WO2020179679A1

WO2020179679A1 - Shock damper

Info

Publication number: WO2020179679A1
Application number: PCT/JP2020/008375
Authority: WO
Inventors: 宏一郎粟野
Original assignee: Ｋｙｂ株式会社
Priority date: 2019-03-04
Filing date: 2020-02-28
Publication date: 2020-09-10
Also published as: JP2020143679A

Abstract

This shock damper (D) comprises: a cylinder (1); a piston (2) inserted inside the cylinder (1), the piston (2) dividing the interior of the cylinder (1) into an extension-side chamber (La) and a pressing-side chamber (Lb); a piston rod (3) connected to the piston (2); an attenuation passage (3a) provided in the piston rod (3), the attenuation passage (3a) allowing communication between the extension-side chamber (La) and the pressing-side chamber (Lb); and a damping force adjustment valve (V) provided to the attenuation passage (3a), the shock damper (D) being such that the attenuation passage (3a) is formed so as to include a vertical hole (3e) that opens from the tip end of the piston rod (3) and allows communication from the pressure-side chamber (Lb) to the damping force adjustment valve (V), and a horizontal hole (30g) that opens from the side of the piston rod (3) and allows communication from the pressure-side chamber (Lb) to the vertical hole (30e).

Description

Buffer

The present invention relates to an improvement of a shock absorber.

Some shock absorbers for vehicles can adjust the damping force in order to effectively suppress vehicle body vibration. A damping force adjusting valve is used to adjust the damping force of the shock absorber. The damping force adjusting valve includes a cylindrical housing having a port for communicating the inside and the outside, a cylindrical spool slidably inserted into the housing, a spool spring for urging the spool, and a spool spring. There is known one provided with a solenoid that drives the spool against the urging force of the above (see, for example, Patent Document 1).

In such a damping force control valve, the solenoid drives the spool with respect to the housing, the outer circumference of the spool faces the port to open and close the port, and the opening degree of the port is adjusted to determine the flow path area. To be variable. If the damping force adjusting valve configured as described above is provided in the middle of the passage through which the hydraulic oil passes when the shock absorber expands and contracts, the flow passage resistance given to the flow of the hydraulic oil passing through the passage can be made variable, and the shock absorber The damping force of is adjustable.

JP2013-139865A

When such a damping force control valve is used in a shock absorber, for example, as disclosed in JP2005-351419A, in the middle of a passage that connects the expansion side chamber and the compression side chamber defined by a piston in the cylinder of the shock absorber. A damping force adjustment valve may be installed in.

In such a case, the damping force adjusting valve may be housed in the piston rod and the damping force adjusting valve may give resistance to the hydraulic oil passing through the passage. Specifically, the pressure side chamber is communicated with the accommodating portion by a vertical hole provided on the piston mounting shaft that holds the piston of the piston rod, and the accommodating portion is communicated with the extending side chamber through a through hole that opens from the side of the accommodating portion, A passage is formed in the vertical hole, the through hole and the accommodating part, and the damping force adjusting valve is installed in the accommodating part. With this configuration, the damping force adjusting valve is provided in the passage that connects the expansion side chamber and the compression side chamber, and the damping force of the shock absorber can be adjusted.

On the other hand, the shock absorber mounted between the vehicle body and the wheels of the vehicle is required to be lightweight, and the outer diameter dimension is restricted. The piston rod is generally provided with a piston mounting shaft for mounting the piston on the outer periphery, and a nut for fixing the piston is screwed onto the tip of the piston mounting shaft. The outer diameter of the portion of the piston mounting shaft where the nut is screwed is smaller than the portion of the piston mounting shaft where the piston is mounted, and is the portion where the piston rod has the smallest diameter in the cylinder.

Since the piston mounting shaft has a vertical hole that communicates with the damping force adjusting valve, the diameter of the vertical hole must be small, and it becomes impossible to secure a sufficient flow passage area. In some cases, the pressure loss in the vertical hole may be larger than the pressure loss in.

Then, the minimum damping force of the shock absorber is determined by the resistance of the vertical hole and cannot be adjusted by the damping force adjustment valve, and the damping force adjustment width of the shock absorber is narrowed and the damping force in full soft becomes high. It ends up.

Therefore, an object of the present invention is to provide a shock absorber capable of increasing the damping force adjustment range and reducing the damping force in full soft.

A shock absorber that solves the above problems is a cylinder, a piston that is movably inserted into the cylinder in the axial direction and divides the inside of the cylinder into an expansion side chamber and a compression side chamber, and one end of the piston is connected to the outside of the cylinder. And a damping passage that is provided in the piston rod and connects the extension side chamber and the compression side chamber, and a damping force adjusting valve that is provided in the damping passage.The damping passage is opened from the tip of the piston rod. The pressure side chamber is formed to include a vertical hole that communicates with the damping force adjusting valve, and a lateral hole that opens from the side of the piston rod to communicate the pressure side chamber with the vertical hole.

In the shock absorber configured in this way, since the horizontal passage is provided in addition to the vertical hole in providing the damping passage communicating with the damping force adjusting valve in the piston rod, the flow passage area in the damping passage is expanded.

Further, the shock absorber has a piston mounting shaft on which the piston is mounted on the outer periphery of the piston rod and a nut for fixing the piston is screwed. A collar, which is arranged on the outer periphery of the shaft and is interposed between the piston and the nut, is provided, and the lateral hole is opened at a position facing the collar of the piston mounting shaft. According to the shock absorber thus configured, the lateral hole can be communicated with the pressure side chamber simply by providing the collar with a simple shape. Since it is not necessary to communicate the pressure chamber with the pressure side chamber, the manufacturing cost is low.

According to the shock absorber according to the present invention, the damping force adjustment range can be increased and the damping force in full soft can be lowered.

FIG. 1 is a vertical sectional view of a shock absorber which is a shock absorber according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing a part of FIG. 1 in an enlarged manner. FIG. 3 is a damping force characteristic diagram showing characteristics of the compression side damping force with respect to the piston speed of the shock absorber which is the shock absorber according to the embodiment of the present invention. FIG. 4 is a hydraulic circuit diagram of a shock absorber in a modified example of the embodiment of the present invention.

The shock absorber D according to the embodiment of the present invention will be described below with reference to the drawings. The same reference numerals allotted throughout the several figures refer to the same or corresponding parts. Further, the shock absorber D according to the embodiment of the present invention is used for a front fork that suspends the front wheels of a saddle type vehicle. In the following description, the upper and lower sides with the front fork including the shock absorber D attached to the vehicle are simply referred to as “upper” and “lower” unless otherwise specified. The shock absorber D can also be used for vehicles other than the storage type vehicle.

The shock absorber D is connected to the cylinder 1, a piston 2 that is movably inserted into the cylinder 1 in the axial direction and divides the inside of the cylinder 1 into an extension side chamber La and a compression side chamber Lb, and one end thereof. The piston rod 3 projecting to the outside of the cylinder 1, the bypass path 3a provided in the piston rod 3 as a damping passage for communicating the extension side chamber La and the compression side chamber Lb, and the damping force adjusting valve V provided in the bypass path 3a. It is configured with and.

In this embodiment, the shock absorber D is a one-sided shock absorber that exerts a damping force only when contracting, and the damping force adjusting valve V is used for adjusting the pressure side damping force of the shock absorber D. There is. Although not shown, the shock absorber D is connected to a one-sided shock absorber that exerts a damping force only when extended by a bracket connected to the steering shaft of the saddle-type vehicle. Therefore, the shock absorber D and the shock absorber that exerts a damping force only when extended form a pair to form a front fork that supports the front wheels of the saddle-ride type vehicle, and cooperate to vibrate the vehicle body of the saddle-ride type vehicle. Suppress. The shock absorber D may be one that exerts a damping force only when it is extended, or one that exerts a damping force in both expansion and contraction, and the damping force adjusting valve V adjusts the damping force. Used to do.

Hereinafter, the shock absorber D according to the embodiment of the present invention will be specifically described. As shown in FIG. 2, the shock absorber D includes a telescopic tube member T including an outer tube 10 and an inner tube 11 slidably inserted into the outer tube 10.

Then, when the front wheels vibrate up and down, such as when the saddle riding type vehicle travels on an uneven road surface, the inner tube 11 moves in and out of the outer tube 10, and the tube member T expands and contracts. Expansion and contraction of the tube member T is also referred to as expansion and contraction of the shock absorber D. The tube member T may be an upright type, the outer tube 10 may be an axle side tube, and the inner tube 11 may be a vehicle body side tube.

Subsequently, the upper end of the outer tube 10 which is the upper end of the tube member T is closed by the cap 12. On the other hand, the lower end of the inner tube 11 which is the lower end of the tube member T is closed by the bracket B on the axle side. Further, the cylindrical gap formed between the overlapping portion of the outer tube 10 and the inner tube 11 is closed by an annular seal member 13 that is attached to the lower end of the outer tube 10 and is in sliding contact with the outer circumference of the inner tube 11. ..

In this way, the inside of the tube member T is a closed space, and the shock absorber main body S is accommodated in the tube member T. The shock absorber body S has a cylinder 1 provided in an inner tube 11, a piston 2 slidably inserted in the cylinder 1, a lower end connected to the piston 2, and an upper end outside the cylinder 1. It has a piston rod 3 that protrudes and is connected to the cap 12.

Since the cap 12 is connected to the outer tube 10, it can be said that the piston rod 3 is connected to the outer tube 10. Further, the cylinder 1 is connected to the inner tube 11. In this way, the shock absorber body S is interposed between the outer tube 10 and the inner tube 11.

An annular head member 14 is attached to the upper end of the cylinder 1, and the piston rod 3 penetrates the inside of the head member 14 so as to be movable in the axial direction. The head member 14 slidably supports the piston rod 3, and a suspension spring 15 made of a coil spring is interposed between the head member 14 and the cap 12.

When the shock absorber D expands and contracts and the inner tube 11 moves in and out of the outer tube 10, the piston rod 3 moves in and out of the cylinder 1, and the piston 2 moves up and down (axial direction) in the cylinder 1.

Also, when the shock absorber D contracts and the piston rod 3 enters the cylinder 1, the suspension spring 15 is compressed and exerts an elastic force to urge the shock absorber D in the extending direction. In this way, the suspension spring 15 exerts an elastic force according to the amount of compression to elastically support the vehicle body.

The shock absorber D of the present embodiment is a single rod type, and the piston rod 3 extends from one side of the piston 2 to the outside of the cylinder 1. However, the shock absorber D may be a double rod type, and the piston rod may extend from both sides of the piston to the outside of the cylinder. Further, the piston rod 3 may project downward from the cylinder 1 and be connected to the axle side, and the cylinder 1 may be connected to the vehicle body side. The suspension spring 15 may be a spring other than a coil spring such as an air spring.

Next, in the cylinder 1, a liquid chamber filled with a liquid such as hydraulic oil is formed, and this liquid chamber is divided by the piston 2 into the expansion side chamber La and the compression side chamber Lb. The expansion side chamber here is the one of the two chambers partitioned by the piston that is compressed by the piston when the shock absorber extends. On the other hand, the pressure side chamber is one of the two chambers partitioned by the piston, which is compressed by the piston when the shock absorber contracts.

Further, outside the cylinder 1, more specifically, the space between the shock absorber main body S and the tube member T is a liquid reservoir R. In the liquid storage chamber R, the same liquid as the liquid in the cylinder 1 is stored, and a gas chamber G in which a gas such as air is sealed is formed above the liquid surface. As described above, the tube member T functions as an outer shell of the tank 16 for storing the liquid separately from the liquid in the cylinder 1.

The liquid reservoir chamber R inside the tank 16 is communicated with the expansion side chamber La, and the pressure of the expansion side chamber La is always substantially the same pressure (tank pressure) as the pressure in the tank 16 (liquid reservoir chamber R). Further, the liquid storage chamber R is separated from the compression side chamber Lb by a valve case 4 fixed to the lower end of the cylinder 1. The valve case 4 is provided with a suction passage 4a that communicates the pressure side chamber Lb and the liquid storage chamber R with a suction valve 40 that opens and closes the suction passage 4a.

The suction valve 40 is an extension-side check valve, which opens the suction passage 4a when the shock absorber D extends, and allows the liquid to flow from the liquid reservoir chamber R to the pressure-side chamber Lb through the suction passage 4a. When the shock absorber D contracts, the suction passage 4a is kept closed. Although the suction valve 40 of the present embodiment is a leaf valve, it may be a poppet valve or the like.

In addition, the piston 2 is formed with an expansion side passage 2a and a compression side passage 2b that communicate the expansion side chamber La and the compression side chamber Lb, and also includes an expansion side check valve 20 that opens and closes the expansion side passage 2a and a compression side passage 2b. A hard-side damping element 21 that provides resistance to the flow of liquid from the pressure-side chamber Lb toward the extension-side chamber La is mounted.

The hard-side damping element 21 is configured to have a leaf valve 21a stacked on the upper side of the piston 2 and an orifice 21b provided in parallel with the leaf valve 21a.

The leaf valve 21a is a thin annular plate formed of metal or the like, or a laminated body formed by stacking the annular plates, has elasticity, and is attached to the piston 2 in a state in which the outer peripheral side is allowed to bend. The pressure of the pressure side chamber Lb acts in a direction to bend the outer peripheral portion of the leaf valve 21a upward. Further, the orifice 21b is formed by a notch provided on the outer peripheral portion of the leaf valve 21a that is detached and seated on the valve seat (not indicated) of the piston 2R, but is formed by a stamp or the like provided on the valve seat. It may be formed.

The pressure side chamber Lb is compressed by the piston 2 when the shock absorber D contracts, and its internal pressure rises, and becomes higher than the pressure in the extension side chamber La. When the piston speed is in the low speed range when the shock absorber D contracts and the differential pressure between the compression side chamber Lb and the extension side chamber La is less than the valve opening pressure of the leaf valve 21a, the liquid passes through the orifice 21b. Resistance is given to the flow of the liquid while moving from the pressure side chamber Lb to the expansion side chamber La. Further, when the differential pressure becomes large and becomes equal to or higher than the valve opening pressure of the leaf valve 21a, the outer peripheral portion of the leaf valve 21a bends, and the liquid passes through the gap formed between the outer peripheral portion and the piston 2 to the pressure side chamber Lb. To the extension side chamber La, resistance is imparted to the liquid flow.

As described above, the hard side damping element 21 having the orifice 21b and the leaf valve 21a parallel to the orifice 21b is a liquid that goes from the compression side chamber Lb to the extension side chamber La when the shock absorber D contracts. Is the first damping element on the pressure side that provides resistance to the flow of. The resistance of the compression-side hard damping element 21 results from the orifice 21b when the piston speed is in the low speed range, and from the leaf valve 21a when the piston speed is in the medium to high speed range.

On the other hand, the extension-side check valve 20 opens the extension-side passage 2a when the shock absorber D extends, and allows the liquid to flow through the extension-side passage 2a from the expansion-side chamber La to the compression-side chamber Lb. When D contracts, the extension side passage 2a is maintained in a closed state. In addition, although the expansion side check valve 20 of the present embodiment is a leaf valve, it may be a poppet valve. Furthermore, the extension-side passage 2a and the extension-side check valve 20 may be omitted as long as the liquid is not sufficiently sucked into the cylinder 1.

Subsequently, in order to change the flow rate of the liquid passing through the hard side damping element 21 to the piston rod 3, the bypass path 3a that bypasses the hard side damping element 21 and communicates the extension side chamber La and the compression side chamber Lb is in the middle. A damping force adjusting valve V that can change the flow passage area and is provided in the bypass passage 3a and a soft side damping element 50 that is provided in series with the damping force adjusting valve V are provided.

More specifically, as shown in FIG. 2, the piston rod 3 is mounted on a cylindrical yoke 31 into which the damping force adjusting valve V is inserted, and on the inner circumference of the opening at the lower end in FIG. It has a piston holding member 30 to be formed, and a tubular rod body 32 connected to the terminal side of the yoke 31 and extending to the outside of the cylinder 1. The piston holding member 30 includes a bottomed tubular housing portion 30a and a piston mounting shaft 30b projecting downward from the bottom portion of the housing portion 30a, and an annular piston 2 is placed on the hard side on the outer periphery of the piston mounting shaft 30b. Both the damping elements 21 are fixed with nuts N.

A valve case 5 that partitions the inside of the cylinder portion of the housing portion 30a of the piston holding member 30 into an upper chamber 30c and a lower chamber 30d is fixed. The valve case 5 is formed with a passage 5a that communicates the upper chamber 30c and the lower chamber 30d, and the soft side damping element 50 is provided in the passage 5a. Further, the piston attachment shaft 30b of the piston holding member 30 has a vertical hole that opens from the lower end in FIG. 2 and connects the pressure side chamber Lb to the damping force adjusting valve V via the upper chamber 30c and the lower chamber 30d. 30e is provided. A screw portion 30f to which a nut N is screwed is provided on the outer circumference of the tip of the piston mounting shaft 30b. The inner diameter of the vertical hole 30e is minimum at the portion 30e1 on the inner peripheral side of the screw portion 30f of the piston mounting shaft 30b, and the strength of the portion of the piston mounting shaft 30b where the screw portion 30f is provided is secured.

Further, the piston mounting shaft 30b is provided with a lateral hole 30g which is open to the side of the piston mounting shaft 30b from above the screw portion 30f in FIG. 2 and communicates with the vertical hole 30e. That is, the horizontal hole 30g is opened at a portion 30e2 having a larger outer diameter than the portion 30e1 where the inner diameter of the vertical hole 30e is the smallest. A leaf valve 21, a piston 2, an extension side check valve 20 and a tubular collar 19 are mounted on the outer periphery of the piston mounting shaft 30b. These leaf valve 21a, piston 2, extension side check valve 20 and tubular collar 19 are attached. The collar 19 is sandwiched between the nut N screwed to the screw portion 30f and the housing portion 30a and fixed to the piston mounting shaft 30b.

The inner circumference of the leaf valve 21a is fixed to the piston mounting shaft 30b to allow bending of the outer circumference, and the compression side passage 2b is opened and closed, and the extension side check valve 20 slides axially on the outer circumference of the piston mounting shaft 30b. Then, the extension side passage 2a is opened and closed.

Further, the collar 19 has a cylindrical portion 19a having an inner diameter larger than the outer diameter of the piston mounting shaft 30b, and the piston mounting shaft 30b provided on the inner circumference of the lower end in FIG. 2 of the tubular portion 19a. And a plurality of holes 19c provided in the tubular portion 19a for communicating the inside and outside of the tubular portion 19a. When the collar 19 is mounted on the outer periphery of the piston mounting shaft 30b as described above, the tubular portion 19a faces the lateral hole 30g in the radial direction, and the lateral hole 30g of the piston mounting shaft 30b passes through the hole 19c. It is communicated with the compression side chamber Lb.

As described above, since the portion 30e2 having a larger inner diameter than the portion 30e1 having the smallest inner diameter of the vertical hole 30e of the piston rod 3 is communicated with the pressure side chamber Lb through the horizontal hole 30g, the piston mounting shaft 30b in the vertical hole 30e is connected. A flow passage area larger than the flow passage area of the inner peripheral portion 30e1 of the screw portion 30f can be secured.

The total flow path area of the holes 19c of the collar 19 is set to be equal to or larger than the total flow path area of the horizontal holes 30g, and if this condition is satisfied, the number of holes 19c to be installed can be arbitrarily set. The total flow passage area of the portion 30e2 of the vertical hole 30e and the horizontal hole 30g may be equal to or larger than the flow passage area of the damping force adjusting valve V in the fully opened state, and the number of the horizontal holes 30g installed is arbitrary. .. Further, the shape of the lateral hole 30g is arbitrary, and may be, for example, an elongated hole along the circumferential direction of the piston mounting shaft 30b.

Subsequently, the yoke 31 has a flange portion 31a protruding from the outer periphery of the tip of the rod body 32 in the outer peripheral direction, an accommodating cylinder 31b hanging from the flange portion 31a into which the damping force adjusting valve V is inserted, and the accommodating cylinder 31b side. It is configured to include a plurality of through holes 31c that are opened from the side and lead to the inside, and a plurality of grooves 31d that are the outer periphery of the accommodating cylinder 31b and extend from the anti-piston side end and lead to each through hole 31c. Therefore, a plurality of grooves 31d extending in the axial direction are provided on the outer circumference of the yoke 31 from the end opposite to the piston to each through hole 31c.

Further, a screw portion 31e that is screwed to the inner circumference of the upper end of the housing portion 30a is provided on the inner circumference of the housing cylinder 31b that is the inner circumference of the lower end of the yoke 31, and the piston holding member 30 is screwed to the yoke 31. Is installed by. The yoke 31 and the piston holding member 30 may be fastened by a fastening method other than welding, press-fitting, or screw fastening. In this way, the extension side chamber La and the inside of the yoke 31 are communicated with each other by the through hole 31c, and the damping force adjusting valve V is provided in the middle of the passage connecting the through hole 31c and the upper chamber 30c. The yoke 31 may accommodate the entire damping force adjusting valve V, or may accommodate a part of the damping force adjusting valve V.

Further, the outer diameters of the yoke 31 and the piston holding member 30 that house the damping force adjusting valve V and the soft side damping element 50 are smaller than the inner diameter of the cylinder 1, so that the expansion side chamber La is not partitioned by these. ..

Although the six through holes 31c are provided at equal intervals along the circumferential direction of the yoke 31, the entire flow passage area of the through hole 31c and the through hole 31c between the yoke 31 and the cylinder 1 are provided. The flow passage area of the annular gap X at a portion on the side opposite to the piston in FIG. 2 above the position where is provided is not less than the flow passage area of the damping force adjusting valve V in the fully open state. The number of grooves 31d installed is arbitrary. Further, the shape of the through hole 31c is arbitrary, and may be a long hole or the like along the circumferential direction of the yoke 31. Further, in the present embodiment, six grooves 31d are provided corresponding to each through hole 31c, but one groove 31d may be communicated with a plurality of through holes 31c.

Further, in the present embodiment, the groove 31d is provided along the outer circumference of the yoke 31 along the axial direction, and the length of the groove 31d is determined by connecting the end of the yoke 31 on the side opposite to the piston to the through hole 31c. It will be the shortest. Therefore, it is considered that the resistance when the liquid passes through the groove 31d is minimized as compared with the case where the groove 31d is formed obliquely or meanders with respect to the axial direction of the yoke 31.

In the present embodiment, the bypass path 3a is configured to have a through hole 31c, an upper chamber 30c, a lower chamber 30d, a vertical hole 30e, and a horizontal hole 30g formed in the yoke 31 or the piston holding member 30 described above. Therefore, the hard side damping element 21 is bypassed and the extension side chamber La and the compression side chamber Lb are communicated with each other. A damping force adjusting valve V and a soft side damping element 50 are provided in series in the middle of the bypass path 3a.

The soft-side damping element 50 is configured to have a leaf valve 50a stacked on the upper side of the valve case 5 and an orifice 50b provided in parallel with the leaf valve 50a.

The leaf valve 50a is a thin annular plate formed of metal or the like, or a laminated body in which the annular plates are stacked, has elasticity, and is attached to the valve case 5 in a state in which the outer peripheral side is allowed to bend. Then, the pressure of the lower chamber 30d acts in the direction of bending the outer peripheral portion of the leaf valve 50a upward. Further, the orifice 50b is formed by a notch provided on the outer peripheral portion of the leaf valve 50a which is seated on and off the valve seat of the valve case 5, but may be formed by stamping or the like provided on the valve seat. Good.

The pressure in the lower chamber 30d becomes higher than the pressure in the upper chamber 30c when the shock absorber D is contracted and the damping force adjusting valve V opens the bypass passage 3a. When the piston speed is in the low speed range when the shock absorber D contracts and the differential pressure between the upper chamber 30c and the lower chamber 30d is less than the opening pressure of the leaf valve 50a, the liquid passes through the orifice 50b. From the lower chamber 30d to the upper chamber 30c, that is, from the pressure side chamber Lb to the extension side chamber La, resistance is imparted to the flow of the liquid. When the differential pressure becomes larger than the valve opening pressure of the leaf valve 50a, the outer peripheral portion of the leaf valve 50a bends, and the liquid passes through the gap formed between the outer peripheral portion and the valve case 5 to form a lower chamber. From 30d to the upper chamber 30c, that is, from the pressure side chamber Lb to the extension side chamber La, resistance is given to the flow of the liquid.

As described above, the soft side damping element 50 having the orifice 50b and the leaf valve 50a parallel to the orifice 50b makes the compression side bypass path 3a from the compression side chamber Lb to the extension side chamber when the shock absorber D contracts. A second damping element on the pressure side that provides resistance to the flow of liquid towards La. The resistance of the soft-side damping element 50 results from the orifice 50b when the piston speed is in the low speed range, and from the leaf valve 50a when the piston speed is in the medium to high speed range.

Further, the leaf valve 50a of the soft side damping element 50 is a valve having a lower valve rigidity (easy to bend) as compared with the leaf valve 21a of the hard side damping element 21, and when the flow rate is the same, it gives to the flow of liquid. Resistance (pressure loss) is small. In other words, the liquid is more likely to pass through the leaf valve 50a than the leaf valve 21a under the same conditions. Further, the orifice 50b of the soft-side damping element 50 is a large-diameter orifice having a larger opening area than the orifice 21b of the hard-side damping element 21, and when the flow rates are the same, the resistance (pressure loss) given to the liquid flow is small.

Subsequently, the damping force adjusting valve V is, as shown in FIG. 2, a cylindrical spool 7 as a damping force adjusting section that is reciprocally inserted into a cylindrical holder 6 fixed in the piston rod 3. And a solenoid 9 that drives the spool 7 in the axial direction, and a biasing spring 8 that biases the spool 7 in opposition to the thrust of the solenoid 9. Then, the damping force adjusting valve V adjusts the position of the spool 7 in the holder 6 to adjust the opening degree.

More specifically, the holder 6 has one end in the axial direction directed to the upper side (yoke 31 side) and the other end directed to the lower side (valve case 5 side) with respect to the valve case 5 in the piston rod 3. In this state, it is arranged along the central axis of the piston rod 3. Further, the holder 6 is formed with a plurality of

ports

6a, 6b which are provided at positions displaced in the axial direction and penetrate in the radial direction. The port 6a is composed of four elongated holes 6a1 and 6a2 provided at equal intervals in the circumferential direction with respect to the holder 6. Since FIG. 2 is a cross-sectional view, the elongated holes on the front side and the back side of the paper surface are not shown. The port 6b is composed of four elongated holes 6b1 and 6b2 arranged at positions shifted downward from the port 6a with respect to the holder 6 and provided at equal intervals along the circumferential direction in FIG. .. Since FIG. 2 is a cross-sectional view, the elongated holes on the front side and the back side of the paper surface are not shown. As described above, the holder 6 is provided with the plurality of

ports

6a and 6b at positions displaced in the axial direction. The

ports

6 a and 6 b are communicated with the extension side chamber La through the through holes 31 c of the yoke 31 and are opened and closed by the spool 7. Further, the holder 6 is provided with a flange portion 6d at the lower end in FIG. 2 that fits into the inner circumference of the housing portion 30a of the piston holding member 30.

The spool 7 is cylindrical and is slidably inserted into the holder 6 so that it can be reciprocated in the vertical direction in FIG. More specifically, the spool 7 includes a communication port 7a corresponding to the port 6a and facing the port 6a, and a communication port 7b corresponding to the port 6b and facing the port 6b. The communication ports 7a and 7b are arranged at positions displaced from the spool 7 in the axial direction which is the moving direction of the spool 7, and specifically, the same arrangement as the axial arrangement of the

ports

6a and 6b with respect to the holder 6. Is provided on the spool 7. That is, the axial spacing of the communication ports 7a and 7b is equal to the axial spacing of the

ports

6a and 6b, and when the port 6a communicates with the corresponding communication port 7a, the port 6b and the communication port 7b also communicate with each other. Therefore, when any port 6a (6b) communicates with the corresponding communication port 7a (7b), all the ports 6a and 7b communicate with the corresponding communication ports 7a and 7b, respectively. The communication port 7a is composed of four elongated holes 7a1, 7a2, 7a3 provided at equal intervals in the circumferential direction with respect to the spool 7. Since FIG. 2 is a cross-sectional view, the elongated hole on the front side is not shown. The communication ports 7b are four elongated holes 7b1, 7b2, 7b3 arranged at positions shifted below the communication port 7a with respect to the spool 7 and provided at equal intervals along the circumferential direction in FIG. It is configured. Since FIG. 2 is a cross-sectional view, the elongated hole on the front side is not shown. The expression "communication ports 7a and 7b corresponding to each of the

ports

6a and 6b" means that the communication ports 7a and 7b correspond one-to-one with each of the

ports

6a and 6b, and the ports 6a are communicated with each other. This means that the port 7a corresponds to the communication port 7b with the port 6b.

Further, on the outer periphery of the spool 7, an annular groove 7c provided along the circumferential direction and communicating with all the communication ports 7a, and an annular groove 7d provided along the circumferential direction and communicating with all the communication ports 7b. Equipped with. In the present embodiment, the annular groove 7c faces the communication port 7a, its vertical width corresponds to the vertical width in FIG. 2 of the communication port 7a, and the annular groove 7d faces the communication port 7b. The vertical width in FIG. 2 coincides with the vertical width in FIG. 2 of the communication port 7b. The axial distance between the annular groove 7c and the annular groove 7d in the spool 7 is equal to the axial distance between the

ports

6a and 6b.

When the spool 7 configured in this way is inserted into the holder 6, it opens and closes the

ports

6a and 6b provided in the holder 6. Specifically, when the annular groove 7c provided on the outer circumference of the spool 7 faces the corresponding port 6a and the annular groove 7d provided on the outer circumference of the spool 7 faces the corresponding port 6b, the spool 7 is The

ports

6a and 6b are communicated with the spool 7 through the communication ports 7a and 7b. The

ports

6a and 6b are communicated with the extension side chamber La through the through holes 31c provided in the yoke 31. On the other hand, the inside of the spool 7 is communicated with the pressure side chamber Lb through the upper chamber 30c, the passage 5a provided in the valve case 5, the lower chamber 30d and the vertical hole 30e. Therefore, a damping force adjusting valve V is provided in the middle of the bypass path 3a, and when the

ports

6a and 6b communicate with each other in the spool 7, the damping force adjusting valve V is opened to open the bypass path 3a, and the bypass path 3a is opened. The extension side chamber La and the compression side chamber Lb are communicated with each other.

When the spool 7 moves with respect to the holder 6, the area where the port 6a faces the annular groove 7c and the area where the port 6b faces the annular groove 7d change. The flow passage area can be changed. When the spool 7 moves downward in FIG. 2 with respect to the holder 6 and the

ports

6a and 6b do not completely face the

annular grooves

7c and 7d, respectively, and are blocked at the outer periphery of the spool 7, they correspond to the

ports

6a and 6b. The communication with the communication ports 7a and 7b is cut off and the bypass 3a is cut off. The spool 7 moves downward with respect to the holder 6 from the position shown in FIG. 2, and at the same time when the annular groove 7c starts to face the port 6a, the annular groove 7d also starts to face the port 6b. Further, from the state where the annular groove 7c and the port 6a face each other and the annular groove 7d and the port 6b face each other, the spool 7 moves upward with respect to the holder 6, and the annular groove 7c faces the port 6a. At the same time, the annular groove 7d does not face the port 6b. Thus, when the spool 7 moves axially with respect to the holder 6, the opening degree of the

ports

6a and 6b changes, and the flow passage area of the damping force adjusting valve V changes greatly.

A plate 70 is laminated on the upper end of the spool 7, and a plunger 9a of the solenoid 9 which will be described later is in contact with the plate 70. On the other hand, the biasing spring 8 contacts the lower end of the spool 7 and biases the spool 7 upward in FIG. 2, which is one of the moving directions. The biasing spring 8 is a spiral spring that exerts a biasing force that returns the inner periphery to its original position when the inner periphery is displaced in the vertical direction in FIG. 2 relative to the outer periphery. The urging spring 8 is sandwiched between a tubular spacer 22 whose outer circumference is below the urging spring 8 and which is fitted to the inner circumference of the housing portion 30a of the piston holding member 30 and a flange portion 6d of the holder 6. It is fixed to the piston rod 3. The inner circumference of the urging spring 8 is fitted into the annular recess 7e provided on the outer periphery of the lower end in FIG. 2 of the spool 7, and the urging spring 8 has the spool 7 with respect to the holder 6 in the upper middle of FIG. When the spool 7 is displaced downward in FIG. 2 with respect to the holder 6, an urging force that returns the spool 7 to the original position is exerted. While the spool 7 is urged by the urging force of the urging spring 8, the spool 7 is positioned at the uppermost position as shown in FIG. 2 in a state where the solenoid 9 does not receive a thrust opposed to the urging force of the urging spring 8. The

annular grooves

7c and 7d are not opposed to the

ports

6a and 6b. Therefore, the damping force adjusting valve V shuts off the bypass path 3a when the power is not supplied.

The solenoid 9 of the damping force adjusting valve V is housed in the yoke 31, and although not shown in detail, a cylindrical stator including a coil and a cylindrical movable member movably inserted in the stator. It has an iron core and a plunger 9a which is attached to the inner circumference of the movable iron core and whose tip abuts on the plate 70. The harness 90 that supplies electric power to the solenoid 9 projects outward through the inside of the rod body 32 and is connected to a power source.

Then, when the solenoid 9 is energized through the harness 90, the movable iron core is pulled downward, the plunger 9a moves downward, and the spool 7 is pushed down against the urging force of the urging spring 8. Then, the port 6a and the communication port 7a communicate with each other through the annular groove 7c, and the port 6b and the communication port 7b communicate with each other through the annular groove 7d, so that the damping force adjusting valve V opens. Further, the relationship between the opening degree of the damping force adjusting valve V and the energization amount to the solenoid 9 becomes a proportional relationship having a positive proportional constant, and the opening degree increases as the energization amount increases. Further, when the energization of the solenoid 9 is cut off, the damping force adjusting valve V closes.

As described above, the damping force adjusting valve V of the present embodiment is a normally closed type, and the spool 7, which is the valve element thereof, is biased in the closing direction by the biasing spring 8 and the thrust force in the opening direction is generated by the solenoid 9. It is designed to be given to the spool 7. Further, the opening degree increases in proportion to the energization amount of the damping force adjusting valve V, and the flow passage area of the bypass passage 3a increases as the opening degree increases. Therefore, it can be said that the flow path area of the bypass path 3a increases in proportion to the amount of electricity supplied to the damping force adjusting valve V.

Next, the shock absorber D of the present embodiment is provided with a manual valve 41 for manually adjusting the flow rate of the hard side damping element 21. As shown in FIG. 1, the manual valve 41 is provided in the bottom portion of the shock absorber D, and can change the flow passage area of the discharge passage 4b that connects the pressure side chamber Lb and the liquid storage chamber R by a manual operation.

The manual valve 41 includes a needle-shaped valve body 41a which is seated on and detached from an annular valve seat (not shown) provided in the middle of the discharge passage 4b. When the manual valve 41 is rotationally operated, the valve body 41a moves closer to the valve seat depending on the rotation direction, and the flow passage area of the discharge passage 4b is adjusted to be small or large. In the present embodiment, when the damping force adjusting valve V is normally energized normally, the valve body 41a is seated on the valve seat, and the manual valve 41 blocks the communication of the discharge passage 4b.

Summarizing the above, as shown in FIG. 1, the shock absorber D includes a cylinder 1 and a piston 2 that is slidably inserted into the cylinder 1 and divides the inside of the cylinder 1 into an extension side chamber La and a compression side chamber Lb. The piston rod 3 has a tip connected to the piston 2 and a distal end protruding outside the cylinder 1, and a tank 16 connected to the expansion side chamber La in the cylinder 1, and the pressure in the expansion side chamber La is the tank pressure. It has become.

Further, the shock absorber D is provided with an extension side passage 2a, a compression side passage 2b, and a bypass passage 3a as passages for communicating the extension side chamber La and the compression side chamber Lb. The expansion side passage 2a is provided with an expansion side check valve 20 that allows only one-way flow of liquid from the expansion side chamber La to the compression side chamber Lb, and the liquid from the compression side chamber Lb to the expansion side chamber La is 2b or the bypass 3a.

The pressure side passage 2b is provided with an orifice 21b and a leaf valve 21a arranged in parallel with the orifice 21b, and a hard side damping element 21 that gives resistance to the flow of liquid. On the other hand, the bypass passage 3a is configured to have an orifice 50b having a larger opening area than the orifice 21b and a leaf valve 50a arranged in parallel with the leaf valve 21a and having a valve rigidity lower than that of the leaf valve 21a. A soft side damping element 50 having a reduced resistance is provided.

Further, a damping force adjusting valve V is provided in the bypass passage 3a in series with the soft side damping element 50, and the flow passage area of the bypass passage 3a is changed by adjusting the energization amount to the damping force adjusting valve V. You can do it. The damping force adjusting valve V is a normally closed type and is set so as to increase the flow passage area of the bypass passage 3a in proportion to the amount of energization.

Further, the shock absorber D is provided with a suction passage 4a and a discharge passage 4b as passages that connect the pressure side chamber Lb and the tank 16 to each other. The suction passage 4a is provided with a suction valve 40 that allows only one-way flow of the liquid from the tank 16 to the pressure side chamber Lb. On the other hand, the discharge passage 4b is provided with a normally closed manual valve 41 that is opened and closed by manual operation.

The shock absorber D is configured as described above, and when the shock absorber D contracts, the piston rod 3 invades into the cylinder 1 and the piston 2 compresses the compression side chamber Lb. Normally, the manual valve 41 closes the discharge passage 4b. Therefore, when the shock absorber D contracts, the liquid in the pressure side chamber Lb moves to the extension side chamber La through the pressure side passage 2b or the bypass passage 3a. A resistance is given to the flow of the liquid by the hard side damping element 21 or the soft side damping element 50, and a compression side damping force due to the resistance is generated.

In addition, when the shock absorber D contracts in a normal state, the distribution ratio of the liquid passing through the hard damping element 21 and the soft damping element 50 changes depending on the flow passage area of the bypass passage 3a, whereby the damping coefficient is large or small. The compression-side damping force generated as a result is adjusted in magnitude.

Specifically, as described above, the hard-side damping element 21 and the soft-side damping element 50 are configured to have the

orifices

21b and 50b and the leaf valves 21a and 50a arranged in parallel with the

orifices

21b and 50b, respectively. Therefore, the damping force characteristic becomes an orifice characteristic proportional to the square of the piston speed peculiar to the orifice when the piston speed is in the low speed range, and becomes the piston speed peculiar to the leaf valve when the piston speed is in the medium to high speed range. The valve characteristics are proportional.

When the opening amount is increased by increasing the energization amount to the damping force adjusting valve V, the flow rate of the bypass passage 3a is increased and the ratio of the liquid passing through the hard side damping element 21 is reduced, and at the same time, when passing through the soft side damping element 50. Increases the proportion of liquid that is produced. Since the orifice 50b of the soft side damping element 50 is a large-diameter orifice having a larger opening area than the orifice 21b of the hard side damping element 21, the damping coefficient is increased in the soft mode in which the proportion of the liquid toward the soft side damping element 50 increases. Becomes smaller in both the low speed range and the medium and high speed range, and the compression side damping force generated with respect to the piston speed becomes small. When the amount of current supplied to the damping force adjusting valve V is maximized, the damping coefficient is minimized and the compression side damping force generated with respect to the piston speed is minimized.

On the contrary, when the energization amount to the damping force adjusting valve V is reduced and the opening degree is reduced, the flow rate of the bypass passage 3a decreases, the proportion of the liquid passing through the hard side damping element 21 increases, and the soft side damping element increases. The percentage of liquid that passes through element 50 is reduced. Then, the damping coefficient becomes large and the compression side damping force with respect to the piston speed becomes large. When the damping force adjusting valve V is shut off and the damping force adjusting valve V is closed, the communication of the bypass passage 3a is cut off, so that the entire flow rate passes through the hard side damping element 21. Then, the damping coefficient becomes maximum, and the compression side damping force generated with respect to the piston speed becomes maximum.

As described above, when the distribution ratio of the liquid passing through the hard damping element 21 and the soft damping element 50, which are the first and second damping elements, is changed by the damping force adjusting valve V, the damping coefficient becomes large and small. As shown, the slope of the characteristic line indicating the damping force characteristic on the compression side changes. Then, the compression side damping force is adjusted between the hard mode in which the inclination of the characteristic line is maximized to increase the damping force generated and the soft mode in which the inclination is minimized to decrease the damping force generated.

Then, in the soft mode, the slope of the characteristic line showing the damping force characteristic becomes smaller in both the low speed region and in the middle/high speed region, and in the hard mode, the slope of the characteristic line showing the damping force property becomes smaller in the low speed region and the middle/high speed region. It gets bigger in both. Therefore, the change in the damping force characteristic from the orifice characteristic to the valve characteristic is gradual in any mode.

Further, the soft side damping element 50 has a leaf valve 50a having low valve rigidity in parallel with the orifice 50b. Therefore, even if a valve with high valve rigidity and high valve opening pressure is adopted as the leaf valve 21a of the hard side damping element 21 and the adjustment range in the direction of increasing the compression side damping force is increased, the damping force in the soft mode is increased. Does not become too large.

Also, at the time of failure (normal time), the power supply to the damping force adjustment valve V is cut off and the mode is switched to the hard mode. At this time, if the manual valve 41 is opened, the liquid in the compression side chamber Lb passes through not only the compression side passage 2b but also the discharge passage 4b, so that the flow rate of the liquid passing through the hard side damping element 21 is reduced. The compression side damping force is reduced.

Also, the liquid equivalent to 3 volumes of the piston rod that has entered the cylinder 1 when the shock absorber D contracts is discharged from the expansion side chamber La to the tank 16.

On the contrary, when the shock absorber D is extended, the extension side check valve 20 opens, and the liquid in the extension side chamber La moves to the compression side chamber Lb through the extension side passage 2a. At this time, the liquid can pass through the extension check valve 20 without any resistance. Further, the extension side chamber La is communicated with the tank 16 and is maintained at the tank pressure. Therefore, the shock absorber D does not exert a damping force on the extension side. As described above, the shock absorber D forms a front fork by forming a pair with a shock absorber that generates a damping force only when the vehicle is extended. Therefore, when the front wheels are separated from the vehicle body, the damping is performed only when the vehicle is extended. A shock absorber that exerts power suppresses vibration of the vehicle body.

The operation and effect of the shock absorber D according to the embodiment of the present invention will be described below. The shock absorber D according to the present embodiment includes a cylinder 1, a piston 2 that is movably inserted into the cylinder 1 in the axial direction, and divides the inside of the cylinder 1 into an expansion side chamber La and a compression side chamber Lb, and a piston 2. A piston rod 3 that is connected and has one end protruding outside the cylinder 1, a bypass passage (attenuation passage) 3a that is provided in the piston rod 3 and connects the extension side chamber La and the compression side chamber Lb, and a bypass passage (attenuation passage). ) 3a, the damping force adjusting valve V is provided, and the bypass passage (damping passage) 3a is opened from the tip of the piston rod 3 and the vertical hole 30e communicating the compression side chamber Lb with the damping force adjusting valve V, and the piston The rod 3 is formed to include a lateral hole 30g that opens from the side of the rod 3 and connects the compression side chamber Lb to the vertical hole 30e.

In the shock absorber D configured in this way, in providing the piston rod 3 with a bypass path (damping passage) 3a leading to the damping force adjusting valve V, a horizontal hole 30 g is provided in addition to the vertical hole 30e, so that the bypass path is provided. (Attenuation passage) The flow path area in 3a is expanded. In this shock absorber D, the flow path resistance can be reduced even if a bypass path (damping passage) 3a is provided in the piston rod 3, and the minimum damping force is determined by the flow path resistance of the vertical hole 30e provided in the piston rod 3. The problem of this can be solved, and the minimum damping force can be adjusted by the damping force adjusting valve V. Therefore, according to the shock absorber D of the present invention, the damping force adjustment range can be increased and the damping force at the time of full soft can be lowered.

In the shock absorber D of the present embodiment, the piston rod 3 has a piston mounting shaft 30b on the outer periphery of which the piston 2 is mounted and a nut N for fixing the piston 2 is screwed, and is a tubular shape. The collar 19 is provided on the outer circumference of the piston mounting shaft 30b having a hole 19c for communicating the inside and the outside, and is provided between the piston 2 and the nut N. The lateral hole 30g has a collar 19 of the piston mounting shaft 30b. It is open at a position facing the. In the shock absorber D configured as described above, even if the piston 2 and the nut N are mounted on the piston mounting shaft 30b, the lateral hole 30g provided in the piston mounting shaft 30b is provided in the pressure side chamber Lb by the hole 19c provided in the collar 19. Can be communicated. Therefore, according to the shock absorber D of the present embodiment, the lateral hole 30g can be communicated with the pressure side chamber Lb by merely providing the collar 19 having a simple shape. Therefore, the piston 2 and the nut N are processed to have a complicated shape. It is not necessary to provide the holes of 30 g to communicate with the compression side chamber Lb, and the manufacturing cost is reduced.

Further, the piston rod 3 in the shock absorber D according to the present embodiment is mounted on the cylindrical yoke 31 into which the damping force adjusting valve V is inserted and the inner circumference of the yoke 31 to hold the piston 2. The yoke 31 has a piston holding member 30, and the yoke 31 has a plurality of through holes 31c which are opened from the side and communicate with the inside to form a part of the bypass passage (attenuation passage) 3a, and the anti-piston side provided on the outer periphery. It has a groove 31d extending from the end and communicating with the through hole 31c.

In the shock absorber D configured as described above, since the damping force adjusting valve V is inserted and the through hole 31c and the groove 31d are formed on the outer circumference of the yoke 31 in which the annular gap between the cylinder 1 and the cylinder 1 is narrowest, The flow path area of the annular gap X between the cylinder 1 and the yoke 31 is expanded. In this shock absorber D, even if the damping force adjusting valve V including the solenoid 9 is housed in the piston rod 3, the flow passage resistance in the annular gap X can be reduced, and the minimum damping force is the flow passage resistance in the annular gap X. You can also solve the problem that is decided. Therefore, according to the shock absorber D of the present invention, even if the damping force adjusting valve using the solenoid is provided, the damping force adjusting range can be widened and the damping force in full soft can be lowered.

Further, in the present embodiment, the groove 31d is provided on the outer periphery of the yoke 31 along the axial direction. According to the shock absorber D configured in this way, the length of the groove 31d is the shortest for connecting the yoke 31 from the anti-piston side end to the through hole 31c, and the liquid passes through the groove 31d. Since the resistance is minimized, the damping force at the time of full soft can be further reduced and the riding comfort in the vehicle can be improved.

The damping force adjusting valve V in the shock absorber D of the present embodiment is a cylindrical holder 6 having a plurality of

ports

6a and 6b communicating between the inside and the outside, and a cylindrical holder 6 axially reciprocates in the holder 6. Each port is provided with a spool 7 that is movably inserted and can open and close the communication ports 7a and 7b that can be opposed to each of the

ports

6a and 6b, and a solenoid 9 that drives the spool 7 in the axial direction. 6a and 6b are provided at positions axially displaced with respect to the holder 6, and the communication ports 7a and 7b are arranged axially with respect to the spool 7 in the same arrangement as the axial arrangement of the

ports

6a and 6b. It is provided at a displaced position.

According to the shock absorber D configured in this way, the holder 6 and the spool 7 are displaced in the axial direction, which is the moving direction of the spool 7, and a plurality of

ports

6a, 6b and the communication ports 7a, 7b are arranged in the same arrangement. Are provided so that the

ports

6a and 6b and the communication ports 7a and 7b can face each other at the same time. Therefore, according to the shock absorber D of the present embodiment, a large flow path area can be secured when the spool 7 is fully opened even if the stroke amount of the spool 7 is smaller than that of the holder 6. In the present embodiment, the two

ports

6a and 6b and the two communication ports 7a and 7b are provided at positions deviated in the axial direction, but three or more ports and the communication port may be provided.

Further, in the present embodiment, the

ports

6a and 6b are each composed of elongated holes 6a1, 6a2, 6a3, 6b1, 6b2, 6b3 provided along the circumferential direction of the holder 6, and the flow path of the port 6a itself. A large area can be secured.

The

ports

6a and 6b may be formed of one elongated hole as long as the strength of the holder 6 is not lowered, but if the

ports

6a and 6b are formed of a plurality of elongated holes, the rigidity of the holder 6 is ensured. There is an advantage that the flow passage area can be increased. Similarly, the communication ports 7a and 7b may be formed of one elongated hole as long as the strength of the spool 7 is not lowered, but if the spool 7 is formed of a plurality of elongated holes, the rigidity of the spool 7 is ensured. However, there is an advantage that the flow path area can be increased.

In the shock absorber D configured in this way, even if the stroke amount of the damping force adjusting valve V is reduced, a large flow path area when fully opened can be secured, so that the damping force adjusting valve does not become large and the shock absorber D is used. , The resistance of the liquid passing through the bypass passage 3a can be minimized without sacrificing the stroke length of the shock absorber D. Therefore, according to the shock absorber D of the present invention, a large damping force adjustment range can be realized while ensuring the stroke length.

Further, in the present embodiment, the shock absorber D bypasses the hard side damping element 21 that gives resistance to the flow of the liquid from the compression side chamber Lb to the extension side chamber La, and the hard side damping element 21 and bypasses the compression side chamber Lb. It is provided with a damping force adjusting valve V capable of changing the flow path area of the bypass path 3a communicating the extension side chamber La and a soft side damping element 50 provided in series with the damping force adjusting valve V in the bypass path 3a. .. The hard damping element 21 has an orifice 21b and a leaf valve 21a provided in parallel with the orifice 21b. On the other hand, the soft side damping element 50 has an orifice (large diameter orifice) 50b having an opening area larger than that of the orifice 21b.

According to the above configuration, the characteristic of the damping force generated when the shock absorber D contracts is the orifice characteristic peculiar to the orifice when the piston speed is in the low speed range, and when the piston speed is in the medium to high speed range, The valve characteristics are unique to leaf valves. Then, if the opening area of the bypass path 3a is changed by the solenoid valve V, among the liquids that move from the compression side chamber Lb to the extension side chamber La when the shock absorber D contracts, the hard side damping element 21 and the soft side damping element 50 Since the distribution ratio of the flow rate passing through each changes, both the damping coefficient when the piston speed is in the low speed range and the damping coefficient when the piston speed is in the medium and high speed range can be freely set, and the piston speed can be set to the medium and high speed range. The adjustment range of the compression side damping force in a certain case can be increased.

Further, in the soft mode in which the opening area of the bypass path 3a is increased, both the damping coefficient when the piston speed is in the low speed range and the damping coefficient when the piston speed is in the medium and high speed range become small. On the other hand, in the hard mode in which the opening area of the bypass path 3a is reduced, both the damping coefficient when the piston speed is in the low speed region and the damping coefficient when the piston speed is in the medium and high speed region are large. Therefore, when the characteristic of the compression side damping force changes from the orifice characteristic in the low speed region to the valve characteristic in the medium and high speed region, the change in the slope of the characteristic line becomes gentle in any mode. As a result, when the shock absorber D according to the present embodiment is mounted on a vehicle, it is possible to reduce the discomfort caused by the change in the inclination and improve the ride comfort of the vehicle.

Further, in the shock absorber D of the present embodiment, the soft side damping element 50 is configured to have the orifice (large diameter orifice) 50b and a leaf valve 50a provided in parallel with the orifice 50b. In this way, if the soft-side damping element 50 is also provided with the leaf valve 50a, even if the leaf valve 21a of the hard-side damping element 21 has a high valve rigidity and a high valve opening pressure, the damping force in the soft mode is high. It doesn't become excessive. That is, according to the above configuration, a valve having high valve rigidity can be used as the leaf valve 21a of the hard damping element 21. Then, since the adjustment range of the damping force increases in the direction of increasing the compression side damping force, the adjustment range of the compression side damping force can be further increased when the piston speed is in the middle and high speed range.

Also, in the shock absorber D of the present embodiment, the piston 2 is connected to the other end of the piston rod 3 to form a single rod type. Further, the shock absorber D includes a tank 16 connected to the extension side chamber La, and a suction valve 40 that allows only the flow of liquid from the tank 16 to the compression side chamber Lb. With this configuration, the tank 16 can compensate for the volume of the piston rod 3 that moves in and out of the cylinder 1. Furthermore, the shock absorber D can be a one-sided shock absorber that exerts a damping force only in the compression stroke.

Further, in the shock absorber D of the present embodiment, the damping force adjusting valve V is set so that the opening degree changes in proportion to the energization amount. With this configuration, the opening area of the bypass 3a can be changed steplessly.

Further, the shock absorber D of the present embodiment is provided with a manual valve 41 capable of manually changing the flow passage area of the discharge passage 4b that connects the pressure side chamber Lb and the tank 16. According to this configuration, even if the damping force adjusting valve V is closed at the time of failure, the compression side damping force generated by manually opening the manual valve 41 is reduced. For this reason, it is possible to prevent the compression side damping force in the fail mode from becoming excessive, and it is possible to improve the ride comfort of the vehicle.

In the present embodiment, the shock absorber D is a one-sided shock absorber that exerts a damping force only when it contracts, but it is hard in the compression side passage 2b like the shock absorber shown in the hydraulic circuit diagram in FIG. Instead of the side damping element 21, a check valve 60 that allows only the flow of the liquid from the compression side chamber Lb to the expansion side chamber La is provided, and the expansion side passage 2a is used as a damping passage for the liquid flow from the expansion side chamber La to the compression side chamber Lb. A hard side damping element 61 that gives resistance is provided, and a soft side damping element 62 that gives resistance to the flow of liquid from the extension side chamber La to the compression side chamber Lb is provided in the bypass path 3a instead of the soft side damping element 50, and a suction passage is provided. The suction valve 40 in 4a may be abolished, and the discharge passage 4b and the manual valve 41 may be abolished so that the shock absorber D exerts a damping force only when it is extended. When the shock absorber D is configured in this way, the damping coefficient becomes large and small if the distribution ratio of the liquid passing through the hard damping element and the soft damping element configured with the leaf valve is changed by the damping force adjusting valve V. The inclination of the characteristic line showing the damping force characteristic on the extension side can be changed similarly to the shock absorber D that exerts the damping force only on the compression side.

Further, if it is not necessary to set the damping force characteristic when the piston speed is in the normal speed range to the valve characteristic, only the damping force adjusting valve V is provided in the bypass path 3a as the damping passage, and the soft side damping element 50 is provided. May be omitted, or the hard side damping element 21 may be abolished and the damping force on both sides of contraction, extension or expansion / contraction may be adjusted only by the damping force adjusting valve V.

The preferred embodiments of the present invention have been described above in detail, but modifications, variations, and changes can be made without departing from the scope of the claims. The present application claims priority based on Japanese Patent Application No. 2019-038125 filed with the Japan Patent Office on March 4, 2019, and the entire contents of this application are incorporated herein by reference.

1 ... Cylinder, 2 ... Piston, 3 ... Piston rod, 3a ... Bypass path (damping passage), 19 ... Collar, 19c ... Hole, 30b ... Piston mounting shaft, 30e ... vertical hole, 30g ... horizontal hole, 31 ... yoke, 31c ... through hole, 31d ... groove, D ... shock absorber, La ... extension side chamber, Lb ...・ Compression side chamber, N ・・・ nut, V ・・・ damping force adjustment valve

Claims

It ’s a shock absorber,
Cylinder and
A piston that is movably inserted in the cylinder in the axial direction to partition the inside of the cylinder into an expansion side chamber and a compression side chamber,
A piston rod that is connected to the piston and one end of which protrudes out of the cylinder.
A damping passage that is provided in the piston rod and connects the expansion side chamber and the compression side chamber,
A damping force adjusting valve provided in the damping passage,
The damping passage has a vertical hole that opens from the tip of the piston rod and communicates the compression side chamber with the damping force adjusting valve, and a vertical hole that opens from the side of the piston rod and communicates the compression side chamber with the vertical hole. A shock absorber formed including a side hole.
The shock absorber according to claim 1.
The piston rod has a piston mounting shaft on which an outer periphery of the piston is mounted and a nut for fixing the piston is screwed.
It is tubular and has holes that communicate inside and outside, and has a collar that is arranged on the outer circumference of the piston mounting shaft and is interposed between the piston and the nut.
A shock absorber that opens in the lateral hole at a position facing the collar of the piston mounting shaft.