 and the disc 193 to the base valve member 191.

The base valve member 191 has an annular shape, and a mounting pin 194 is inserted in the center in the radial direction. The base valve member 191 has a plurality of passage holes 195 through which oil and liquid can flow between the lower chamber 20 and the reservoir chamber 6, and is below the passage holes 195 outside the base valve member 191 in the radial direction. A plurality of passage holes 196 capable of flowing oil liquid are formed between the chamber 20 and the reservoir chamber 6. The disk 192 on the reservoir chamber 6 side allows the flow of oil liquid from the lower chamber 20 to the reservoir chamber 6 through the passage hole 195, while allowing the oil liquid to flow from the reservoir chamber 6 to the lower chamber 20 through the passage hole 195. Suppress the flow. The disk 193 allows the flow of oil liquid from the reservoir chamber 6 to the lower chamber 20 through the passage hole 196, while suppressing the flow of oil liquid from the lower chamber 20 through the passage hole 196 to the reservoir chamber 6.

The disk 192 and the base valve member 191 form a compression valve mechanism 197 on the contraction side that opens the valve in the contraction stroke of the shock absorber 1 to allow oil and liquid to flow from the lower chamber 20 to the reservoir chamber 6 and generate a damping force. ing. The disk 193, together with the base valve member 191, constitutes a suction valve mechanism 198 that opens a valve in the extension stroke of the shock absorber 1 and allows oil liquid to flow from the reservoir chamber 6 into the lower chamber 20. The suction valve mechanism 198 applies oil and liquid from the reservoir chamber 6 to the lower chamber 20 without substantially generating a damping force so as to make up for the shortage of the liquid mainly caused by the extension of the piston rod 21 from the cylinder 2. It fulfills the function of flowing.

As shown in FIG. 2, when assembling the piston 18 or the like to the piston rod 21, the annular member 67 and the disc 66 are inserted into the shaft step portion 29 while inserting the screw shaft portion 31 and the mounting shaft portion 28 of the piston rod 21. , Disc 65, a plurality of discs 64, a plurality of discs 63, a disc 62, and a piston 18 are stacked in this order. At this time, the piston 18 is oriented so that the small-diameter hole portion 45 is located closer to the shaft step portion 29 than the large-diameter hole portion 46. In addition, the disc 82, the plurality of discs 83, the disc 84, and the first case member 100 are sequentially stacked on the piston 18 while inserting the screw shaft portion 31 and the mounting shaft portion 28. At this time, in the first case member 100, the annular protrusion 113 is oriented so as to be located closer to the piston 18 than the bottom 111, and the annular protrusion 113 abuts on the disc 84. In addition, while inserting the screw shaft portion 31 and the mounting shaft portion 28, the disc 101, the disc valve 102, the disc 103, the disc 104, the disc 105, and the second disc 101 are inserted into the bottom portion 111 of the first case member 100. The case members 106 are stacked in this order. At this time, the disc 101, the disc valve 102, and the discs 103, 104, 105 are fitted to the tubular portion 112 of the first case member 100. Further, at this time, the passage forming portion 132 of the second case member 106 is oriented so as to be located closer to the piston 18 than the base 131, and the second case member 106 fits into the tubular portion 112 at the base 131 and abuts on the disc 105.

In this state, the nut 108 is screwed into the male screw 32 of the screw shaft portion 31 of the piston rod 21 protruding from the second case member 106, and the nut 108 and the shaft step portion 29 clamp these in the axial direction. .. Then, the fastening axial force of the nut 108 is applied to the inner peripheral side of the nut 108, the inner peripheral side of the base 131 of the second case member 106, the outer peripheral side of the base 131 of the second case member 106, the disc 105, and the sub valve. The outer peripheral side of 161, the outer bottom 115 of the first case member 100, the annular protrusion 113 of the first case member 100, the disc 84, the inner peripheral side of the main valve 91, and the inner peripheral side of the disc 82. The inner seat portion 47 of the piston 18, the inner seat portion 49 of the piston 18, the inner peripheral side of the disc 62, the inner peripheral side of the main valve 71, the disc 65, the inner peripheral side of the disc 66, and the annular member 67. It is transmitted by a path connecting the inner peripheral side of the shaft and the shaft step portion 29.

In this state, the main valve 71 is clamped to the inner seat portion 49 of the piston 18 and the disc 65 via the disc 62 on the inner peripheral side, and abuts on the valve seat portion 50 of the piston 18 over the entire circumference. Further, in this state, the main valve 91 is clamped to the inner seat portion 47 of the piston 18 and the disc 84 via the disc 82 on the inner peripheral side, and is in contact with the valve seat portion 48 of the piston 18 over the entire circumference.

Further, in this state, the outer peripheral side of the disc 101, the disc valve 102, and the discs 103, 104 constituting the sub valve 161 is clamped to the outer bottom portion 115 and the disc 105 of the first case member 100. At this time, the inner peripheral side of the sub valve 161 is not clamped. Therefore, the sub-valve 161 including the disc valve 102 is cantilevered and supported by the first case member 100, the disc 105, and the second case member 106. The first case member 100, the disc 105, and the second case member 106 are integrally connected to the piston rod 21 together with the outer peripheral portion of the sub valve 161.

The discs 101, 103 to 105 and the disc valve 102 are positioned in the radial direction with respect to the first case member 100 by being fitted to the outer bottom portion 115 of the first case member 100. Therefore, by tightening and fitting the tubular portion 112 of the first case member 100 and the base 131 of the second case member 106, the first case member 100, the discs 101, 103 to 105, the disc valve 102, and the second case The member 106 can be integrated and sub-assembled. Therefore, the first case member 100, the discs 101, 103 to 105, the disc valve 102, and the second case member 106 can be assembled to the piston rod 18 in the sub-assembled state.

Of the extension-side first damping force generating mechanism 41 and the second damping force generating mechanism 182, the main valve 91 of the first damping force generating mechanism 41 is opened with higher rigidity than the sub valve 161 of the second damping force generating mechanism 182. The valve pressure is high. Therefore, in the extension stroke, the second damping force generating mechanism 182 opens with the first damping force generating mechanism 41 closed in the extremely low speed region where the piston speed is lower than the predetermined value. Further, in the normal speed region where the piston speed is equal to or higher than this predetermined value, both the first damping force generating mechanism 41 and the second damping force generating mechanism 182 are opened. In other words, the first damping force generating mechanism 41 provided in the first passage portion 92 of the passages 185 capable of communicating with the upper chamber 19 and the lower chamber 20 by traversing the piston 18 in the axial direction has a low piston speed. The valve is closed in the region of, and the valve is opened in the speed region where the piston speed is higher than the low speed, and the second damping force generating mechanism 182 provided in the second passage portion 181 of the passage 185 has a low piston speed. The valve is opened from the area of. The sub-valve 161 is an extremely low-speed valve that opens a valve in a region where the piston speed is extremely low in the extension stroke to generate a damping force.

That is, in the extension stroke, the pressure of the upper chamber 19 increases and the pressure of the lower chamber 20 decreases as the piston 18 moves toward the upper chamber 19, but the piston speed extends below the first predetermined value. In the process, the second passage portion 181 communicates the upper chamber 19 and the lower chamber 20 via the variable passage 173 in the state where the cross section of the flow path is the minimum. Therefore, the oil liquid in the upper chamber 19 flows through the passages in the plurality of passage holes 37 and the annular groove 55 of the piston 18, the orifice 175, the passage in the large diameter hole portion 46 of the piston 18, and the passage of the piston rod 21. The passage in the notch 30, the upper chamber communication chamber 171, the variable passage 173 in the state where the passage cross-sectional area is the minimum, the lower chamber communication chamber 172, and the passage in the passage groove 134 of the second case member 106. It flows to the lower chamber 20 through.

Then, in the region where the piston speed is higher than the first predetermined value and is lower than the second predetermined value, which is faster than the first predetermined value, the first damping force generating mechanism 41 closes the valve. In this state, the sub-valve 161 of the second damping force generating mechanism 182 is deformed to the lower chamber communication chamber 172 side and opens to supply oil liquid from the upper chamber 19 to the lower chamber 20 in the second passage portion 181 including the variable passage 173. Shed. At this time, as the piston speed increases, the amount of deformation of the sub valve 161 toward the lower chamber communication chamber 172 side increases, and the variable passage 173 between the sub valve 161 and the passage forming portion 132 expands. As a result, the damping force of the valve characteristic (the characteristic in which the damping force is substantially proportional to the piston speed) can be obtained even in the extremely low speed region where the piston speed is lower than the second predetermined value.

Further, in the extension stroke, in the normal speed region where the piston speed is equal to or higher than the second predetermined value, the sub valve 161 of the second damping force generating mechanism 182 is deformed to the lower chamber communication chamber 172 side as described above to increase the valve opening amount. The first damping force generating mechanism 41 opens the valve in this state. That is, the sub valve 161 is deformed to the lower chamber communication chamber 172 side, and the oil liquid flows from the upper chamber 19 to the lower chamber 20 in the second passage portion 181 including the variable passage 173. At this time, the second passage portion In 181 the oil liquid flow is throttled by the orifice 175 provided on the upstream side of the sub valve 161, so that the pressure applied to the main valve 91 increases and the differential pressure increases, and the main valve 91 separates from the valve seat portion 48. Sit down and let the oil liquid flow from the upper chamber 19 to the lower chamber 20 at the first passage portion 92 on the extension side. Therefore, the oil liquid in the upper chamber 19 flows into the lower chamber 20 via the passages in the plurality of passage holes 37 and the annular groove 55 and the passages between the main valve 91 and the valve seat portion 48.

Here, in the extension stroke, in the normal speed region where the piston speed is equal to or higher than the second predetermined value, the differential pressure between the upper chamber 19 and the lower chamber 20 is larger than that in the low speed region of the first predetermined value or more and less than the second predetermined value. However, since the first passage portion 92 does not have a throttle due to an orifice, the oil liquid can flow through the first passage portion 92 at a large flow rate by opening the main valve 91. By this and by narrowing the second passage portion 181 with the orifice 175, the deformation of the sub valve 161 can be suppressed.

In the shock absorber 1, a flow path for flowing oil liquid from the upper chamber 19 to the lower chamber 20 is provided in parallel with the first passage portion 92 and the second passage portion 181 in the extension stroke, and the main valve 91 and the sub valve 161 are arranged in parallel. It is provided. Further, the orifice 175 is connected in series with the sub valve 161.

As described above, in the extension stroke, in the normal speed region where the piston speed is equal to or higher than the second predetermined value, the main valve 91 is opened so that the oil liquid can flow at a large flow rate through the first passage portion 92. .. As a result, the flow rate flowing through the variable passage 173 between the sub valve 161 and the passage forming portion 132 is reduced. Therefore, the valve rigidity of the sub valve 161 can be reduced. Therefore, for example, the rate of increase in the damping force with respect to the increase in the piston speed in the normal speed region can be reduced. In other words, the slope of the rate of increase in the damping force on the extension side with respect to the increase in piston speed in the normal speed region can be laid down more than in the extremely low speed region. As a result, the degree of freedom in design can be expanded.

Of the first damping force generating mechanism 42 and the second damping force generating mechanism 182 on the contraction side, the main valve 71 of the first damping force generating mechanism 42 is opened with higher rigidity than the sub valve 161 of the second damping force generating mechanism 182. The valve pressure is high. Therefore, in the contraction stroke, in the extremely low speed region where the piston speed is lower than the predetermined value, the second damping force generating mechanism 182 opens with the first damping force generating mechanism 42 closed, and the piston speed is the predetermined value. In the above normal speed region, both the first damping force generating mechanism 42 and the second damping force generating mechanism 182 are opened. In other words, the first damping force generating mechanism 42 provided in the first passage portion 72 of the passages 185 capable of communicating with the upper chamber 19 and the lower chamber 20 by traversing the piston 18 in the axial direction has a low piston speed. The valve is closed in the region of, and the valve is opened in the speed region where the piston speed is higher than the low speed, and the second damping force generating mechanism 182 provided in the second passage portion 181 of the passage 185 has a low piston speed. The valve is opened from the area of. The sub-valve 161 is an extremely low-speed valve that opens in a region where the piston speed is extremely low even in the contraction stroke to generate a damping force.

That is, in the contraction stroke, the pressure of the lower chamber 20 increases and the pressure of the upper chamber 19 decreases as the piston 18 moves toward the lower chamber 20, but the piston speed extends below the third predetermined value. In the process, the second passage portion 181 communicates the upper chamber 19 and the lower chamber 20 via the variable passage 173 in the state where the cross section of the flow path is the minimum. Therefore, the oil liquid in the lower chamber 20 is the passage in the passage groove 134 of the second case member 106, the lower chamber communication chamber 172, the variable passage 173 in the state where the flow path cross-sectional area is the minimum, and the upper chamber communication chamber 171. The passage in the passage notch 30 of the piston rod 21, the passage in the large-diameter hole 46 of the piston 18, the orifice 175, and the passage in the annular groove 55 of the piston 18 and in the plurality of passage holes 37. It flows to the upper room 19 through.

Then, in the extremely low speed region where the piston speed is higher than the third predetermined value and is lower than the fourth predetermined value, which is faster than the third predetermined value, the first damping force generating mechanism 42 closes the valve. In this state, the sub-valve 161 of the second damping force generating mechanism 182 is deformed to the upper chamber communication chamber 171 side and opens, and the oil liquid is discharged from the lower chamber 20 to the upper chamber 19 at the second passage portion 181 including the variable passage 173. Shed. At this time, as the piston speed increases, the amount of deformation of the sub valve 161 toward the upper chamber communication chamber 171 side increases, and the variable passage 173 between the sub valve 161 and the passage forming portion 132 expands. As a result, the damping force of the valve characteristic (the characteristic in which the damping force is substantially proportional to the piston speed) can be obtained even in the extremely low speed region where the piston speed is as low as the fourth predetermined value.

Further, in the contraction stroke, in the normal speed region where the piston speed is equal to or higher than the fourth predetermined value, the sub valve 161 of the second damping force generating mechanism 182 is deformed to the upper chamber communication chamber 171 side as described above to increase the valve opening amount. The first damping force generating mechanism 42 opens in the enlarged state. That is, the sub valve 161 is deformed to the upper chamber communication chamber 171 side, and the oil liquid flows from the lower chamber 20 to the upper chamber 19 in the second passage portion 181 including the variable passage 173. At this time, the second passage portion Since the flow rate of the oil liquid in 181 is throttled by the orifice 175, the differential pressure generated in the main valve 71 becomes large, the main valve 71 is separated from the valve seat portion 50, and the first passage portion 72 on the contraction side The oil solution is flowed from the lower chamber 20 to the upper chamber 19. Therefore, the oil liquid in the lower chamber 20 flows through the passages in the plurality of passage holes 39 and the annular groove 56, and the passages between the main valve 71 and the valve seat portion 50. As a result, even in the normal speed region where the piston speed is equal to or higher than the fourth predetermined value, the damping force having valve characteristics (damping force is substantially proportional to the piston speed) can be obtained. The rate of increase in the damping force on the contraction side with respect to the increase in piston speed in the normal speed region is lower than the rate of increase in the damping force on the contraction side with respect to the increase in piston speed in the extremely low speed region. In other words, the slope of the rate of increase in the damping force on the contraction side with respect to the increase in piston speed in the normal speed region can be laid down more than in the extremely low speed region.

In the contraction stroke, in the normal speed region where the piston speed is equal to or higher than the fourth predetermined value, the differential pressure between the lower chamber 20 and the upper chamber 19 is larger than in the low speed region, but the first passage portion 72 is not throttled by the orifice. By opening the main valve 71, the oil liquid can flow at a large flow rate through the first passage portion 72. As a result, the flow rate flowing through the sub valve 161 is reduced, so that the valve rigidity of the sub valve 161 can be reduced. Therefore, the damping force in the normal speed region of the piston speed can be reduced, and the degree of freedom in design can be expanded.

Further, at this time (when the piston speed is high), the differential pressure between the lower chamber 20 and the upper chamber 19 becomes large, but by narrowing the second passage portion 181 with the orifice 175, the upper chamber 19 is connected to the upper chamber 19 via the orifice 175. Since the pressure in the upper chamber communicating chamber 171 that communicates is the pressure between the lower chamber 20 and the upper chamber 19, it is possible to prevent the differential pressure from the lower chamber 20 from becoming too large. By opening the main valve 71 and allowing the oil liquid to flow at a large flow rate through the first passage portion 72, the deformation of the sub valve 161 can be suppressed.

In the above shock absorber 1, a flow path for flowing oil liquid from the lower chamber 20 to the upper chamber 19 in a contraction stroke is provided in parallel with the first passage portion 72 and the second passage portion 181, and the main valve 71 and the sub valve 161 are provided. It is provided in parallel. Further, the orifice 175 is connected in series with the sub valve 161 in the second passage portion 181.

In the contraction stroke, the damping force characteristic by the damping valve mechanism 197 is also combined.

Patent Document 1 described above describes a shock absorber having two valves that open in the same stroke. If there are two valves that open in the same stroke, there is a problem that the productivity decreases, and it is required to suppress the decrease in the productivity in such a shock absorber.

The shock absorber 1 of the first embodiment is cantilevered by the first case member 100, the disc 105, and the second case member 106 together with the discs 101, 103, 104, and is supported by the differential pressure between the upper chamber 19 and the lower chamber 20. The free end of the elastically deformable disc valve 102 faces the piston rod 21 via the passage forming portion 132. Therefore, even if the minimum flow path cross section with the passage forming portion 132 is small, the radial gap with the passage forming portion 132 can be increased.

That is, if the outer peripheral side of the disc valve is the free end, the diameter of the free end becomes large and the circumferential length of the free end becomes long, so that the diameter with the opposing component for forming a predetermined minimum flow path cross-sectional area. The directional gap becomes narrow and the processing for ensuring the accuracy of parts becomes troublesome. On the other hand, in the shock absorber 1 of the first embodiment, the free end of the disc valve 102 faces the piston rod 21. Specifically, the disc valve 102 has a perforated disk shape, and the free end of the inner peripheral portion faces the piston rod 21 via the passage forming portion 132, and the first case member 100, the disc 105, and the disc valve 102 The second case member 106 is integrally connected to the piston rod 21 and cantileverly supports the outer peripheral side of the disc valve 102 together with the outer peripheral side of the discs 101, 103, 104. Therefore, the diameter of the free end of the disc valve 102 becomes small, and the circumferential length of the free end becomes short. Therefore, a passage is formed to form the same predetermined minimum flow path cross-sectional area with the passage forming portion 132. The radial gap between the portion 132 and the portion 132 can be increased. Therefore, assembling becomes easy, and it becomes possible to suppress a decrease in productivity. In addition, since the circumferential length of the free end is shortened, processing for ensuring component accuracy becomes easy, and from this point as well, it is possible to suppress a decrease in productivity. In addition, it is possible to suppress variations in the damping force of the shock absorber 1 among individuals.

Further, the disc valve 102 is attached to the second case member 106 of the first case member 100, the disc 105 and the second case member 106, which cantileverly support the outer peripheral side of the disc valve 102 together with the outer peripheral side of the discs 101, 103, 104. Since the passage forming portion 132 facing the inner peripheral portion of the above is integrally formed, the disc valve 102 and the passage forming portion 132 can be easily positioned.

Further, since the second case member 106 has a case portion 167 forming the case inner chamber 165 and a washer portion 166 covering the incompletely threaded portion 109 of the piston rod 21, it is compared with the case where these are separated. The number of parts can be reduced.

Further, the orifice 175 is arranged on the upstream side of the flow sub-valve 161 during the extension stroke and on the downstream side of the flow sub-valve 161 during the contraction stroke of the second passage portion 181. As a result, the deformation of the sub valve 161 can be suppressed in both the expansion and contraction strokes, and the durability of the sub valve 161 can be improved.

Further, since the orifice 175 is formed by cutting out the disk 82 that abuts on the piston 18 in the first damping force generating mechanism 41 on the extension side, the orifice 175 can be easily formed.

Further, since the second passage portion 181 is formed by cutting out a part of the piston rod 21, the second passage portion 181 can be easily formed.

Further, since the differential pressure between the case inner chamber 165 and the lower chamber 20 does not increase in both expansion and contraction strokes, it becomes possible to use a thin sheet pressed part as the sub valve 161 including the disc valve 102, and the manufacturability and light weight of the sub valve 161 can be used. It is advantageous in terms of conversion.

Further, by adopting a structure in which the sub valve 161 is supported on the outer peripheral side, the first case member 100, the sub valve 161 and the disc 105 and the second case member 106 can be subassembled, and these can be attached to the piston rod 18 in the sub-assembled state. Can be assembled. Therefore, it becomes possible to further suppress the decrease in productivity.

Here, by setting the disc valve 102 as the inner peripheral side bending with the inner peripheral side as the free end, the rigidity becomes higher and the disc valve 102 is greatly bent as compared with the case of the outer peripheral side bending with the outer peripheral side as the free end. Can't. In addition, the stress on the valve lift amount also increases. Therefore, in such a structure of the inner peripheral side deflection, the lift amount does not increase with respect to the series, and the second damping force generating mechanism 182 is parallel to the first damping force generating mechanisms 41 and 42 in the first embodiment. It is easy to establish by setting it to, and it is desirable.

[Second Embodiment]
Next, the second embodiment will be described mainly based on FIG. 4, focusing on the differences from the first embodiment. The parts common to the first embodiment are represented by the same name and the same reference numerals.

In the shock absorber 1A of the second embodiment, as shown in FIG. 4, a piston rod 21A that is partially different from the piston rod 21 of the first embodiment is used. The piston rod 21A has a mounting shaft portion 28A that is partially different from the mounting shaft portion 28, and the mounting shaft portion 28A is not formed with a passage notch 30.

Further, in the shock absorber 1A of the second embodiment, a piston 18A that is partially different from the piston 18 of the first embodiment is used. The piston body 35A of the piston 18A is partially different from the piston body 35. The piston body 35A is formed with a plurality of passage holes 37A penetrating in the axial direction and a plurality of passage holes 39A penetrating in the axial direction (only one place is shown in FIG. 4 due to the cross section).

The plurality of passage holes 37A have a shape extending linearly along the axial direction of the piston body 35A, and are formed at equal pitches in the circumferential direction of the piston body 35A. The piston body 35A is formed with an annular groove 55A that allows a plurality of passage holes 37A to communicate with each other on the side opposite to the upper chamber 19 in the axial direction. On the side opposite to the upper chamber 19 of the annular groove 55A, a first damping force generating mechanism 41A on the extension side is provided.

The plurality of passage holes 39A have a shape extending linearly along the axial direction of the piston body 35A, and are formed at a predetermined pitch in the circumferential direction of the piston body 35A. All the passage holes 39A are formed outside the piston body 35A in the radial direction with respect to all the passage holes 37A. A first damping force generating mechanism 42A on the contraction side is provided on the upper chamber 19 side of the plurality of passage holes 39A.

The piston body 35A has a substantially disk shape, and an insertion hole 44A into which the mounting shaft portion 28A of the piston rod 21A is inserted is formed in the center in the radial direction so as to penetrate in the axial direction. The insertion hole 44A has a straight shape and fits the mounting shaft portion 28A of the piston rod 21A.

At the end of the piston body 35A on the opposite side of the upper chamber 19 in the axial direction, an inner seat portion that is annular in the radial direction of the piston body 35A from the opening on the side opposite to the upper chamber 19 of the annular groove 55A. 47A is formed. At the end of the piston body 35A opposite to the upper chamber 19 in the axial direction, a first damping force is generated outside the opening of the annular groove 55A opposite to the upper chamber 19 in the radial direction of the piston body 35A. An annular valve seat portion 48A forming a part of the mechanism 41A is formed. The valve seat portion 48A is formed with a passage groove 210 that penetrates the valve seat portion 48A in the radial direction.

At the end of the piston body 35A on the upper chamber 19 side in the axial direction, an annular inner seat portion 49A is formed inside the piston body 35A in the radial direction from the openings on the upper chamber 19 side of the plurality of passage holes 37A. There is. Further, at the end of the piston body 35A on the upper chamber 19 side in the axial direction, an annular and irregularly shaped valve seat portion 50A is provided so as to surround one or a plurality of openings on the upper chamber 19 side of the plurality of passage holes 39A. It is formed. A plurality of valve seat portions 50A are formed at intervals in the circumferential direction of the piston body 35A. The plurality of passage holes 37A are always connected to the upper chamber 19 through a gap between the valve seat portions 50A.

The first damping force generating mechanism 42A on the contraction side includes the valve seat portion 50A of the piston 18A, the disc 62 of the first embodiment is not provided, and the outer diameter is larger than that of the disc 63 of the first embodiment. It has a plurality of discs 63A having a large diameter and the same inner diameter and the same outer diameter (specifically, four discs), and a plurality of discs 64 similar to those in the first embodiment. The plurality of discs 63A are always in contact with the inner seat portion 49A, and can be seated on the valve seat portion 50A to close the valve seat portion 50A. A plurality of discs 63A and a plurality of discs 64 made of a thin metal plate constitute a contraction-side main valve 71A that is flexible and can be detached and seated on the valve seat portion 50A.

The extension-side first damping force generating mechanism 41A includes a valve seat portion 48A of the piston 18A, and has a plurality of (specifically, two) disks 83A having the same inner diameter and the same outer diameter. On the side of the disc 83A opposite to the valve seat portion 48A, a plurality of discs (specifically, two discs) having the same inner diameter and the same outer diameter are provided. The discs 83A and 84A are made of metal, and both have a perforated circular flat plate shape having a constant thickness to which the mounting shaft portion 28A of the piston rod 21A can be fitted inside. The plurality of discs 83A are always in contact with the inner seat portion 47A, and can be seated on the valve seat portion 48A to close the valve seat portion 48A. The disc 84A has an outer diameter smaller than the outer diameter of the disc 83A and a smaller diameter than the outer diameter of the inner seat portion 47A of the piston 18A. A plurality of discs 83A made of a thin metal plate constitute a main valve 91A on the extension side which is flexible and can be attached to and detached from the valve seat portion 48A.

The piston body 35A is formed with an annular fitting cylinder portion 211 that projects outward from the valve seat portion 48A in the radial direction of the piston body 35A and protrudes from the valve seat portion 48A to the side opposite to the upper chamber 19. There is. The inner peripheral surface of the fitting cylinder portion 211 is a cylindrical surface coaxial with the insertion hole 44A.

On the side of the disk 84A opposite to the upper chamber 19, a first case member 100A (support member), which is partially different from the first case member 100 of the first embodiment, has a mounting shaft portion 28A of the piston rod 21A inside. It is provided so as to be fitted to. On the side of the first case member 100A opposite to the disc 84A, the disc 101, the disc valve 102, the disc 103, the disc 104, the disc 105, and the second case member 106 are attached to the piston rod 21A as in the first embodiment. The shaft portion 28A is provided so as to be fitted inside each of them.

The first case member 100A does not have an annular protrusion 113 formed on the first case member 100, and has a bottom portion 111A that is partially different from the bottom portion 111. The bottom portion 111A has a large-diameter portion 215 whose outer peripheral surface forms the same cylindrical surface as the outer peripheral surface of the tubular portion 112, and a small-diameter portion 216 whose outer diameter is smaller than that of the large-diameter portion 215. The first case member 100A is fitted to the inner peripheral surface of the fitting cylinder portion 211 of the piston 18A on the outer peripheral surface formed of the cylindrical surface of the small diameter portion 216, and abuts on the disk 84A at the bottom portion 111A.

A through hole 221 is formed in the bottom portion 111A at a position of the intermediate bottom portion 116 in the radial direction to penetrate the bottom portion 111A in the axial direction. A plurality of through holes 221 are formed at intervals in the circumferential direction of the bottom portion 111A.

The first case member 100A has an insertion hole 125A formed in the center in the radial direction thereof so as to penetrate the bottom portion 111A in the axial direction and to insert the mounting shaft portion 28A and the screw shaft portion 31A of the piston rod 21A. The insertion hole 125A is coaxial with the small diameter portion 216, and the mounting shaft portion 28A is fitted.

Penetration of the passage in the passage groove 134 of the second case member 106, the lower chamber communication chamber 172, the variable passage 173 between the sub valve 161 and the passage forming portion 132, the upper chamber communication chamber 171 and the first case member 100A. A passage in the hole 221, an intermediate chamber 225 between the first case member 100A and the second case member 106, a plurality of passage holes 39A of the piston 18A, and a main valve 71A and a valve seat portion 50A appearing at the time of valve opening. The passage between them constitutes a contraction-side passage portion 231 in which the oil liquid flows out from the lower chamber 20 on the upstream side to the upper chamber 19 on the downstream side in the contraction stroke. The contraction-side first damping force generating mechanism 42A that generates a damping force includes a main valve 71A and a valve seat portion 50A, and is therefore provided in the passage portion 231. The passage portion 231 also includes a passage in the passage groove 210 formed in the piston 18A, in the annular groove 55A, and in the plurality of passage holes 37A. The passage in the passage groove 210 constitutes an orifice 175A.

Between the passages in the plurality of passage holes 37A and the annular groove 55A of the piston 18A, the passage between the main valve 91A and the valve seat portion 48A that appear when the valve is opened, and between the first case member 100A and the second case member 106. The intermediate chamber 225, the passage in the through hole 221 of the first case member 100A, the upper chamber communication chamber 171, the variable passage 173 between the sub valve 161 and the passage forming portion 132, the lower chamber communication chamber 172, and the first The passage in the passage groove 134 of the two-case member 106 becomes a passage portion 232 on the extension side where the oil liquid flows from the upper chamber 19 on the upstream side to the lower chamber 20 on the downstream side in the extension stroke. The extension-side first damping force generating mechanism 41A that generates a damping force includes a main valve 91A and a valve seat portion 48A, and is therefore provided in the passage portion 232. The passage portion 232 includes a passage in the passage groove 210 formed in the piston 18A. The passage portions 231 and 232 form a passage 185A in which the working fluid flows from one of the upper chamber 19 and the lower chamber 20 in the cylinder 2 to the downstream side due to the movement of the piston 18A.

The passage between the main valve 71A and the valve seat portion 50A that appears when the valve is opened and the passage in the plurality of passage holes 39A shrink due to the movement of the piston 18A toward the lower chamber 20 so that the oil liquid flows out into the upper chamber 19. It constitutes the first passage portion 72A on the side. Therefore, the first passage portion 72A is formed on the piston 18A. The first passage portion 72A is provided with a contraction-side first damping force generating mechanism 42A that opens and closes the first passage portion 72A to generate a damping force.

The passage between the main valve 91A and the valve seat portion 48A that appears at the time of valve opening and the passage in the annular groove 55A and in the plurality of passage holes 37A move into the cylinder 2 due to the movement of the piston 18A toward the upper chamber 19 side. It constitutes the first passage portion 92A on the extension side from which the oil liquid flows out from the upper chamber 19 on the upstream side. Therefore, the first passage portion 92A is formed on the piston 18A. The first passage portion 92A is provided with a first damping force generation mechanism 41A on the extension side that opens and closes the first passage portion 92A to generate a damping force.

Between the intermediate chamber 225 between the first case member 100A and the second case member 106, the passage in the through hole 221 of the first case member 100A, the upper chamber communication chamber 171 and the sub valve 161 and the passage forming portion 132. The variable passage 173, the lower chamber communication chamber 172, and the passage in the passage groove 134 of the second case member 106 form a second passage portion 181A common to the passage portion 231 and the passage portion 232. The second passage portion 181A serves as a contraction-side passage through which oil liquid flows from the lower chamber 20 on the upstream side in the contraction stroke toward the upper chamber 19 on the downstream side, and the upper chamber 19 on the upstream side in the expansion stroke. It becomes a passage on the extension side where the oil liquid flows out from the lower chamber 20 on the downstream side. The second damping force generating mechanism 182 that generates the damping force includes the sub valve 161 and the passage forming portion 132, and is therefore provided in the second passage portion 181A common to the passage portion 231 and the passage portion 232.

The second passage portion 181A is in series with the first passage portion 72A on the contraction side, the first passage portion 72A has the first damping force generating mechanism 42A, and the second passage portion 181A has the second damping force generating mechanism 182. Each is provided. Therefore, the first damping force generating mechanism 42A and the second damping force generating mechanism 182 are arranged in series.

The second passage portion 181A is in series with the first passage portion 92A on the extension side, the first passage portion 92A has the first damping force generating mechanism 41A, and the second passage portion 181A has the second damping force generating mechanism 182. Each is provided. Therefore, the first damping force generating mechanism 41A and the second damping force generating mechanism 182 are arranged in series.

When assembling the piston 18A or the like to the piston rod 21A, a plurality of annular members 67, a disc 66, and a disc 65 are inserted into the shaft step portion 29 while the screw shaft portion 31 and the mounting shaft portion 28A of the piston rod 21A are inserted. Disc 64, a plurality of discs 63A, and a piston 18A are stacked in this order. At this time, the piston 18A is oriented so that the inner seat portion 49A and the valve seat portion 50A are located on the shaft step portion 29 side. In addition, a plurality of discs 83A, a plurality of discs 84A, and a first case member 100A are sequentially stacked on the piston 18A while inserting the screw shaft portion 31 and the mounting shaft portion 28A. At this time, in the first case member 100A, the small diameter portion 216 of the bottom portion 111A is oriented so as to be located closer to the piston 18A than the large diameter portion 215, and the small diameter portion 216 is fitted to the fitting cylinder portion 211 of the piston 18A. The bottom 111A abuts on the disc 84A. In addition, the disc 101, the disc valve 102, the disc 103, the disc 104, the disc 105, and the second disc 101, the disc valve 102, the disc 103, and the disc 105 are inserted into the bottom 111A of the first case member 100A while the screw shaft portion 31 and the mounting shaft portion 28A are inserted. The case members 106 are stacked in this order. At this time, the disc 101, the disc valve 102, and the discs 103, 104, 105 are fitted to the tubular portion 112 of the first case member 100A. Further, at this time, in the second case member 106, the passage forming portion 132 is oriented so as to be located closer to the piston 18A than the base portion 131, and the base portion 131 fits into the tubular portion 112 and comes into contact with the disk 105.

In this state, the nut 108 is screwed into the male screw 32 of the screw shaft portion 31 of the piston rod 21A protruding from the second case member 106, and the nut 108 and the shaft step portion 29 clamp these in the axial direction. ..

In this state, the main valve 71A is clamped to the inner seat portion 49A of the piston 18A and the disc 65 on the inner peripheral side, and is in contact with the entire circumference of the entire valve seat portion 50A of the piston 18A. Further, in this state, the main valve 91A is clamped to the inner seat portion 47A of the piston 18A and the disc 84A on the inner peripheral side, and is in contact with the valve seat portion 48A of the piston 18A over the entire circumference.

Further, in this state, the outer peripheral side of the disc 101, the disc valve 102, and the discs 103, 104 constituting the sub valve 161 is clamped to the outer bottom portion 115 and the disc 105 of the first case member 100A as in the first embodiment. To. Therefore, the sub-valve 161 including the disc valve 102 is cantilevered and supported by the first case member 100A, the disc 105, and the second case member 106. The first case member 100A, the disc 105, and the second case member 106 are integrally connected to the piston rod 21A together with the outer peripheral portion of the sub valve 161.

Also in the second embodiment, the first case member 100A, the discs 101, 103 to 105, the disc valve 102 and the second case member 106 can be sub-assembled and can be assembled to the piston rod 18A in the sub-assembled state.

Of the extension-side first damping force generating mechanism 41A and the second damping force generating mechanism 182, the main valve 91A of the first damping force generating mechanism 41A is opened with higher rigidity than the sub valve 161 of the second damping force generating mechanism 182. The valve pressure is high. Therefore, in the extension stroke, in the extremely low speed region where the piston speed is lower than the predetermined value, the second damping force generating mechanism 182 opens with the first damping force generating mechanism 41A closed. Further, in the normal speed region where the piston speed is equal to or higher than this predetermined value, both the first damping force generating mechanism 41A and the second damping force generating mechanism 182 are opened.

That is, in the extension stroke, the piston 18A moves to the upper chamber 19 side, so that the pressure in the upper chamber 19 increases and the pressure in the lower chamber 20 decreases, but the piston speed extends below the fifth predetermined value. In the process, the passage portion 232 communicates the upper chamber 19 and the lower chamber 20 via the variable passage 173 in the state where the cross section of the flow path is the minimum. Therefore, the oil liquid in the upper chamber 19 reaches the passages in the plurality of passage holes 37A and the annular groove 55A of the piston 18A, the orifice 175A, the intermediate chamber 225, and the passage in the through hole 221 of the first case member 100A. , Flows into the lower chamber 20 via the upper chamber communication chamber 171, the variable passage 173 in the state where the cross section of the flow path is the smallest, the lower chamber communication chamber 172, and the passage in the passage groove 134 of the second case member 106. ..

Then, in the region where the piston speed is higher than the fifth predetermined value and is lower than the sixth predetermined value, which is faster than the fifth predetermined value, the first damping force generating mechanism 41A closes the valve. In this state, the sub-valve 161 of the second damping force generating mechanism 182 is deformed to the lower chamber communication chamber 172 side and opens to flow oil liquid from the upper chamber 19 to the lower chamber 20 at the passage portion 232 including the variable passage 173. At this time, as the piston speed increases, the amount of deformation of the sub valve 161 toward the lower chamber communication chamber 172 side increases, and the variable passage 173 between the sub valve 161 and the passage forming portion 132 expands. As a result, the damping force of the valve characteristic (the characteristic in which the damping force is substantially proportional to the piston speed) can be obtained even in the extremely low speed region where the piston speed is lower than the sixth predetermined value.

Further, in the extension stroke, in the normal speed region where the piston speed is equal to or higher than the sixth predetermined value, the sub valve 161 of the second damping force generating mechanism 182 is deformed to the lower chamber communication chamber 172 side as described above to increase the valve opening amount. The first damping force generating mechanism 41A opens the valve in this state. That is, the sub valve 161 is deformed to the lower chamber communication chamber 172 side, and the oil liquid flows from the upper chamber 19 to the lower chamber 20 in the passage portion 232 including the variable passage 173. At this time, the sub valve 161 in the passage portion 232 Since the flow of oil and liquid is throttled by the orifice 175A provided on the upstream side, the pressure applied to the main valve 91A in the passage portion 232 increases and the differential pressure increases, and the main valve 91A separates from the valve seat portion 48A. Sit down and let the oil flow from the upper chamber 19 to the lower chamber 20. Therefore, the oil liquid in the upper chamber 19 of the passages in the plurality of passage holes 37A and the annular groove 55A, the passage between the main valve 91A and the valve seat portion 48A, the intermediate chamber 225, and the first case member 100A. The passage in the through hole 221 and the upper chamber communication chamber 171, the variable passage 173 in a state where the flow path cross-sectional area is expanded, the lower chamber communication chamber 172, and the passage in the passage groove 134 of the second case member 106. It flows to the lower chamber 20 via and.

Of the first damping force generating mechanism 42A and the second damping force generating mechanism 182 on the contraction side, the main valve 71A of the first damping force generating mechanism 42A is opened with higher rigidity than the sub valve 161 of the second damping force generating mechanism 182. The valve pressure is high. Therefore, in the contraction stroke, in the extremely low speed region where the piston speed is lower than the predetermined value, the second damping force generating mechanism 182 opens with the first damping force generating mechanism 42A closed, and the piston speed is the predetermined value. In the above normal speed region, both the first damping force generating mechanism 42A and the second damping force generating mechanism 182 are opened.

That is, in the contraction stroke, the piston 18A moves to the lower chamber 20 side, so that the pressure in the lower chamber 20 increases and the pressure in the upper chamber 19 decreases, but the piston speed extends below the seventh predetermined value. In the process, the passage portion 231 communicates the upper chamber 19 and the lower chamber 20 via the variable passage 173 in the state where the cross section of the flow path is the minimum. Therefore, the oil liquid in the lower chamber 20 is the passage in the passage groove 134 of the second case member 106, the lower chamber communication chamber 172, the variable passage 173 in the state where the cross section of the flow path is the smallest, and the upper chamber communication chamber 171. Flows into the upper chamber 19 through the passage in the through hole 221 of the first case member 100A, the intermediate chamber 225, the orifice 175A, and the passage in the annular groove 55A of the piston 18A and in the plurality of passage holes 37A. ..

Then, in the region where the piston speed is higher than the 7th predetermined value and is lower than the 8th predetermined value, which is faster than the 7th predetermined value, the first damping force generating mechanism 42A closes the valve. In this state, the sub valve 161 of the second damping force generating mechanism 182 is deformed to the upper chamber communication chamber 171 side and opens. At this time, as the piston speed increases, the amount of deformation of the sub valve 161 toward the upper chamber communication chamber 171 side increases, and the variable passage 173 between the sub valve 161 and the passage forming portion 132 expands. As a result, the damping force of the valve characteristic (the characteristic in which the damping force is substantially proportional to the piston speed) can be obtained even in the extremely low speed region where the piston speed is lower than the eighth predetermined value.

Further, in the contraction stroke, in the normal speed region where the piston speed is equal to or higher than the eighth predetermined value, the sub valve 161 of the second damping force generating mechanism 182 is deformed to the upper chamber communication chamber 171 side as described above to increase the valve opening amount. The first damping force generating mechanism 42A opens the valve in the enlarged state. That is, the sub valve 161 is deformed to the upper chamber communication chamber 171 side, and the oil liquid flows from the lower chamber 20 to the upper chamber 19 in the passage portion 231 including the variable passage 173. At this time, the passage portion 231 is one of them. Since the flow rate of the oil liquid at the orifice 175A is throttled, the differential pressure generated in the main valve 71A of the other flow becomes large, and the main valve 71A separates from the valve seat portion 50A and from the lower chamber 20. An oil solution is poured into the upper chamber 19. Therefore, the oil liquid in the lower chamber 20 is the passage in the passage groove 134 of the second case member 106, the lower chamber communication chamber 172, the variable passage 173 in a state where the flow path cross-sectional area is expanded, and the upper chamber communication chamber 171. , The passage in the through hole 221 of the first case member 100A, the intermediate chamber 225, the passage in the plurality of passage holes 39A, and the passage between the main valve 71A and the valve seat portion 50A. As a result, a damping force having valve characteristics (damping force is substantially proportional to the piston speed) can be obtained even in a normal speed region where the piston speed is equal to or higher than the eighth predetermined value.

The first and second embodiments have shown an example in which the present invention is used for a double-cylinder hydraulic shock absorber, but the present invention is not limited to this, and the outer cylinder is eliminated and the upper chamber 19 of the lower chamber 20 in the cylinder 2 is used. May be used in monotube hydraulic shock absorbers that form a gas chamber with slidable compartments on the opposite side, and any shock absorber, including pressure control valves using packing valves with a disc-sealed construction. Can be used for vessels.

In the first aspect of the embodiment described above, a cylinder in which a working fluid is sealed, a piston slidably provided in the cylinder, and a piston for partitioning the inside of the cylinder into two chambers are connected to the piston. A piston rod extending to the outside of the cylinder, a passage through which the working fluid flows from the chamber on the upstream side in the cylinder to the chamber on the downstream side by the movement of the piston, and a passage provided in the passage. A first damping force generating mechanism that closes the valve in a region where the piston speed is low and opens a valve in a speed region where the piston speed is higher than the low speed, and a second valve that is provided in the passage and opens from a region where the piston speed is low. The second damping force generating mechanism has a damping force generating mechanism, and the second damping force generating mechanism has a disc valve that is cantilevered by a support member and elastically deforms due to a differential pressure between the two chambers, and is a free end of the disc valve. Is opposed to the piston rod. This makes it possible to suppress a decrease in productivity.

In the second aspect, in the first aspect, the disc valve has a perforated disk shape and the inner peripheral portion faces the piston rod, and the support member is integrally connected to the piston rod. The outer peripheral side of the disc valve is cantilevered and supported.

1,1A Shock absorber 2 Cylinder 18,18A Piston 19 Upper chamber 20 Lower chamber 21,21A Piston rod 41, 42, 41A, 42A First damping force generation mechanism 100, 100A First case member (support member)
102 Disc valve 105 Disc (support member)
106 Second case member (support member)
185,185A Passage 182 Second damping force generation mechanism

Claims (2)

A cylinder in which the working fluid is sealed and
A piston that is slidably provided in the cylinder and divides the inside of the cylinder into two chambers,
A piston rod that is connected to the piston and extends to the outside of the cylinder,
A passage through which the working fluid flows from the chamber on the upstream side in the cylinder to the chamber on the downstream side due to the movement of the piston.
A first damping force generating mechanism provided in the passage, which closes the valve in the region where the piston speed is low and opens the valve in the region where the piston speed is higher than the low speed.
A second damping force generating mechanism provided in the passage and opening a valve from a region where the piston speed is low,
Have,
The second damping force generation mechanism is
It has a disc valve that is cantilevered by a support member and elastically deforms due to the differential pressure between the two chambers.
A shock absorber characterized in that the free end of the disc valve faces the piston rod. The disc valve has a perforated disk shape, and the inner peripheral portion faces the piston rod.
The shock absorber according to claim 1, wherein the support member is integrally connected to the piston rod to cantilever support the outer peripheral side of the disc valve.

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