JPH09229127A - Variable damping force type hydraulic shock absorber - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: It is possible to simplify and downsize a device by performing variable drive of damping force characteristics using a stroke of a piston, and it is possible to reduce cost and improve vehicle mountability. Of a variable damping force type hydraulic shock absorber. SOLUTION: The expansion side second flow passage E and the compression side second flow passage G are slidably provided in a shaft center hole 21 of a piston 2.
And a centering springs 8 and 9 for biasing the spool 7 to a neutral position,
A control rod 12 having one end fixed to the base 4 and the other end inserted through the shaft center hole 74 of the spool 7, and the inner peripheral surface side of the shaft center hole 74 of the spool 7 and a space a therebetween. Both facing surfaces on the outer peripheral surface side of the control rod 7 facing each other have conductivity, and the rayon plain woven cloth 1 is provided on both facing surfaces.
3, 14 are fixed, the working fluid is filled in the space a,
A power source 16 is connected to both conductive facing surfaces of the spool 7 and the control rod 12 via a changeover switch 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a damping force variable type hydraulic shock absorber that ensures ride comfort and steering stability of a vehicle by optimally controlling the damping force characteristics of each shock absorber, and more particularly to damping force characteristics. The present invention relates to an actuator structure for variably controlling a damping force characteristic of a shock absorber by driving a changing unit in an axial direction.

[0002]

2. Description of the Related Art Conventionally, as a damping force variable type hydraulic shock absorber for controlling the damping force characteristic of a shock absorber, for example,
The thing described in Unexamined-Japanese-Patent No. 5-231462 is known. This conventional damping force variable type hydraulic shock absorber includes a cylinder, a piston slidably inserted in the cylinder, and a piston defining two oil chambers in the cylinder, and one end side fixed to the piston, A damping rod that adjusts the damping force by changing the cross-sectional area of the oil passage and the oil passage that connects the oil chambers to each other and has a piston rod whose other end projects outside the cylinder. The damping force adjusting mechanism is provided in the piston rod so as to extend in the axial direction, and has a cylindrical shape in which an oil hole is formed in the radial direction to form a part of the oil passage. A guide tube, a spool slidably provided in the guide tube in the axial direction and changing the opening area of the oil hole, and a guide tube for preventing the pressure from acting on the spool from the axial direction. Located on both ends, separated from each oil chamber A pair of chambers, an urging means provided on one side of the spool for constantly urging the spool toward the other side in the axial direction, and an urging means provided on the piston rod for receiving an electric signal supplied from the outside. And an actuator that adjusts the damping force by pushing the spool to an arbitrary position in the axial direction against the biasing means. The actuator is an electromagnetic proportional solenoid that expands and contracts the rod according to an electric signal supplied from the outside of the piston rod.
The rod of the electromagnetic proportional solenoid is arranged so as to push the spool at its tip side.

[0003]

However, since the conventional hydraulic shock absorber uses an actuator such as an electromagnetic proportional solenoid as described above, it has the following problems. . That is, since an actuator such as an electromagnetic proportional solenoid needs to be arranged at the upper end portion of the piston rod, it is limited in space to a mountable vehicle. Further, since the actuator such as the electromagnetic proportional solenoid is expensive, the cost is high. Further, the sealing structure for forming the pair of chambers on both end sides of the guide cylinder is very complicated, the number of parts is increased, and the cost is increased.

The present invention has been made by paying attention to the above-mentioned conventional problems, and by making variable the damping force characteristic by utilizing the stroke of the piston, the apparatus can be simplified and made compact. Thus, it is an object of the present invention to provide a damping force variable hydraulic shock absorber capable of reducing the cost and improving the vehicle mountability.

[0005]

In order to achieve the above object, a damping force variable hydraulic shock absorber according to claim 1 of the present invention defines a cylinder and a state in which the inside of the cylinder is divided into two chambers, an upper chamber and a lower chamber. A slidable piston, a piston rod having one end fixed to the piston and the other end protruding outside the cylinder, and slidable in an axial hole formed in the piston or piston rod. A cylindrical spool, which is provided and whose flow passage cross-sectional area of a liquid passage communicating between the upper and lower chambers in the cylinder can be changed by sliding thereof, and an urging means for urging the spool to a predetermined position. A control rod having one end fixed to the cylinder side opposite to the projecting side of the piston rod through an insulating member and the other end side inserted into the axial hole of the spool. The inner peripheral surface side of the control rod and the opposing surface of the control rod facing the outer peripheral surface side at a predetermined interval have at least conductivity, and the inner peripheral surface side of the axial hole in the spool and / or this A fiber or a fiber aggregate is fixed to the opposing surface on the outer peripheral surface side of the control rod that faces the outer peripheral surface of the control rod facing the inner peripheral surface side of the axial hole of the spool and the opposing outer peripheral surface of the control rod. Liquid is filled in a predetermined space formed between the facing surfaces facing each other, and voltage applying means for electrically controlling motion transmission is connected to both conductive facing surfaces of the spool and the control rod. It was taken as a means.

According to a second aspect of the present invention, there is provided a damping force variable type hydraulic shock absorber, wherein the fiber or the fiber assembly is opposed to the inner peripheral surface side of the axial hole of the spool and a predetermined space therebetween. The control rod was fixed to both facing surfaces on the outer peripheral surface side.

According to a third aspect of the present invention, in the variable damping force type hydraulic shock absorber, the fiber or the fiber assembly is opposed to the inner peripheral surface side of the axial hole of the spool or with the predetermined interval. The control rod was fixed to one of the facing surfaces on the outer peripheral surface side.

According to a fourth aspect of the present invention, there is provided a variable damping force type hydraulic shock absorber, wherein the fibers constituting the fibers or the fiber assembly are
At least one selected from natural fibers and synthetic fibers was used.

According to a fifth aspect of the present invention, there is provided a variable damping force type hydraulic shock absorber, wherein the fiber assembly is made of yarn, woven fabric, knitted fabric, non-woven fabric,
1 selected from felt, flock cloth, leather and paper
It is assumed to be composed of one kind or a combination of two or more kinds.

[0010]

The variable damping force type hydraulic shock absorber according to the first aspect of the present invention is configured as described above, and therefore, as described in the second aspect, the fiber or the fiber assembly is arranged in the axial hole of the spool. When fixed to both the peripheral surface side and the opposing surfaces on the outer peripheral surface side of the control rod that are opposed to the peripheral surface with a predetermined distance, the fibers or fiber aggregates fixed to one of the opposed surfaces are opposed to the other. Since the fibers or the fiber aggregates fixed to the surfaces face each other in a state where they can come into contact with each other gently or with an appropriate overlap, when a voltage is applied between the opposing surfaces, the fibers or the fiber aggregates facing each other are opposed to each other. The body becomes more entangled and shear stress is induced, which transfers the axial displacement of the control rod to the spool. In this case, it is considered that the phenomenon in which the shear stress is induced by the voltage application is an attractive force (or a repulsive force) generated between the fibers fixed to the opposing surfaces of the control rod and the spool. As described above, when the spool is displaced in the axial direction,
The flow passage cross-sectional area of the flow passage communicating between the chambers is changed, whereby the damping force characteristic of the hydraulic shock absorber can be changed.
Further, by variably controlling the applied voltage, it is possible to variably control the transmission displacement amount, that is, the changing amount of the damping force characteristic.

In this case, the phenomenon in which the shear stress is induced by the voltage application is an attractive force (or a repulsive force) generated between the fibers fixed to the opposing surfaces of the control rod and the spool.

Further, when the control rod and the spool are fixed to only one of the facing surfaces of the spool, the fibers and the facing surface on which the fibers are not fixed are fixed. The frictional force is increased by applying a voltage, so that shear stress is induced and the axial displacement is transmitted from the control rod side to the spool side.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. (First Embodiment of the Invention) FIG. 1 shows a first embodiment of the present invention.
FIG. 3 is an enlarged cross-sectional view of an essential part of a variable damping force type hydraulic shock absorber, showing a cylinder 1 and a piston 2 in which the inside of the cylinder 1 is divided into an upper chamber A and a lower chamber B. An outer cylinder 3 having a reservoir chamber C formed on the outer periphery of the cylinder 1 and a base 4 defining a lower chamber B and a reservoir chamber C are provided.

The base 4 has a base body 41. The base body 41 has a plurality of inner communication holes 42 for ensuring the flow of the working fluid from the lower chamber B to the reservoir chamber C, and the reservoir chamber. A plurality of outer communication holes 43 for ensuring the flow of hydraulic fluid from C to the lower chamber B are formed, and an inner groove 44 and outer communication hole 43 communicating with the inner communication hole 42 are formed on the upper surface side of the base body 41. An outer groove 45 communicating with is formed. A pressure side base valve 46 is provided on the lower surface side of the base body 41 to restrict the flow of the hydraulic fluid through the inner communication hole 42, and the outer communication hole 43 of the outer communication hole 43 is provided on the upper surface side of the base body 41. An extension-side base valve 47 is provided that allows the hydraulic fluid to flow in a limited manner.

Both of the base valves 46 and 47 are in a state where the inner peripheral side thereof is fastened and fixed by a fastening member 48 which penetrates the axial center portion of the base body 41 from above and is caulked at its lower end on the lower end surface side of the base body 41. It is installed in. A through hole 49 is formed on the inner peripheral side of the extension side base valve 47 so that the lower chamber B and the inner groove 44 are always communicated with each other.

The piston 2 is formed in a cylindrical shape having a shaft hole 21, and the upper end side thereof is a piston rod 5
It is fixed by being screwed onto the lower end of. The piston 2 is formed with a pressure side through hole 22 and an extension side through hole 23 that connect the upper chamber A and the lower chamber B, and
A compression side damping valve 24 and an extension side damping valve 25 for opening and closing the through holes 22 and 23 are provided on the upper and lower end surfaces of the piston 2, respectively. The compression side damping valve 24
The inner peripheral side of the piston 2 is fastened and fixed when the piston 2 is screwed onto the piston rod 5, and the extension side damping valve 25 is
The piston 2 is attached in a state where its inner peripheral side is fastened and fixed by a nut 6 screwed to a threaded portion at the lower end of the piston 2.

A cylindrical spool 7 is axially slidably provided in the shaft center hole 21 of the piston 2. The sliding range of the spool 7 is restricted by the lower end surface 5a of the piston rod 5 and an annular step portion 21a formed to project below the shaft hole 21, and centering springs 8 and 9 are provided above and below the sliding range. Is biased to the neutral position by.

On the inner peripheral surface of the shaft hole 21 of the piston 2, an upper annular groove 27 which is always in communication with the lower chamber B by an upper communication hole 26 and a lower side which is always in communication with the reservoir chamber C by a lower communication hole 28. An annular groove 29 is formed and also shown in FIGS.
4, the outer peripheral surface of the spool 7 communicates with the upper annular groove 27 within the sliding range from the neutral position to the upper side, and the upper annular groove 27 when sliding downward. Upper notch 71 communicating with lower annular groove 29 together
And a lower notch 72 that communicates with the lower annular groove 29 within a sliding range from the neutral position to the lower side and communicates with the upper annular groove 27 and the lower annular groove 29 when sliding upward.
Are formed. Further, the spool 7 is formed with a pressure relief hole 73 penetrating in the vertical direction. In addition, 30 is a bush.

Therefore, as shown in FIG. 6, a pressure side through hole 22 is provided between the upper chamber A and the lower chamber B as a flow passage through which the fluid can flow in the pressure stroke of the shock absorber. The pressure side first flow path F that opens the passage pressure side damping valve 24 to reach the upper chamber A, the lower communication hole 28 from the lower chamber B, and the lower annular groove 2
9, lower cutout 72, upper annular groove 27, upper communication hole 26
There are two flow paths, a pressure side second flow path G and a pressure side second flow path G that reach the lower chamber B via the. Further, as a flow path through which the fluid can flow in the extension stroke of the shock absorber, as shown in FIG. 7, the extension side damping valve 25 is opened from the upper chamber A through the extension side through hole 23 to reach the lower chamber B. The expansion side first flow path D and the expansion side from the upper chamber A to the lower chamber B via the upper communication hole 26, the upper annular groove 27, the upper cutout 71, the lower annular groove 29, and the lower communication hole 28. There are two channels, the second channel E.

Inside the shaft center hole 74 of the spool 7, the upper end side of the spool 7 is inserted into the shaft center hole 5b formed in the piston rod 5 and mounted on the outer periphery thereof. The insulating O-ring 10 is hydraulically sealed between the inner peripheral surface of the shaft center hole 5b and supported so as to be slidable in the axial direction, while the lower end side is an insulating connector with respect to the fastening member 48 of the base 4. A control rod 12 fixed via 11 (insulating member) is provided. The O-ring 10 is made of an insulating material such as rubber, and the control rod 12 and the piston rod 5 are electrically insulated from each other.

The inner peripheral surface of the shaft center hole 74 in the spool 7 and the outer peripheral surface of the control rod 12 facing the inner peripheral surface of the shaft center hole 74 are as shown in FIGS. The rayon plain woven fabrics 13 and 14 having a cylindrical gap a and forming a fiber or a fiber aggregate are fixed.

At least the control rod 12, the spool 7, the centering springs 8 and 9, and the piston rod 5 are made of a conductive material, and a power source 16 is connected to the control rod 12 and the piston rod 5 via a changeover switch 15. By turning on the changeover switch 15, a predetermined voltage can be applied between the inner peripheral surface of the spool 7 and the outer peripheral surface of the control rod 12.

Next, the operation of the first embodiment of the invention will be described. (B) When the changeover switch is OFF As shown in FIG. 1, when the changeover switch 15 is turned off, the control rod 12 fixed to the base 4 side during the extension stroke or the pressure stroke of the shock absorber.
And the spool 7 provided on the piston 2 side reciprocate relative to each other in the axial direction, but a cylindrical gap a is formed between the outer peripheral surface of the control rod 12 and the inner peripheral surface of the shaft center hole 74 in the spool 7. Since it is formed, even if the hydraulic fluid is filled in the cylindrical gap a, the frictional force generated between the opposing surfaces is very small. Therefore, the spool 7 is urged by the centering springs 8 and 9. The piston 2 is held in the neutral position.

Therefore, only the expansion-side first flow path D can flow during the expansion stroke of the shock absorber, and only the pressure-side first flow path F can flow during the compression stroke of the shock absorber. Both the damping force generated during the stroke and the pressure stroke have hard characteristics.

(B) When the changeover switch is ON As shown in FIG. 6 or 7, the changeover switch 15 is turned ON.
In this state, the voltage of the power supply 16 is applied between the inner peripheral surface of the shaft center hole 74 of the spool 7 and the outer peripheral surface of the control rod 12 via the piston rod 5 and the centering springs 8 and 9. Becomes

Then, the rayon plain woven fabric 13 as a fiber or a fiber aggregate fixed to one of the facing surfaces can come into contact with the rayon plain woven fabric 14 fixed to the other facing surface gently or with an appropriate overlap. Since they face each other in such a state that the opposing rayon plain woven fabrics 13 and 14 become more entangled with each other when a voltage is applied between the opposing faces, shear stress is induced, which causes control. Since the axial movement of the rod 12 is transmitted to the spool 7, during the pressure stroke of the shock absorber, the spool 7 slides upward with respect to the piston 2 as shown in FIG. Becomes a flowable state, and during the stroke of the shock absorber, as shown in FIG. 7, the spool 7 slides downward with respect to the piston 2 and the second stretched-side flow passage E becomes a flowable state. .

Therefore, in addition to the expansion-side first flow path D and the compression-side first flow path F, the expansion-side second flow path E and the compression-side second flow path G can also be circulated. Both damping forces generated during the stroke have soft characteristics.

In this case, the phenomenon in which the shear stress is induced by the voltage application is that the two rayon plain woven cloths 1 fixed to the control rod 12 and the spool 7 on their respective opposing surfaces.
It is considered to be an attractive force (or a repulsive force) generated between 3 and 14.

Then, both rayon plain woven cloths 13 and 14
Since the strength of the induced shear stress that occurs between them changes according to the applied voltage (see FIG. 12), the applied voltage is variably controlled, so that the spool 7 relative to the relative movement amount between the piston 2 and the control rod 12 is changed. The amount of movement can be variably controlled. Therefore, by variably controlling the applied voltage, the amount of change in the damping force characteristic from the hard characteristic to the soft characteristic can be variably controlled in a stepless manner.

As described above, in the damping force variable type hydraulic shock absorber according to the embodiment of the present invention, since the stroke of the piston 2 can be used to perform variable drive of the damping force characteristics, The effects listed in are obtained. Since the structure is simplified, the cost can be reduced. Since it is not necessary to dispose the actuator on the upper end portion of the piston rod as in the conventional example, it is possible to make the external appearance compact, thereby improving the vehicle mountability.

(Second Embodiment of the Invention) FIG. 8 is an enlarged cross-sectional view of an essential part of a damping force variable type hydraulic shock absorber showing a second embodiment of the present invention. The first embodiment is different from the first embodiment in the variable pattern of the damping force characteristic by the spool 7, and since the other configurations are the same as those of the first embodiment of the invention, the same reference numerals are given to the same components. Will be omitted, and only the differences will be described.

That is, on the outer peripheral surface of the spool 7 according to the second embodiment of the present invention, an annular groove 75 communicating with the upper annular groove 27 and the lower annular groove 29 is formed at the neutral position shown in FIG. It has a structure (see an enlarged perspective view of FIG. 9).

Therefore, as shown in FIG. 8, when the changeover switch 15 is turned off, the spool 7 is held in the neutral position of the piston 2 by the urging force of the centering springs 8 and 9. Both the compression side second flow channel G and the expansion side second flow channel E are in a flowable state, whereby the expansion side second flow channel E and the compression side are provided in addition to the expansion side first flow channel D and the compression side first flow channel F. Since the second flow path G can also be circulated, the damping force generated during the extension stroke and the compression stroke both have soft characteristics.

Further, as shown in FIG. 10 or 11,
When the changeover switch 15 is turned on, the voltage of the power supply 16 is passed between the inner peripheral surface of the shaft center hole 74 of the spool 7 and the outer peripheral surface of the control rod 12 via the piston rod 5 and the centering springs 8 and 9. Therefore, during the pressure stroke of the shock absorber, as shown in FIG. 10, the spool 7 slides upward with respect to the piston 2 and the pressure side second flow passage G is closed. Further, during the extension stroke of the shock absorber, as shown in FIG. 11, the spool 7 slides downward with respect to the piston 2 and the extension-side second flow passage E is closed.

Therefore, during the pressure stroke of the shock absorber shown in FIG. 10, only the pressure side first flow path F can flow, and during the stroke of the shock absorber shown in FIG. 11, only the expansion side first flow path D can flow. Therefore, the damping force generated during the compression stroke and during the extension stroke both have hard characteristics.

As described above, in the second embodiment of the present invention, the switching direction of the heart characteristic and the soft characteristic of the damping force based on the ON / OFF switching of the changeover switch 15 is reversed, but the embodiment of the invention is described. The same effect as 1 can be obtained.

As the fibers or fibers constituting the fiber aggregate, all substances which are generally in a fiber state and aggregates of fibers formed from them can be used.

For example, the fibers include cotton, wool, silk, hemp,
Viscose (rayon) fiber, cuprammonium (rayon) fiber, acetate fiber, polypromix fiber, polyamide (nylon) fiber, polyvinyl alcohol (vinylon) fiber, polyvinyl chloride fiber, polyvinylidene chloride (saran) Type) fiber, polyester type (Tetoron type) fiber, polyacrylonitrile type (Orlon type) fiber, polyethylene type fiber, polypropylene type fiber, polyurethane type (parlon type) fiber, polyalkylene paraoxybenzoate type fiber, polyclar type fiber, aromatic Polyamide (aramid) fiber, wholly aromatic polyester fiber, fluorine fiber, chitin fiber, alginic acid fiber, collagen fiber, glass fiber, carbon fiber, silicon carbide fiber, boron fiber, alumina fiber and the like can be used.

As the aggregate of fibers, there are threads, strings,
In general, fabrics, that is, woven fabrics, knitted fabrics, laces, braids, non-woven fabrics, leathers, papers, felts and the like can be used. The fabric may be subjected to a process for changing the surface form, and may be a flocked (electrodeposited) fabric, an embossed fabric, a crepe fabric, a wrinkle fabric, a patterned fabric, a presse fabric, a moire. Work cloth or the like can be used.

Upon fixing, generally, it may be fixed by using an adhesive, and the control rod (hereinafter sometimes referred to as a driving body) 12 or the spool (hereinafter sometimes referred to as a driven body). ), The material of the facing surface, the material of the fixed fiber or fiber aggregate, and the like can be selected.

Fibers or fiber aggregates may be pressed onto the facing surfaces of the driving body and the driven body by a suitable jig, or the fibers may be directly electrostatically fixed and fixed on the facing surfaces of the driving body and the driven body. It is also possible. The surface of the fiber or fiber assembly fixed between the facing surface of the driving body and the facing surface of the driven body is so-called fluff.
The higher the standing state, the larger the induced shear stress can be given. Therefore, for example, in the case of a fabric, a woven fabric (velvet or the like) called a bristle tissue with a lot of fluff on the surface is particularly preferable.

The hydraulic fluid as a medium can be any fluid as long as it has low electric conductivity and does not dissolve the fibers or fiber aggregates to be used. Broadly, mineral oil, animal or vegetable oil, synthetic oil, etc. are used. Liquids such as paraffin-based, naphthene-based and olefin-based mineral oils and hydrocarbons, silicone oils and the like can be used as synthetic oils.

(Experimental Example 1) As shown in FIG. 12, the circular facing surface 82a of the driving member 82 and the circular facing surface 83a of the driven member 83 are opposed to each other in parallel with a circular space. In the motion transmitting device 81 in which the fibers or the fiber aggregates 84 are provided in the space, as the fiber aggregates 84, a cotton velvet cloth (cloth thickness: 1.1 mm, surface fluff density: about 60,000 pcs / cm ² , fluff) Fiber thickness: about 20 μm)
This cloth is used as the driving body 82 and the driven body 83 and has a diameter of 5 cm.
Of one set of stainless steel circular electrodes (82, 83) is fixed to one surface (that is, opposite surfaces 82a, 83a) with an epoxy resin to fix the fiber assembly 84a (84a, 84b), and the fluff is opposed to each other. The electrodes are arranged in such a manner that the distance between the electrodes is 2.2 mm, and the surrounding area is a medium 8 made of silicone oil (TSF451-10 manufactured by Toshiba Silicone).
8 and by connecting the voltage applying means 87 through the electric wirings 85 and 86, it is possible to switch the voltage application so that one circular electrode on the side of the driving body 82 is connected to the motor 8
The torque transmitted to the other circular electrode on the side of the driven body 83 when rotated by 9 was detected by the torque detector 90 to measure the shear stress with respect to the rotation speed.

FIG. 13 shows the relationship between the rotational speed and the shear stress. As is clear from FIG. 13, when the voltage at which the electric field strength (E) is 2.7 KV / mm is applied and when the voltage is applied. Compared with when not, 50 in the low rotation speed region
It was found that a shear stress of about gf / cm ² was induced. The current value at this time was very small, about 5 μA / cm ² .

(Experimental Example 2) The change in induced shear stress with respect to the applied voltage was measured in the same manner as in Experimental Example 1 except that the rotation speed was 1 rpm and the electrode interval was 2 mm. The results are shown in FIG. 14. As is clear from FIG. 14, the induced shear stress monotonically increases with the applied voltage, and the electric field strength:
A large induced shear stress of 130 gf / cm ² occurred at 5.5 KV / mm. It was also found that the induced shear stress can be changed by changing the voltage applied by the voltage applying means 87.

(Experimental Example 3) As a fiber assembly 84, Table 1
As shown in, the same measurement as in Experimental Example 1 was performed using plain woven fabrics having different fiber materials (however, as shown in Table 1, the fabric thickness, the electrode interval, the applied voltage, the current density, and the electric field strength were measured for each sample. Depending on). Table 1 also shows the results obtained by summarizing the relationships between the maximum induced shear stress, the shear stress in the absence of electric field, and the fiber material obtained here.

[0047]

[Table 1]

As is clear from the results shown in Table 1, it was found that both natural fibers and synthetic fibers produced large induced shear stress when cellulosic fiber fabrics were used.

(Experimental Example 4) As the fiber assembly 84, cotton velvet (fabric thickness: 1.1 mm, surface fluff density: about 4)
Ten thousand pieces / cm ² ), using mineral oil and silicone oil as the medium 88 (2 types with densities of 10 cP and 50 cP)
The electrode spacing, applied voltage, current density, and
The electric field strength was measured in the same manner as in Experimental Example 1 to investigate the influence of the induced shear stress due to the different medium 88. The results are also shown in Table 2.

[0050]

[Table 2]

As is clear from the results shown in Table 2, it was found that a considerably large induced shear stress was obtained when silicone oil was used as the medium 88.

(Experimental Example 5) As the fiber assembly 84, a cloth made of rayon velvet (cloth thickness: 1.45 mm, surface fluff density: about 10,000 fibers / cm ² , fluff fiber thickness: about 20 μm) Was measured in the same manner as in Experimental Example 1, and the shear stress when the electrode interval was changed was measured. This result is shown in Figure 1.
As is clear from FIG. 15, it is found that the induced shear stress can be changed by changing the electrode spacing, as shown in FIG.

(Experimental Example 6) As the fiber assembly 84, cotton velvet (fabric thickness: 1.1 mm, surface fluff density: about 4)
Using a cloth of 10,000 pieces / cm ² ), only the negative electrode (ground side electrode) of the set of stainless circular electrodes to be the driving body 82 and the driven body 83 is bonded with the epoxy resin, and the electrode interval is 1 mm. Shear stress was measured using the same method as in Experimental Example 1 except for the above.

[0054] As a result, shear stress when applying no electric field shear stress at the time of applying an electric field 8gf / cm ^2, 5KV / mm was 30 gf / cm ^2. Also, almost the same result was obtained when the cloth was adhered only to the positive electrode.

Although the embodiment of the present invention has been described above, the specific configuration is not limited to this embodiment, and the present invention can be made even if there is a design change or the like within the scope not departing from the gist of the present invention. include.

For example, in the embodiment of the invention, the rayon plain woven fabric constituting the fiber or the fiber assembly is fixed to both the inner peripheral surface of the shaft center hole and the outer peripheral surface of the control rod in the spool. However, a predetermined induced shear stress can be generated even when fixed to only one of the two facing surfaces. In this case, the frictional force between the fiber and the facing surface on which the fiber is not fixed is increased by applying a voltage, and thus shear stress is induced,
It is considered that the relative movement from the control rod side as the driving body is transmitted to the spool side as the driven body.

Further, although the spool is provided on the piston side in the embodiment of the invention, it may be provided on the piston rod side.

[0058]

As described above, the first aspect of the present invention is as follows.
In the damping force variable type hydraulic shock absorber described above, as described above, the damping force variable hydraulic shock absorber is slidably provided in the axial hole formed in the piston or the piston rod, and by the sliding, the upper and lower two chambers in the cylinder are moved. A cylindrical spool capable of changing the flow passage cross-sectional area of the communicating fluid passage, a biasing means for biasing the spool to a predetermined position, and one end insulated on the cylinder side opposite to the projecting side of the piston rod. A control rod which is fixed via a member and whose other end is inserted into the axial hole of the spool, and a control rod which faces the inner peripheral surface side of the axial hole of the spool and which opposes the inner peripheral surface side with a predetermined interval. Both opposing surfaces on the outer peripheral surface side of the rod have at least conductivity, and the inner peripheral surface side of the axial hole in the spool and /
Alternatively, a fiber or a fiber assembly 84 may be provided on the facing surface on the outer peripheral surface side of the control rod that faces this with a predetermined distance.
Is fixed, and a liquid is filled in a predetermined space formed between the facing surfaces of the inner peripheral surface side of the axial hole of the spool and the outer peripheral surface side of the control rod facing the axial hole. By adopting a structure in which a voltage applying means for electrically controlling motion transmission is connected to both conductive facing surfaces of the control rod, it is possible to perform variable drive of damping force characteristics by utilizing the stroke of the piston. You can
As a result, the device can be simplified and made compact, and it is possible to reduce the cost and improve the vehicle mountability.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of essential parts of a variable damping force type hydraulic shock absorber according to a first embodiment of the present invention.

FIG. 2 is an enlarged plan view showing the spool according to the first embodiment of the present invention.

FIG. 3 is a vertical sectional front view taken along the line I-I of FIG.

FIG. 4 is an enlarged perspective view showing the spool according to the first embodiment of the present invention.

5 is an enlarged cross-sectional view taken along the line II-II in FIG.

FIG. 6 is an enlarged cross-sectional view of a main part of the damping force variable type hydraulic shock absorber according to the first embodiment of the present invention, showing an operating state during a pressure stroke with a changeover switch ON.

FIG. 7 is an enlarged sectional view of an essential part of the variable damping force type hydraulic shock absorber according to the first embodiment of the present invention, showing an operating state at the time of extension stroke with the changeover switch ON.

FIG. 8 is an enlarged sectional view of a main part of a damping force variable hydraulic shock absorber according to a second embodiment of the present invention.

FIG. 9 is an enlarged perspective view showing a spool according to a second embodiment of the present invention.

FIG. 10 is an enlarged cross-sectional view of a main part of a damping force variable hydraulic shock absorber according to a second embodiment of the present invention, showing an operating state during a pressure stroke with a changeover switch ON.

FIG. 11 is an enlarged cross-sectional view of a main part of a damping force variable hydraulic shock absorber according to a second embodiment of the present invention, showing an operating state at the time of extension stroke with a changeover switch ON.

FIG. 12 is a partial cross-sectional view (A) showing an outline of a torque detection device used to evaluate a torque transmission characteristic as an experimental example, a plan explanatory view of an electrode (B) and a side explanatory view (C) of the electrode. is there.

13 is a graph showing the results of measuring the relationship between the rotation speed and shear stress in Experimental Example 1. FIG.

FIG. 14 is a graph showing the results of measuring changes in induced shear force with applied voltage in Experimental Example 2.

FIG. 15 is a graph showing the results of measuring changes in induced shear force with respect to applied voltage in Experimental Example 5.

[Explanation of symbols]

 1 Cylinder 2 Piston 5 Piston Rod 5b Shaft Center Hole (Axial Hole) 7 Spool 8 Centering Spring (Biasing Means) 9 Centering Spring (Biasing Means) 12 Control Rod 13 Rayon Plain Woven Fabric (Fiber or Fiber Assembly 84) 14 Rayon Plain Woven Fabric (Fiber or Fiber Aggregate 84) 15 Changeover Switch (Voltage Applying Means) 16 Power Supply (Voltage Applying Means) 21 Shaft Center Hole (Axial Hole) 74 Shaft Center Hole (Axial Hole) A Upper Chamber B Lower chamber E Elongation side second flow path (liquid path) G Pressure side second flow path (liquid path) a Cylindrical gap

Claims (5)

[Claims] 1. A cylinder, a piston slidably provided in a state in which the inside of the cylinder is divided into upper and lower chambers, and a piston rod having one end fixed to the piston and the other end protruding outside the cylinder. Is slidably provided in an axial hole formed in the piston or the piston rod, and the sliding can change the flow passage cross-sectional area of the liquid passage communicating between the upper and lower two chambers in the cylinder. A cylindrical spool, a biasing means for biasing the spool to a predetermined position, and one end fixed to the cylinder side opposite to the projecting side of the piston rod through an insulating member and the other end side of the spool shaft. And a control rod inserted into the direction hole, wherein the opposing surfaces on the inner peripheral surface side of the axial hole in the spool and on the outer peripheral surface side of the control rod facing the same at a predetermined interval. A fiber or a fiber aggregate is fixed to the inner peripheral surface side of the axial hole in the spool and / or the outer peripheral surface side facing surface of the control rod that faces at least a predetermined distance and has conductivity. Liquid is filled in a predetermined space formed between the facing surfaces of the inner circumferential surface side of the axial hole of the spool and the outer circumferential surface side of the control rod facing the axial hole. A variable damping force type hydraulic shock absorber, characterized in that voltage applying means for electrically controlling motion transmission is connected to both conductive opposing surfaces. 2. The fiber or fiber assembly is fixed to both the inner peripheral surface side of the axial hole in the spool and the outer peripheral surface side of the control rod opposed to the inner peripheral surface side with a predetermined distance. The variable damping force type hydraulic shock absorber according to claim 1, wherein: 3. The fiber or the fiber assembly is provided on either one of the inner peripheral surface side of the axial hole in the spool or the outer peripheral surface side of the control rod opposed to the inner peripheral surface at a predetermined distance. The variable damping force type hydraulic shock absorber according to claim 1, which is fixed. 4. The damping force variable hydraulic buffer according to claim 1, wherein the fibers or fibers constituting the fiber aggregate are at least one selected from natural fibers and synthetic fibers. vessel. 5. The fiber assembly comprises one or a combination of two or more selected from yarn, woven fabric, knitted fabric, non-woven fabric, felt, flock fabric, leather and paper. A variable damping force type hydraulic shock absorber according to any one of 1.