JP7064980B2 - Suspension device - Google Patents

Description

The present invention relates to a suspension device mounted on a vehicle such as a four-wheeled vehicle and preferably used to cushion the vibration of the vehicle.

Generally, in a suspension device including a shock absorber provided between the vehicle body side and the wheel side of a vehicle whose damping force can be adjusted by an actuator and a controller for driving and controlling the actuator, the shock absorber is subject to high-frequency vibration. On the other hand, it is known that a frequency sensitive portion for reducing the damping force is provided (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2012-206685

By the way, in the suspension device according to the prior art, the damping force is adjusted by the shock absorber by driving and controlling the actuator by the controller for the low frequency vibration among the vibrations during vehicle running, but for the high frequency vibration. Does not adjust the damping force according to the vibration state by the controller. As a result, the frequency-sensitive portion can mechanically reduce the damping force against high-frequency vibration, and can improve the riding comfort of the vehicle. However, it is not always possible to sufficiently improve the riding comfort of the vehicle simply by mechanically reducing the damping force against high-frequency vibration by the frequency-sensitive part, and it depends on the driving scene such as the magnitude of unspring vibration. Therefore, there is a problem that the damping force cannot be controlled.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to be able to control the damping force corresponding to a wide vibration range from low frequency to high frequency when the vehicle is running, and to improve the riding comfort. The purpose is to provide a suspension device that can be improved.

In order to solve the above-mentioned problems, the present invention is a suspension provided between the vehicle body side and the wheel side of the vehicle, a shock absorber whose damping force can be adjusted by an actuator, and a controller for controlling the actuator. In the device, the shock absorber is provided with a frequency-sensitive unit that reduces the damping force against vibrations having a high frequency higher than a predetermined vibration frequency, and the controller is provided with the actuator according to the motion state of the vehicle. The damping force is adjusted so that the damping force of the first soft characteristic to the first hard characteristic is generated according to the motion state for the motion of the vehicle having a low frequency lower than the predetermined vibration frequency. For the high-frequency motion whose vibration frequency is higher than that of the low-frequency motion, the second soft characteristic whose lower limit is a damping force higher than the first soft characteristic is higher than the first hard characteristic depending on the motion state. It is characterized in that the damping force is adjusted so as to be generated up to the second hard characteristic with a low damping force as the upper limit .

Further, in the present invention, a cylinder in which a working fluid is sealed, a piston provided in the cylinder and divided into a one-side chamber and another side chamber, and one end connected to the piston and the other end extended to the outside of the cylinder. A piston rod, a main valve that suppresses the flow of working fluid from the upstream chamber to the downstream chamber caused by the movement of the piston to generate a damping force, and a back pressure in the valve closing direction of the main valve. A back pressure chamber to be operated and a back pressure chamber introduction orifice for introducing working fluid from the upstream chamber into the back pressure chamber are provided, and the main valve is opened by the back pressure of the back pressure chamber. A pressure adjustment mechanism that adjusts the pressure, a frequency-sensitive part that reduces the damping force against high-frequency vibration and supplies the working fluid through the back pressure chamber introduction orifice, and a damping force that can adjust the damping force by an actuator. In the suspension device including the adjustment mechanism and the controller for controlling the actuator, the controller is the first in the motion of the vehicle for the motion of a low frequency lower than the predetermined vibration frequency according to the motion state. The damping force of the first hard characteristic is adjusted from the soft characteristic to be generated, and for the high-frequency motion having a vibration frequency higher than the low frequency, the damping force higher than the first soft characteristic is applied according to the motion state . It is characterized in that the damping force is adjusted so as to be generated from the second soft characteristic which is the lower limit to the second hard characteristic which is the upper limit of the damping force lower than the first hard characteristic .

According to the present invention, it is possible to adjust the damping force corresponding to a wide vibration range from low frequency to high frequency when the vehicle is running, and it is possible to improve the riding comfort.

It is a vertical sectional view which shows the damping force adjustment type hydraulic shock absorber which constitutes the shock absorber of the suspension apparatus by embodiment of this invention. FIG. 3 is a partially enlarged cross-sectional view showing an enlarged view of the bottom valve and the damping force adjusting device in FIG. 1. FIG. 3 is an enlarged cross-sectional view of a main part showing an enlarged piston and a part where a damping force is generated on an extension side and a contraction side in FIG. 1. It is a control block diagram of the controller which controls the energization to the solenoid of the damping force adjusting device. It is a characteristic diagram which shows the control characteristic of the damping force with respect to the vibration frequency of a vehicle.

Hereinafter, a case where the suspension device according to the embodiment of the present invention is configured by a damping force adjusting hydraulic shock absorber as a shock absorber and a controller will be taken as an example, and will be described in detail based on FIGS. 1 to 5 of the attached drawings. explain.

In FIG. 1, the damping force adjusting type hydraulic shock absorber 1 (hereinafter referred to as hydraulic shock absorber 1) includes an outer cylinder 2, an inner cylinder 4, a piston 5, a piston rod 6, a rod guide 9, a bottom valve 13, and a damping force, which will be described later. It includes an adjusting device 17, an extension side damping force generating unit 31, a contraction side damping force generating unit 42, and the like. The generated damping force of the hydraulic shock absorber 1 is variably adjusted by the damping force adjusting mechanism (damping force adjusting device 17) in response to a control command from the controller 50.

The bottomed cylindrical outer cylinder 2 forming the outer shell of the hydraulic shock absorber 1 is closed at one end (lower end) side by a bottom cap 3 using a welding means or the like, and the other end (upper end) side is bent inward in the radial direction. It is a welded part 2A. The outer cylinder 2 constitutes a cylinder together with the inner cylinder 4 described later. On the other hand, an opening 2B is formed concentrically with the connection port 12C of the intermediate cylinder 12 described later on the lower side of the outer cylinder 2, and a damping force adjusting device 17 described later is attached to a position facing the opening 2B. There is. Further, the bottom cap 3 is provided with a mounting eye 3A that is mounted on the wheel side of the vehicle, for example.

An inner cylinder 4 is provided on the inner side in the radial direction of the outer cylinder 2 so as to be located coaxially with the outer cylinder 2. The inner cylinder 4 constitutes a cylinder together with the outer cylinder 2. The lower end side of the inner cylinder 4 is fitted and attached to the bottom valve 13, and the upper end side is fitted and attached to the rod guide 9. A working fluid as a working fluid is sealed in the inner cylinder 4. The hydraulic fluid is not limited to oil and oil, and for example, water mixed with additives can be used.

An annular reservoir chamber A is formed between the outer cylinder 2 and the inner cylinder 4, and gas is sealed in the reservoir chamber A together with the hydraulic fluid. This gas may be air in an atmospheric pressure state, or a gas such as compressed nitrogen gas may be used. Further, in the middle of the inner cylinder 4 in the length direction (axial direction), an oil hole 4A in the radial direction is formed at a predetermined position, and the oil hole 4A allows the rod-side oil chamber C and the annular oil described later to be described. It is always in communication with room D.

The piston 5 is slidably inserted and provided in the inner cylinder 4. The piston 5 defines the inside of the inner cylinder 4 into one side chamber (that is, the bottom side oil chamber B) and the other side chamber (that is, the rod side oil chamber C). A plurality of oil passages 5A and 5B that allow the bottom side oil chamber B and the rod side oil chamber C to communicate with each other are formed in the piston 5 so as to be separated from each other in the circumferential direction. These oil passages 5A and 5B form a first passage for circulating pressure oil between the bottom side oil chamber B and the rod side oil chamber C in the inner cylinder 4.

As shown in FIG. 3, on the upper end surface of the piston 5, an annular recess 5C formed so as to surround the upper opening of each oil passage 5A and a contraction side located on the radial outer side of the annular recess 5C, which will be described later. An annular valve seat 5D on which the damping force generating portion 42 (that is, the disc valve) is taken off and seated is provided. On the lower end surface of the piston 5, an annular recess 5E formed so as to surround the lower opening of each oil passage 5B, and an extension side damping force generating portion 31 located on the radial outer side of the annular recess 5E and described later. An annular valve seat 5F on which (that is, the main disk 35A) is taken off and seated is provided.

Here, the extension-side damping force generating portion 31 provided on the lower surface side of the piston 5 is the rod-side oil when the piston 5 is slidably displaced upward in the extension (elongation) stroke of the piston rod 6, as will be described later. When the pressure in the chamber C exceeds the valve opening set pressure, the valve is opened, and the pressure oil at this time is circulated to the bottom side oil chamber B side via each oil passage 5B. Further, the contraction side damping force generating portion 42 provided on the upper surface side of the piston 5 opens when the piston 5 slides and displaces downward in the contraction stroke of the piston rod 6, as described later, and at other times, the valve is opened. It is kept closed.

The piston rod 6 extending in the inner cylinder 4 in the axial direction has a small diameter rod portion 6A on one end side (lower end side) thereof, and the piston 5 is attached to the small diameter rod portion 6A by a nut 8 via a spacer 7 or the like. It is fixed in the fastened state. On the outer peripheral surface of the small diameter rod portion 6A, a plurality of recessed grooves 6B that always communicate with the inside of the annular recess 5E of the piston 5 are formed so as to extend in the axial direction. The other end side (upper end side) of the piston rod 6 extends (projects) to the outside of the outer cylinder 2 and the inner cylinder 4 via a rod guide 9 or the like. For the nut 8, the piston 5 is attached to the small diameter rod portion 6A of the piston rod 6 in a screwed state, and the extension side and contraction side damping force generating portions 31 and 42, which will be described later, are fastened to both the upper and lower sides of the piston 5. It is to be fixed.

A stepped cylindrical rod guide 9 is provided on the upper end side of the inner cylinder 4. The rod guide 9 has a function of positioning the upper end portion of the inner cylinder 4 at the center of the outer cylinder 2 and guiding the piston rod 6 so as to be slidable in the axial direction on the inner peripheral side thereof. An annular sealing member 10 is provided between the caulked portion 2A of the outer cylinder 2 and the rod guide 9. The sealing member 10 seals between the inner peripheral side and the piston rod 6 by sliding contact with the outer peripheral side of the piston rod 6 to prevent the pressure oil in the outer cylinder 2 and the inner cylinder 4 from leaking to the outside. ing.

Further, the seal member 10 is formed with a lip seal 10A as a check valve extending so as to come into contact with the rod guide 9 on the lower surface side. The lip seal 10A is arranged between the oil reservoir 11 and the reservoir chamber A, and the hydraulic fluid or the like in the oil reservoir 11 flows toward the reservoir chamber A side through the return passage 9A of the rod guide 9. It allows and blocks the flow in the opposite direction.

An intermediate cylinder 12 is arranged between the outer cylinder 2 and the inner cylinder 4. The intermediate cylinder 12 is attached to, for example, the outer peripheral side of the inner cylinder 4 via upper and lower seal rings 12A and 12B. The intermediate cylinder 12 surrounds the outer peripheral side of the inner cylinder 4 over the entire circumference and is arranged so as to extend in the axial direction, and forms an annular oil chamber D with the inner cylinder 4. The annular oil chamber D is an oil chamber independent of the reservoir chamber A, and is always in communication with the rod side oil chamber C by the radial oil hole 4A formed in the inner cylinder 4. Further, on the lower end side of the intermediate cylinder 12, a connection port 12C to which the tubular holder 20 of the damping force adjusting valve 18 described later is attached is provided.

The bottom valve 13 is located on the lower end side of the inner cylinder 4 and is provided between the bottom cap 3 and the inner cylinder 4. As shown in FIG. 2, the bottom valve 13 has a valve body 14 that defines a reservoir chamber A and a bottom side oil chamber B between the bottom cap 3 and the inner cylinder 4, and a lower surface side (shaft) of the valve body 14. It is composed of a disc valve 15 on the reduction side provided on one side in the direction) and a check valve 16 on the extension side provided on the upper surface side (other side in the axial direction) of the valve body 14. Oil passages 14A and 14B are formed in the valve body 14 at intervals in the circumferential direction, and these oil passages 14A and 14B allow communication between the reservoir chamber A and the bottom side oil chamber B. ..

Here, the disc valve 15 on the reduction side opens when the pressure in the oil chamber B on the bottom side exceeds the relief set pressure when the piston 5 slides and displaces downward in the contraction stroke of the piston rod 6. The pressure oil (pressure) at that time is relieved to the reservoir chamber A side via each oil passage 14A. This relief set pressure is set to a valve opening pressure higher than the pressure when the damping force adjusting device 17, which will be described later, is set hard.

The extension-side check valve 16 opens when the piston 5 slides and displaces upward during the extension stroke of the piston rod 6, and closes at other times. The extension-side check valve 16 allows the pressure oil (hydraulic fluid) in the reservoir chamber A to flow in each oil passage 14B toward the bottom-side oil chamber B, and the hydraulic fluid flows in the opposite direction. Stop flowing. The valve opening pressure of the extension side check valve 16 is set to a valve opening pressure lower than the pressure when the damping force adjusting device 17 described later is softly set, and substantially no damping force is generated. ..

Next, the damping force adjusting device 17 as a damping force adjusting mechanism for variably adjusting the generated damping force of the hydraulic shock absorber 1 will be described with reference to FIGS. 1 and 2.

The damping force adjusting device 17 is arranged so that its base end side (left end side in FIG. 1) is interposed between the reservoir chamber A and the annular oil chamber D, and the tip end side (right end side in FIG. 1) is the outer cylinder 2. It is provided so as to project radially outward from the lower side of the. The damping force adjusting device 17 controls the flow of the pressure oil flowing from the annular oil chamber D in the intermediate cylinder 12 to the reservoir chamber A by the damping force adjusting valve 18, and variably adjusts the damping force generated at this time. That is, in the damping force adjusting valve 18, the generated damping force is variably controlled by adjusting the valve opening pressure of the set pressure variable valve 22, which will be described later, by the damping force variable actuator (solenoid 25).

Here, the damping force adjusting valve 18 has a valve case 19 whose base end side is fixed around the opening 2B of the outer cylinder 2 and whose tip end side protrudes radially outward of the outer cylinder 2 and the base end side. The tubular holder 20 is connected (fixed) to the connection port 12C of the intermediate cylinder 12, and the flange portion 20A (see FIG. 2) at the tip is arranged inside the valve case 19 with a gap, and is arranged inside the valve case 19. For a set pressure variable valve 22 composed of a valve member 21 that abuts on the flange portion 20A of the tubular holder 20 and a main disc valve that takes off and sits on the valve seat 21A of the valve member 21, and the set pressure variable valve 22. The back pressure chamber 23 on which the back pressure is applied and the pilot pressure (back pressure) in the back pressure chamber 23 are set variably according to the energization (current value) to the solenoid 25, and the set pressure variable valve 22 is opened. It includes a pilot valve member 24 for adjusting the valve pressure.

The set pressure variable valve 22 receives the pressure in the direction of being seated on the valve seat 21A of the valve member 21 (that is, the valve closing direction) by the pilot pressure (back pressure) from the back pressure chamber 23. That is, the set pressure variable valve 22 receives the pressure on the inlet (annular oil chamber D) side of the tubular holder 20, and when this pressure exceeds the pilot pressure (back pressure) on the back pressure chamber 23 side, the valve member 21 The valve is opened by separating from the valve seat 21D.

In this case, in the variable set pressure valve 22, the valve opening pressure is variably set by adjusting the pilot pressure (back pressure) in the back pressure chamber 23 via the pilot valve member 24. When the variable set pressure valve 22 is released (opened) from the valve seat 21D of the valve member 21, the pressure oil from the annular oil chamber D (intermediate cylinder 12) side passes through the oil passage in the valve member 21 to set the set pressure. It flows out to the outside of the variable valve 22 and flows from between the flange portion 20A of the tubular holder 20 and the valve case 19 to the reservoir chamber A side through the opening 2B of the outer cylinder 2.

Next, the solenoid 25 constitutes the damping force adjusting device 17 together with the damping force adjusting valve 18, and is used as a damping force variable actuator. As shown in FIG. 2, the solenoid 25 is a tubular coil 26 that generates a magnetic force by energization from the outside, a stator core 27 arranged on the inner peripheral side of the coil 26, and an inner peripheral side of the stator core 27. It is configured to include a plunger 28 as a movable iron core provided so as to be movable in the axial direction, an actuating pin 29 integrally provided on the center side of the plunger 28, a cover member 30 covering the outer periphery of the coil 26, and the like. ing.

The cover member 30 constitutes a yoke made of a magnetic material, and forms a magnetic circuit on the outer peripheral side of the coil 26. The actuating pin 29 extends in the plunger 28 in the axial direction (left and right directions in FIG. 2), and the pilot valve member 24 of the damping force adjusting valve 18 is fixed to the protruding end on the left side. That is, the actuating pin 29 of the solenoid 25 is fitted and fixed inside the pilot valve member 24, and the pilot valve member 24 is displaced in the horizontal direction (left, right direction) integrally with the plunger 28 and the actuating pin 29. ..

Here, an axial thrust proportional to the energization (current value) of the coil 26 is generated in the plunger 28 of the solenoid 25, and the pilot pressure (back pressure) in the back pressure chamber 23 is the pilot pressure (back pressure) of the pilot valve member 24. It is set variably according to the thrust of the plunger 28 due to the displacement. That is, the valve opening pressure of the set pressure variable valve 22 that opens the valve against the pressure in the back pressure chamber 23 is adjusted by displaced the pilot valve member 24 in the axial direction in response to the energization of the solenoid 25. .. In other words, the valve opening pressure of the variable set pressure valve 22 is increased or decreased by controlling the current value of energizing the coil 26 of the solenoid 25 by the controller 50 described later and displacing the pilot valve member 24 in the axial direction. Ru. Therefore, the generated damping force of the hydraulic shock absorber 1 can be variably adjusted according to the valve opening pressure of the set pressure variable valve 22 proportional to the energization (current value) of the solenoid 25.

Next, FIG. 3 shows a specific configuration of the extension side damping force generating portion 31 and the contraction side damping force generating portion 42 provided on the small diameter rod portion 6A of the piston rod 6 located on both the upper and lower sides of the piston 5. Will be described with reference to.

The extension side damping force generating unit 31 suppresses the flow of the hydraulic fluid from the upstream chamber (rod side oil chamber C) to the downstream chamber (bottom side oil chamber B) caused by the movement of the piston 5, and suppresses the damping force. (That is, the damping force control valve 35), the back pressure chamber 36 that exerts back pressure in the valve closing direction of the main valve, and the hydraulic fluid from the upstream side chamber are transferred to the back pressure chamber 36. A back pressure chamber introduction orifice 41 for introduction, a pressure adjusting mechanism for adjusting the opening of the main valve by the back pressure of the back pressure chamber 36 (for example, an elastic sealing member 35B described later), and high frequency vibration. It is provided with a frequency-sensitive portion (free valve 37 described later) that reduces the damping force and supplies the hydraulic fluid via the back pressure chamber introduction orifice 41.

Here, on the outer peripheral surface of the small diameter rod portion 6A of the piston rod 6, a plurality of concave grooves 6B that always communicate with the inside of the annular recess 5E of the piston 5 are formed so as to extend in the axial direction. The concave groove 6B communicates with the back pressure chamber 36, which will be described later, via the back pressure chamber introduction orifice 41. A pressure difference is generated between the inside of the annular recess 5E of the piston 5 and the back pressure chamber 36 due to, for example, the throttle action of the back pressure chamber introduction orifice 41.

As shown in FIG. 3, the extension side damping force generating portion 31 is located in the bottom side oil chamber B of the inner cylinder 4 and is fixedly attached to the lower side of the piston 5. When the piston 5 slides upward in the inner cylinder 4 in the extension (extension) stroke of the piston rod 6, the extension-side damping force generating portion 31 is provided from the rod-side oil chamber C to each oil passage 5B of the piston 5. A resistance force is applied to the pressure oil flowing toward the bottom side oil chamber B through the annular recess 5E or the like, and a damping force on the extension side is generated with predetermined characteristics.

The extension side damping force generating portion 31 is located between the piston 5 and the spacer 7 and is fixed to the outer peripheral side of the piston rod 6 (small diameter rod portion 6A). , 33, a relief valve 34 arranged between the first and second valve seat members 32 and 33, a damping force control valve 35 as a main valve, and a free valve 37 (that is, a frequency sensitive valve) described later. The second valve) and the like are included. The damping force control valve 35 has the elastic seal member 35B described later, which is fitted to the inner peripheral side of the first valve seat member 32 (the inner peripheral surface of the short tubular portion 32B described later) with a tightening margin, and is the first valve seat. It is a first valve that forms an annular back pressure chamber 36 with the member 32.

Of the two valve seat members 32 and 33, the upper first valve seat member 32 has an annular plate portion 32A fitted to the outer peripheral side of the small diameter rod portion 6A and an outer peripheral side of the annular plate portion 32A. An annular portion 32B extending from the upper side (other side) in the axial direction to a position close to the lower end surface of the piston 5 and an annular portion formed on the lower side surface of the annular plate portion 32A and opened and closed by the relief valve 34. It is configured to include a recess 32C and a plurality of through holes 32D formed in the radial intermediate portion of the annular plate portion 32A so as to communicate the inside of the short cylinder portion 32B with the inside of the annular recess 32C and opened upward and downward. ing.

Of the two valve seat members 32 and 33, the lower second valve seat member 33 has a small diameter rod portion 6A so as to sandwich the relief valve 34 from the first valve seat member 32 from above and below. It is configured to include an annular plate portion 33A fitted on the outer peripheral side and a short one-side cylinder portion 33B extending downward from the outer peripheral side of the annular plate portion 33A to one side in the axial direction. ing. The lower second valve seat member 33 has a configuration in which a free valve 37, which will be described later, is housed inside the one-side cylinder portion 33B.

The relief valve 34 is composed of a disc valve provided so as to be sandwiched between the valve seat members 32 and 33 on the outer peripheral side of the small diameter rod portion 6A. The relief valve 34 always closes the annular recess 32C of the first valve seat member 32. However, the pressure in the back pressure chamber 36 communicating with the annular recess 32C through the through hole 32D rises to the valve opening set pressure of the relief valve 34 (pressure higher than the valve opening set pressure of the damping force control valve 35). Then, the relief valve 34 is released (opened) from the end surface of the first valve seat member 32, and functions as a safety valve for relieving the excess pressure at this time to the bottom side oil chamber B side.

The damping force control valve 35 is an annular elastic seal provided on the outer peripheral side of the lower surface of the main disk 35A which is detached and seated on the annular valve seat 5F of the piston 5 and fixed by means such as vulcanization or baking. It is composed of a member 35B. The elastic sealing member 35B is formed in a thick ring shape using an elastic material such as rubber, and is between the inner back pressure chamber 36 (that is, the short cylinder portion 32B) with respect to the outer bottom side oil chamber B. ) Is liquidtightly sealed.

The elastic seal member 35B of the damping force control valve 35 comes into contact with the inner peripheral surface of the short tubular portion 32B of the first valve seat member 32 in an elastically deformed state, and the back pressure of the back pressure chamber 36 causes the main disk 35A (main). It constitutes a pressure adjustment mechanism that adjusts the valve opening. The valve opening set pressure of the damping force control valve 35 is adjusted with a variable width by the elastic deflection deformation of the elastic sealing member 35B.

In the damping force control valve 35, the pressure oil from the oil chamber C on the rod side passes through each oil passage 5B of the piston 5, the annular recess 5E, the back pressure chamber introduction orifice 41, and the like in the extension stroke of the piston rod 6, and the back pressure chamber 36. When introduced into the inside, a pressure difference is generated between the rod side oil chamber C (annular recess 5E) and the back pressure chamber 36 (that is, the inside of the short cylinder portion 32B). Then, when this pressure difference becomes larger than the predetermined valve opening set pressure, the main disk 35A of the damping force control valve 35 separates from the annular valve seat 5F and generates a predetermined extension side damping force. do. The extension side damping force at this time is set to a predetermined damping force in relation to the damping force variably adjusted by the damping force adjusting device 17 (see FIG. 2).

When the damping force control valve 35 (main disk 35A) is opened, the bottom side oil chamber B and the rod side oil chamber C communicate with each other via the oil passage 5B of the piston 5, the annular recess 5E, and the annular valve seat 5F. .. On the other hand, when the damping force control valve 35 (main disk 35A) is closed, for example, the pressure oil in the oil chamber C on the rod side is concave from the oil passage 5B of the piston 5, the annular recess 5E to the piston rod 6 (small diameter rod portion 6A). It is introduced into the back pressure chamber 36 through the groove 6B, the back pressure chamber introduction orifice 41, and the like.

The extension side damping force generating portion 31 has a free valve 37 provided in the one side cylinder portion 33B of the second valve seat member 33. The free valve 37 is composed of a disc valve 37A and an annular elastic sealing member 37B. The disc valve 37A of the free valve 37 is attached to the one side cylinder portion 33B of the second valve seat member 33 via a plurality of valve seat discs 38 and a lid plate 39, and is detached and seated on the outer peripheral side of the valve seat disc 38. It is configured as a check valve body.

The elastic sealing member 37B of the free valve 37 is provided fixed to the outer peripheral side of the disc valve 37A by means such as vulcanization and baking. The elastic sealing member 37B is formed in a ring shape using an elastic material such as rubber, and is in liquid-tight contact with the inner peripheral surface of the one-side cylinder portion 33B with a tightening margin. As a result, the one-side cylinder portion 33B of the second valve seat member 33 is internally defined by the free valve 37 into a frequency-sensitive damper upper chamber B1 and a damper lower chamber B2.

Further, an oil guide for communicating the concave groove 6B of the piston rod 6 (small diameter rod portion 6A) to the damper upper chamber B1 between the annular plate portion 33A of the second valve seat member 33 and the disc valve 37A of the free valve 37. A road 40 is provided. Therefore, the damper upper chamber B1 communicates with the back pressure chamber 36 via the oil guide passage 40, the concave groove 6B, and the back pressure chamber introduction orifice 41.

Here, the volume in the damper upper chamber B1 is expanded or contracted by the displacement (including elastic deformation) of the disc valve 37A and the elastic sealing member 37B. In this case, the free valve 37 is configured as a second valve for adjusting the pressure (internal pressure) in the back pressure chamber 36. The lid plate 39 is provided so as to be fitted between the outer peripheral side of the small diameter rod portion 6A and the inner peripheral side of the one-side cylinder portion 33B, and the fastening force from the nut 8 is provided between the valve seat disc 38 and the spacer 7. Is sandwiched by. A plurality of through holes 39A are bored in the radial intermediate portion of the lid plate 39 in the upward and downward directions. These through holes 39A are communication holes that allow the inside of the one-side cylinder portion 33B (damper lower chamber B2) of the second valve seat member 33 to always communicate with the outer bottom-side oil chamber B.

In the free valve 37, the disc valve 37A as a check valve body continues to be seated on the outer peripheral side of the valve seat disc 38 during the extension stroke of the piston rod 6, and in this state, the vibration frequency of the piston rod 6 and / or the inner cylinder 4 is adjusted. Accordingly, the relative displacement is performed so as to move or stop in the one-side cylinder portion 33B up and down. As a result, the free valve 37 operates as a frequency-sensitive valve that adjusts the internal pressure of the damper upper chamber B1 (that is, the back pressure chamber 36) according to the frequency.

On the other hand, in the contraction stroke of the piston rod 6, the damper lower chamber B2 has a relatively higher pressure than the damper upper chamber B1. Therefore, in the free valve 37, the disc valve 37A as a check valve body is the outer periphery of the valve seat disk 38. Open the valve so that it is separated from the side. As a result, the pressure oil (hydraulic fluid) in the bottom side oil chamber B flows from the damper lower chamber B2 to the damper upper chamber B1, the oil guide passage 40, the recessed groove 6B of the piston rod 6 (small diameter rod portion 6A), and the like. It circulates to the back pressure chamber 36, and a part of it circulates from the annular recess 5E of the piston 5 and the oil passage 5B toward the rod side oil chamber C via the back pressure chamber introduction orifice 41 and the like.

Between the annular recess 5E of the piston 5 and the main disk 35A of the damping force control valve 35, the passage 41A which communicates with the recess 6B of the piston rod 6 (small diameter rod portion 6A) and constitutes the back pressure chamber introduction orifice 41. Is provided. Further, between the main disk 35A of the damping force control valve 35 and the first valve seat member 32, the concave groove 6B is communicated with the back pressure chamber 36 to form a back pressure chamber introduction orifice 41 together with the passage 41A. Passage 41B is provided. The back pressure chamber introduction orifice 41 introduces the pressure oil from the rod side oil chamber C into the back pressure chamber 36 via the oil passage 5B of the piston 5, the annular recess 5E, the passage 41A, the concave groove 6B and the other passage 41B. do.

The concave groove 6B of the piston rod 6 (small diameter rod portion 6A) communicates the back pressure chamber introduction orifice 41 to the damper upper chamber B1 via the oil guide passage 40 on the second valve seat member 33 side. As a result, in the damper upper chamber B1 between the second valve seat member 33 and the free valve 37, the pressure oil from the rod side oil chamber C is supplied to the oil passage 5B of the piston 5, the annular recess 5E, the passage 41A, and the concave groove. It is supplied via 6B and the oil conduit 40. Here, the passage 41A of the back pressure chamber introduction orifice 41 is formed in a predetermined orifice area in order to determine the cutoff frequency fc (see FIG. 5) of the free valve 37.

That is, in the extension stroke of the piston rod 6, the volume in the damper upper chamber B1 is expanded due to the displacement (including elastic deformation) of the disc valve 37 A of the free valve 37 and the elastic seal member 37 B. In this expanded range, the pressure oil in the back pressure chamber 36 circulates toward the damper upper chamber B1. Therefore, the pressure in the back pressure chamber 36 is lowered by the displacement of the free valve 37, and the valve opening set pressure of the damping force control valve 35 is lowered accordingly. As a result, the damping force control valve 35 of the extension side damping force generation unit 31 is soft from the hard state to the characteristic of the generated damping force before and after the cutoff frequency fc as shown in the characteristic line 58 shown in FIG. It is switched to the state.

In this way, the free valve 37 operates as a frequency-sensitive valve that adjusts the internal pressure of the damper upper chamber B1 (that is, the back pressure chamber 36) according to the vibration frequency of the piston rod 6 and / or the inner cylinder 4. In this case, the cutoff frequency fc is a frequency determined by the orifice area of the back pressure chamber introduction orifice 41 (passage 41A), and is preferably set to, for example, frequencies before and after 1 Hz.

As a result, in the damping force control valve 35 of the extension side damping force generating unit 31, the vibration frequency of the piston rod 6 and / or the inner cylinder 4 is lower than the cutoff frequency fc, as shown in the characteristic line 58 shown in FIG. At the time of frequency, the pressure in the back pressure chamber 36 is not lowered by the free valve 37, and the valve opening set pressure of the damping force control valve 35 is maintained at a relatively high pressure. However, when the vibration frequency is higher than the cutoff frequency fc (for example, when traveling on a rough road), the pressure in the back pressure chamber 36 is reduced by the free valve 37, and the damping force control valve 35 is set to open. Since the pressure is reduced, the characteristics of the generated damping force switch to a soft state.

The compression side damping force generating portion 42 is a disk provided between the upper end surface (annular recess 5C) of the piston 5 and the spacer 43 so as to block the oil passage 5A of the piston 5 from the rod side oil chamber C. It is composed of valves. When the piston 5 slides and displaces downward in the inner cylinder 4 in the contraction stroke of the piston rod 6, the compression side damping force generating portion 42 is provided from the bottom side oil chamber B to each oil passage 5A of the piston 5 and the annular recess. A resistance force is applied to the pressure oil flowing toward the rod side oil chamber C via the 5C, and a damping force on the contraction side is generated with predetermined characteristics.

Next, the configuration of the controller 50 as a control device for driving and controlling the solenoid 25 (actuator of the damping force adjusting device 17 shown in FIG. 2) will be described with reference to FIG.

In the controller 50, a vertical acceleration sensor (hereinafter referred to as G sensor 51) and a CAN 52 are connected to the input side thereof, and a solenoid 25 or the like is connected to the output side. The G sensor 51 detects the vibration acceleration in the upward and downward directions on the unsprung (wheel) side and / or the unsprung (vehicle body) side of the vehicle. The CAN 52 is a serial communication unit mounted on the vehicle body side of the vehicle, and performs multiplex communication for a vehicle between a large number of electronic devices (not shown) mounted on the vehicle and the controller 50. In this case, the vehicle driving information sent to the CAN 52 includes, for example, detection signals (information) from a steering angle sensor, a brake operation detector, an accelerator sensor, a wheel speed sensor (none of which are shown), and the like.

In this embodiment, since the vehicle driving information from the CAN 52 is input to the controller 50, it is only necessary to provide one G sensor 51 for one vehicle body. However, for example, a total of three G sensors 51 may be provided on the vehicle body. In this case, the G sensor 51 is attached to the vehicle body at a position near the upper end side (rod protruding end side) of the hydraulic shock absorber 1 on each front wheel side, and is also attached to the vehicle body at an intermediate position between the left and right rear wheels. Can be installed.

The controller 50 is a control device configured by a microcomputer or the like. The controller 50 includes, for example, a storage unit (not shown) composed of ROM, RAM, non-volatile memory, etc., a vehicle body vibration estimation unit 53, a spring vibration damping control unit 54, a steering stability control unit 55, a vehicle speed sensitive control unit 56, and control. It is configured to include a command calculation unit 57. The controller 50 reads the upper and lower vibrations on the vehicle body side from the G sensor 51, and reads each detection signal from the steering angle sensor, the brake operation detector, the accelerator sensor, the wheel speed sensor, etc. by serial communication from the CAN 52. ..

On this basis, the controller 50 estimates the vibration of the vehicle body by the vehicle body vibration estimation unit 53 from the sensor information from the G sensor 51 and the CAN 52, and estimates the steering state of the vehicle by the steering stability control unit 55. The vehicle speed sensitive control unit 56 estimates the traveling state of the vehicle. The control command calculation unit 57 is a damping force adjusting device for the hydraulic shock absorber 1 on each wheel side according to control signals from the spring-up vibration damping control unit 54, the steering stability control unit 55, and the vehicle speed-sensitive control unit 56 connected in parallel with each other. The damping force command signal to be output to 17 (solenoid 25) is calculated and processed as a control command value (current value).

The damping force adjusting device 17 of each hydraulic shock absorber 1 axially displaces the pilot valve member 24 of the damping force adjusting valve 18 according to the current value (damping force command signal) output from the control command calculation unit 57 to the solenoid 25. .. As a result, in the damping force adjusting valve 18, the valve opening pressure of the set pressure variable valve 22 is adjusted by the damping force variable actuator (solenoid 25), and the characteristics of the generated damping force are continuously or plural between hard and soft. It is variably controlled by the stage.

The steering stability control unit 55 of the controller 50 controls according to a control amount (for example, a calculation formula performed by estimating lateral acceleration, a control rule, etc.) based on the steering angle signal from the steering angle sensor and the vehicle speed signal from the wheel speed sensor. Amount) is calculated, and the calculated control amount is output to the control command calculation unit 57 as a control command value. Further, the vehicle speed sensitive control unit 56 calculates a control amount from the vehicle speed signal or the like, and outputs the calculated control amount as a control command value to the control command calculation unit 57.

Further, the controller 50 of the damping force adjusting device 17 generates a damping force having a soft characteristic to a hard characteristic according to the motion state for the motion of the vehicle whose frequency is lower than the cutoff frequency fc. The solenoid 25 is energized to variably adjust the damping force characteristic of the hydraulic shock absorber 1 within the range of the variable width 60 (see FIG. 5) described later. For motion in the high frequency range above the cutoff frequency fc, the lower limit is a damping force (see value 61 in FIG. 5) that is higher than the soft characteristic (see value 59 in FIG. 5), and depending on the motion state. The damping force characteristic of the hydraulic shock absorber 1 is variably adjusted within the range of the variable width 62 described later, up to the hard characteristic.

The suspension device according to the present embodiment has the above-mentioned configuration, and its operation will be described next.

When the hydraulic shock absorber 1 is mounted on the vehicle, the upper end side of the piston rod 6 is attached to the vehicle body side of the vehicle, and the attachment eye 3A is attached to the wheel side of the bottom cap 3 side of the outer cylinder 2. When the vehicle travels, when vibrations in the upward and downward directions occur due to unevenness of the road surface, the piston rod 6 is displaced so as to extend and contract from the inner cylinder 4, and the extension side damping force generating portion 31 and the contraction side damping force are generated. A damping force can be generated by the portion 42 or the like, and the vibration of the vehicle can be buffered.

That is, in the contraction stroke of the piston rod 6, the piston rod 6 enters the inner cylinder 4, and the pressure inside the bottom oil chamber B becomes higher than that in the rod side oil chamber C. Therefore, the pressure oil in the bottom side oil chamber B flows into the annular recess 5C from the oil passage 5B of the piston 5, and the inflow oil generates a predetermined damping force by the contraction side damping force generating portion 42. , Flows to the rod side oil chamber C. At this time, the pressure oil in the oil chamber C on the rod side flows from the oil hole 4A to the damping force adjusting device 17 side via the annular oil chamber D by the volume of the approaching body into the inner cylinder 4 in the contraction stroke of the piston rod 6. do.

On the other hand, in the extension stroke of the piston rod 6, the pressure inside the rod side oil chamber C is higher than that in the bottom side oil chamber B, so that the pressure oil in the rod side oil chamber C is from the oil passage 5B of the piston 5 to the inside of the annular recess 5E. Inflow to. This inflow oil is introduced from the annular recess 5E of the piston 5 into the back pressure chamber 36 via the back pressure chamber introduction orifice 41, the concave groove 6B of the piston rod 6, and the like, and further, the concave groove 6B of the piston rod 6 and the first. 2 It is also guided to the damper upper chamber B1 via the oil guide passage 40 on the valve seat member 33 side.

In the damping force control valve 35 of the extension side damping force generating unit 31, the pressure oil from the rod side oil chamber C in the extension stroke of the piston rod 6 is in each oil passage 5B of the piston 5, the annular recess 5E, and the back pressure chamber introduction orifice 41. When introduced into the back pressure chamber 36 via the like, a pressure difference is generated between the rod side oil chamber C (annular recess 5E) and the back pressure chamber 36. Then, when this pressure difference becomes larger than the predetermined valve opening set pressure, the main disk 35A of the damping force control valve 35 separates from the annular valve seat 5F and generates a predetermined extension side damping force. do.

Here, the internal pressure of the damper upper chamber B1 (that is, the back pressure chamber 36) is applied to the second valve seat member 33 of the extension side damping force generating portion 31 according to the vibration frequency of the piston rod 6 and / or the inner cylinder 4. A free valve 37 is provided as a frequency sensitive valve to be adjusted. That is, in the extension stroke of the piston rod 6, when the free valve 37 is displaced according to the vibration of the vehicle, the pressure oil in the back pressure chamber 36 circulates toward the damper upper chamber B1. Therefore, the pressure in the back pressure chamber 36 is lowered by the displacement of the free valve 37, and the valve opening set pressure of the damping force control valve 35 is lowered accordingly.

In this case, in the damping force control valve 35 of the extension side damping force generating unit 31, the vibration frequency of the piston rod 6 and / or the inner cylinder 4 is lower than the cutoff frequency fc as shown in the characteristic line 58 shown in FIG. At the time of frequency, the pressure in the back pressure chamber 36 is not lowered by the free valve 37, and the valve opening set pressure of the damping force control valve 35 is maintained at a relatively high pressure. However, when the vibration frequency is higher than the cutoff frequency fc (for example, when traveling on a rough road), the pressure in the back pressure chamber 36 is reduced by the free valve 37, and the damping force control valve 35 is opened. Since the set pressure is lowered, the characteristics of the generated damping force switch to a soft state.

Even in the extension stroke of the piston rod 6, the pressure oil in the oil chamber C on the rod side flows out from the inner cylinder 4 into the annular oil chamber D through the oil hole 4A as the piston 5 is displaced, and the annular oil flows. The pressure oil in the chamber D flows to the damping force adjusting device 17 side through the connection port 12C of the intermediate cylinder 12. Here, the outer cylinder 2 of the hydraulic shock absorber 1 is provided with a damping force adjusting device 17 so as to be interposed between the annular oil chamber D and the reservoir chamber A, which are always in communication with the rod-side oil chamber C. The controller 50 calculates a damping force command signal to be output to the damping force adjusting device 17 (solenoid 25) of the hydraulic shock absorber 1 based on the sensor information from the G sensor 51 and the CAN 52.

In this way, the controller 50 controls the flow of the pressure oil flowing from the annular oil chamber D in the intermediate cylinder 12 to the reservoir chamber A by the damping force adjusting valve 18 of the damping force adjusting device 17, and the damping generated at this time is controlled. The force is variably adjusted according to a control command from the controller 50. That is, in the damping force adjusting valve 18, the generated damping force is variably controlled by adjusting the valve opening pressure of the set pressure variable valve 22 by the solenoid 25, and the generated damping force of the hydraulic shock absorber 1 is transferred to the solenoid 25. The set pressure variable valve 22 can be variably adjusted according to the valve opening pressure in proportion to the energization (current value) of the valve.

Therefore, the process of variably controlling the damping force characteristic of the hydraulic shock absorber 1 by the controller 50 will be described with reference to FIG.

The characteristic line portion 58A of the characteristic line 58 shown in FIG. 5 is a case where the vibration frequency of the vehicle is a low frequency lower than the cutoff frequency fc. The controller 50 calculates a damping force command signal to be output to the damping force adjusting device 17 (solor 25) of the hydraulic shock absorber 1 based on the sensor information from the G sensor 51 and CAN 52 shown in FIG. 4, and hardens the damping force. When the characteristics are set, the control current Ih1 (for example, 1.6A) set by the hardware is output to the solenoid 25. The characteristic line portion 58A corresponds to a state in which the control current Ih1 set by the hardware is output to the solenoid 25.

On the other hand, when the damping force is set to a soft characteristic, the control current Is1 (for example, 0.3A) set by the soft is output from the controller 50 to the solenoid 25. The soft damping force value 59 shown by the dotted line in FIG. 5 corresponds to the control current Is1 set by the soft line. When the vibration frequency of the vehicle is a low frequency lower than the cutoff frequency fc, the damping force command signal output from the controller 50 to the solenoid 25 is between the hard setting control current Ih1 and the soft setting control current Is1. It is calculated variably based on the sensor information. Therefore, the damping force characteristic of the hydraulic shock absorber 1 is variably adjusted in the range of the variable width 60 in FIG. 5 in the low frequency region lower than the cutoff frequency fc.

Next, when the vibration frequency of the vehicle is a high frequency of the cutoff frequency fc or higher, the controller 50 is used to suppress unspring vibration (fluttering, etc.) in addition to suppressing the high frequency vibration component that makes the ride uncomfortable. Controls to raise the soft damping to some extent. For example, when it is determined from the sensor information from the G sensor 51 and the CAN 52 that the unspring vibration is large, the controller 50 raises the soft-set control current Is1 to the soft-set control current value Isx (for example, about 0.5 A). .. The soft damping force value 61 shown by the dotted line in FIG. 5 corresponds to the control current value Isx set by the soft line.

When the vibration frequency of the vehicle is a high frequency equal to or higher than the cutoff frequency fc, the damping force command signal output from the controller 50 to the solenoid 25 is set hard as shown in the characteristic line portion 58B of the characteristic line 58 shown in FIG. It is variably calculated based on the sensor information between the control current Ih1 and the control current value Isx set by the software. However, at high frequencies above the cutoff frequency fc, the valve opening set pressure of the damping force control valve 35 is lowered by the free valve 37 of the extension side damping force generation unit 31, so that the characteristics of the generated damping force are switched to a soft state. .. Therefore, in the high frequency range of the cutoff frequency fc or higher, the damping force characteristic of the hydraulic shock absorber 1 is variably adjusted within the range of the variable width 62 shown in FIG.

Further, when the vibration frequency becomes a low frequency region of the cutoff frequency fc or less, the controller 50 shifts the damping force command signal output to the solenoid 25 to the control current Is1 (for example, 0.3A) of the original soft setting. Control. Therefore, the damping force can be adjusted by simple control without the need for an expensive ECU corresponding to high frequency.

Thus, according to the present embodiment, for the motion of the vehicle whose frequency is lower than the cutoff frequency fc, the controller 50 is used to generate a damping force of the soft characteristic to the hard characteristic according to the motion state. The damping force characteristic of the hydraulic shock absorber 1 is variably adjusted within the range of the variable width 60 in FIG. For motion in the high frequency range above the cutoff frequency fc, the lower limit is the damping force (value 61 in FIG. 5) higher than the soft characteristic (value 59 in FIG. 5), and the hard characteristic is reached according to the motion state. The damping force characteristic of the hydraulic shock absorber 1 is variably adjusted within the range of the variable width 62 in FIG.

As a result, the unpleasant vibration to the high frequency input is mechanically adjusted by the frequency sensitive part (free valve 37), the damping force is appropriately lowered so as to have a soft characteristic, and the controller 50 is variable in that the high frequency is also limited. In width 62. The damping force adjusting device 17 can be controlled so as to have an appropriate soft damping force according to the unsprung vibration, and the riding comfort in various driving scenes can be improved.

That is, when the vibration frequency of the vehicle is a high frequency equal to or higher than the cutoff frequency fc, the controller 50 controls to raise the control current Is1 of the soft setting to the control current value Isx and raise the soft attenuation to some extent, as shown in FIG. .. As a result, in addition to suppressing only the high-frequency vibration component that makes the ride quality unpleasant, it is possible to perform control that suppresses unsprung vibration (fluttering or the like).

Then, the controller 50 adjusts to various driving scenes by changing the increase width of the soft attenuation that raises the control current Is1 of the soft setting shown in FIG. 5 to the control current value Isx according to the magnitude of the unspring vibration, the time of continuous vibration, and the like. Therefore, it is possible to adjust the damping force so that the optimum spring vibration is obtained.

Therefore, in the present embodiment, even in the high frequency range where the vibration frequency of the vehicle is equal to or higher than the cutoff frequency fc, the controller 50 energizes the solenoid 25 of the damping force adjusting device 17 to perform so-called semi-acoustic control. Even the hydraulic shock absorber 1 provided with the free valve 37) can improve the responsiveness to the road surface change. This makes it possible to improve the riding comfort on a compound input road surface (superimposed road in which low frequency and high frequency are mixed), for example.

Moreover, while ensuring steering stability and low-frequency riding comfort such as swelling roads, control for high-frequency input can also be controlled according to the driving scene, and the degree of freedom of adjustment can be increased. Further, even if the steering stability control by the semi-active suspension (that is, the semi-ac) is activated, such as when changing lanes when the vehicle is running, it is possible to reduce unpleasant vibration due to the increase in the damping force of the hydraulic shock absorber 1. can. Furthermore, it is possible to improve the riding comfort in the high frequency range and reduce the steering / floor vibration.

Further, in the present embodiment, the under-spring vibration is controlled by the controller 50, but the magnitude of the under-spring vibration exceeds a certain threshold instead of being controlled in real time by changing the command current at the frequency of the under-spring vibration. If it continues continuously, the control current Isx of the soft setting is shifted to some extent, and when the vibration becomes equal to or less than the threshold value, the control current Is1 of the original soft setting is shifted. Therefore, the controller 50 can improve the ride quality by simple control without requiring an expensive ECU corresponding to a high frequency.

In the above embodiment, the case where the vibration on the vehicle body side is obtained by calculation from the signals from the G sensor 51 and the CAN 52 has been described as an example. However, the present invention is not limited to this, and may be configured to obtain the vibration state of the vehicle body from, for example, preview information of the front road surface using an image pickup element such as a digital camera or a laser sensor, or a detection signal from a vehicle height sensor. ..

Further, in the above-described embodiment, the case where the actuator of the damping force adjusting mechanism (damping force adjusting device 17) is configured by the solenoid 25 has been described as an example. However, the present invention is not limited to this, and the damping force of the shock absorber may be adjusted by an actuator such as an electric motor.

Next, as the suspension device included in the above embodiment, for example, the suspension device described below can be considered.

A first aspect of the suspension device is a suspension device provided between the vehicle body side and the wheel side of the vehicle, which comprises a shock absorber whose damping force can be adjusted by an actuator, and a controller for controlling the actuator. The shock absorber is provided with a frequency-sensitive unit that reduces the damping force against high-frequency vibrations having a vibration frequency higher than a predetermined vibration frequency, and the controller applies the damping force by the actuator according to the motion state of the vehicle. It is characterized in that the damping force is reduced by the frequency-sensitive portion when the frequency is adjusted and the frequency is high.

As a second aspect of the suspension device, a cylinder in which a working fluid is enclosed, a piston provided in the cylinder and divided into a one-side chamber and another side chamber, and one end connected to the piston and the other end outside the cylinder. The piston rod extended to, the main valve that suppresses the flow of working fluid from the upstream chamber to the downstream chamber caused by the movement of the piston to generate a damping force, and the valve closing direction of the main valve. The back pressure chamber is provided with a back pressure chamber for applying back pressure to the back pressure chamber, and a back pressure chamber introduction orifice for introducing the working fluid from the upstream chamber into the back pressure chamber. The pressure adjustment mechanism that adjusts the valve opening, the frequency sensitive part that reduces the damping force against high frequency vibration and the working fluid is supplied through the back pressure chamber introduction orifice, and the damping force are adjusted by the actuator. In a suspension device including a possible damping force adjusting mechanism and a controller for controlling the actuator, the controller has a soft characteristic to a hard characteristic depending on the motion state for low frequency motion of the vehicle motion. Adjust to generate damping force, and for motion higher than the low frequency, the lower limit is the damping force higher than the soft characteristic, and the damping force is generated up to the hard characteristic according to the motion state. It is characterized by adjusting to.

1 Hydraulic shock absorber (buffer)
2 Outer cylinder 4 Inner cylinder (cylinder)
5 Piston 6 Piston rod 17 Damping force adjustment device (damping force adjustment mechanism)
25 Solenoid (actuator)
31 Extension side damping force generator 35 Damping force control valve (main valve)
35B elastic seal member (pressure adjustment mechanism)
36 Back pressure chamber 37 Free valve (frequency sensitive part)
41 Back pressure chamber introduction orifice 50 Controller A Reservoir chamber B Bottom side oil chamber (one side chamber)
C Rod side oil chamber (other side chamber)
fc cutoff frequency

Claims (3)

A shock absorber that is installed between the vehicle body side and the wheel side and whose damping force can be adjusted by an actuator,
The controller that controls the actuator and
In a suspension device consisting of
The shock absorber is provided with a frequency-sensitive portion that reduces the damping force against high-frequency vibrations having a vibration frequency higher than a predetermined vibration frequency.
The controller adjusts the damping force by the actuator according to the motion state of the vehicle, and for the motion of the vehicle having a low frequency lower than the predetermined vibration frequency, the first motion is according to the motion state. The damping force of the first hard characteristic is adjusted from the soft characteristic so as to generate the damping force of the first hard characteristic, and for the motion of the high frequency having a vibration frequency higher than the low frequency, the damping force higher than the first soft characteristic is applied according to the motion state. A suspension device characterized in that a damping force is adjusted to be generated between a second soft characteristic as a lower limit and a second hard characteristic having a damping force lower than the first hard characteristic as an upper limit . A cylinder filled with working fluid and
A piston provided in the cylinder and divided into a concubine and a concubine,
A piston rod having one end connected to the piston and the other end extending to the outside of the cylinder.
A main valve that suppresses the flow of working fluid from the upstream chamber to the downstream chamber caused by the movement of the piston and generates a damping force.
A back pressure chamber that applies back pressure in the valve closing direction of the main valve,
A back pressure chamber introduction orifice for introducing the working fluid from the upstream chamber into the back pressure chamber is provided.
A pressure adjusting mechanism that adjusts the opening of the main valve by the back pressure of the back pressure chamber, and
A frequency-sensitive unit that reduces the damping force against high-frequency vibrations above a predetermined vibration frequency and supplies the working fluid via the back pressure chamber introduction orifice.
A damping force adjustment mechanism that can adjust the damping force with an actuator,
The controller that controls the actuator and
In a suspension device consisting of
The controller adjusts the motion of the vehicle to generate the damping force of the first soft characteristic to the first hard characteristic according to the motion state for the motion of a low frequency lower than the predetermined vibration frequency . For the high-frequency motion having a vibration frequency higher than the low frequency, the damping force lower than the first hard characteristic from the second soft characteristic whose lower limit is the damping force higher than the first soft characteristic depending on the motion state. A suspension device characterized by adjusting so as to generate a damping force up to the second hard characteristic up to the upper limit . The suspension device according to claim 1 or 2.
The second hardware characteristic is a suspension device characterized in that the damping force generated in the frequency sensitive portion is the upper limit.

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