JP2572022Y2 - Variable damping force type shock absorber - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable damping force type shock absorber, and more particularly to a frequency-sensitive type shock absorber which automatically changes a damping force characteristic in response to a vibration frequency.

[0002]

2. Description of the Related Art Hitherto, as a frequency-sensitive type variable damping force type shock absorber, for example, one described in Japanese Utility Model Publication No. 63-27157 is known. The conventional variable damping force type shock absorber includes an extension communication path communicating two chambers defined by pistons, an extension damping valve formed in the extension communication path, and a bending of the extension damping valve. A disk valve slidably provided in a sliding hole to change the characteristics, and an expansion side pressure receiving chamber formed on the upper end surface side of the disk valve and communicating with the expansion side communication passage via a check valve and a throttle. It is provided. That is, during the extension stroke of the piston, when the vibration frequency is less than a certain value, the fluid pressure in the extension-side pressure receiving chamber rises and slides the disk valve downward. The flexural strength is increased to provide high damping force characteristics, and when the vibration frequency is equal to or higher than a certain value, the high-frequency cut action by the throttle prevents the fluid pressure in the extension-side pressure receiving chamber from rising, thereby increasing the extension-side damping. The bending strength of the valve is kept low to provide low damping force characteristics.

[0003]

However, in such a conventional variable damping force type shock absorber, the fluid pressure in the upper chamber on the upstream side of the throttle increases as the piston speed increases. Since the pressure on the pressure receiving chamber side increases in proportion to the hydraulic pressure in the upper chamber when the opening area of the piston is constant, as shown in FIG. It becomes impossible to reduce the damping force based on the cutting action (hereinafter referred to as a high-cut action), so that the value of the frequency at which the high-cut action occurs becomes high, and a desired high-cut action cannot be obtained.

The present invention has been made in view of the above-mentioned conventional problems, and has a damping force in a predetermined frequency range from a low piston speed range to a high piston speed range without being affected by the piston speed. It is an object of the present invention to provide a variable damping force type shock absorber that can change the damping force.

[0005]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, a variable damping force type shock absorber according to the present invention has a valve body in which the interior of the shock absorber is defined as two chambers, and the defined body. A damping force is generated by restricting the flow of fluid between the two chambers,
And a movable member that receives and moves the fluid pressure in the pressure receiving chamber that is communicated with the defined chamber, and that is configured to change the generated damping force characteristic in accordance with the movement of the movable member. A force generating means, provided in the middle of a flow path connecting the defined chamber and the pressure receiving chamber, for inhibiting the flow of the fluid from the defined chamber to the pressure receiving chamber and permitting the flow in the opposite direction. A check plate having a check valve portion, a constant plate having a valve port opened and closed by the check valve portion and forming a constant orifice bypassing the check valve portion, a valve port of the constant plate and a pressure receiving chamber; When a ring-shaped variable throttle is formed between a seat plate having a valve opening communicating therewith and provided between the seat plate and the constant plate, and a peripheral edge of the valve opening of the seat plate. From the constant plate to
Wherein by receiving the fluid pressure to Topureto direction
A variable orifice plate having a variable throttle valve for reducing the annular variable throttle area by bending in the direction of the seat plate .

[0006]

[Function] During the stroke of the piston, fluid flows from one chamber defined by the valve body to the other chamber based on the fluid pressure difference, whereby a damping force is generated in the damping force generating means. Then, the movable member provided in the damping force generating means slides by receiving the liquid pressure in the pressure receiving chamber, and the damping force characteristic is automatically changed in response to the sliding. in this case,
For example, if the difference between the liquid pressures of the two chambers is large, the sliding amount becomes large, and a change can be made such that the cross-sectional area of the flow path between the two liquid chambers is narrowed to obtain high damping force characteristics.

As described above, the damping force characteristic can be changed by sliding the movable member, but the change in the damping force characteristic is canceled in accordance with the stroke frequency of the shock absorber. That is, when the shock absorber strokes at a low frequency lower than the predetermined frequency, the fluid pressure in the defined chamber is transmitted to the pressure receiving chamber through the constant orifice, and is received by the movable member. Accordingly, the movable member slides, and the damping force characteristic is changed. On the other hand, when the shock absorber strokes at a high frequency equal to or higher than the predetermined frequency, the transmission of the fluid pressure to the pressure receiving chamber is regulated by the high cut action by the constant orifice, and the movable member receives the fluid pressure of the chamber defined by the movable member. Will not be achieved. Therefore, the movable member does not slide, and the damping force characteristic is not changed.

By the way, as the stroke speed of the shock absorber increases, the fluid pressure of the chamber defined in the shock absorber increases. And when the fluid pressure rises in this way, the flow rate of the fluid per unit area increases and the fluid pressure transmission property rises, so the fluid pressure transmission to the pressure receiving chamber via the constant orifice becomes smooth, For this reason, the frequency at which the high cut action by the constant orifice occurs is shifted to the higher frequency side. However, receiving this high pressure, the variable throttle valve of the variable orifice plate bends to the side that reduces the area of the annular variable throttle. Accordingly, the fluid pressure is less likely to be transmitted to the pressure receiving chamber due to the reduced area of the variable throttle, and the pressure in the pressure receiving chamber is prevented from increasing, whereby a high cut action can be secured.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

First, the configuration of the embodiment will be described.
FIG. 1 is a sectional view showing a piston portion which is a main part of a variable damping force type shock absorber according to an embodiment of the present invention (a left half sectional view shows a state at the time of high frequency input, and a right half sectional view shows a state at the time of low frequency input). In the figure, reference numeral 1 denotes a cylindrical cylinder. The cylinder 1 is divided into an upper chamber A and a lower chamber B by a slidably mounted piston (valve body) 2, and both chambers A and B are filled with a fluid such as oil. The piston 2 is attached to a small-diameter portion 3 a of the piston rod 3. That is, the tip small diameter portion 3 of the piston rod 3
a, a retainer 4a, a washer 5a, a compression-side high damping valve 6, a piston 2, an extension-side first-stage damping valve (damping force generating means) 7, a washer 5b, a retainer 4b, and an extension-side second-stage damping valve (damping force). (Generating means) 8, a washer 5c, a collar 9, a spring seat 10, and a spring S are sequentially mounted, and are finally fastened with a nut 11 to be mounted. In addition, a flow path 3b communicating the upper chamber A and the lower chamber B is formed in the shaft core of the piston rod 3.

Further, the piston 2 will be described in detail.
The upper end surface of the piston 2 on the upper chamber A side has an inner recess 2.
a and an outer concave portion 2b are formed.
2b is communicated with the lower chamber B by a plurality of extension-side communication passages 2c and compression-side communication passages 2d formed in the piston 2 in the vertical direction. Outer concave portion 2 of pressure side communication passage 2d
The pressure-side high-attenuation valve 6 is in contact with b, and the pressure-side high-attenuation valve 6 can open and close the pressure-side communication passage 2d. The inner concave portion 2a of the extension side communication passage 2c is open to the upper chamber A side by a communication hole 2k formed in the inner peripheral portion of the compression side high attenuation valve 6. An inner annular groove 2e is formed at a lower end portion of the extension side communication path 2c, and a first sheet surface 2f is formed around the inner annular groove 2e. The stage-side damping valve 7 is in contact, and the extension-side communication passage 2c can be opened and closed by the extension-side first stage damping valve 7. In addition, the first
An outer annular groove 2g is formed on the outer periphery of the seat surface 2f, and a second seat surface 2h is formed on the outer periphery and below the first seat surface 2f. The expansion-side second-stage damping valve 8 is in contact with the expansion-side communication passage 2c.
Can be opened and closed. The set load of the spring S is applied to the position of the second seat surface 2h of the extension-side second-stage damping valve 8 via the spring seat 10.

A cylindrical housing portion 11b having a large-diameter hole 11a communicating with the flow path 3b is provided integrally with a lower portion of the nut 11, and is provided inside the large-diameter hole 11a of the housing portion 11b. , In order from the top, a retainer 12, a washer 13, an extension-side check plate 14, an extension-side constant plate 15, an extension-side variable orifice plate 40, an extension-side seat plate 16, and a spool body 1.
7. Compression side seat plate 18, Compression side variable orifice plate 41, Compression side constant plate 19, Compression side check plate 20, Washer 30, Retainer 21, Stud 22, Washer 23a, Compression side low damping valve 24, Sub-valve body 25, Extension side low attenuation Valve 26, washer 2
3b, a collar 27 and a retainer 28 are mounted.

The spool body 17 is formed in a cylindrical shape having a spool hole 17a formed in the axis thereof, and a seal ring 29 for sealing between the spool body 17 and the large-diameter hole 11a in the middle of the outer peripheral surface. An attached annular projection 17b is formed.

The retainer 12 has a central hole 12a formed in the center of a thin plate material, and a notch 12b formed in the outer peripheral portion at equal intervals in the circumferential direction from a middle portion thereof. It has a structure in which a plurality of leg pieces 12c each bent downward are formed.

As shown in FIG. 3, the extension side check plate 14 is formed by forming a cutout annular hole 14a with a part thereof left in a flexible thin plate material, thereby forming an annular outer peripheral fixing portion 14b. , A circular valve portion (check valve portion) 14c at the center, and a connecting portion 14d communicating the two.

As shown in FIG. 4, the extension-side constant plate 15 has a central hole (valve port) 15a having a smaller diameter than the valve portion 14c of the compression-side check plate 14 in the center of a thin plate material. An arc-shaped long hole 15b is formed in the outer periphery of the center hole 15a at a position facing the cutout annular hole 14a of the pressure-side check plate 14 along the circumferential direction thereof. The holes 15a are connected by narrow notches 15c.

The extension side variable orifice plate 40 includes:
As shown in FIG. 5, by forming a cutout annular hole 40a with a part thereof left in a flexible thin plate material, an annular outer peripheral fixing portion 40b and a central circular valve portion (variable throttle valve) are formed. ) 40c and a connecting portion 40d communicating the two are formed, and the outer periphery thereof is bent downward to form the pedestal portion 4c.
0e is formed.

The extension side sheet plate 16 is provided at the center of a thick plate material with the extension side variable orifice plate 40.
A central hole (valve port) 16a having a smaller diameter than the circular valve portion 40c is formed (see FIG. 2).

Returning to FIG. 1, the washer 13, the extension side check plate 14, the extension side constant plate 15, the extension side variable orifice plate 40, and the extension side sheet plate 16 are formed to have the same diameter as the spool body 17. At the same time, the outer peripheral portion is provided between the retainer 12 and the upper opening end surface of the spool body 17 so as to be clamped and fixed. The retainer 12 is provided in a state where the tip of the leg portion 12c is inserted into an upper annular space 17c formed between the housing portion 11b and the spool body 17.

[0020] That is, as shown in FIG. 2, the seat surface a ₁ the valve portion 14c to the opening edge the upper surface of the central hole 15a is in contact of the extension side constant plate 15 is formed, the opening width of the cutout portion 15c w constant orifice c ₁ by an opening formed in (see FIG. 4) and the thickness h ₁ of the expansion side constant plate 15 is configured and opening circular valve portion 40c is throttled by bent downwards, that is, the extension side with annular openings formed in the central hole 16a in the lower surface and the extension side seat plate 16 of the circular valve portion 40c between the upper opening edge of the (pore size .phi.d) (height of the pedestal portion 40e h ₂₎ A second variable stop b ₁ (see FIG. 6) is formed. In other words, the constant orifice c ₁ is the extension side Constant width up to an aperture sectional area of the thickness of the plate 15 and the notch portion 15c (w × h ₁₎ is determined, and the extension side second variable throttle b _1, the annular Variable stop cross-sectional area (φd ×
π × h ₂ ) is determined (see FIGS. 4 and 6).

Further, as shown in FIG.
1, the compression-side sheet plate 18, the compression-side constant plate 19, the compression-side variable orifice plate 41, and the compression-side check plate 20 include the retainer 12, the expansion-side sheet plate 16, the expansion-side constant plate 15, the expansion-side variable orifice plate 40, And the retainer 21 has the same shape as the extension side check plate 14, respectively.
Only the pressure-side variable orifice plate 41 is assembled with the retainer 12 and the extension-side variable orifice plate 40 in opposite directions. That is, in the figure, 18a is a central hole,
41a is a notched annular hole, 41b is an outer peripheral fixing portion, 41c is a circular valve portion, 41d is a connecting portion, 41e is a pedestal portion, 19a is a central hole, 19b is a long hole, 19c is a notched portion, 20a is a notched annular groove, 20b the outer peripheral fixing portion, 20c the valve unit, 20d are coupling portion, 21a is the central hole, 21b are notches, 21c are leg portions, a ₂ is sheet surface, b ₂ a diaphragm second variable pressure side, c
₂ indicates a constant orifice.

Next, returning to FIG. 1, the stud 22
A small-diameter portion 22c in which a through-hole 22b is formed in the center of the lower center of the large-diameter portion 22a having a smaller diameter than the large-diameter hole 11a.
Are formed. The pressure side seat plate 18, the pressure side constant plate 19, and the pressure side check plate 20 are provided in a state where the outer peripheral portion thereof is sandwiched between the lower opening end surface of the spool body 17 and the retainer 21.

The washer 23a and the pressure-side low-attenuation valve 2 are sequentially provided on the small-diameter portion 22c of the stud 22 from the top.
4, a sub-valve body 25, an extension side low attenuation valve 26, a washer 23b, a collar 27, and a retainer 28 are mounted. By caulking the lower end opening edge of the housing portion 11b to the lower surface side of the retainer 28, the above-described members are all incorporated into the large-diameter hole 11a of the nut 11. More specifically, a partially cut-out annular groove 25a is formed on the upper surface of the sub-valve body 25, and a seat surface 25b is formed on the outer periphery thereof.
The pressure side low damping valve 24 is in contact with b.
The annular groove 25a communicates with the lower chamber B through a pressure-side flow passage 25c formed in the sub-valve body 25 and a communication hole 28a formed in the retainer 28.

On the other hand, a partially cut-out annular groove 25d is formed on the lower surface of the sub-valve body 25, and further on the outer periphery thereof,
A sheet surface 25e is formed, and the sheet surface 25e includes
The extension side low attenuation valve 26 is in contact with the extension side low attenuation valve 26. And
The annular groove 25d communicates with the large-diameter hole 11a by an extension-side flow passage 25f formed in the sub-valve body 25. The retainer 21 is provided in a state where the distal end of the leg portion 12c is inserted into a lower annular space 17d formed between the housing portion 11b and the spool body 17.

The spool body 17 has an upper annular space and a spool hole 17a which are vertically arranged with an annular protrusion 17b interposed therebetween.
Are formed, and a plurality of compression-side ports 17f that communicate the lower annular space 17d with the spool hole 17a are formed. Within the spool hole 17a, the extension side pressure receiving chamber D ₁ and pressure side pressure receiving chamber D on the upper and lower both sides
₂ , a spool 31 as a movable member is provided slidably in the vertical direction. The spool 31 has a substantially H-shaped cross section, and has centering springs 32, 33 between the expansion-side pressure receiving surface 31a at the upper end and the expansion-side sheet plate 16 and between the compression-side pressure receiving surface 31b at the lower end and the compression-side sheet plate 18. Interposed, both centering springs 3
Spools 31 are biased by 2 and 33 so as to be held at the neutral position.

An annular groove 31c is formed in the outer peripheral surface of the spool 31 at the neutral position of the spool 31 so as to communicate the expansion side port 17e and the compression side port 17f. The expansion side first variable throttle 34 as damping force variable means is formed by the port 17e, and the compression side first variable throttle 35 as damping force variable means is formed by the lower edge of the annular groove 31c and the compression side port 17f. ing. Therefore, the extension phase pressure receiving chamber D _1, the flow path 3b, center hole 12a, the notch ring hole 14a, the long hole 15b, constant orifice c _1, the extension side second variable throttle b _1, the central bore 15
a, the fluid pressure on the upper chamber A side can be transmitted via the central hole 16a. On the other hand, the compression side pressure receiving chamber D ₂ is the communication hole 28a, the center hole 21a, the notch ring hole 20a, the elongated hole 19
b, constant orifice c ₂ , pressure side second variable throttle b
₂ , the fluid pressure on the lower chamber B side can be transmitted via the central hole 19a and the central hole 18a.

In this embodiment having the above-described structure, three communication paths are formed to allow fluid to flow between the upper chamber A and the lower chamber B. First, the first communication path F is
a, the extension side communication path 2c is a path that sequentially follows the inner annular groove 2e and the outer annular groove 2g.

Next, the second communication path G is a path which sequentially follows the outer side recess 2b from the pressure side communication path 2d. The third communication path H includes the flow path 3b, the notch 12b, the upper annular space 17c, the expansion port 17e, the annular groove 31c, the compression port 17f, the lower annular space 17d, the notch 21b, and the expansion side flow. It is a path that follows the path 25f, the partially cut annular groove 25d, and the communication hole 28a in order, or a path that passes from the communication hole 28a through the pressure-side flow path 25c and the partially cut annular groove 25a, and a path that reverses the above. .

Next, the operation of the embodiment will be described.

(A) At the time of the extension stroke That is, when the extension stroke of the piston 2 is completed, the fluid in the upper chamber A can flow into the lower chamber B through the two paths of the communication path F and the communication path H. It is. In this case, if the expansion-side first variable throttle 34 is opened and the communication path H can flow, the fluid flows through the communication path H by opening the expansion-side low-attenuation valve 26, The first variable throttle 34 is closed and the communication path H
When the fluid cannot flow, the fluid passes through the communication passage F, opens the first-stage damping valve 7 on the expansion side, and further, the second-stage damping valve 8 on the expansion side resists the closing force of the spring S. And flows to the lower chamber B.

In the communication path H side of the two paths, the opening of the first variable throttle 34 on the extension side can be changed by sliding the spool 31, thereby increasing the damping force range from low damping force. It can be continuously and continuously changed to a high damping force. That is, the low damping force range is set when the communication passage H side is open. In this case, piston 2
In the low-speed operation range, the fluid smoothly flows through the communication path H, and a damping force having a velocity square characteristic is generated in the first variable throttle 34 on the expansion side. A damping force having a speed 2/3 characteristic in which the rate of change changes symmetrically is generated, and a linear damping force characteristic linearly proportional to the piston speed is obtained. On the other hand, in the high-speed operation region, the fluid flows through the communication path F, and a damping force having a speed 2/3 power characteristic is generated in series between the expansion-side first-stage damping valve 7 and the expansion-side second-stage damping valve 8. ,
In this case, a decrease in the rate of change of the 2/3 power characteristic, in which the rate of change decreases as the piston speed increases, is suppressed, and a linear characteristic that is linearly proportional to the piston speed is obtained.

The high damping force range is set when the spool 31 slides downward and the flow passage area on the communication passage H side (extension-side first variable throttle 34) is reduced. in this case,
The expansion-side first-stage damping valve 7 and the expansion-side second-stage damping valve 8 generate a damping force having a speed 2/3 power characteristic in series, so that a linear damping force characteristic is obtained.

Switching of the damping force range as described above
In other words, the sliding of the spool 31 is performed according to the vibration frequency of the fluid pressure.

A) At the time of low frequency input When the vibration frequency of the fluid pressure on the upper fluid chamber A side is lower than a predetermined value (low frequency), the fluid smoothly passes through the constant orifice c ₁ and the expansion-side second variable throttle b _1. since the fluid pressure is transmitted to the expansion side pressure receiving chamber D ₁ side and the difference in fluid pressure is generated fluid pressure of the expansion side pressure receiving chamber D ₁ is increased between both pressure receiving chamber D _1, D _2, thereby As shown in the right half sectional view of FIG.
1 is slid downward, the extension-side first variable throttle 34 is closed, and the flow of the communication path H is regulated, thereby providing a high damping force range.

B) At the time of inputting high frequency That is, when the vibration frequency of the fluid pressure on the upper fluid chamber A side is higher than a predetermined value (high frequency), the constant orifice c ₁
And a high frequency cut action by throttling of the extension side second variable throttle b _1, since the amount of transmission of the fluid pressure on the extension side pressure receiving chamber D ₁ side is small, the difference in fluid pressure between both pressure receiving chamber D _1, D ₂ Therefore, as shown in the left half sectional view of FIG. 1, the communication passage H can flow while the spool 31 is held at the neutral position by the urging force of the centering springs 32, 33. This results in a low damping force range.

C) High-speed operation of the piston As the operation of the piston 2 becomes faster, the upper fluid chamber A
The fluid pressure on the upper fluid chamber A side, even when the vibration frequency of the fluid pressure on the upper fluid chamber A side is a certain value or higher (high frequency),
Increased negotiable amount of fluid per unit area in the constant orifice c ₁ is, thereby, extension phase pressure receiving chamber D
It acts to increase the amount of transmission of fluid pressure to the _first side, but downstream thereof, as shown in FIG.
By fluid pressure in the upper fluid chamber A side acting on the upper surface of 0c rises, circular type valve portion 40c is a distance h ₂ between the upper opening edge of the center hole 16a in the extension side seat plate 16 bends downward reduced, thereby, the extension side second opening area of the variable throttle b ₁ is reduced inverse proportionally. Therefore, as shown in FIG. 8, even if the operation of the piston 2 becomes faster, the sliding of the spool 31 can be prevented to obtain a desired high cut action (ie, a damping force reducing action at a desired frequency). it can.

(B) During the pressure stroke When the pressure stroke of the piston 2 is completed, the fluid in the lower chamber B can flow to the upper chamber A through the communication paths G and H. In this case, when the pressure side first variable throttle 35 is opened and the flow path cross-sectional area of the communication path H is large, the fluid passes through the communication path H and flows by opening the pressure side low attenuation valve 24, and When the first compression throttle 35 is closed and the communication path H cannot be circulated, the fluid flows through the communication path G, opens the compression high attenuation valve 6, and circulates to the upper chamber A. Of the two paths, the communication path H side can change the opening degree of the pressure-side first variable throttle 35 by sliding the spool 31 in the same manner as in the above-described extension stroke, thereby providing the damping force range. Can be continuously and continuously changed from a low damping force to a high damping force. That is, the low damping force range is set when the communication passage H side is open. In this case, in the low-speed operation range of the piston 2, the fluid flows through the communication path H, and a damping force having a speed square characteristic is generated in the first variable throttle 35 on the pressure side. With respect to the characteristic, a damping force having a speed 2/3 characteristic in which the rate of change changes symmetrically is generated, and a linear damping force characteristic linearly proportional to the piston speed is obtained. On the other hand, in the high-speed operation range, the fluid flows through the pressure-side communication passage 2d, and the pressure-side high damping valve 6 generates a damping force having a speed 2/3 power characteristic.

The high damping force range is caused by the communication passage H.
Is when is closed. In this case, the compression side high damping valve 6
, A damping force having a speed 2/3 power characteristic is generated in series. The switching of the damping force range (sliding of the spool 31) as described above is performed according to the vibration frequency of the fluid pressure as in the extension stroke.

[0039] a) when the vibration frequency of the low-frequency input when the lower fluid chamber B side of the fluid pressure is lower than the predetermined value (low frequency) is a constant orifice c ₂ and the compression side second variable throttle b ₂ smoothly pass since the fluid pressure is transmitted Te to the compression side pressure receiving chamber D ₂ side, the difference in fluid pressure is generated fluid pressure in the pressure side pressure receiving chamber D ₂ is increased between both pressure receiving chamber D _1, D _2, thereby, the spool 31 Is slid upward, the pressure-side first variable throttle 35 is narrowed, the opening of the communication passage H is small, and a high damping force range is achieved.

B) High-frequency input When the vibration frequency of the fluid pressure on the lower chamber B side is equal to or higher than a predetermined value (high frequency), the constant orifice c ₂ and the high-frequency cut-off action of the pressure-side second variable throttle b ₂ reduce the frequency. since the amount of transmission of the fluid pressure on the pressure side pressure receiving chamber D ₂ side is small, the difference in fluid pressure hardly occurs between both the pressure receiving chamber D _1, D _2, Therefore, the spool 31, the centering spring 3
The opening degree of the communication passage H is large while being kept at the neutral position by the urging forces of 2, 33, and the low damping force range is obtained.

C) High-speed operation of the piston As the operation of the piston 2 becomes faster, the lower fluid chamber B
The fluid pressure on the lower fluid chamber B side increases, so that even when the vibration frequency of the fluid pressure on the lower fluid chamber B side is a predetermined value or higher (high frequency),
Increased negotiable amount of fluid per unit area in the constant orifice c ₂ is thereby, the compression side pressure receiving chamber D
Acts to increase the amount of transmission of the fluid pressure to the _second side, but the fluid pressure on the lower fluid chamber B side acting on the upper surface of the circular valve portion 41c increases downstream thereof, so that the circular valve portion 41c Is bent upward to reduce the interval between the upper end opening edge of the central hole 18a in the pressure side sheet plate 18,
Accordingly, the compression side second variable throttle opening area of b ₂ is reduced inverse proportionally. Therefore, even if the operation of the piston 2 becomes faster, the sliding of the spool 31 can be prevented, and a desired high cut action can be obtained.

As described above, the variable damping force type shock absorber of the embodiment is characterized in that a desired high cut action can be obtained from a low piston speed range to a high piston speed range.

Further, since all the damping force variable structures for automatically changing the damping force characteristics of both the extension and compression strokes in response to the vibration frequency are incorporated in the piston 2 side, the base side is A standard type structure can be used. Further, components other than the extension / pressure high damping valve in the variable damping force structure include a piston rod 3 and a piston 2
Are all incorporated in the nut 11 for fastening the piston, so that the assembling work is simplified, and the piston 2 itself can be of a standard type structure.
It is characterized in that parts can be shared with the standard type and assembly work can be simplified, thereby reducing costs.

Further, the structure is simplified by sharing one communication passage H for the extension side and the compression side, thereby having a feature that the apparatus can be made compact.

Further, in the low damping force range, a linear damping force characteristic with respect to the piston speed can be obtained in the entire operation range from the low speed operation range to the high speed operation range in both the extending stroke and the pressure stroke. In addition, it has a feature that it is possible to achieve both improved steering stability and improved ride comfort.

Further, regarding the setting of the damping force characteristic in the extremely low speed operation range, in the low speed operation range, in the case of the low damping force range, the characteristic of the first variable throttle 34 (35) (speed square characteristic).
And the characteristic of the low damping valve 26 (24) (speed ／ power characteristic). In this case, the degree of freedom in setting is higher than in the case of setting only with the damping valve. The characteristics of the valve and the variable throttle characteristic are symmetrical, and the change rates of both characteristics are averaged, so that setting is easier.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and there are design changes and the like within the scope of the present invention. Is also included in the present invention. For example, although the spool is used as the movable member in the embodiment, a diaphragm, a bellows, or the like may be used. Further, in the embodiment, the generated damping force is changed by changing the flow passage cross-sectional area side of the communication passage provided with the low damping valve with the variable throttle with respect to the communication passage provided with the high damping valve. Although the case where it was shown was shown, the specific variable structure of the damping force generation means and the generated damping force is arbitrary, and in addition, for example, by changing the bending characteristic of the damping valve, the generated damping force is changed. Is also good.

[0048]

As described above, the variable damping type shock absorber according to the present invention is provided between the defined chamber and the pressure receiving chamber in the middle of the flow path connecting the defined chamber and the pressure receiving chamber. A check plate having a check valve portion prohibiting the flow of the fluid and permitting the flow in the opposite direction, and a constant orifice having a valve port opened and closed by the check valve portion and bypassing the check valve portion. A constant plate to be provided, a sheet plate in which a valve port communicating the valve port of the constant plate and the pressure receiving chamber is formed, provided between the sheet plate and the constant plate,
An annular variable throttle is formed between the peripheral edge of the valve opening of the seat plate and the constant pressure plate.
Receiving the fluid pressure in the direction of the sheet
A variable orifice plate having a variable throttle valve that reduces the annular variable throttle area by bending in the rate direction is provided, so that an increase in fluid pressure accompanying an increase in stroke speed is transmitted to the pressure receiving chamber. It can be suppressed by the variable throttle valve to obtain a constant high-cut action, whereby the damping force can be changed in a predetermined frequency range in the entire range from the low piston speed range to the high piston speed range. This has the effect of obtaining damping force characteristics.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a piston portion, which is a main part of a variable damping force type shock absorber according to an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view of an extension-side second variable throttle unit.

FIG. 3 is a plan view showing a check plate.

FIG. 4 is a plan view showing a constant plate.

FIG. 5 is a plan view showing a variable orifice plate.

FIG. 6 is a sectional view of a main part showing an operation of a variable orifice plate.

FIG. 7 is an enlarged sectional view of a pressure-side second variable throttle unit.

FIG. 8 is a graph showing damping force characteristics with respect to frequency.

FIG. 9 is a diagram showing damping force characteristics with respect to frequency in a conventional example.

[Explanation of symbols]

A upper chamber B lower chamber b ₁ extension side second variable throttle b ₂ pressure side second variable throttle c ₁ constant orifice c ₂ constant orifice D ₁ extension side pressure receiving chamber D ₂ pressure side pressure receiving chamber 2 piston (valve body) 6 compression side high damping Valve (damping force generating means) 7 Extension side first-stage damping valve (damping force generation means) 8 Extension side second-stage damping valve (damping force generation means) 14 Extension side check plate 14c Circular valve section (check valve section) 15 Extension side constant plate 15a Central hole (valve port) 16 Extension side sheet plate 16a Central hole (valve port) 18 Compression side sheet plate 18a Central hole (valve port) 19 Compression side constant plate 19a Central hole (valve port) 20 Compression side check plate 20c Circular valve part (check valve part) 24 Pressure side low damping valve (damping force generating means) 26 Extension side low damping valve (damping force generating means) 31 Spool (movable member movement) 34 Expansion-side first variable throttle (damping force generation means) 35 Compression-side first variable throttle (damping force generation means) 40 Expansion-side variable orifice plate 40c Circular valve (variable throttle valve) 41 Pressure-side variable Orifice plate 41c Circular valve (variable throttle valve)

Claims (1)

(57) [Scope of request for utility model registration] 1. A valve body having two chambers defined in a shock absorber, and a damping force is generated by restricting a flow of a fluid between the two chambers, and the chamber is defined. Having a movable member that receives and moves the fluid pressure of the pressure receiving chamber that is communicated with,
A damping force generating means formed so as to be capable of changing a generated damping force characteristic in accordance with the movement of the movable member; and a damping force generating means provided in the middle of a flow path connecting the defined chamber and the pressure receiving chamber. A check plate having a check valve portion prohibiting the flow of fluid from the chamber to the pressure receiving chamber side and allowing the flow in the opposite direction, and a valve port opened and closed by the check valve portion, and the check valve portion is provided. A constant plate forming a detouring constant orifice; a seat plate having a valve port communicating the valve port of the constant plate with the pressure receiving chamber; a sheet plate provided between the sheet plate and the constant plate; The annular variable throttle is formed between the valve and the peripheral edge of the valve, and the constant plate is
By receiving the fluid pressure in the direction of the sheet plate from
And a variable orifice plate having a variable throttle valve that reduces the annular variable throttle area by bending in the direction of the seat plate .