JP6132859B2 - Suspension device - Google Patents

Description

  The present invention relates to a suspension device that is mounted on a vehicle such as an automobile and is preferably used for buffering vibration of the vehicle.

  Generally, in a vehicle such as a four-wheel automobile, a shock absorber is provided between the vehicle body side and each wheel side. There is a type of such a shock absorber whose damping force can be adjusted by an actuator, and a suspension device is known in which the damping force characteristic is variably controlled in accordance with the vehicle posture during driving, vertical vibration, and the like. (For example, refer to Patent Document 1).

  This type of prior art suspension device obtains the absolute vertical velocity based on the signal from the G sensor that detects the vertical acceleration of the vehicle body, variably adjusts the damping force characteristic of the shock absorber according to the absolute velocity, and Based on the signal from the G sensor, it is determined whether the running road surface is a good road or a bad road. By setting a small dead zone when the road surface is good and setting a large dead zone when the road surface is bad, the influence of frequent vertical vibrations associated with driving on bad roads can be reduced. Can be secured.

Japanese Patent Laid-Open No. 7-232530

  By the way, the suspension device according to the prior art has a configuration in which vibrations ranging from a low frequency to a high frequency during vehicle travel are buffered by a damping force generation mechanism (a mechanism for adjusting the damping force by an actuator) of the shock absorber. Among these, in order to perform control corresponding to high-frequency vibration, control with high responsiveness capable of high-speed response is required. However, a controller capable of high-speed correspondence is expensive, and an actuator capable of high-speed correspondence with an actuator of a damping force generation mechanism needs to use expensive equipment.

  In addition, the suspension device that does not use an expensive controller and actuator that can be used at high speed does not perform damping force control in the high-frequency vibration region, but sacrifices ride comfort and steering stability in the high-frequency region. The reality is that damping force control is performed in a low-frequency vibration region that does not require high-speed response.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a damping force corresponding to a wide frequency range from a low frequency to a high frequency when the vehicle is running without using an expensive controller or actuator. An object of the present invention is to provide a suspension apparatus that can perform control.

In order to solve the above-described problem, the structure adopted by the invention of claim 1 is provided between the vehicle body side and the wheel side of the vehicle, and the working fluid generated in the passage by the movement of the piston connected to the piston rod is provided . a damper having adjustable damping force varying mechanism damping force distribution is controlled by an actuator, and a controller for adjusting the actuator, the suspension system consisting of, wherein the shock absorber, the rod side chamber and bottom chamber It is composed of a free piston provided so as to close the passage in a passage provided in between, and a frequency sensitive part is provided for reducing the damping force by the movement of the free piston against high frequency vibration, and the damping force is variable. consists of passages different passages of the passage and the frequency response unit of the mechanism, and the damping force varying mechanism and the frequency response unit is provided independently, before The controller extracts the low-frequency component of the vibration in the composite road in which the high-frequency component and the low-frequency component are superimposed on the vibration of the vehicle, and the damping force variable mechanism according to the change of the low-frequency component of the vibration The damping force is switched to remove the high frequency component from the control target.

  According to the present invention, by having the configuration as described above, it is possible to achieve both riding comfort and steering stability.

1 is an overall configuration diagram showing a four-wheeled vehicle to which a suspension device according to a first embodiment of the present invention is applied together with a controller. It is a longitudinal cross-sectional view which expands and shows the principal part of the shock absorber mounted in the motor vehicle in FIG. It is a block diagram which shows the structure of the sprung mass damping control part by the controller in FIG. It is a characteristic diagram which concretely shows the characteristic of the control command value of the damping force with respect to the road surface state. It is a characteristic diagram which shows the characteristic of the sprung acceleration with respect to the vibration frequency at the time of vehicle travel compared with a conventional product. It is a block diagram which shows the structure of the controller used by 2nd Embodiment. It is a block diagram which shows the structure of the controller used by 3rd Embodiment.

  The embodiment described below solves various problems and has an effect without stopping at the contents described in the column of problems to be solved by the above-described invention and the column of effects of the invention. The main problems to be solved by the following embodiments are listed below.

(Characteristic improvement)
When the damping force characteristic (damping force with respect to the piston speed) is changed in the frequency sensitive part according to the vibration state, characteristic setting such as a smoother change is required. This is because if the characteristics that generate a small damping force and the characteristics that generate a large damping force occur suddenly, the actual damping force also switches suddenly, which deteriorates the ride comfort of the vehicle and further reduces the damping force. This is because the behavior of the vehicle becomes unstable and the driver may feel uncomfortable with respect to the steering when the changeover occurs during the steering of the vehicle. In particular, when the damping force is adjusted to a high damping force by the actuator, the width of the change in the damping force according to the frequency becomes large, so it is important to change more smoothly.

[Suppression of enlargement]
A high output actuator corresponding to a high frequency has a problem that a solenoid needs to be enlarged. Further, when the piston section is provided with the frequency sensitive section and the damping force adjusting section using the actuator, the axial length of the piston section becomes longer, and therefore the entire cylinder device including the actuator becomes longer in the axial direction. For this reason, when the size of the cylinder device is increased, the degree of freedom of attachment to the vehicle body is reduced, and thus an increase in the axial length of the cylinder device is a big problem.

[Reduction of the number of parts]
In order to accurately control the high-frequency vibration, a highly sensitive acceleration sensor, vehicle height sensor, or the like that measures the vibration state (spring vertical speed, unsprung speed, relative speed) is required. In this case, providing a large number of sensors has a problem of increasing the number of components, and further requires wiring, so that there is a problem that attachment to a vehicle is deteriorated. In recent years, sensors that reduce the number of sensors and estimate the vibration state have been developed. However, when high frequency is accurately controlled, there is a problem that sufficient accuracy cannot be obtained by estimation.

  Hereinafter, a suspension device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings, taking as an example a case where the suspension device is applied to a four-wheeled vehicle.

  Here, FIG. 1 to FIG. 5 show a first embodiment of the present invention. In FIG. 1, for example, left and right front wheels 2 and left and right rear wheels 3 (only one is shown) are provided on the lower side of a vehicle body 1 constituting a vehicle body. Between the left and right front wheels 2 and the vehicle body 1, suspensions 4 and 4 (hereinafter referred to as front wheel suspensions 4) on the front wheels are provided.

  The left and right front wheel suspensions 4 are provided between the left and right front wheels 2 and the vehicle body 1 in parallel with the left and right suspension springs 5 (hereinafter referred to as springs 5). And left and right shock absorbers 6. As will be described later, the left and right shock absorbers 6 are configured by a damping force adjusting hydraulic shock absorber provided with a frequency sensitive portion 24 (that is, damping force adjustment + frequency sensitive shock absorber).

  Rear wheel suspensions 7 and 7 (hereinafter referred to as rear wheel suspensions 7) are provided between the left and right rear wheels 3 and the vehicle body 1. The left and right rear wheel suspensions 7 are arranged between a left and right rear wheel 3 and the vehicle body 1 in parallel with the left and right suspension springs 8 (hereinafter referred to as springs 8). The left and right shock absorbers 9 are provided. As will be described later, these shock absorbers 9 are also configured by a damping force adjustment type hydraulic shock absorber provided with a frequency sensitive portion 24 (that is, damping force adjustment + frequency sensitive shock absorber). In addition, although the example which provided damping force adjustment + frequency sensitive buffer to four wheels was shown, it is good also considering the front wheel side or the rear wheel side as a damper only for damping force adjustment or only frequency sensitivity.

  Here, the front wheel side and rear wheel side shock absorbers 6 (9) will be described with reference to FIG. Since the configurations of both are basically the same, for example, the front wheel side shock absorber 6 will be described, and the description of the rear wheel side shock absorber 9 will be omitted.

  In FIG. 2, the inner cylinder 11 constituting the cylinder of the shock absorber 6 (9) is provided coaxially in an outer cylinder (not shown) that forms the outer shell of the shock absorber 6 (9). The lower end side of the inner cylinder 11 is fixed to the lower end side of the outer cylinder via a bottom valve (not shown). The upper end side of the inner cylinder 11 is fixed to the upper end side of the outer cylinder via a rod guide (not shown) or the like. An oil liquid as a working fluid is sealed in the inner cylinder 11, and an annular reservoir chamber (not shown) in which the oil liquid and the gas are sealed is formed between the outer cylinder and the inner cylinder 11. Yes.

  A piston 12 is slidably inserted into the inner cylinder 11, and the piston 12 defines the inner cylinder 11 in two chambers, a rod-side oil chamber A and a bottom-side oil chamber B. The piston 12 is formed with a plurality of oil passages 12A and 12B that can communicate with the rod-side oil chamber A and the bottom-side oil chamber B, respectively, and are separated from each other in the circumferential direction. The oil hole is inclined obliquely with respect to 12 axes. The oil passages 12 </ b> A and 12 </ b> B constitute a main passage through which oil is circulated between the rod-side oil chamber A and the bottom-side oil chamber B.

  In addition, the piston 12 has an annular recess 12C formed on the lower end surface that becomes one side of the piston 12 so as to surround the one side opening of the oil passage 12A, and the piston 12 is positioned on the radially outer side of the annular recess 12C and extends. An annular valve seat 12D on which the side disk valve 13 is seated and detached, an annular recess 12E formed on the upper end surface on the other side of the piston 12 so as to surround the other opening of the oil passage 12B, and the annular recess 12E An annular valve seat 12F is provided on the outer side in the radial direction and on which the disk valve 14 on the reduction side is seated.

  A piston rod 15 extends in the inner cylinder 11 in the axial direction. The piston rod 15 is inserted into the inner cylinder 11 at the lower end side as one end side, and is attached to the piston 12 by a nut 26 with a lid of a housing 25 described later. It is fixed and provided. Further, the upper end side as the other end side of the piston rod 15 protrudes outside the outer cylinder and the inner cylinder 11 through the rod guide and the like. On the inner peripheral side of the piston rod 15, a shutter insertion hole 15 </ b> A is formed that opens to the lower end side of the piston rod 15, and a shutter 18 to be described later is rotatably fitted, and upward from the upper end side of the shutter insertion hole 15 </ b> A And a small-diameter rod insertion hole 15 </ b> B extending in the axial direction.

  The piston rod 15 is provided with a plurality of oil holes 15C, 15D, 15E, and 15F extending radially outward from the shutter insertion hole 15A so as to be separated in the axial direction and the circumferential direction. Of these oil holes 15C to 15F, the oil holes 15C to 15E are arranged so as to open to the rod side oil chamber A, and the remaining oil holes 15F open to the bottom side oil chamber B in the inner cylinder 11. Are arranged to be. Of the oil holes 15C to 15F, the uppermost oil hole 15C is always in communication with an inner hole 18A of the shutter 18 described later via a radial communication path 18B.

  The oil holes 15D and 15E located on the lower side of each oil hole 15C are separated from each other in the circumferential direction of the piston rod 15, and are disposed at substantially the same position in the axial direction. However, the oil holes 15D and 15E have different hole diameters (orifice diameters), and are selectively opened and closed by an oil groove 18C of the shutter 18 described later. Thereby, the damping force is variably adjusted as will be described later. Further, an annular step portion 15G is formed on the outer peripheral side of the piston rod 15, and this step portion 15G positions the disk valve 14 on the reduction side in the axial direction with the piston 12.

  The extension-side disk valve 13 provided on the lower end surface, which is one side of the piston 12, of the disk valves 13, 14 is configured so that when the piston 12 slides upward in the extension stroke of the piston rod 15, A predetermined damping force is generated by applying a resistance force to the oil liquid flowing through the passage 12A. Further, the reduction-side disc valve 14 provided on the upper end surface which is the other side of the piston 12 circulates in each oil passage 12B when the piston 12 slides downward in the reduction stroke of the piston rod 15. A predetermined damping force is generated by applying a resistance force to the oil liquid.

  Reference numeral 16 denotes a port member provided between a nut 26 with a lid of the frequency sensitive portion 24 and a piston 12 which will be described later. The port member 16 is an annular ring provided by being fitted to the outer peripheral side of the piston rod 15. Etc. The port member 16 allows oil liquid to flow in and out between the bottom side oil chamber B and the oil hole 15F of the piston rod 15.

  Reference numeral 17 denotes a damping force variable mechanism employed in the present embodiment. The damping force variable mechanism 17 includes a shutter 18, a control rod 19, and an actuator 20 such as a stepping motor, which will be described later. The actuator 20 of the damping force variable mechanism 17 is provided, for example, on the protruding end side of the piston rod 15 and rotates the shutter 18 via a control rod 19 described later. At this time, the shutter 18 opens and closes the oil holes 15D, 15E and the like of the piston rod 15 to intermittently adjust the damping force characteristic of the shock absorber 6 (9) in two stages or three or more stages.

  The actuator 20 of the damping force variable mechanism 17 is not necessarily configured to intermittently adjust the damping force characteristic, and the oil holes 15D and 15E are holes whose opening areas gradually change in the circumferential direction. Thus, the damping force characteristic may be continuously changed. In addition, the actuator 20 is not limited to an electric motor such as a stepping motor and is configured by a linear actuator such as a solenoid to continuously adjust from a hard characteristic (hard characteristic) to a soft characteristic (soft characteristic). Also good.

  A shutter 18 is rotatably provided in the shutter insertion hole 15 </ b> A of the piston rod 15, and the shutter 18 constitutes an opening area adjusting member of the damping force varying mechanism 17. The shutter 18 is provided to rotate integrally with the lower end side of the control rod 19, and is rotated together with the control rod 19 in the shutter insertion hole 15 </ b> A of the piston rod 15. The control rod 19 is inserted through the rod insertion hole 15 </ b> B of the piston rod 15, and its upper end side is connected to an output shaft (not shown) of the actuator 20.

  The inner peripheral side of the shutter 18 is an inner hole 18A extending in the axial direction, and the lower end thereof is always in communication with an upper chamber C in the housing 25 described later. Further, the shutter 18 is formed on the outer peripheral surface of the shutter 18 with a radial communication path 18B that always communicates the inner hole 18A with the oil hole 15C of the piston rod 15 and spaced apart from the communication path 18B in the axial direction of the shutter 18. An oil groove 18C is provided as an oil passage. The oil groove 18 </ b> C extends in the axial direction of the shutter 18, and the lower end side thereof is always in communication with the oil hole 15 </ b> F of the piston rod 15. Further, the upper end side of the oil groove 18C is selectively communicated with or blocked from any of the oil holes 15D, 15E, etc. of the piston rod 15 according to the rotation operation of the shutter 18.

  Here, the inner hole 18 </ b> A and the oil groove 18 </ b> C of the shutter 18 constitute two passages parallel to each other between the rod-side oil chamber A and the bottom-side oil chamber B in the inner cylinder 11. Of the two passages, the first passage 100 includes oil holes 15D and 15E of the piston rod 15, an oil groove 18C of the shutter 18, an oil hole 15F of the piston rod 15, a port member 16, and the like. In the first passage 100, when the oil liquid flows through the oil groove 18C between the rod-side oil chamber A and the bottom-side oil chamber B, the shutter 18 is rotated (for example, oil holes 15D, 15E, etc.). A damping force corresponding to the opening area is generated. The oil holes 15D and 15E of the piston rod 15 constitute a damping force generating section in which the damping force can be adjusted via the shutter 18 by the actuator 20.

  In this case, the first passage 100 is configured by oil holes 15D and 15E of the piston rod 15, oil grooves 18C of the shutter 18, oil holes 15F of the piston rod 15, the port member 16, and the like. Are formed as the same common passage. Thereby, the structure of the flow path (passage | path) which connects and interrupts | blocks the rod side channel | path A and the bottom side channel | path B in the inner cylinder 11 can be simplified and simplified.

  On the other hand, the second passage 101 includes an oil hole 15C of the piston rod 15, a communication passage 18B of the shutter 18, an inner hole 18A, an upper chamber C described later, and the like. The second passage 101 is also a bypass passage that bypasses the damping force generator (oil holes 15D and 15E) on the first passage 100 side. In the second passage 101, when the oil liquid flows between the rod-side oil chamber A and the bottom-side oil chamber B in the inner hole 18A of the shutter 18, it will be described later regardless of the rotational position of the shutter 18. The damping force characteristic is variably controlled by the frequency sensitive unit 24.

  A cylindrical guide member 21 and a seal member 22 are provided in the shutter insertion hole 15A of the piston rod 15 so as to be located above the shutter 18 (on the other side in the axial direction). A cylindrical body 23 constituting a part of the second passage 101 is provided (on one side in the axial direction). The seal member 22 prevents the oil liquid from leaking from between the shutter insertion hole 15A and the control rod 19. The cylindrical body 23 constitutes a drop-off preventing member that prevents the shutter 18 from dropping downward from the shutter insertion hole 15A.

  Reference numeral 24 denotes a frequency sensitive portion provided on the lower end side of the piston rod 15. The frequency sensitive portion 24 includes a cylindrical housing 25 that is displaced integrally with the piston rod 15 in the inner cylinder 11, as shown in FIG. A free piston 28, which will be described later, and O-rings 29 and 30 are provided in the housing 25 so as to be relatively displaceable.

  The housing 25 includes a nut 26 with a lid as a lid member that is screwed to the lower end side of the piston rod 15 and a bottomed cylindrical body 27. The nut 26 with a lid includes an inner nut portion 26A screwed to the outer periphery on the lower end side of the piston rod 15, an annular lid portion 26B extending radially outward from the upper end side of the inner nut portion 26A, and the annular lid portion. The outer cylindrical hanging portion 26 </ b> C has an inner peripheral surface that serves as a guide surface for the free piston 28. The lower end surface of the cylindrical hanging portion 26C constitutes a housing contact surface with which an O-ring 29 described later contacts.

  The bottomed cylindrical body 27 has a cylindrical portion 27A whose upper end is fixed to the annular lid portion 26B of the nut 26 with a lid by caulking or the like from the outside and extends downward in the inner cylinder 11, and the cylindrical portion 27A. It is comprised by the cyclic | annular baseplate part 27B which obstruct | occludes a lower end side. A communication hole 27 </ b> C for communicating a lower chamber D and a bottom oil chamber B, which will be described later, is formed on the center side of the bottom plate portion 27 </ b> B.

  On the inner peripheral side of the cylindrical portion 27A, an inclined arc surface 27D is formed as a housing contact surface with which an O-ring 30 described later contacts, and this inclined arc surface 27D is a moving direction of the free piston 28 described later (that is, The surface is inclined with respect to the axial direction and has a curved surface. Here, the inclined arcuate surface 27D elastically compresses and deforms the O-ring 30 with an annular convex portion 28A described later when the free piston 28 is displaced downward, and the resistance force of the free piston 28 causes the free piston 28 to be deformed. It has a function to suppress displacement toward the stroke end.

  A free piston 28 is slidably provided in the housing 25. The free piston 28 is formed as a bottomed cylindrical piston as shown in FIG. An annular convex portion 28A that protrudes outward in the direction is provided. The free piston 28 is slidably fitted into the cylindrical portion 27A of the bottomed cylindrical body 27 at the lower end side which is one side in the axial direction, and the upper end side which is the other side in the axial direction is a cylindrical shape of the nut 26 with a lid. It is inserted in the hanging part 26C so as to be displaceable.

  The free piston 28 that is relatively displaced in the axial direction in the housing 25 abuts against the annular lid portion 26B of the nut 26 with lid and the bottom plate portion 27B of the bottomed cylindrical body 27, so that the stalk end in the upper and lower directions is increased. It is prescribed. The free piston 28 partitions the inside of the housing 25 (that is, the second passage 101) into an upper chamber C and a lower chamber D that are two chambers on the upstream side and the downstream side. That is, the inside of the housing 25 constituting a part of the second passage 101 is defined by the free piston 28 into an upper chamber C and a lower chamber D.

  Here, the 2nd channel | path 101 is obstruct | occluded by the free piston 28, and the flow which an oil liquid substitutes between the rod side oil chamber A and the bottom side oil chamber B does not arise. However, while the free piston 28 is moving up and down in the housing 25, the oil in the rod side oil chamber A flows into and out of the upper chamber C, and the same amount of oil from the lower chamber D. Flows out and flows into the bottom side chamber B through the communication hole 27C of the bottomed cylindrical body 27. For this reason, the flow of the oil liquid substantially occurs also on the second passage 101 side.

  The annular convex portion 28A provided on the outer periphery of the free piston 28 is formed with inclined arc surfaces 28B and 28C on the upper and lower surfaces thereof, and these inclined arc surfaces 28B and 28C are in contact with O-rings 29 and 30 described later. Piston contact surface. The inclined arc surfaces 28B and 28C constitute surfaces having curved surfaces inclined with respect to the axial direction of the free piston 28. Here, the inclined arc surface 28B of the free piston 28 is opposed to the lower end surface of the cylindrical hanging portion 26C in the axial direction with the O-ring 29 interposed therebetween, and the inclined arc surface 28C has a bottomed cylindrical shape with the O-ring 30 interposed therebetween. It faces the inclined circular arc surface 27D of the body 27 in the axial direction.

  Reference numerals 29 and 30 denote O-rings as elastic bodies constituting the resistance element of the frequency sensitive portion 24. The O-rings 29 and 30 are disposed between the cylindrical portion 27A of the housing 25 and the outer peripheral surface of the free piston 28. , Liquid-tight seal between the two. The upper chamber C and the lower chamber D in the housing 25 are held in a state of being sealed with each other by O-rings 29 and 30.

  When the free piston 28 is displaced upward in the housing 25, the O-ring 29 is elastically compressed and deformed between the lower end surface of the cylindrical hanging portion 26C and the annular convex portion 28A (inclined arc surface 28B) of the free piston 28. Is done. At this time, the O-ring 29 generates a resistance force against upward displacement toward the stroke end of the free piston 28. When the free piston 28 is displaced downward in the housing 25, the O-ring 30 is elastic between the inclined circular arc surface 27D on the cylindrical portion 27A side and the annular convex portion 28A (inclined circular arc surface 28C) of the free piston 28. Compression deformation. At this time, the O-ring 30 generates a resistance force against the downward displacement toward the stroke end of the free piston 28.

  As shown in FIG. 2, the frequency sensitive portion 24 provided in the lower end side of the piston rod 15 and located in the inner cylinder 11 has a free piston 28 in the axial direction in the housing 25 against high-frequency vibrations during vehicle travel. By the relative displacement, for example, the amount of the oil liquid flowing through the communication path 18B of the shutter 18 is reduced, so that it has a function of reducing the generated damping force.

  The shock absorber that can be used in the present invention only needs to have a frequency sensitive part and a damping force adjusting part by an actuator, and the frequency sensitive part supports the free piston 28 with a coil spring. There may be a type in which the rod side oil chamber A and the bottom side oil chamber B are communicated and cut off by a free piston. Further, the damping force adjusting unit by the actuator has been described as an example of the rotary shutter 18. However, the damping force adjusting unit may move in the vertical direction, or may be a pilot control type damping valve. Further, the damping force adjusting unit by the actuator may be of a type attached to the side surface of the outer cylinder. Furthermore, although the said buffer was demonstrated to the example of the double cylinder type shock absorber, the buffer of a monotube may be sufficient.

  Reference numeral 31 denotes a spring upper vertical acceleration sensor (hereinafter referred to as a G sensor 31) provided in the vehicle body 1. The G sensor 31 detects the vibration acceleration in the upward and downward directions on the vehicle body 1 side above the spring. . In the present embodiment, since vehicle operation information from CAN 32, which will be described later, and information from other devices and sensors are input to the controller 37, one G sensor for one vehicle body 1 is used. It is only necessary to provide 31. However, for example, a total of three G sensors 31 may be provided in the vehicle body 1. In this case, the G sensor 31 is attached to the vehicle body 1 at a position near the upper end side (rod protruding end side) of the shock absorber 6 on each front wheel 2 side, and at the intermediate position between the left and right rear wheels 3. 1 is attached.

  Reference numeral 32 denotes a CAN as a serial communication unit mounted on the vehicle body 1, and the CAN 32 performs multiplex communication for in-vehicle use between a large number of electronic devices mounted on the vehicle and the controller 37. In this case, examples of the vehicle driving information sent to the CAN 32 include detection signals (information) from the steering angle sensor 33, the brake state detector 34, the accelerator sensor 35, the wheel speed sensor 36, and the like.

  As shown in FIG. 1, the steering angle sensor 33 is disposed at a position near the driver's seat of the vehicle body 1 and detects a steering operation of the vehicle. That is, the steering angle sensor 33 detects an operation amount of a steering handle (not shown) of the vehicle, and outputs a detection signal from the CAN 32 to a controller 37 described later. The vehicle body 1 is provided with a brake state detector 34, an accelerator sensor 35, a wheel speed sensor 36, and the like.

  The brake state detector 34 detects, for example, a depression operation of a brake pedal (not shown) or a braking state by automatic braking. The accelerator sensor 35 detects a depression operation of an accelerator pedal (not shown), for example. The wheel speed sensor 36 is provided, for example, in close proximity to the left and right front wheels 2 and the left and right rear wheels 3, and detects the rotational speed of each wheel as the vehicle speed.

  37 is a controller as a control means constituted by a microcomputer or the like. As shown in FIG. 1, the controller 37 is connected to the G sensor 31, CAN 32, etc. on the input side, and each buffer 6 (9) on the output side. Connected to the actuator 20 or the like. The controller 37 reads the upper and lower vibrations on the vehicle body 1 side from the G sensor 31, and from the CAN 32 serially outputs various detection signals from the steering angle sensor 33, the brake state detector 34, the accelerator sensor 35, the wheel speed sensor 36, and the like. Read by communication.

  The controller 37 includes a storage unit (not shown) including a ROM, a RAM, a nonvolatile memory, and the like, a vehicle body vibration estimation unit 38 that estimates upward and downward vibrations as a vehicle motion, and a sprung mass damping control unit. 39, a steering stability control unit 40, a vehicle speed response control unit 41, and a control command calculation unit 42. That is, the controller 37 estimates the vibration of the vehicle body 1 by the vehicle body vibration estimation unit 38 from the sensor information from the G sensor 31 and the CAN 32, and the steering stability control unit 40 estimates the steering state of the vehicle. The vehicle speed sensitive control unit 41 estimates the running state of the vehicle.

  The control command calculation unit 42 outputs to the actuator 20 of each shock absorber 6 (9) according to control signals from the sprung mass damping control unit 39, the steering stability control unit 40, and the vehicle speed response control unit 41 connected in parallel with each other. The power damping force command signal is processed as a control command value (current value). The actuator 20 of each shock absorber 6 (9) rotates the shutter 18 in accordance with the current value (damping force command signal) output from the control command calculation unit 42, thereby changing the damping force characteristic between hardware and software. Variable control is performed continuously or in multiple stages.

  As the vehicle body vibration estimation unit 38 of the controller 37, for example, the technique previously proposed by the present applicant (for example, Japanese Patent Application Laid-Open No. 2009-83614, Japanese Patent Application Laid-Open No. 2009-83641, Japanese Patent Application Laid-Open No. 2009-262926, Japanese Patent Application Laid-Open No. 2010-083329, etc.) is used to estimate the vibration of the vehicle body 1 (for example, the sprung speed and pitch rate shown in FIG. 3).

  As shown in FIG. 3, the sprung mass damping control unit 39 includes first and second filter units 39A and 39B, first and second gain multiplication units 39C and 39D, an addition unit 39E, and a map calculation unit 39F. It is configured to include. The sprung mass damping control unit 39 performs a filtering process for extracting a low frequency component by the first filter unit 39 </ b> A with respect to the sprung speed V estimated by the vehicle body vibration estimating unit 38. The second filter unit 39B performs a filter process for extracting a low frequency component on the pitch rate P estimated by the vehicle body vibration estimation unit 38. That is, the first and second filter units 39A and 39B are configured to remove the high frequency component from the control target by performing a filter process for extracting the low frequency component, and to perform the adjustment control of the damping force according to the low frequency component. is there.

  Here, the cutoff frequency by the first and second filter units 39A and 39B is preferably set to be equal to or lower than the cutoff frequency of the frequency sensitive unit 24 (see FIG. 2). The cutoff frequency is preferably set so that sprung resonance can be extracted. Next, the first gain multiplication unit 39C calculates a target damping force F by multiplying the sprung speed subjected to the filter processing by the first filter unit 39A by a predetermined gain. The second gain multiplication unit 39D calculates a target damping force F by multiplying the pitch rate subjected to the filter processing by the second filter unit 39B by a predetermined gain.

  The adder 39E adds the target damping forces F calculated by the first and second gain multipliers 39C and 39D. The map calculation unit 39F calculates the command value I by performing map calculation on the target damping force F added by the addition unit 39E according to the characteristic line 43 shown in FIG. In this case, in the case of normal skyhook control, it is necessary to calculate the control amount from the relationship between the expansion / contraction stroke (relative speed) and the target damping force according to the sprung speed. This is because, for example, when the sprung is moving upward, the expansion-side damping force has a damping action, but the contraction-side damping force has an excitation action. It is necessary to output a signal so as to obtain a damping force, and to output a signal so as to obtain a soft damping force during the contraction stroke. However, in the present embodiment, the shock absorber 6 (9) is constituted by a damping force adjusting hydraulic shock absorber (ie, damping force adjustment + frequency sensitive shock absorber) provided with a frequency sensitive portion 24 as shown in FIG. Therefore, the excitation action due to the damping force is alleviated due to the delay of the rising of the damping force by the frequency sensitive part, etc., so the command can be obtained simply by substituting the target damping force F into the map of the characteristic line 43 shown in FIG. Even when the value I is calculated, a control effect can be obtained, and the control calculation can be simplified.

  The steering stability control unit 40 of the controller 37 is controlled according to a control amount (for example, an arithmetic expression performed by estimating lateral acceleration, a control law, etc.) from the steering angle signal from the steering angle sensor 33 and the vehicle speed signal from the wheel speed sensor 36. Amount) and the calculated control amount is output to the control command calculation unit 42 as a control command value. That is, the anti-roll control for controlling the damping force according to the lateral acceleration is performed by the steering stability control unit 40.

  Further, the steering stability control unit 40 estimates the front and rear accelerations of the vehicle body 1 based on detection signals from the brake state detector 34 and the accelerator sensor 35, and performs anti-dive squat control for controlling the damping force in accordance therewith. It also has a function to perform. On the other hand, the vehicle speed sensitive control unit 41 is a control unit for adjusting the damping force according to the vehicle speed, calculates a control amount based on the vehicle speed signal or the like, and uses the calculated control amount as a control command value. Output to.

  A characteristic line 44 shown in FIG. 4 is an example of a road surface state during vehicle travel, and represents a rough road, a wavy road, and a compound road with large road surface unevenness. A compound road is a road surface state that is generated by superimposing low-frequency vibrations and high-frequency vibrations when the vehicle is traveling. A characteristic line 45 shown in FIG. 4 represents the sprung speed filter processing value, and is an output signal in the first filter unit 39A of the sprung mass damping control unit 39. As shown by the characteristic line 45, in the case of a rough road, the signal falls within a predetermined dead zone by extracting (filtering) a low frequency component. On the other hand, in the swell road and the composite road, a signal exceeding the range of the dead zone even when the low frequency component is extracted is, for example, between time T1 and T2, between time T3 and T4, and between time T5 and T6. Are output during the time T7 to T8.

  A characteristic line 46 in FIG. 4 indicates a target damping force obtained by multiplying the sprung speed (filter processing value by the characteristic line 45) output from the first filter unit 39A by a gain by the first gain multiplication unit 39C. The characteristic of the command value which calculated F is represented. In the command value by the characteristic line 46, for example, the target damping force becomes a soft characteristic until the time T1, and the hard characteristic is switched between the times T1 and T2 and between the times T3 and T4. From time T4 to T5, the target damping force has a soft characteristic, and during time T5 to T6, the period from time T7 to T8 is switched to a hard characteristic, and after time T8, the characteristic is switched to a soft characteristic.

  Therefore, the command value output from the sprung mass damping control unit 39 is a soft characteristic in order to improve the ride comfort when the road surface during vehicle travel is bad as shown by the characteristic line 46 in FIG. The low damping force is maintained, and control is performed so as not to deteriorate the ride comfort. On a wavy road, for example, by switching to hard characteristics between times T1 and T2 and between times T3 and T4, the damping force can be increased, so that the displacement on the spring can be suppressed, and fluffing on the vehicle body 1 side can be suppressed. Can be suppressed.

  In a composite road where low-frequency vibration and high-frequency vibration are superimposed, for example, the soft characteristic is maintained until time T5, and the damping force is switched by switching to a hard characteristic between time T5 and T6 and between time T7 and T8. Increase control. In such a case, the control of the prior art has set the damping force to a medium characteristic between soft and hard in order to prevent the ride comfort from deteriorating. However, in the present embodiment, the damping force can be reduced without using an actuator or the like by the frequency sensitive unit 24 with respect to the high frequency vibration by attaching the frequency sensitive unit 24 to the shock absorbers 6 and 9. Can be set to a high damping force between .about.T6 and between times T.sub.7 and T.sub.8, so that the control can be simplified and a low-cost system can be obtained.

  The suspension device according to the first embodiment has the above-described configuration. Next, the operation thereof will be described.

  First, when the shock absorbers 6 and 9 are mounted on a vehicle, the upper end side of the piston rod 15 is attached to the vehicle body 1 side, and the bottom side of the outer cylinder is attached to the wheel (front wheel 2 and rear wheel 3) side. When the vehicle is traveling, when the upward and downward vibrations are generated due to the unevenness of the road surface, the shock absorbers 6 and 9 are displaced so that the piston rod 15 extends and contracts from the inner cylinder 11, and extends and contracts. Damping force can be generated by the disc valve 13, 14, the damping force variable mechanism 17 including the shutter 18, the actuator 20, and the like, and the frequency sensitive unit 24, and the vibration of the vehicle can be buffered.

  That is, in the extension stroke of the piston rod 15, the piston 12 is slid upward in the inner cylinder 11, and the inside of the rod side oil chamber A becomes higher than the bottom side oil chamber B. From the oil passage 12A of the piston 12 flows into the annular recess 12C. This inflowing oil generates a predetermined damping force by flowing into the bottom-side oil chamber B through a notch (not shown) or the like provided in the extension-side disc valve 13. In this state, when the extension speed of the piston rod 15 increases and the pressure difference between the oil chambers A and B exceeds the relief set pressure, the disc valve 13 is separated from the annular valve seat 12D and opened. A predetermined extension side damping force can be generated.

  In the first passage 100, the oil in the rod side oil chamber A flows into the shutter 18 through the oil holes 15 </ b> C, 15 </ b> D, 15 </ b> E of the piston rod 15. When the oil groove 18C of the shutter 18 communicates with the oil hole 15D, the oil liquid in the rod side oil chamber A enters the bottom side oil chamber B via the oil hole 15D, the oil groove 18C, the oil hole 15F, and the port member 16. At this time, a relatively soft damping force can be generated. Further, when the oil groove 18C of the shutter 18 communicates with the oil hole 15E, the oil in the rod side oil chamber A passes through the oil hole 15E, the oil groove 18C, the oil hole 15F, and the port member 16, and the bottom side oil chamber. At this time, a relatively hard damping force can be generated by the oil hole 15E having a small orifice diameter.

  In the second passage 101, the oil that has flowed from the rod-side oil chamber A to the upper chamber C of the frequency sensitive portion 24 through the oil hole 15C of the piston rod 15, the communication passage 18B of the shutter 18, and the inner hole 18A, A force is generated in the housing 25 (bottomed cylindrical body 27) to displace the free piston 28 downward against the O-ring 30. When the free piston 28 is displaced downward in the housing 25 (when the vibration frequency is high), a soft damping force is generated by flowing the oil liquid through the communication path 18B of the shutter 18, for example. Thus, the damping force generated by the shock absorber 6 (9) can be reduced as a whole.

  Further, in the reduction stroke of the piston rod 15, the piston 12 slides and displaces downward in the inner cylinder 11, and the inside of the bottom side oil chamber B becomes higher than the rod side oil chamber A. From the oil passage 12B of the piston 12 flows into the annular recess 12E. This inflowing oil generates a predetermined damping force by flowing into the rod-side oil chamber A through a notch (not shown) provided in the reduction-side disk valve 14 or the like. In this state, when the reduction speed of the piston rod 15 increases and the pressure difference between the oil chambers A and B exceeds the relief set pressure, the disc valve 14 is separated from the annular valve seat 12F and opened. A predetermined reduction side damping force can be generated.

  In the first passage 100, the oil in the bottom side oil chamber B flows from the port member 16 side into the oil groove 18 </ b> C of the shutter 18 through the oil hole 15 </ b> F of the piston rod 15. When the oil groove 18C of the shutter 18 communicates with the oil hole 15D, a relatively soft damping force can be generated by the oil flowing from the oil groove 18C to the rod side oil chamber A through the oil hole 15D. . Further, when the oil groove 18C of the shutter 18 communicates with the oil hole 15E, a relatively hard damping force is generated by the oil flowing from the oil groove 18C to the rod side oil chamber A through the oil hole 15E. Can do.

  Further, in the second passage 101, the fluid in the bottom side oil chamber B is communicated with the housing 25 (bottomed tubular body 27) into the lower side chamber D of the frequency sensitive portion 24 during the reduction stroke of the piston rod 15. It flows in through the hole 27C. The oil liquid flowing into the lower chamber D generates a force that displaces the free piston 28 upward against the O-ring 29 in the housing 25. When the free piston 28 is displaced upward in the housing 25 (when the vibration frequency is high), the rod passes from the upper chamber C in the housing 25 through the inner hole 18A, the communication path 18B, and the oil hole 15C of the shutter 18. The oil liquid flows into the side oil chamber A, and the oil liquid flows through the communication passage 18B, for example, thereby generating a soft damping force and reducing the damping force generated by the shock absorber 6 (9) as a whole. Can do.

  Here, according to the first embodiment, the shock absorber 6 of the left and right front wheel suspension 4 and the shock absorber 9 of the left and right rear wheel suspension 7 are combined with each other as shown in FIG. Is provided with a damping force adjustment type hydraulic shock absorber (that is, damping force adjustment + frequency sensitive shock absorber), and the controller 37 that drives and controls the actuator 20 of the damping force variable mechanism 17 has a vertical vibration on the vehicle body 1 side. When the frequency is low, the damping force by the damping force variable mechanism 17 (shutter 18) is variably adjusted between software and hardware according to the vertical vibration, and when the vibration is higher than the low frequency, the damping is performed. The force adjustment control is not performed.

  As a result, for example, as shown by characteristic lines 44 to 46 in FIG. 4, even in a composite road in which low-frequency vibrations and high-frequency vibrations are superimposed, the soft characteristics are maintained until, for example, time T5. It is possible to ensure the ride comfort of the vehicle and to simplify the damping force control process simply by switching to a hard characteristic during the period between time T7 and time T8 and performing control to increase the damping force.

  In such a case, the control of the prior art has set the damping force to a medium characteristic between soft and hard in order to prevent the ride comfort from deteriorating. However, in the present embodiment, the damping force can be reduced by the frequency sensitive unit 24 with respect to the high frequency vibration by attaching the frequency sensitive unit 24 to the shock absorbers 6 and 9, so that the time between the time T5 and the time T6 can be reduced. A high damping force can be set between T7 and T8, and the control process can be simplified and simplified.

  Characteristic lines 47 to 50 shown in FIG. 5 are simulation results for comparing the riding comfort of the suspension device of the prior art (characteristic lines 47 to 49) and the suspension device according to the present embodiment (characteristic line 50 shown by a solid line). It is. The simulation model uses a model that takes into account the vibrations of the sprung and unsprung parts as a vehicle model. The shock absorbers 6 and 9 of the suspension device according to the present embodiment are models in which a damping force adjustment type hydraulic shock absorber (ie, damping force adjustment + frequency sensitive shock absorber) provided with a frequency sensitive portion 24 is constructed by a hydraulic model. is there.

  Among the suspension devices of the conventional product, the characteristic of the shock absorber having no damping force adjustment function is indicated by a dotted characteristic line 47, and the characteristic of a semi-active suspension (hereinafter referred to as semi-active) that performs skyhook control is indicated by a two-dot chain line. A characteristic line 48 indicates a characteristic of the conventional damping force adjusting hydraulic shock absorber by a one-dot chain line characteristic line 49. Characteristic lines 47 to 50 shown in FIG. 5 represent the characteristics of the power spectral density PSD (dB) of the sprung acceleration with respect to the vibration frequency f (Hz) when the vehicle is running.

  Thereby, in the sprung resonance frequency region where the vibration frequency f is 1 Hz before and after, the sprung acceleration of the standard damper is large as shown by the characteristic line 47 shown by the dotted line. On the other hand, other suspension devices (semi-actives of skyhook control indicated by the two-dot chain line characteristic line 48, damping force adjusting hydraulic shock absorber of the characteristic line 49 indicated by the one-dot chain line, and buffering of the characteristic line 50 indicated by the solid line) 6 and 9), it can be seen that there is no difference in sprung acceleration in the sprung resonance frequency region before and after 1 Hz, and there is no difference in displacement suppression.

  In the horizontal region where the vibration frequency f is 2 to 8 Hz, as shown by the characteristic line 48 indicated by a two-dot chain line, the semi-active of the skyhook control has the smallest sprung acceleration and vibration level. As for the shock absorbers 6 and 9 according to the present embodiment, the sprung acceleration and vibration level are small as in the characteristic line 50 indicated by the solid line, the standard damper (characteristic line 47 indicated by the dotted line), the damping force adjusting hydraulic shock absorber ( Compared to the characteristic line 49) indicated by the alternate long and short dash line, it can be kept small.

  In the frequency region where the vibration frequency f is 8 Hz or more, the shock absorbers 6 and 9 (characteristic line 50 shown by a solid line) according to the present embodiment are equal to or higher than the semi-active (characteristic line 48 shown by a two-dot chain line). Compared with the standard damper (characteristic line 47 shown by the dotted line) and the damping force adjustment type hydraulic shock absorber (characteristic line 49 shown by the one-dot chain line), the frequency is equivalent up to 5 Hz. In the above region, the vibration level can be greatly reduced, and it can be seen that the damping effect is high.

  Thus, according to this embodiment, the shock absorber 6 of the left and right front wheel suspensions 4 and the shock absorber 9 of the left and right rear wheel suspensions 7 are provided with a damping force adjusting hydraulic pressure provided with the frequency sensitive portion 24. A controller 37 configured by a shock absorber (that is, damping force adjustment + frequency sensitive shock absorber) and driving and controlling the actuator 20 of the damping force variable mechanism 17 is specifically controlled for low-frequency vibrations during vibration. It is set as the structure which performs.

  As a result, it is possible to improve riding comfort on a rough road, which has been a problem in the conventional damping force adjustment (damper device), without sacrificing fluff suppression. In addition, the shock absorbers 6 and 9 can ensure almost the same riding comfort even for a semi-active type that does not have a frequency sensitive part using skyhook control, and does not detect or calculate unsprung information. By using a simple system, it is possible to enhance the vibration control effect and secure the ride comfort.

  That is, each of the front and rear wheel side shock absorbers 6 and 9 is a semi-active suspension that does not have a frequency sensitive part using the skyhook control by combining the damping force variable mechanism 17 with the function of the frequency sensitive part 24. It is possible to realize a suspension device that is simpler, lower cost, and has higher performance. Since the control process by the controller 37 may leave the response to the high frequency input to the frequency sensitive unit 24 of the shock absorbers 6 and 9, depending on the low frequency component of the acceleration on the spring and the magnitude of the sprung speed. As indicated by the characteristic line 46 in FIG. 4, the command value may be controlled so as to increase from software to hardware.

  For this reason, it is possible to reduce the number of times of switching (the number of times of damping force adjustment) in the high frequency region of the vibration frequency during vehicle travel, and to improve the durability of the entire apparatus. In addition, since detection and estimation of unsprung information is not necessary, it is possible to reduce sensor input ports, reduce microcomputer performance, simplify the ECU circuit, and reduce manufacturing costs. In addition, by adopting such a system and control, it is possible to realize both the reduction of the fluffing and the securing of the riding comfort in the high frequency range, both of which are problems in the conventional system, by a low-cost system.

  In the first embodiment, an example in which the damping force is controlled between software and hardware has been shown. However, in the same manner as in the conventional skyhook control, the sprung speed is linearly changed according to the filtered value. The damping force may be switched.

  Next, FIG. 6 shows a second embodiment of the present invention, and the feature of the second embodiment is that it is configured to control to stabilize the posture of the vehicle body as the movement of the vehicle. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

  Here, the controller 61 employed in the present embodiment is configured in substantially the same manner as the controller 37 described in the first embodiment, and the output side thereof includes the shock absorber 6 of the left and right front wheel suspensions 4 and the left , The right rear wheel suspension 7 is connected to the shock absorber 9 and the actuator 20. Each shock absorber 6 (9) is configured by a damping force adjustment type hydraulic shock absorber (ie, damping force adjustment + frequency sensitive shock absorber) provided with a frequency sensitive portion 24. However, the controller 61 in this case is different from the first embodiment in that it includes a posture change detection unit 62 and a control amount calculation unit 63.

  The sensor information unit 64 connected to the input side of the controller 61 includes, for example, a G sensor 31, a steering angle sensor 33 (see FIG. 1), a vehicle height sensor, a brake state detector 34, an accelerator sensor 35, and a wheel speed sensor 36 (see FIG. 1) and the like. The sensor information unit 64 includes a signal for detecting the driving force of the engine and the braking force of the brake, and also includes information from an in-vehicle camera and car navigation. The other information unit 65 connected to the input side of the controller 61 includes a mode switch (for example, a selection switch between a sport mode and a normal mode).

  The posture change detection unit 62 constitutes posture change detection means for detecting at least one of roll, pitch, and heap, which is the motion of the vehicle. Based on information from the sensor information unit 64, the posture change of the vehicle body 1 ( For example, the state of roll, pitch, and heap) is detected, predicted, or estimated. That is, the posture change detection unit 62 includes a case where the posture change of the vehicle is predicted by an operation state detection unit (for example, a steering angle, an accelerator, a brake, a driving force detection signal, a braking force detection signal, etc.). is there.

  The control amount calculator 63 suppresses the posture change (that is, roll, pitch, heap, etc.) of the vehicle body 1 according to the posture change signal output from the posture change detector 62, and stabilizes the vehicle body 1 side posture. , A control signal for adjusting the damping force between the shock absorber 6 on the right front wheel 2 side and the shock absorber 9 on the left and right rear wheel 3 side is calculated, and this is used as a command value for the actuator of each shock absorber 6 (9). 20 is output.

  Thus, also in the second embodiment configured as described above, the control processing by the controller 61 may leave the response to the high frequency input to the frequency sensitive unit 24 of each of the buffers 6 and 9, and the first embodiment described above. It is possible to obtain substantially the same effect as that of the embodiment. In particular, in the second embodiment, the posture change (for example, roll, pitch, heap, etc.) that is low-frequency motion of the vehicle can be suppressed, and the posture on the vehicle body 1 side can be stabilized. It is possible to achieve both prevention of deterioration of riding comfort on rough roads and suppression of fluff.

  Next, FIG. 7 shows a third embodiment of the present invention. The feature of the third embodiment is that the vertical vibration of the vehicle body as the movement of the vehicle is detected by the vibration detection means, and the detection signal (vibration) In other words, the control is performed to adjust the damping force according to the frequency. Note that in the third embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted.

  Here, the controller 71 employed in the present embodiment is configured in substantially the same manner as the controller 37 described in the first embodiment, and its output side includes the shock absorber 6 of the left and right front wheel suspensions 4 and the left. , The right rear wheel suspension 7 is connected to the shock absorber 9 and the actuator 20. Each shock absorber 6 (9) is configured by a damping force adjustment type hydraulic shock absorber (ie, damping force adjustment + frequency sensitive shock absorber) provided with a frequency sensitive portion 24. However, the controller 71 in this case is different from the first embodiment in that the controller 71 includes a control gain adjustment unit 72, an integrator 73, a gain multiplication unit 74, and a multiplier 75.

  The controller 71 reads the upper and lower vibrations on the vehicle body 1 side from the G sensor 31 as vibration detection means, and calculates the vibration frequency. Here, the vibration frequency may be calculated by separating a low frequency component and a high frequency component using a low-pass filter (not shown), and detecting the frequency according to the magnitude of the value. The frequency may be calculated from the period. Further, the frequency may be calculated using means such as FFT analysis. The vibration frequency detected in this way is input to the control gain adjustment unit 72.

  The control gain adjustment unit 72 outputs a control gain (0 ≦ gain ≦ 1) according to the characteristic line 72A shown in FIG. That is, when the input vibration frequency is a low frequency, for example, the control gain “1” is output from the control gain adjustment unit 72, and when the vibration frequency is higher than the low frequency, for example, a control gain smaller than “1” is set to the characteristic line 72A. According to the output. When the input vibration frequency is equal to or higher than a predetermined high frequency, for example, the control gain becomes “0”, and at this time, the command value (for example, current value) of the target damping force is controlled to zero as described later.

  The integrator 73 of the controller 71 integrates the signal (upward and downward vibration acceleration) of the G sensor 31 and calculates an absolute speed (speed signal) in the up and down direction. The gain multiplication unit 74 calculates a target damping force by multiplying the speed signal by a gain. Next, the multiplier 75 multiplies the control gain (0 ≦ gain ≦ 1) output from the control gain adjustment unit 72 and the target damping force calculated by the gain multiplication unit 74, and finally determines the final value according to the control gain. The command value as the target damping force is output to the actuator 20 of each shock absorber 6 (9), for example.

  Thus, the command value as the final target damping force output from the controller 71 is set so that the control gain by the control gain adjusting unit 72 is set to “1” when the input vibration frequency is low. It becomes relatively large, and the level of the command value (that is, damping force adjustment) can be increased. On the other hand, when the input vibration frequency is higher than the low frequency, the control gain by the control gain adjustment unit 72 is gradually smaller than “1”, so that the command value becomes relatively small and the damping force adjustment is performed. The level of can be gradually reduced. When the input vibration frequency is equal to or higher than a predetermined high frequency, the target damping force command value (for example, current value) is controlled to zero, and the damping force adjustment according to the vehicle motion (vertical vibration) is not performed. Can be.

  Therefore, also in the third embodiment configured as described above, the control processing by the controller 71 may leave the response to the high frequency input to the frequency sensitive unit 24 of each of the shock absorbers 6 and 9, and the first embodiment described above. It is possible to obtain substantially the same effect as that of the embodiment.

  In the first embodiment, the case where the G sensor 31 and the CAN 32 are connected to the input side of the controller 37 has been described as an example. However, the present invention is not limited to this. For example, a total of four wheel speed sensors 36 and a steering angle sensor 33 provided on the left and right front wheels 2 and the left and right rear wheels 3 are provided on the input side of the controller. It is good also as a structure to connect. In this case, the pitch (dive, squat) state of the vehicle body 1 can be detected by signals from a total of four wheel speed sensors 36, and the roll state of the vehicle body 1 can be detected by signals from the steering angle sensor 33. This point is the same as in the second embodiment.

  Further, on the input side of the controller, for example, a total of two G sensors 31 provided on the front and rear wheels, and a total of two wheel speed sensors 36 provided on the left and right front wheels 2 side, respectively. The steering angle sensor 33 may be connected. Further, on the input side of the controller, for example, a total of three G sensors 31 provided at the left and right front wheels 2 side and an intermediate position between the left and right rear wheels 3, and the left and right front wheels 2 side A total of two wheel speed sensors 36 provided in each may be connected to the steering angle sensor 33.

  On the other hand, a configuration is possible in which one vehicle height sensor, a total of two wheel speed sensors 36 respectively provided on the left and right front wheels 2 side, and the steering angle sensor 33 are connected to the input side of the controller. Good. Further, on the input side of the controller, for example, a total of two vehicle height sensors provided on the front wheel 2 side and the rear wheel 3 side, and a total of two wheel speeds provided respectively on the left and right front wheels 2 side. The sensor 36 and the steering angle sensor 33 may be connected.

  Further, on the input side of the controller, for example, a total of three vehicle height sensors provided on the left and right front wheels 2 side and the rear wheel 3 side, and a total of 2 provided on the left and right front wheels 2 side, respectively. The individual wheel speed sensors 36 and the steering angle sensor 33 may be connected. Further, on the input side of the controller, for example, a total of four vehicle height sensors provided on the left and right front wheels 2 side and the left and right rear wheels 3 side, and provided on the left and right front wheels 2 side, respectively. The total two wheel speed sensors 36 and the steering angle sensor 33 may be connected.

  Next, the invention included in the above embodiment will be described. That is, according to the present invention, the low-frequency motion is configured to be at least one of a roll, a pitch, and a heap, which are vehicle motions. This suppresses changes in posture such as roll, pitch, and heap of the vehicle, which are low-frequency motion, and stabilizes the posture on the vehicle body side. It is possible to achieve both suppression of sticking.

  According to the present invention, the posture change detecting means for detecting the roll, pitch and heap of the vehicle is constituted by an operation state detecting means for detecting a driver's operation. In this case, a change in the posture of the vehicle can be predicted and estimated by operation state detection means (for example, a steering angle, an accelerator, a brake, a driving force detection signal, a braking force detection signal, etc.).

  According to the present invention, the motion state is the vertical vibration of the vehicle, and the controller adjusts the damping force according to the vertical vibration of the vehicle when the vertical vibration of the vehicle is a low frequency, and the vertical vibration of the vehicle is the low frequency When the frequency is higher than that, the damping force adjustment level is set smaller than that when the frequency is low.

  According to the present invention, the motion state is the vertical vibration of the vehicle, and the controller is configured to adjust the damping force according to the vertical vibration of the vehicle at a predetermined low frequency among the vertical vibrations of the vehicle.

  According to the present invention, in a suspension device including a shock absorber provided between a vehicle body side and a wheel side of a vehicle and capable of adjusting a damping force by an actuator, and a controller for adjusting the actuator, the shock absorber has a high frequency. A frequency sensitive unit that reduces damping force against vibration is provided, and the vehicle is provided with posture change detecting means for detecting at least one of roll, pitch, and heap of the vehicle, and the controller detects the posture change. The damping force is adjusted according to the posture state of the vehicle detected by the means.

  According to the present invention, in the suspension device, the shock absorber is provided with a frequency sensitive unit that reduces a damping force against high-frequency vibrations, and the vehicle is provided with vibration detection means for detecting vibrations of the vehicle, and the controller When the vibration detected by the vibration detection means has a low frequency, the damping force is adjusted according to the detection value of the vibration detection means, and the vibration detected by the vibration detection means is reduced to the low frequency. When the frequency is higher, the damping force adjustment level corresponding to the detection value of the vibration detection means is reduced.

  According to the present invention, the shock absorber has a damping force generation unit that can be adjusted by the actuator, and the frequency sensitive unit is capable of moving in the bypass passage and the bypass passage that bypasses the damping force generation portion. And a free piston provided. Thereby, the frequency sensitive part can reduce the damping force which a shock absorber generate | occur | produces, when a free piston moves to an axial direction relatively with respect to the high frequency vibration at the time of vehicle travel.

  In each of the above-described embodiments, since the actuator does not need to support high frequency, a small solenoid can be used, and the actuator can be built in the piston rod. Therefore, the axial length as the cylinder device can be shortened. Furthermore, since the control can be simplified as described above, the number of sensors can be reduced, and the attachment to the vehicle is also improved.

DESCRIPTION OF SYMBOLS 1 Car body 2 Front wheel 3 Rear wheel 4 Front wheel suspension 5,8 Spring 6,9 Shock absorber (damping force adjustment + frequency sensitive shock absorber)
7 Rear wheel suspension 11 Inner cylinder 12 Piston 13 Extension side disc valve 14 Reduction side disc valve 15 Piston rods 15D, 15E Oil hole (damping force generating part)
17 Damping force variable mechanism 18 Shutter (opening area variable member)
18A inner hole (bypass passage)
18B Communication path 18C Oil groove 19 Control rod 20 Actuator 24 Frequency sensitive part 25 Housing 28 Free piston 29, 30 O-ring (elastic body, resistance element)
31 G sensor (vertical acceleration sensor above the spring)
33 Steering angle sensor 34 Brake state detector 35 Accelerator sensor 36 Wheel speed sensor (vehicle speed sensor)
37, 61, 71 Controller (control means)
38 Car body vibration estimation unit 39 Sprung vibration suppression control unit 39A, 39B Filter unit 39C, 39D Gain multiplication unit 39E Addition unit 39F Map calculation unit 40 Steering stability control unit 41 Vehicle speed sensitive control unit 42 Control command calculation unit 62 Attitude change detection unit 63 Control amount calculator 72 Control gain adjuster 73 Integrator 74 Gain multiplier 75 Multiplier 100 First passage 101 Second passage (bypass passage)
A Rod side oil chamber B Bottom side oil chamber C Upper chamber D Lower chamber

Claims (6)

A buffer provided between a vehicle body side and a wheel side of a vehicle and having a damping force variable mechanism capable of adjusting a damping force by controlling the flow of a working fluid generated in a passage by movement of a piston connected to a piston rod by an actuator. And
In a suspension device comprising a controller for adjusting the actuator,
The shock absorber is composed of a free piston provided so as to close the passage in a passage provided between the rod side chamber and the bottom side chamber, and a damping force is generated by the movement of the free piston against high frequency vibrations. the frequency response unit to reduce provided,
The path of the damping force variable mechanism and the path of the frequency sensitive part are configured by different paths, and the damping force variable mechanism and the frequency sensitive part are provided independently,
The controller extracts a low-frequency component of vibration in a composite road in which the high-frequency component and a low-frequency component are superimposed on the vibration of the vehicle, and the damping force is variable according to a change in the low-frequency component of the vibration. A suspension device characterized in that the damping force of the mechanism is switched to remove the high frequency component from the controlled object.   The suspension device according to claim 1, wherein the vibration of the vehicle is a sprung vibration of the vehicle.   The suspension device according to claim 2, wherein the sprung vibration is a sprung speed.   The controller includes a filter that extracts the low-frequency component, and the filter extracts the low-frequency component based on a cutoff frequency, and determines the cutoff frequency of the filter as a vehicle sprung resonance frequency. The suspension device according to any one of claims 1 to 3, wherein an extractable cutoff frequency is used.   The suspension device according to any one of claims 1 to 4, wherein the controller includes a steering stability control unit that performs at least anti-roll control or anti-dive squat control.   The suspension device according to any one of claims 1 to 5, wherein the controller adjusts a damping force without determining whether the shock absorber is in an expansion stroke or a contraction stroke.

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